Hip Pelvis 2024; 36(1): 12-25
Published online March 1, 2024
https://doi.org/10.5371/hp.2024.36.1.12
© The Korean Hip Society
Correspondence to : Roop Bhushan Kalia, MS https://orcid.org/0000-0002-3418-5942
Department of Orthopaedics, All India Institute of Medical Sciences, Virbhadra Road, Rishikesh 249203, India
E-mail: roopkalia2003@yahoo.com
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Protrusio acetabuli, or abnormal protrusion of the femoral head into the acetabulum, requires performance of a total hip arthroplasty (THA) for which various reconstruction techniques and outcomes have been described. The aim of this systematic review is to provide a comprehensive analysis of the current evidence, evaluate treatment efficacy, compare surgical techniques, and identify topics for future research along with improving evidence-based decision-making, improving patient outcomes in the management of this condition. A thorough systematic review of the PubMed, Embase, Cochrane Library databases, and Scopus library was conducted, and articles describing techniques of THA for treatment of protrusion acetabuli were extracted. The initial search generated 751 results. After exclusion, 18 articles were included. Of these, eight were prospective studies and 10 were retrospective. Surgery was performed on 783 hips with a mean age of 60 years; 80% of females who mostly had inflammatory arthritis were followed up for 8.86 years (range, 2-15.4 years). Good outcomes have been achieved with THA using uncemented cups with bone graft; however, no conclusion could be drawn with regard to the femoral side. It can be concluded that the concept of restoration of the anatomical hip center of rotation is paramount for good outcome and better survival of the implant is important when using uncemented cups with a bone graft. In addition, screw augmentation for fixation is not recommended unless absolutely necessary. The most common complications were aseptic loosening and heterotopic ossification. While the former required revision, conservative management was administered for the latter.
Keywords Total hip arthroplasty, Protrusio acetabuli, Systematic review
Protrusio acetabuli (PA), or acetabular protrusion, is a complex condition that poses unique challenges in the context of total hip arthroplasty (THA). It refers to the abnormal protrusion of the acetabulum into the pelvic cavity, which is associated with a variety of symptoms and functional limitations. It is defined as a medial projection of the acetabular line beyond the ilioischial line (Kohler’s line) by 6 mm in females and 3 mm in male patients. The etiology of primary or idiopathic PA is unknown, whereas development of secondary PA can occur as a result of various underlying conditions, including rheumatoid arthritis, osteoarthritis, developmental dysplasia of the hip or genetic predisposition, Paget’s disease, or inflammatory hip diseases. THA can be considered as a viable treatment option in cases where use of conservative measures has not resulted in alleviation of pain and restoration of joint function1-3).
Comprehensive preoperative evaluation and thorough surgical planning is required for successful management of PA with THA. Treatment with THA should be administered in cases of painful and progressive PA. Due to concerns regarding poor bone quality or cortical bone defects, the stability of the socket is an important consideration after arthroplasty. In addition, successful clinical and radiological results may not always be achieved after conventional THA for treatment of PA1). The objectives of performing THA for treatment of PA include restoration of abductor function and hip mechanics as well as restoration of the anatomical relationship between the femoral head and the acetabulum2). Potential concerns include surgical exposure, implant selection, lack of bone stock, deficient medial support to the cup, and medialization of the joint center3).
Various techniques for management of PA have been described in the literature. Commonly used techniques include the use of morselized impacted autografts or allografts with a cemented or uncemented cup for acetabular reconstruction, metal cages, reinforcement rings, and solid grafts for acetabular reconstruction4-7). The aim of this systematic review is to provide a comprehensive analysis of the current evidence, evaluate treatment efficacy, compare surgical techniques, and identify topics for future research. Through synthesis of the available data, such a review can be helpful in the management of this particular condition by contributing to evidence-based decision-making, informing clinical practice guidelines, and ultimately improving patient outcomes.
This study (Systematic Review) does not involve direct participation of patients, but assimilating data from studies conducted by other authors who have obtained permission from their respective boards. Thus, ethical approval is not required for conduct of a systematic review, which was confirmed after subjecting the information to the Medical Research Council (MRC) Health Research authority. Informed consent was not required for this study.
A comprehensive search of the literature was conducted for the systematic review following the principles of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The search of online databases included PubMed (http://www.ncbi.nlm.nih.gov/pubmed), Embase (http://www.elsevier.com/online-tools/embase), Scopus, and the Cochrane Library database (http://www.cochrane.org) for all studies published until 17th June 2023. Search terms used were ‘Protrusio acetabuli’ OR ‘Acetabular protrusion’ AND ‘total hip replacement’ OR ‘total hip arthroplasty’. The search was restricted to articles on human subjects in the English language. A hand search of references for the included full text articles was also performed for identification of any other relevant studies (Fig. 1).
The abstracts were identified first using the above-mentioned search methods and an assessment for eligibility was performed based on strict criteria mentioned below. The shortlisted abstracts were then followed up for full texts and another assessment for eligibility was performed. Another search of the reference list for the finalized articles was performed for identification of additional relevant studies.
The review included all original studies that included adult patients with a diagnosis of PA due to any cause undergoing THA, who underwent primary THA, with a minimum follow up period of one year and articles on the study of functional or radiological outcomes and survival after the THA procedure. Only papers in the English language were included. The exclusion criteria included (1) articles with incomplete data, (2) case reports, reviews, biomechanical studies, expert opinions, letters to editors or editorials, and (3) non-English language, (4) case series that included less than 10 patients, (5) Studies that included patients with an etiology, who did not have acetabular protrusion, were also excluded. All cases that were available for follow-up after accounting for losses during follow up were included in the review.
The systematic review was conducted by two authors (S.A. and K.G.) who each performed an independent analysis of the data. Any controversy was resolved by mutual agreement and consultation with the senior author (R.B.K.). Data from full text articles was extracted into Microsoft Excel 2019 (Microsoft). Information on the demographic details of patients including author name, year of publication, sample size, follow-up period, outcomes (scores if present), prosthesis and surgical approach used, technique of protrusio management, complications, and survival of the prosthesis was extracted. In the case of an eligible study with incomplete data/information or not accessible by internet, the authors were contacted by email using the correspondence address provided requesting the required information. In cases where the author had not responded by the data extraction stage or when data were considered irrelevant to our study, the study was excluded. The continuous variables were extracted and expressed as mean±standard deviation.
The quality of the studies included in the review was assessed by two separate reviewers (T.G. and P.J.). The Newcastle–Ottawa scale was used for assessment of the methodological quality of each study (Table 1)2,3,8-23). Assessment was performed for each included study by each reviewer and any disagreements were resolved by a third reviewer (B.S.R.).
Table 1 . Quality Assessment of Studies according to New Castle–Ottawa Score
Cohort studies | Representativeness of cohort | Ascertainment of exposure | Ascertainment of outcome (functional) | Adjustment for confounder | Follow-up mentioned |
---|---|---|---|---|---|
Zhen et al.3) (2018) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.8) (2015) | Yes | Yes | Yes | Yes | Yes |
Dutka et al.10) (2011) | Yes | Yes | Yes | Yes | Yes |
Mullaji and Marawar20) (2007) | Yes | Yes | Yes | Yes | Yes |
Krushell et al.15) (2008) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.2) (2013) | Yes | Yes | Yes | Yes | Yes |
Hansen and Ries12) (2006) | Yes | Yes | Yes | Yes | Yes |
Rosenberg et al.21) (2000) | Yes | Yes | No | Yes | Yes |
Matsuno et al.18) (2000) | Yes | Yes | Yes | Yes | Yes |
Gates et al.11) (1989) | Yes | Yes | No | Yes | Yes |
Kondo et al.14) (2002) | Yes | Yes | Yes | Yes | Yes |
Liu et al.17) (2023) | Yes | Yes | Yes | Yes | Yes |
Zuh et al.23) (2015) | Yes | Yes | Yes | Yes | Yes |
Yun et al.22) (2021) | Yes | Yes | Yes | Yes | Yes |
Mibe et al.19) (2005) | Yes | Yes | Yes | Yes | Yes |
Lee et al.16) (2022) | Yes | Yes | Yes | Yes | Yes |
Figueras Coll et al.9) (2008) | Yes | Yes | Yes | Yes | Yes |
Johnsson et al.13) (1984) | Yes | Yes | No | Yes | Yes |
After an extensive search and performance of quality assessment prior to extraction of data in order to avoid selection bias, 751 studies were identified in the search. Titles and abstracts of all articles were evaluated for potential inclusion in the review. After assessing the studies against inclusion criteria, 18 studies were finally included in this review2,3,8-23). A flow chart of the literature search using the PRISMA format is shown in Fig. 1. Among the included studies, eight studies were prospective (Level II) and 10 studies were retrospective (Level III) in nature. A list of the study demographics is provided in Table 2. Surgery was performed on 783 hips, in 665 patients with a mean age of 60 years (range, 45.8-71.1 years). The patient population included 80% females. The mean follow-up period was 8.86 years (range, 2-15.4 years). The most common etiology was inflammatory arthritis, predominantly rheumatoid arthritis. Other types of inflammatory arthritis included psoriatic, systemic lupus erythematosus, and ankylosing spondylitis. Other common etiologies included idiopathic, degenerative osteoarthritis, and post traumatic, in that order (Table 2).
Table 2 . Study Characteristics and Demographic Details
Study | Country | Inclusion/exclusion criteria | Etiology | Total hips | Study design | Mean age (yr) | Sex (F:M) | Extension of protrucio from Kohler’s line/Sotelo-Garza classification | Intervention | Approach | Implant | Follow-up |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | China | Protrusio in RA | RA | 20 hips (18 patients) | Prospective cohort | 45.8±8.3 | 12:6 | 12.7 mm | Uncemented with bone grafting | Posterolateral approach | Porous tantalum cups, 16 hips; titanium porous coated cups, 4; 4th generation ceramic-ceramic implantations, 8; polyethylene-lined ceramic implantations, 12 | 4.5±1.7 yr |
Baghdadi et al.8) (2015) | USA | THA done in protrusio | OA, 48 hips; RA, 15; sequele of septic arthritis, 2 | 65 hips (53 patients) | Retrospective cohort | 66 | 53:12 | 7±4 mm | Uncemented 58 hips, impacted with morselized bone graft; 26 hips, supplementary screw fixation | Anterolateral, 34 procedures; posterior, 28; transtrochanteric, 3 | Harris-Galante (HG)-I, 6 hips; Harris-Galante (HG)-II, 13; Omnifit, 17; Reflection™, 7; Porous-Coated Anatomic (PCA), 4; Press-Fit Condylar (PFC), 2; Elliptical, 1; Bi-Articular, 1; Trilogy®, 11; Hedrocel®, 3 | 15.4 yr |
Dutka et al.10) (2011) | Poland | 1. THA done in patients with protrusion acetabuli with any etiology 2. Minimum 4-year follow-up 3. Full medical records available | RA, 122 hips; Otto’s disease, 6; psoriatic arthritis, 3; SLE, 2; acetabular fracture, 1; radiation damage, 1 | 135 hips (127 patients) | Retrospective cohort | 55.2 | 119:8 | Grade 1, 48; grade 2, 36; grade 3, 21 | 128 hips, cemented; 7 hips, uncemented Autogenous grafts, 97 hips; mixed grafts, 38 | NA | NA | 12.7 yr |
Mullaji et al.20) (2007) | India | 1. Primary THAs in significant protrusio acetabuli 2. Minimum follow-up of 2 years | RA, 14 patients; ankylosing spondylitis, 5; Idiopathic, 4 | 30 hips (23 patients) | Prospective cohort | 46 | 17:6 | Grade 1, 8; grade 2, 10; grade 3, 12 | Uncemented THR with morselized BG | Anterolateral approach | Duraloc porous-coated cups, 17 cases; Bicontact cups, 13 One screw used to augment, 15 cases; 2 screws used, 12; no screw used, 3 A porous-coated stem used 21 cases: Bicontact, 13; Summit, 8 Cemented Charnley stems used, 9 cases | 4.2 yr |
Krushell et al.15) (2008) | England | Primary THA of any cause with acetabular protrusio | Inflammatory arthritis in 22 cases and OA in 7 cases | 29 hips (27 patients) | Retrospective cohort | 66 | 20:7 | Mean, 4.1 mm protrucio medial to Kohler’s line | Uncemented, Autologous BG in all cases Additional synthetic grafts, 3 cases | Posterolateral approach | Beaded dual-geometry acetabular shell design with multilayer titanium MicroStructured porous ingrowth surface | 4 yr |
Baghdadi et al.2) (2013) | USA | All patients with protrusio acetabuli who had undergone primary THR with a minimum follow-up of 2 years | Idiopathic, 117 hips; underlying inflammatory component, 38; genetic - 2, post infectious - 2, post radiation - 1, metabolic - 2 | 162 hips (127 patients) | Retrospective cohort | 66±13 | 112:15 | 7±5 mm | Cemented, 55 hips (14/55 cemented hips, bone grafting) Uncemented, 107 hips (83/107 uncemented hips, bone grafting done) | First-generation designs: Charnley, Aufranc Turner, Elliptical, Ti-Bac Cups Second-generation designs: Harris-Galante (HG)-I, Harris-Galante (HG)-II, Omnifit, Reflection, Porous-Coated Anatomic, PressFit Condylar Third-generation designs: Pinnacle, Trilogy, Hedrocel, Trident, Trabecular Metal Modular, Tritanium Hemispherical Cluster | 10±6 yr | |
Hansen and Ries12) (2006) | USA | 1. Revision surgeries 2. Large medial defect with at least 50% radiographic projected acetabular bone loss 3. Minimum 2-year follow-up | OA in 9 patients, RA in 3, posttraumatic arthritis in 2, avascular necrosis in 1, PVNS in 1, and DDH in 1 | 19 hips (17 patients) | Prospective cohort | 66 | 13:9 | 10.5 mm | Uncemented porous coated acetabular cup and morselized allograft | Posterior approach+ extended trochanteric osteotomy if necessary | Cementless hemispherical component with a widened peripheral rim | 2.8 yr |
Rosenberg et al.21) (2000) | Netherlands | 1. Patients diagnosed as RA with protrusio hip who under goes THA 2. Patients with minimum 8-year follow-up | RA | 20 hips (16 patients) | Prospective cohort | 53 | 13:3 | NA | Cemented cups with Morselized allograft | Posterolateral approach | 32 mm polyethylene Mueller or Allopro cup | 11.7 yr |
Matsuno et al.18) (2000) | Japan | Patients diagnosed to have RA with protrusio hip | RA | 15 hips (13 patients) | Prospective cohort | 61.9 | 9:4 | NA | Uncemented with iliac crest and morsellised femoral head graft | Aposterior approach | MC cup supporter | 53.6 mo |
Gates et al.11) (1989) | USA | Painful progressive protrusio acetabuli | RA, hemiarthroplasty, THA, OA | 48 hips (40 patients) | Prospective cohort | 57.8 | 29:11 | 8.6 mm | Cemented THA with medial acetabular reinforcement with BG Autologous BG, 39 hips; Allograft, 9 | NA | NA | 12.3 yr |
Kondo et al.14) (2002) | Japan | RA with protrusion acetabuli treated with THA Minimum 9-year follow-up | RA | 25 hips (19 patients) | Prospective cohort | 56.7 | 16:3 | Grade 1, 8; grade 2, 13; grade 3, 4 | Cemented with autologous graft | NA | NA | 129.6 mo |
Liu et al.17) (2023) | China | 1. RA 2. Moderate and severe in patients with acetabular protrusions in which the bottom of the acetabulum exceeded Kohler’s line in the pelvic AP radiography | RA | 56 hips (45 patients) | Prospective cohort | 55.64±5.38 | 28:17 | 10.97±3.08 mm | Uncemented THA with impacted bone grafting | Posterolateral approach | Biological total hip prostheses: A porous tantalum cup, 42 hips; sintered, three-dimensional, asymmetric, titanium, and porous-coated cups, 14; weight-bearing interfaces, 24; fourth-generation ceramic-on-ceramic implantations, and ceramic-on-highly cross-linked polyethylene, 32 | 5.20±1.20 yr |
Zuh et al.23) (2015) | Romania | THA in protrusio | Protrusion of unknown aetiology, 16 hips; RA, 6; protrusion secondary to tuberculous arthritis, 3; post-traumatic protrusion, 2; hip arthritis with thin medial acetabular wall, 12 | 39 hips (32 patients) | Retrospective study | 58.3±8.9 | 15:17 | I, 15 hips; II, 9; III, 3; thin medial wall, 12 | Medial acetabular wall – augmented by impaction bone grafting Uncemented cup – all cases | Direct lateral approach | 4.5 yr | |
Yun et al.22) (2021) | USA | THA in protrusio | 5 patients, RA; 18 patients, idiopathic PA | 23 THAs in 21 patients | Retrospective study | 68±9 | 19:2 | Mild, 7 patients; moderate, 13; severe, 3 | Morcellized femoral head autograft using Bone Mill, cementless acetabular cups | Direct anterior approach | 5.3 yr | |
Mibe et al.19) (2005) | Japan | Protrusio in RA | RA | 19 hips of 15 patients | Retrospective | 60.2 (48-75) | All F | 12 hips, grade 1; 3 hips, grade 2; 1 hip, grade 3 Medial-proximal type, 3 hips | THA using a support ring All cups- cemented | Not mentioned | 4 hips, TACT cup supporter; 1 hip, Kerboull plate; 6 hips, a Ganz ring; 5 hips, Müller ring | 38 mo |
Lee et al.16) (2022) | Korea | THA in protrusio | RA, 14 hips; post-traumatic arthritis, 7; ankylosing spondylitis, 4; previous infection, 1 | 26 cementless THAs of 22 patients | Retrospective study | 59.9 | 17:5 | Mild, 5 hips; moderate, 19; severe, 2 | Uncemented THA, reinforcement acetabular components in 2 hips | Kocher-Langenbeck approach | PLASMACUP SC, 9 hips; Bencox cup, 7; Pinnacle cup, 5; G7 cup, 1; ABT cup, 1; Delta TT cup, 1 SPH reinforcement cups, 2 hips with defective rim of the acetabulum | 5.1 yr |
Figueras Coll et al.9) (2008) | Spain | THA in protrusio | Severe arthrosis (50% of cases), protrusio due to hemiarthroplasties (15%), and rheumathoid arthritis (15%) Aseptic loosening of the acetabular cup in THA, and some other causes- less common diagnoses | 25 hips (25 patients) | Retrospective study | 71.1 | 16:9 | Paproski’s classification – 20 type IIa cases, 4 type IIb and 1 type IIc | Cemented acetabular cup, autogenous morcellized bone-graft and acetabular wiremesh | Anterolateral | Charnley stem and cemented cup (7 right and 18 left hips) | 8.6 yr |
Johnsson et al.13) (1984) | Sweden | Protrusio in RA | RA | 27 hips (25 patients) | Retrospective study | 56 (29-76) | 21:4 | Joint destruction according to Larsen and Larsen et al. 12 hips, grade IV; 15 hips, grade V Mean acetabular protrusion, 6 mm | Spongious bone chips from the trochanter and/or the femoral head, and iliac crest, 10 cases – thin titanium net A high density polyethylene (HDPE) protrusion cup – last 5 cases | 26 hips, postero-lateral; 1 hip, anterior approach without trochanteric osteotomy | Lubinus (25) and McKee-Arden (2) types | 2 yr |
Values are presented as mean±standard deviation or mean (range).
F: female, M: male, RA: rheumatoid arthritis, THA: total hip arthroplasty, OA: osteoarthritis, SLE: systemic lupus erythematosus, NA: not available, THR: total hip replacement, BG: bone graft, PVNS: pigmented villonodular synovitis, DDH: developmental dysplasia of hip, AP: anteroposterior, PA: protrusio acetabuli.
Restoring the native hip center of rotation (COR) is at the core of THA in treatment of protrusion acetabuli. While the Ranawat triangle method24) was used by Baghdadi et al.2) for estimation of the COR, Zuh et al.23) used the method developed by Pierchon et al.25). Yun et al.22) performed the procedure using a direct anterior approach and intra-operative fluoroscopy was used for placement of the implant and restoration of the COR. Other studies have used Kohler’s line, teardrop, or inter-teardrop line as a reference for measuring COR distance. An uncemented cup was used in the majority of hips (n=436). Of these, a porous coated cup was used in 160 hips. Details on the various components used are shown in Table 2. An uncemented cup was used along with bone grafting for acetabular reconstruction in most studies. Six studies evaluated use of a cemented acetabular cup supported by a bone graft9,11,13,14,19,21). Both reconstruction techniques were used in two studies and the outcomes were compared2,10). Wherever deemed necessary, based on the lack of acetabular support, screws or acetabular support rings were used to aid stability. According to the pooled data, augmentation of the cup with screw fixation was performed in 148 uncemented hips3,8,12,17,20). An acetabular support ring was used in three studies in 37 hips; the details are provided in Table 214,18,19). Lee et al.16) reported on use of acetabular reinforcement components in two out of 26 hips in which press fit could not be achieved due to >50% rim defect. The type of stem used has been mentioned in eight studies. There were 113 uncemented stems (34.1%) and 218 cemented stems (65.9%). No consensus nor rationale has been identified among the various studies with regard to the type of stem that should be used. Femoral anatomy and bone quality can be considered when deciding on the type of stem and fixation. Another major problem in these patients is that dislocating the head is difficult due to its incarceration within the acetabulum. Four studies have mentioned performing an in-situ neck cut8,17,22,23). However, in severe cases where the neck is not visible, removal of the lateral part of the edge of the femoral head and neck can be performed using a drill or narrow bone knife. Resection of the neck can then be performed while the head can be removed in pieces if needed3,17). Lee et al.16) reported on removal of a thick part of the neck after two osteotomies to facilitate dislocation.
A morselized autograft from the femoral head, iliac crest, and trochanter was used in almost all studies to fill the medial wall defect and for restoration of the hip COR. A femoral head graft was considered adequate for this purpose. Kondo et al.14) described the use of a sliced bone graft from the femoral neck along with a morselized graft. An allogenic graft can also be used when needed8,10-12,23). Krushell et al.15) and Mibe et al.19) mixed synthetic bone graft in eight patients. Eleven studies reported on the method of graft impaction, including reverse reaming (n=122), impaction with a small trial head (n=96) or impactor (n=55). A wire mesh was used in 52 hips, all cemented, in two studies9,21). Baghdadi et al.2) reported that only 72 patients out of the pool of patients underwent surgery without bone graft (41, cemented; 31, uncemented). Thirteen studies mentioned the approach used in performance of the surgery (Table 2). The most commonly used approach was posterolateral (n=177), followed by anterolateral (n=85) and posterior (n=62).
Extension of protrusio medial to Kohler’s line, which has a mean of 7.99 mm (range, 4.1-12.7 mm), was described in seven studies. Protrusio was classified according to Sotelo-Garza classification in seven studies. There were 103 grade I hips, 103 grade II hips, and 46 grade III hips. Other classification systems including American Academy of Orthopaedic Surgeons (AAOS) Committee on the Hip, Paprosky, and Larsen & Larsen classification were also used. The Harris hip score (HHS) was used in nine studies for evaluation of preop and postop hip function. The mean preoperative HHS was 47.5 (range, 32.3-55.3), which improved to 82.3 (range, 71.7-92.5) postoperatively2,3,8,9,12,15,17,20,23). The Japanese Orthopedic Association score (JOA), which improved from 21.7 (range, 19.6-25.2) to 50.7 (range, 35.2-70.4), was used in three studies14,18,19). Grading the clinical outcome was based on scoring in three studies10,15,20). The results were as follows: 36.6% (n=71) excellent, 46.9% (n=91) good, 11.3% (n=22) fair, and 5.2% (n=10) poor. Only Dutka et al.10) graded the radiological outcome as excellent in 47 hips (34.8%), good in 60 hips (44.5%), fair in 18 hips (13.3%), and poor in 10 hips (7.4%). Three studies reported graft incorporation in all cases17,18,21) while Krushell et al.15) reported graft incorporation in 97% of cases. Mean time for graft union ranging from 3-6 months was reported in three studies3,11,20).
Among the studies, 48 revisions were reported. The mean time to revision surgery was 6.75 years (range, 0.27-8.8 years). The most common cause of revision surgery was aseptic loosening (n=38), followed by polyethylene wear/failure (n=4), and recurrent dislocations (n=4). The details regarding various revisions and other complications are shown in Table 3. Other common complications included heterotopic ossification (n=21), deep vein thrombosis (n=10), and nerve palsies (n=3). Four studies evaluated the survival rate of THAs in treatment of protrusion. Baghdadi et al.8) reported a survival rate free from acetabular revision of 85.4%. In their previous study, a higher 15-year survival rate was reported for uncemented cups as compared to cemented cups (89% vs. 85%)2). Rosenberg et al.21) reported a survival rate of 90% at 12-year follow-up, while Mibe et al.19) reported a survival rate of 72% when using both revisions and deaths as the end point.
Table 3 . Evaluation and Follow-up
Study | Outcome measure | Preop | Postop | Revisions | Complications | Radiological evaluation | Conclusion/remarks | Follow-up mentioned? |
---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | HHS | 55.3±9.5 | 92.5±12.7 | Nil | Nil | Distance from center of femoral head to Kohler’s line increased from 19.87±3.9 mm to 21.5±3.5 mm after the operation. | For patients with PA secondary to RA cementless, trabecular, metal modular cup allowing peripheral press fitting and restoration of bone stock by impacted bone graft - satisfactory short-term results | Yes |
Baghdadi et al.8) (2015) | HHS | 55 | 82 | Revision, 15 hips; aseptic loosening, 12; polyethylene liner failure, 2; recurrent instability, 1 | Aseptic loosening, liner wear, recurrent instability | 5 unrevised acetabular components and 3 unrevised femoral components - non-progressive radiolucency | Satisfactory results for a median follow-up of 15 years for uncemented acetabular component in THR with PA | Yes |
Dutka et al.10) (2011) | HHS | NA | Mean, 86.6; cemented, 84.2; uncemented, 92.6 | Revision in 10 hips Both component loosening, 6; acetabular component loosening, 4 | 10 hips, loosening; HO Brooker II in 15 cases, DVT in 6, and wear of the acetabular component in 4 | The radiographic outcomes: excellent in 47 hips (34.8%), good in 60 (44.5%), fair in 18 (13.3%), and poor in 10 (7.4%) | At 12-year follow-up, better outcomes seen with patients operated with autogenous bone grafting than mixed bone grafting. No significant difference in type of prosthesis, aetiology and severity of PA in final outcome. | Yes |
Mullaji et al.20) (2007) | HHS | 52 | 85 | Nil | 1 postoperative hematoma 1 secondary suturing owing to necrosis of the superficial edges of the wound | All bone grafts united by the 6th month. Several small radiolucencies seen around the screw in 3 cases. | Uncemented porous coated hemispheric cups with peripheral press fit fixation and restoration of bone stock with impacted autologous bone grafting appears to give satisfactory medium-term results. | Yes |
Krushell et al.15) (2008) | HHS Hip centre to Kohler’s line distance | 41 24 mm | 84.6 30.9 mm | 1 case - secondary osteolysis due to polyethylene wear after 8 years | 1 peroneal nerve palsy and 1 case of recurrent dislocation. 1 case of late reoperation for polyethylene wear and secondary osteolysis. | At follow-up, mean protrusion medial to Kohler’s line was 1.0 mm, mean vertical distance 12.5 mm, mean horizontal distance 30.9 mm. | Excellent results obtained in 29 hips both clinically | Yes |
Baghdadi et al.2) (2013) | HHS | 51±12 | 77±18 | 11 revised - 9 asepic loosening, 1 linear wear and liner exchange, 1 instability | 9 - asepic loosening 1 - linear wear and liner exchange 1 - instability | Femoral offset decreased by 4±9 mm Hip COR improved by 11±6 mm | 10-year survival rate is 95% (95% CI). 15-year survival rate is 89% (95% CI) in uncemented. 10-year survival rate is 92% (95% CI). 15-year survival rate is 85% (95% CI) in cemented. | Yes |
Hansen and Ries12) (2006) | HHS | 32.3 | 71.7 | Revision - 1 due to recurrent dislocation | 5 - dislocation, 1 - developed a transient lateral femoral cutaneous neuropraxia, 1 - perioperative cardiac event | Mean protrusio position of the acetabular prostheses medial to Kohler’s line was 10.5 mm. | Uncontained medial acetabular defects can be successfully augmented with morselized bone graft , oversized rim fit acetabular component if good quality peripheral bone exists and integrity of acetabular rim is maintained. | Yes |
Rosenberg et al.21) (2000) | Long-term survival rate for primary THA | NA | NA | 2 revisions due to aseptic loosening | Aseptic loosening - 2 | In all cases, radiographs - the impacted morsellized bone grafts had become incorporated with the surrounding bone. | Long-term survival rate for primary THA in RA patients having protrusio acetabuli and acetabular reconstruction with impacted morselized bone graft is 90% (95% CI) at an average 12-year follow-up. | Yes |
Matsuno et al.18) (2000) | JOA score | 20.6 | 70.4 | Nil | One patient - transient sciatic nerve palsy | The COR of the hips was improved to within 4 mm of normal. | All grafts appeared to heal radiologically with no radiolucent line between graft and acetabulum. | Yes |
Gates et al.11) (1989) | Central edge angle Protrusion medial to Kohler’s line | 80.3° +8.6 mm | 57.7° –10.5 mm | 5 revisions -progressive protrusion | Loosening, 8; trochanteric non-union, 2 | Postoperatively-average distance of migration of the femoral head medial to Kohler’s line 10.5 mm, vertical migration average 5.3 mm. | Vertical migration and horizontal distance, two measurements utilizing a x-y coordinate system based on the tear drop-most useful radiographic measurements for determining the presence of PA and in following postoperative progression | Yes |
Kondo et al.14) (2002) | JOA score | 19.6 | 35.2 | Nil | 6 acetabular component loosening | Acetabular component loosening | The rate of loosening of THA without bone grafting was higher than that of THA with bone grafting. | Yes |
Liu et al.17) (2023) | 1. Range of flexion motion of the hip joint 2. Range of abduction motion 3. HHS | 39.48°±8.36° 10.86°±4.34° 37.84±4.74 | 103.07°±7.64° 36.75°±3.99° 89.55±4.05 | Nil | Reduction of the hip joint was extremely difficult in three patients (4 hips) | The horizontal distance of the hip rotation center increased from preoperative 10.40±2.50 mm to postoperative 24.03±1.77 mm, and the vertical distance increased from preoperative 72.36±3.10 mm to postoperative 92.48±5.31 mm. | Uncemented THA combined with impacted grafting granule bone of the autogenous femoral head and biological acetabular cup-reconstruct the acetabulum, restore the COR of hip joint, and achieve good medium-term outcomes in the treatment of moderate to severe PA secondary to RA. | Yes |
Zuh et al.23) (2015) | HHS | 42.3±3.9 | 85.2±3.0 | Nil | HO, 6 cases | Hip COR was restored close to the ideal values on the vertical axis, while on the horizontal axis the COR obtained was lateral to the ideal point. | Impaction bone grafting for acetabuloplasty, associated with the implantation of an uncemented cup, yields good midterm clinical and radiological results in patients with PA or primary hip arthrosis with a thinned medial acetabular wall. | Yes |
Yun et al.22) (2021) | Hip disability and osteoarthritis outcome score | Not done | 91±10.4 | 1 revision - stem subsidence | 1 case - Meckel’s diverticulum required 20 days of inpatient care for small bowel obstruction and acute pyelonephritis | Preoperative AK distance (mm): 8±4.5; range, 1-16 Postoperative AK distance (mm): 0±2.2; range, -4 to 3 | Anterior approach may decrease the significant risks of dislocation by avoiding posterior dissection. | Yes |
Mibe et al.19) (2005) | JOA score | 25.2±8.6 | 55.6±8.7 | 2 revisions owing to loosening of the Ganz ring | Loosening of the Ganz ring - 2 patients | The mean depth of the protrusio acetabuli was 3.6 mm before operation, and 3.1 mm just after the operation. | With THA for protrusio acetabuli in RA - no loosening, and bone stock maintained by a bone graft using a support ring. It suppresses progression of the PA in the short-term. | Yes |
Lee et al.16) (2022) | Modified HHS | NA | Restored group: 83.6±12.1, Medialized group: 83.8±10.4 | One patient - periprosthetic femoral fracture | No other complications | The mean abduction and anteversion angles (in degrees) of the acetabular component were 37.4 and 23.7 in the medialized group and 43.8 and 24.9 in the restored group, respectively. | Implant stability and favorable results were obtained by press-fitted cups, irrespective of hip center restoration. THA in PA patients-promising clinical and radiological results. | Yes |
Figueras Coll et al.9) (2008) | HHS | 42.3 | 90.6 | Nil | 4 DVT, 3 posterior hip dislocations, 3 wound infection | One had radiolucent lines >2 mm - zone 2, which did not progress. | Bone-grafting and acetabular wiremesh - effective and simple method to arrest the progresion of PA | Yes |
Johnsson et al.13) (1984) | NA | NA | NA | One hip revised - deep infection Recurrent dislocations occurred in one - re-operation planned | Recurrent dislocations, 1 hip; deep infection, 1 | Progressive radiolucent zone of 4-5 mm at the bone- cement interface - 2 hips Calcar resorption of 4-10 mm - 2 hips with 10 mm distal migration of the femoral component in the latter case | THA with the use of autogenous spongious bone graft reinforcement to the medial acetabular wall-successful surgical procedure in patients with RA and PA | Yes |
Values are presented as mean±standard deviation.
Preop: preoperative, Postop: postoperative, HHS: Harris hip score, Nil: nothing, PA: protrusio acetabuli, RA: rheumatoid arthritis, THR: total hip replacement, NA: not available, HO: heterotopic ossification, DVT: deep vein thrombosis, COR: centre of rotation, CI: confidence interval, THA: total hip arthroplasty, JOA: Japanese Orthopaedic Association, AK distance: medial acetabular border to kohler line distance.
PA can pose certain problems for patients requiring a THA. The most common indication of THA for protrusion was inflammatory arthritis, particularly rheumatoid arthritis. In such cases performance of THA can be challenging due to medialization of the acetabulum and the femoral head. However, all of the studies included in this review reported consistently good outcomes. The aim of this first-of-its-kind review is to determine the best method for achieving good outcomes with THA in treatment of protrusion. Literature includes evaluation of both cemented and uncemented options for THA. While achievement of better outcomes with uncemented cups with bone graft as compared to cemented has been confirmed, few studies evaluating the type of femoral stem that should be used have been reported, thus no conclusion can be drawn in that regard.
Opinion regarding the concept of restoration of the anatomical hip COR for achievement of a good outcome and better survival of the implant has been consistent. The Ranawat triangle method is the best-known method for estimation of anatomic hip COR24). When using this method, an isosceles right-angled triangle is drawn with base and perpendicular length equal to 20% of pelvic height projected from a point 5 mm lateral to the teardrop. The anatomic hip centre falls at the centre of the hypotenuse that is drawn. More recent studies have described different formulas for determining COR and maintain that their accuracy is greater than that of previous methods. Fujii et al.26), who formulated two new methods, the Modified Ranawat method and the pelvic height ratio method, reported that these methods are more accurate than the Ranawat triangle method. Pierchon et al.25) developed a method for calculating the hip centre using the teardrops and sacro-iliac joint. However, the COR migrates superomedially and requires inferiorization and lateralization. Baghdadi et al. detected a 24% risk of aseptic loosening with every 1 mm shift of the COR from the native COR. However, no difference was observed with a shift of COR on the vertical axis2). Lee et al.16) reported that implant stability and good outcomes were achieved with a press fit of cups and was not related to the restoration of the COR.
Filling the acetabular cavity secondary to lateralization of the cup with morselized bone graft is the best option. Ranawat and Zahn27) presented the first guidelines for bone grafting in patients with protrusion. Grafting is not recommended in cases of protrusion <5 mm with a strong medial wall; grafting is required for protrusion >5 mm with a thin medial wall; use of additional fixation devices is required in the case of a grossly deficient medial wall. Autogenous morcellised femoral head graft was used in most studies for restoration of the COR. Additional grafts from the iliac crest or trochanter can be used in cases where the femoral head is inadequate. Although allogenic graft and synthetic graft substitutes have also been used, Dutka et al.10) reported that a relatively poorer outcome was observed with use of a mixed graft as compared to an autogenous graft in 12-year follow-up. Histological studies have demonstrated complete graft incorporation after eight months followed by remodeling to the point that conversion of the graft into normal trabecular bone can be observed at 15 months post-surgery28). All studies included in the review reported that good incorporation of the bone graft was observed in almost all patients, which was achieved within approximately 3-6 months followed by consolidation and trabeculation of the graft. Kondo et al.14) reported a higher rate of loosening in hips that underwent surgery without a bone graft and placed emphasis on the importance of bone grafting. The majority of authors preferred to fill the medial acetabular cavity with bone graft and only 72 THAs were performed without bone grafting. Further progression of protrusion post THA can also be prevented with bone grafting. In the series reported by Baghdadi et al.2) poorer clinical scores were observed in hips that underwent surgery without bone grafting.
Commercially available bone mills, reamers, or rongeurs can be used in preparation of bone graft. Mullaji and Marawar20) reported that use of commercial bone mills can result in production of a graft size that is too small for use; however, Yun et al.22), who exclusively used a commercial mill, reported that there were no poor outcomes in terms of ingrowth or consolidation. A review by Mirza and Sadiq29) maintained that larger bone chips of 8 mm are the ideal size to provide stability for acetabular bone grafting. Some authors used only morselized bone graft while others used smaller pieces of bone impacted into the acetabulum while the gaps were filled with morselized graft. Kondo et al.14) reported on use of femoral neck slices when filling the bone defect. Good results were achieved with use of various methods of impaction, from the use of smaller trial heads to specialized impactors for reversal of reaming. Figueras Coll et al.9) reported on use of a titanium mesh in 25 patients while Rosenberg et al.21) used a vitallium mesh over the impacted bone graft to contain it in 27 patients. They reported that bone grafting with mesh is an effective and simple method for arresting progression of protrusion9,21).
Historically, cemented cups have been used routinely with good results11,13,14,21). However, in more recent studies the dynamics have shifted towards the use of uncemented cups based on achieving a peripheral rim fit. Proper acetabular preparation for use of a cementless cup is required in order to avoid overreaming the medial wall and consequent medialization of the cup. Smaller reamers or curettes can be used with care in preparation of the acetabular floor in order to create only a bleeding bed, not to enlarge the cavity. Reaming must be anatomical, with the goal of obtaining an equatorial press-fit fixation while avoiding the process described as “reaming-related medialization”, in order to avoid compromise of the acetabular offset30). Previous studies have reported on several techniques for achieving an adequate press-fit when using cementless cups, from a 2-mm underreaming to 1-mm line-to-line reaming23,31). Most authors have reported avoiding the use of additional screws for fixation until and unless considered necessary. A screw augmentation was used in only 148 out of 436 uncemented cups. Acetabular support rings were also used in two studies. Matsuno et al.18) reported on use of a Harris Galante porous coated cup with an MC ring supporter. The COR was restored within 4 mm of normal18). A study by Mibe et al.19) evaluated use of two cemented rings, the TACT Cup supporter and the Kerboul plate, and two uncemented rings, the Ganz ring and the Müller ring, with all cemented cups. They reported a survival rate of 72% when using both failure and death as end points. Better maintenance of acetabular thickness was achieved with use of uncemented rings as compared to cemented support rings19).
The studies included in this review do not provide adequate evaluation of the choice of femoral stem. Cementless stems were used primarily. The choice of femoral stem, which is based on the patient’s bone quality, should be individualized. The majority of patients with protrusio are females in the age group 65-70 years, many of whom are on chronic steroid therapy. These findings suggest the use of cemented stems in the majority of patients30). Dorr classification based on the cortical thickness of the proximal femur can provide guidance in the selection of a stem. According to a review by Bengoa et al.30), a low femoral neck osteotomy to avoid limb lengthening and use of femoral stems with collodiaphyseal angle in varus are recommended (<125°). Lateralization and posteriorization of the initial box osteotome are required in order to avoid placing a stem in varus, which is highly likely with the overhand of the greater trochanter. However, none of the studies included in the review have offered any rationale regarding the types of femoral stem or the type of fixation that should be used.
Baghdadi et al.2) performed surgery on 162 hips (107 uncemented vs. 55 cemented) and compared survival rates; the 10-year survival rate was 95% and the 15-year survival rate was 89% in the uncemented group and 92% and 85%, respectively, in the cemented group. In another study, they reported acetabular cup revision free survival of 94.3% at 10 years and 85.4% at 15 years for all uncemented cups8). Rosenberg et al.21) reported a survival rate of 90% at 12-year follow-up with use of cemented acetabular cups in rheumatoid patients with protrusion. The most common complications were aseptic loosening (n=55) and heterotopic ossification (n=21). While the former required revision, conservative management was administered for the latter. Other common complications included recurrent dislocations, polyethylene wear, and deep vein thrombosis. The incidence of infection and wound complications was relatively low. However, awareness of such complications is required, particularly in cases of inflammatory arthritis where the patient is on immunomodulatory and biological drugs30).
Our review has limitations. First, the review includes a mix of study types, many of which were retrospective, with no control groups for comparison of the outcome of THA in treatment of PA with that of THA for other indications. Identification of prospective comparative studies would be ideal. Second, in most studies the sample size was less than 50. However, due to the paucity of literature, we needed to utilize all available studies. Third, larger studies on this topic, such as studies utilizing registry data, are currently missing and interest will perhaps increase in the near future.
However, the large number of studies included in the review for analysis is a major strength of our study. To the best of our knowledge, this is the first systematic review reported in recent years that provides details on the various aspects of THA in the cohort of patients with PA. Performance of THA in this subset of patients is technically more difficult compared with other indications for a primary THA, as is the difference in outcome and complications. Therefore, this article would be helpful in assessing the outlook for such patients as it integrates all of the current evidence regarding the outcome of THA in patients with acetabular protrusio.
Performance of THA in patients with PA presents a greater challenge as compared to other routine indications. However, the results of the surgery are promising and, if done properly, survivorship may be comparable with that of THA for other indications. This review supports the use of an uncemented cup with a morselized autograft for filling the medial acetabular defect. Restoration of the anatomic hip centre of rotation and achieving a good press fit is extremely important. Screws or rings can be used to augment the fixation when considered necessary. Selection of the femoral stem should be decided on an individual basis according to anatomy and bone quality. However, there is a lack of good quality case-control studies comparing outcomes in patients undergoing THA for treatment of PA and other indications. Such studies are needed in order to attain a higher quality of evidence on this topic.
No funding to declare.
No potential conflict of interest relevant to this article was reported.
Hip Pelvis 2024; 36(1): 12-25
Published online March 1, 2024 https://doi.org/10.5371/hp.2024.36.1.12
Copyright © The Korean Hip Society.
Sajid Ansari, MCh , Kshitij Gupta, MS , Tushar Gupta, MS , Balgovind S. Raja, MCh* , Pranav J., MBBS , Roop Bhushan Kalia, MS
Department of Orthopaedics, All India Institute of Medical Sciences, Rishikesh, India
Department of Orthopaedics, All India Institute of Medical Sciences, Patna, India*
Correspondence to:Roop Bhushan Kalia, MS https://orcid.org/0000-0002-3418-5942
Department of Orthopaedics, All India Institute of Medical Sciences, Virbhadra Road, Rishikesh 249203, India
E-mail: roopkalia2003@yahoo.com
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Protrusio acetabuli, or abnormal protrusion of the femoral head into the acetabulum, requires performance of a total hip arthroplasty (THA) for which various reconstruction techniques and outcomes have been described. The aim of this systematic review is to provide a comprehensive analysis of the current evidence, evaluate treatment efficacy, compare surgical techniques, and identify topics for future research along with improving evidence-based decision-making, improving patient outcomes in the management of this condition. A thorough systematic review of the PubMed, Embase, Cochrane Library databases, and Scopus library was conducted, and articles describing techniques of THA for treatment of protrusion acetabuli were extracted. The initial search generated 751 results. After exclusion, 18 articles were included. Of these, eight were prospective studies and 10 were retrospective. Surgery was performed on 783 hips with a mean age of 60 years; 80% of females who mostly had inflammatory arthritis were followed up for 8.86 years (range, 2-15.4 years). Good outcomes have been achieved with THA using uncemented cups with bone graft; however, no conclusion could be drawn with regard to the femoral side. It can be concluded that the concept of restoration of the anatomical hip center of rotation is paramount for good outcome and better survival of the implant is important when using uncemented cups with a bone graft. In addition, screw augmentation for fixation is not recommended unless absolutely necessary. The most common complications were aseptic loosening and heterotopic ossification. While the former required revision, conservative management was administered for the latter.
Keywords: Total hip arthroplasty, Protrusio acetabuli, Systematic review
Protrusio acetabuli (PA), or acetabular protrusion, is a complex condition that poses unique challenges in the context of total hip arthroplasty (THA). It refers to the abnormal protrusion of the acetabulum into the pelvic cavity, which is associated with a variety of symptoms and functional limitations. It is defined as a medial projection of the acetabular line beyond the ilioischial line (Kohler’s line) by 6 mm in females and 3 mm in male patients. The etiology of primary or idiopathic PA is unknown, whereas development of secondary PA can occur as a result of various underlying conditions, including rheumatoid arthritis, osteoarthritis, developmental dysplasia of the hip or genetic predisposition, Paget’s disease, or inflammatory hip diseases. THA can be considered as a viable treatment option in cases where use of conservative measures has not resulted in alleviation of pain and restoration of joint function1-3).
Comprehensive preoperative evaluation and thorough surgical planning is required for successful management of PA with THA. Treatment with THA should be administered in cases of painful and progressive PA. Due to concerns regarding poor bone quality or cortical bone defects, the stability of the socket is an important consideration after arthroplasty. In addition, successful clinical and radiological results may not always be achieved after conventional THA for treatment of PA1). The objectives of performing THA for treatment of PA include restoration of abductor function and hip mechanics as well as restoration of the anatomical relationship between the femoral head and the acetabulum2). Potential concerns include surgical exposure, implant selection, lack of bone stock, deficient medial support to the cup, and medialization of the joint center3).
Various techniques for management of PA have been described in the literature. Commonly used techniques include the use of morselized impacted autografts or allografts with a cemented or uncemented cup for acetabular reconstruction, metal cages, reinforcement rings, and solid grafts for acetabular reconstruction4-7). The aim of this systematic review is to provide a comprehensive analysis of the current evidence, evaluate treatment efficacy, compare surgical techniques, and identify topics for future research. Through synthesis of the available data, such a review can be helpful in the management of this particular condition by contributing to evidence-based decision-making, informing clinical practice guidelines, and ultimately improving patient outcomes.
This study (Systematic Review) does not involve direct participation of patients, but assimilating data from studies conducted by other authors who have obtained permission from their respective boards. Thus, ethical approval is not required for conduct of a systematic review, which was confirmed after subjecting the information to the Medical Research Council (MRC) Health Research authority. Informed consent was not required for this study.
A comprehensive search of the literature was conducted for the systematic review following the principles of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The search of online databases included PubMed (http://www.ncbi.nlm.nih.gov/pubmed), Embase (http://www.elsevier.com/online-tools/embase), Scopus, and the Cochrane Library database (http://www.cochrane.org) for all studies published until 17th June 2023. Search terms used were ‘Protrusio acetabuli’ OR ‘Acetabular protrusion’ AND ‘total hip replacement’ OR ‘total hip arthroplasty’. The search was restricted to articles on human subjects in the English language. A hand search of references for the included full text articles was also performed for identification of any other relevant studies (Fig. 1).
The abstracts were identified first using the above-mentioned search methods and an assessment for eligibility was performed based on strict criteria mentioned below. The shortlisted abstracts were then followed up for full texts and another assessment for eligibility was performed. Another search of the reference list for the finalized articles was performed for identification of additional relevant studies.
The review included all original studies that included adult patients with a diagnosis of PA due to any cause undergoing THA, who underwent primary THA, with a minimum follow up period of one year and articles on the study of functional or radiological outcomes and survival after the THA procedure. Only papers in the English language were included. The exclusion criteria included (1) articles with incomplete data, (2) case reports, reviews, biomechanical studies, expert opinions, letters to editors or editorials, and (3) non-English language, (4) case series that included less than 10 patients, (5) Studies that included patients with an etiology, who did not have acetabular protrusion, were also excluded. All cases that were available for follow-up after accounting for losses during follow up were included in the review.
The systematic review was conducted by two authors (S.A. and K.G.) who each performed an independent analysis of the data. Any controversy was resolved by mutual agreement and consultation with the senior author (R.B.K.). Data from full text articles was extracted into Microsoft Excel 2019 (Microsoft). Information on the demographic details of patients including author name, year of publication, sample size, follow-up period, outcomes (scores if present), prosthesis and surgical approach used, technique of protrusio management, complications, and survival of the prosthesis was extracted. In the case of an eligible study with incomplete data/information or not accessible by internet, the authors were contacted by email using the correspondence address provided requesting the required information. In cases where the author had not responded by the data extraction stage or when data were considered irrelevant to our study, the study was excluded. The continuous variables were extracted and expressed as mean±standard deviation.
The quality of the studies included in the review was assessed by two separate reviewers (T.G. and P.J.). The Newcastle–Ottawa scale was used for assessment of the methodological quality of each study (Table 1)2,3,8-23). Assessment was performed for each included study by each reviewer and any disagreements were resolved by a third reviewer (B.S.R.).
Table 1 . Quality Assessment of Studies according to New Castle–Ottawa Score.
Cohort studies | Representativeness of cohort | Ascertainment of exposure | Ascertainment of outcome (functional) | Adjustment for confounder | Follow-up mentioned |
---|---|---|---|---|---|
Zhen et al.3) (2018) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.8) (2015) | Yes | Yes | Yes | Yes | Yes |
Dutka et al.10) (2011) | Yes | Yes | Yes | Yes | Yes |
Mullaji and Marawar20) (2007) | Yes | Yes | Yes | Yes | Yes |
Krushell et al.15) (2008) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.2) (2013) | Yes | Yes | Yes | Yes | Yes |
Hansen and Ries12) (2006) | Yes | Yes | Yes | Yes | Yes |
Rosenberg et al.21) (2000) | Yes | Yes | No | Yes | Yes |
Matsuno et al.18) (2000) | Yes | Yes | Yes | Yes | Yes |
Gates et al.11) (1989) | Yes | Yes | No | Yes | Yes |
Kondo et al.14) (2002) | Yes | Yes | Yes | Yes | Yes |
Liu et al.17) (2023) | Yes | Yes | Yes | Yes | Yes |
Zuh et al.23) (2015) | Yes | Yes | Yes | Yes | Yes |
Yun et al.22) (2021) | Yes | Yes | Yes | Yes | Yes |
Mibe et al.19) (2005) | Yes | Yes | Yes | Yes | Yes |
Lee et al.16) (2022) | Yes | Yes | Yes | Yes | Yes |
Figueras Coll et al.9) (2008) | Yes | Yes | Yes | Yes | Yes |
Johnsson et al.13) (1984) | Yes | Yes | No | Yes | Yes |
After an extensive search and performance of quality assessment prior to extraction of data in order to avoid selection bias, 751 studies were identified in the search. Titles and abstracts of all articles were evaluated for potential inclusion in the review. After assessing the studies against inclusion criteria, 18 studies were finally included in this review2,3,8-23). A flow chart of the literature search using the PRISMA format is shown in Fig. 1. Among the included studies, eight studies were prospective (Level II) and 10 studies were retrospective (Level III) in nature. A list of the study demographics is provided in Table 2. Surgery was performed on 783 hips, in 665 patients with a mean age of 60 years (range, 45.8-71.1 years). The patient population included 80% females. The mean follow-up period was 8.86 years (range, 2-15.4 years). The most common etiology was inflammatory arthritis, predominantly rheumatoid arthritis. Other types of inflammatory arthritis included psoriatic, systemic lupus erythematosus, and ankylosing spondylitis. Other common etiologies included idiopathic, degenerative osteoarthritis, and post traumatic, in that order (Table 2).
Table 2 . Study Characteristics and Demographic Details.
Study | Country | Inclusion/exclusion criteria | Etiology | Total hips | Study design | Mean age (yr) | Sex (F:M) | Extension of protrucio from Kohler’s line/Sotelo-Garza classification | Intervention | Approach | Implant | Follow-up |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | China | Protrusio in RA | RA | 20 hips (18 patients) | Prospective cohort | 45.8±8.3 | 12:6 | 12.7 mm | Uncemented with bone grafting | Posterolateral approach | Porous tantalum cups, 16 hips; titanium porous coated cups, 4; 4th generation ceramic-ceramic implantations, 8; polyethylene-lined ceramic implantations, 12 | 4.5±1.7 yr |
Baghdadi et al.8) (2015) | USA | THA done in protrusio | OA, 48 hips; RA, 15; sequele of septic arthritis, 2 | 65 hips (53 patients) | Retrospective cohort | 66 | 53:12 | 7±4 mm | Uncemented 58 hips, impacted with morselized bone graft; 26 hips, supplementary screw fixation | Anterolateral, 34 procedures; posterior, 28; transtrochanteric, 3 | Harris-Galante (HG)-I, 6 hips; Harris-Galante (HG)-II, 13; Omnifit, 17; Reflection™, 7; Porous-Coated Anatomic (PCA), 4; Press-Fit Condylar (PFC), 2; Elliptical, 1; Bi-Articular, 1; Trilogy®, 11; Hedrocel®, 3 | 15.4 yr |
Dutka et al.10) (2011) | Poland | 1. THA done in patients with protrusion acetabuli with any etiology 2. Minimum 4-year follow-up 3. Full medical records available | RA, 122 hips; Otto’s disease, 6; psoriatic arthritis, 3; SLE, 2; acetabular fracture, 1; radiation damage, 1 | 135 hips (127 patients) | Retrospective cohort | 55.2 | 119:8 | Grade 1, 48; grade 2, 36; grade 3, 21 | 128 hips, cemented; 7 hips, uncemented Autogenous grafts, 97 hips; mixed grafts, 38 | NA | NA | 12.7 yr |
Mullaji et al.20) (2007) | India | 1. Primary THAs in significant protrusio acetabuli 2. Minimum follow-up of 2 years | RA, 14 patients; ankylosing spondylitis, 5; Idiopathic, 4 | 30 hips (23 patients) | Prospective cohort | 46 | 17:6 | Grade 1, 8; grade 2, 10; grade 3, 12 | Uncemented THR with morselized BG | Anterolateral approach | Duraloc porous-coated cups, 17 cases; Bicontact cups, 13 One screw used to augment, 15 cases; 2 screws used, 12; no screw used, 3 A porous-coated stem used 21 cases: Bicontact, 13; Summit, 8 Cemented Charnley stems used, 9 cases | 4.2 yr |
Krushell et al.15) (2008) | England | Primary THA of any cause with acetabular protrusio | Inflammatory arthritis in 22 cases and OA in 7 cases | 29 hips (27 patients) | Retrospective cohort | 66 | 20:7 | Mean, 4.1 mm protrucio medial to Kohler’s line | Uncemented, Autologous BG in all cases Additional synthetic grafts, 3 cases | Posterolateral approach | Beaded dual-geometry acetabular shell design with multilayer titanium MicroStructured porous ingrowth surface | 4 yr |
Baghdadi et al.2) (2013) | USA | All patients with protrusio acetabuli who had undergone primary THR with a minimum follow-up of 2 years | Idiopathic, 117 hips; underlying inflammatory component, 38; genetic - 2, post infectious - 2, post radiation - 1, metabolic - 2 | 162 hips (127 patients) | Retrospective cohort | 66±13 | 112:15 | 7±5 mm | Cemented, 55 hips (14/55 cemented hips, bone grafting) Uncemented, 107 hips (83/107 uncemented hips, bone grafting done) | First-generation designs: Charnley, Aufranc Turner, Elliptical, Ti-Bac Cups Second-generation designs: Harris-Galante (HG)-I, Harris-Galante (HG)-II, Omnifit, Reflection, Porous-Coated Anatomic, PressFit Condylar Third-generation designs: Pinnacle, Trilogy, Hedrocel, Trident, Trabecular Metal Modular, Tritanium Hemispherical Cluster | 10±6 yr | |
Hansen and Ries12) (2006) | USA | 1. Revision surgeries 2. Large medial defect with at least 50% radiographic projected acetabular bone loss 3. Minimum 2-year follow-up | OA in 9 patients, RA in 3, posttraumatic arthritis in 2, avascular necrosis in 1, PVNS in 1, and DDH in 1 | 19 hips (17 patients) | Prospective cohort | 66 | 13:9 | 10.5 mm | Uncemented porous coated acetabular cup and morselized allograft | Posterior approach+ extended trochanteric osteotomy if necessary | Cementless hemispherical component with a widened peripheral rim | 2.8 yr |
Rosenberg et al.21) (2000) | Netherlands | 1. Patients diagnosed as RA with protrusio hip who under goes THA 2. Patients with minimum 8-year follow-up | RA | 20 hips (16 patients) | Prospective cohort | 53 | 13:3 | NA | Cemented cups with Morselized allograft | Posterolateral approach | 32 mm polyethylene Mueller or Allopro cup | 11.7 yr |
Matsuno et al.18) (2000) | Japan | Patients diagnosed to have RA with protrusio hip | RA | 15 hips (13 patients) | Prospective cohort | 61.9 | 9:4 | NA | Uncemented with iliac crest and morsellised femoral head graft | Aposterior approach | MC cup supporter | 53.6 mo |
Gates et al.11) (1989) | USA | Painful progressive protrusio acetabuli | RA, hemiarthroplasty, THA, OA | 48 hips (40 patients) | Prospective cohort | 57.8 | 29:11 | 8.6 mm | Cemented THA with medial acetabular reinforcement with BG Autologous BG, 39 hips; Allograft, 9 | NA | NA | 12.3 yr |
Kondo et al.14) (2002) | Japan | RA with protrusion acetabuli treated with THA Minimum 9-year follow-up | RA | 25 hips (19 patients) | Prospective cohort | 56.7 | 16:3 | Grade 1, 8; grade 2, 13; grade 3, 4 | Cemented with autologous graft | NA | NA | 129.6 mo |
Liu et al.17) (2023) | China | 1. RA 2. Moderate and severe in patients with acetabular protrusions in which the bottom of the acetabulum exceeded Kohler’s line in the pelvic AP radiography | RA | 56 hips (45 patients) | Prospective cohort | 55.64±5.38 | 28:17 | 10.97±3.08 mm | Uncemented THA with impacted bone grafting | Posterolateral approach | Biological total hip prostheses: A porous tantalum cup, 42 hips; sintered, three-dimensional, asymmetric, titanium, and porous-coated cups, 14; weight-bearing interfaces, 24; fourth-generation ceramic-on-ceramic implantations, and ceramic-on-highly cross-linked polyethylene, 32 | 5.20±1.20 yr |
Zuh et al.23) (2015) | Romania | THA in protrusio | Protrusion of unknown aetiology, 16 hips; RA, 6; protrusion secondary to tuberculous arthritis, 3; post-traumatic protrusion, 2; hip arthritis with thin medial acetabular wall, 12 | 39 hips (32 patients) | Retrospective study | 58.3±8.9 | 15:17 | I, 15 hips; II, 9; III, 3; thin medial wall, 12 | Medial acetabular wall – augmented by impaction bone grafting Uncemented cup – all cases | Direct lateral approach | 4.5 yr | |
Yun et al.22) (2021) | USA | THA in protrusio | 5 patients, RA; 18 patients, idiopathic PA | 23 THAs in 21 patients | Retrospective study | 68±9 | 19:2 | Mild, 7 patients; moderate, 13; severe, 3 | Morcellized femoral head autograft using Bone Mill, cementless acetabular cups | Direct anterior approach | 5.3 yr | |
Mibe et al.19) (2005) | Japan | Protrusio in RA | RA | 19 hips of 15 patients | Retrospective | 60.2 (48-75) | All F | 12 hips, grade 1; 3 hips, grade 2; 1 hip, grade 3 Medial-proximal type, 3 hips | THA using a support ring All cups- cemented | Not mentioned | 4 hips, TACT cup supporter; 1 hip, Kerboull plate; 6 hips, a Ganz ring; 5 hips, Müller ring | 38 mo |
Lee et al.16) (2022) | Korea | THA in protrusio | RA, 14 hips; post-traumatic arthritis, 7; ankylosing spondylitis, 4; previous infection, 1 | 26 cementless THAs of 22 patients | Retrospective study | 59.9 | 17:5 | Mild, 5 hips; moderate, 19; severe, 2 | Uncemented THA, reinforcement acetabular components in 2 hips | Kocher-Langenbeck approach | PLASMACUP SC, 9 hips; Bencox cup, 7; Pinnacle cup, 5; G7 cup, 1; ABT cup, 1; Delta TT cup, 1 SPH reinforcement cups, 2 hips with defective rim of the acetabulum | 5.1 yr |
Figueras Coll et al.9) (2008) | Spain | THA in protrusio | Severe arthrosis (50% of cases), protrusio due to hemiarthroplasties (15%), and rheumathoid arthritis (15%) Aseptic loosening of the acetabular cup in THA, and some other causes- less common diagnoses | 25 hips (25 patients) | Retrospective study | 71.1 | 16:9 | Paproski’s classification – 20 type IIa cases, 4 type IIb and 1 type IIc | Cemented acetabular cup, autogenous morcellized bone-graft and acetabular wiremesh | Anterolateral | Charnley stem and cemented cup (7 right and 18 left hips) | 8.6 yr |
Johnsson et al.13) (1984) | Sweden | Protrusio in RA | RA | 27 hips (25 patients) | Retrospective study | 56 (29-76) | 21:4 | Joint destruction according to Larsen and Larsen et al. 12 hips, grade IV; 15 hips, grade V Mean acetabular protrusion, 6 mm | Spongious bone chips from the trochanter and/or the femoral head, and iliac crest, 10 cases – thin titanium net A high density polyethylene (HDPE) protrusion cup – last 5 cases | 26 hips, postero-lateral; 1 hip, anterior approach without trochanteric osteotomy | Lubinus (25) and McKee-Arden (2) types | 2 yr |
Values are presented as mean±standard deviation or mean (range)..
F: female, M: male, RA: rheumatoid arthritis, THA: total hip arthroplasty, OA: osteoarthritis, SLE: systemic lupus erythematosus, NA: not available, THR: total hip replacement, BG: bone graft, PVNS: pigmented villonodular synovitis, DDH: developmental dysplasia of hip, AP: anteroposterior, PA: protrusio acetabuli..
Restoring the native hip center of rotation (COR) is at the core of THA in treatment of protrusion acetabuli. While the Ranawat triangle method24) was used by Baghdadi et al.2) for estimation of the COR, Zuh et al.23) used the method developed by Pierchon et al.25). Yun et al.22) performed the procedure using a direct anterior approach and intra-operative fluoroscopy was used for placement of the implant and restoration of the COR. Other studies have used Kohler’s line, teardrop, or inter-teardrop line as a reference for measuring COR distance. An uncemented cup was used in the majority of hips (n=436). Of these, a porous coated cup was used in 160 hips. Details on the various components used are shown in Table 2. An uncemented cup was used along with bone grafting for acetabular reconstruction in most studies. Six studies evaluated use of a cemented acetabular cup supported by a bone graft9,11,13,14,19,21). Both reconstruction techniques were used in two studies and the outcomes were compared2,10). Wherever deemed necessary, based on the lack of acetabular support, screws or acetabular support rings were used to aid stability. According to the pooled data, augmentation of the cup with screw fixation was performed in 148 uncemented hips3,8,12,17,20). An acetabular support ring was used in three studies in 37 hips; the details are provided in Table 214,18,19). Lee et al.16) reported on use of acetabular reinforcement components in two out of 26 hips in which press fit could not be achieved due to >50% rim defect. The type of stem used has been mentioned in eight studies. There were 113 uncemented stems (34.1%) and 218 cemented stems (65.9%). No consensus nor rationale has been identified among the various studies with regard to the type of stem that should be used. Femoral anatomy and bone quality can be considered when deciding on the type of stem and fixation. Another major problem in these patients is that dislocating the head is difficult due to its incarceration within the acetabulum. Four studies have mentioned performing an in-situ neck cut8,17,22,23). However, in severe cases where the neck is not visible, removal of the lateral part of the edge of the femoral head and neck can be performed using a drill or narrow bone knife. Resection of the neck can then be performed while the head can be removed in pieces if needed3,17). Lee et al.16) reported on removal of a thick part of the neck after two osteotomies to facilitate dislocation.
A morselized autograft from the femoral head, iliac crest, and trochanter was used in almost all studies to fill the medial wall defect and for restoration of the hip COR. A femoral head graft was considered adequate for this purpose. Kondo et al.14) described the use of a sliced bone graft from the femoral neck along with a morselized graft. An allogenic graft can also be used when needed8,10-12,23). Krushell et al.15) and Mibe et al.19) mixed synthetic bone graft in eight patients. Eleven studies reported on the method of graft impaction, including reverse reaming (n=122), impaction with a small trial head (n=96) or impactor (n=55). A wire mesh was used in 52 hips, all cemented, in two studies9,21). Baghdadi et al.2) reported that only 72 patients out of the pool of patients underwent surgery without bone graft (41, cemented; 31, uncemented). Thirteen studies mentioned the approach used in performance of the surgery (Table 2). The most commonly used approach was posterolateral (n=177), followed by anterolateral (n=85) and posterior (n=62).
Extension of protrusio medial to Kohler’s line, which has a mean of 7.99 mm (range, 4.1-12.7 mm), was described in seven studies. Protrusio was classified according to Sotelo-Garza classification in seven studies. There were 103 grade I hips, 103 grade II hips, and 46 grade III hips. Other classification systems including American Academy of Orthopaedic Surgeons (AAOS) Committee on the Hip, Paprosky, and Larsen & Larsen classification were also used. The Harris hip score (HHS) was used in nine studies for evaluation of preop and postop hip function. The mean preoperative HHS was 47.5 (range, 32.3-55.3), which improved to 82.3 (range, 71.7-92.5) postoperatively2,3,8,9,12,15,17,20,23). The Japanese Orthopedic Association score (JOA), which improved from 21.7 (range, 19.6-25.2) to 50.7 (range, 35.2-70.4), was used in three studies14,18,19). Grading the clinical outcome was based on scoring in three studies10,15,20). The results were as follows: 36.6% (n=71) excellent, 46.9% (n=91) good, 11.3% (n=22) fair, and 5.2% (n=10) poor. Only Dutka et al.10) graded the radiological outcome as excellent in 47 hips (34.8%), good in 60 hips (44.5%), fair in 18 hips (13.3%), and poor in 10 hips (7.4%). Three studies reported graft incorporation in all cases17,18,21) while Krushell et al.15) reported graft incorporation in 97% of cases. Mean time for graft union ranging from 3-6 months was reported in three studies3,11,20).
Among the studies, 48 revisions were reported. The mean time to revision surgery was 6.75 years (range, 0.27-8.8 years). The most common cause of revision surgery was aseptic loosening (n=38), followed by polyethylene wear/failure (n=4), and recurrent dislocations (n=4). The details regarding various revisions and other complications are shown in Table 3. Other common complications included heterotopic ossification (n=21), deep vein thrombosis (n=10), and nerve palsies (n=3). Four studies evaluated the survival rate of THAs in treatment of protrusion. Baghdadi et al.8) reported a survival rate free from acetabular revision of 85.4%. In their previous study, a higher 15-year survival rate was reported for uncemented cups as compared to cemented cups (89% vs. 85%)2). Rosenberg et al.21) reported a survival rate of 90% at 12-year follow-up, while Mibe et al.19) reported a survival rate of 72% when using both revisions and deaths as the end point.
Table 3 . Evaluation and Follow-up.
Study | Outcome measure | Preop | Postop | Revisions | Complications | Radiological evaluation | Conclusion/remarks | Follow-up mentioned? |
---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | HHS | 55.3±9.5 | 92.5±12.7 | Nil | Nil | Distance from center of femoral head to Kohler’s line increased from 19.87±3.9 mm to 21.5±3.5 mm after the operation. | For patients with PA secondary to RA cementless, trabecular, metal modular cup allowing peripheral press fitting and restoration of bone stock by impacted bone graft - satisfactory short-term results | Yes |
Baghdadi et al.8) (2015) | HHS | 55 | 82 | Revision, 15 hips; aseptic loosening, 12; polyethylene liner failure, 2; recurrent instability, 1 | Aseptic loosening, liner wear, recurrent instability | 5 unrevised acetabular components and 3 unrevised femoral components - non-progressive radiolucency | Satisfactory results for a median follow-up of 15 years for uncemented acetabular component in THR with PA | Yes |
Dutka et al.10) (2011) | HHS | NA | Mean, 86.6; cemented, 84.2; uncemented, 92.6 | Revision in 10 hips Both component loosening, 6; acetabular component loosening, 4 | 10 hips, loosening; HO Brooker II in 15 cases, DVT in 6, and wear of the acetabular component in 4 | The radiographic outcomes: excellent in 47 hips (34.8%), good in 60 (44.5%), fair in 18 (13.3%), and poor in 10 (7.4%) | At 12-year follow-up, better outcomes seen with patients operated with autogenous bone grafting than mixed bone grafting. No significant difference in type of prosthesis, aetiology and severity of PA in final outcome. | Yes |
Mullaji et al.20) (2007) | HHS | 52 | 85 | Nil | 1 postoperative hematoma 1 secondary suturing owing to necrosis of the superficial edges of the wound | All bone grafts united by the 6th month. Several small radiolucencies seen around the screw in 3 cases. | Uncemented porous coated hemispheric cups with peripheral press fit fixation and restoration of bone stock with impacted autologous bone grafting appears to give satisfactory medium-term results. | Yes |
Krushell et al.15) (2008) | HHS Hip centre to Kohler’s line distance | 41 24 mm | 84.6 30.9 mm | 1 case - secondary osteolysis due to polyethylene wear after 8 years | 1 peroneal nerve palsy and 1 case of recurrent dislocation. 1 case of late reoperation for polyethylene wear and secondary osteolysis. | At follow-up, mean protrusion medial to Kohler’s line was 1.0 mm, mean vertical distance 12.5 mm, mean horizontal distance 30.9 mm. | Excellent results obtained in 29 hips both clinically | Yes |
Baghdadi et al.2) (2013) | HHS | 51±12 | 77±18 | 11 revised - 9 asepic loosening, 1 linear wear and liner exchange, 1 instability | 9 - asepic loosening 1 - linear wear and liner exchange 1 - instability | Femoral offset decreased by 4±9 mm Hip COR improved by 11±6 mm | 10-year survival rate is 95% (95% CI). 15-year survival rate is 89% (95% CI) in uncemented. 10-year survival rate is 92% (95% CI). 15-year survival rate is 85% (95% CI) in cemented. | Yes |
Hansen and Ries12) (2006) | HHS | 32.3 | 71.7 | Revision - 1 due to recurrent dislocation | 5 - dislocation, 1 - developed a transient lateral femoral cutaneous neuropraxia, 1 - perioperative cardiac event | Mean protrusio position of the acetabular prostheses medial to Kohler’s line was 10.5 mm. | Uncontained medial acetabular defects can be successfully augmented with morselized bone graft , oversized rim fit acetabular component if good quality peripheral bone exists and integrity of acetabular rim is maintained. | Yes |
Rosenberg et al.21) (2000) | Long-term survival rate for primary THA | NA | NA | 2 revisions due to aseptic loosening | Aseptic loosening - 2 | In all cases, radiographs - the impacted morsellized bone grafts had become incorporated with the surrounding bone. | Long-term survival rate for primary THA in RA patients having protrusio acetabuli and acetabular reconstruction with impacted morselized bone graft is 90% (95% CI) at an average 12-year follow-up. | Yes |
Matsuno et al.18) (2000) | JOA score | 20.6 | 70.4 | Nil | One patient - transient sciatic nerve palsy | The COR of the hips was improved to within 4 mm of normal. | All grafts appeared to heal radiologically with no radiolucent line between graft and acetabulum. | Yes |
Gates et al.11) (1989) | Central edge angle Protrusion medial to Kohler’s line | 80.3° +8.6 mm | 57.7° –10.5 mm | 5 revisions -progressive protrusion | Loosening, 8; trochanteric non-union, 2 | Postoperatively-average distance of migration of the femoral head medial to Kohler’s line 10.5 mm, vertical migration average 5.3 mm. | Vertical migration and horizontal distance, two measurements utilizing a x-y coordinate system based on the tear drop-most useful radiographic measurements for determining the presence of PA and in following postoperative progression | Yes |
Kondo et al.14) (2002) | JOA score | 19.6 | 35.2 | Nil | 6 acetabular component loosening | Acetabular component loosening | The rate of loosening of THA without bone grafting was higher than that of THA with bone grafting. | Yes |
Liu et al.17) (2023) | 1. Range of flexion motion of the hip joint 2. Range of abduction motion 3. HHS | 39.48°±8.36° 10.86°±4.34° 37.84±4.74 | 103.07°±7.64° 36.75°±3.99° 89.55±4.05 | Nil | Reduction of the hip joint was extremely difficult in three patients (4 hips) | The horizontal distance of the hip rotation center increased from preoperative 10.40±2.50 mm to postoperative 24.03±1.77 mm, and the vertical distance increased from preoperative 72.36±3.10 mm to postoperative 92.48±5.31 mm. | Uncemented THA combined with impacted grafting granule bone of the autogenous femoral head and biological acetabular cup-reconstruct the acetabulum, restore the COR of hip joint, and achieve good medium-term outcomes in the treatment of moderate to severe PA secondary to RA. | Yes |
Zuh et al.23) (2015) | HHS | 42.3±3.9 | 85.2±3.0 | Nil | HO, 6 cases | Hip COR was restored close to the ideal values on the vertical axis, while on the horizontal axis the COR obtained was lateral to the ideal point. | Impaction bone grafting for acetabuloplasty, associated with the implantation of an uncemented cup, yields good midterm clinical and radiological results in patients with PA or primary hip arthrosis with a thinned medial acetabular wall. | Yes |
Yun et al.22) (2021) | Hip disability and osteoarthritis outcome score | Not done | 91±10.4 | 1 revision - stem subsidence | 1 case - Meckel’s diverticulum required 20 days of inpatient care for small bowel obstruction and acute pyelonephritis | Preoperative AK distance (mm): 8±4.5; range, 1-16 Postoperative AK distance (mm): 0±2.2; range, -4 to 3 | Anterior approach may decrease the significant risks of dislocation by avoiding posterior dissection. | Yes |
Mibe et al.19) (2005) | JOA score | 25.2±8.6 | 55.6±8.7 | 2 revisions owing to loosening of the Ganz ring | Loosening of the Ganz ring - 2 patients | The mean depth of the protrusio acetabuli was 3.6 mm before operation, and 3.1 mm just after the operation. | With THA for protrusio acetabuli in RA - no loosening, and bone stock maintained by a bone graft using a support ring. It suppresses progression of the PA in the short-term. | Yes |
Lee et al.16) (2022) | Modified HHS | NA | Restored group: 83.6±12.1, Medialized group: 83.8±10.4 | One patient - periprosthetic femoral fracture | No other complications | The mean abduction and anteversion angles (in degrees) of the acetabular component were 37.4 and 23.7 in the medialized group and 43.8 and 24.9 in the restored group, respectively. | Implant stability and favorable results were obtained by press-fitted cups, irrespective of hip center restoration. THA in PA patients-promising clinical and radiological results. | Yes |
Figueras Coll et al.9) (2008) | HHS | 42.3 | 90.6 | Nil | 4 DVT, 3 posterior hip dislocations, 3 wound infection | One had radiolucent lines >2 mm - zone 2, which did not progress. | Bone-grafting and acetabular wiremesh - effective and simple method to arrest the progresion of PA | Yes |
Johnsson et al.13) (1984) | NA | NA | NA | One hip revised - deep infection Recurrent dislocations occurred in one - re-operation planned | Recurrent dislocations, 1 hip; deep infection, 1 | Progressive radiolucent zone of 4-5 mm at the bone- cement interface - 2 hips Calcar resorption of 4-10 mm - 2 hips with 10 mm distal migration of the femoral component in the latter case | THA with the use of autogenous spongious bone graft reinforcement to the medial acetabular wall-successful surgical procedure in patients with RA and PA | Yes |
Values are presented as mean±standard deviation..
Preop: preoperative, Postop: postoperative, HHS: Harris hip score, Nil: nothing, PA: protrusio acetabuli, RA: rheumatoid arthritis, THR: total hip replacement, NA: not available, HO: heterotopic ossification, DVT: deep vein thrombosis, COR: centre of rotation, CI: confidence interval, THA: total hip arthroplasty, JOA: Japanese Orthopaedic Association, AK distance: medial acetabular border to kohler line distance..
PA can pose certain problems for patients requiring a THA. The most common indication of THA for protrusion was inflammatory arthritis, particularly rheumatoid arthritis. In such cases performance of THA can be challenging due to medialization of the acetabulum and the femoral head. However, all of the studies included in this review reported consistently good outcomes. The aim of this first-of-its-kind review is to determine the best method for achieving good outcomes with THA in treatment of protrusion. Literature includes evaluation of both cemented and uncemented options for THA. While achievement of better outcomes with uncemented cups with bone graft as compared to cemented has been confirmed, few studies evaluating the type of femoral stem that should be used have been reported, thus no conclusion can be drawn in that regard.
Opinion regarding the concept of restoration of the anatomical hip COR for achievement of a good outcome and better survival of the implant has been consistent. The Ranawat triangle method is the best-known method for estimation of anatomic hip COR24). When using this method, an isosceles right-angled triangle is drawn with base and perpendicular length equal to 20% of pelvic height projected from a point 5 mm lateral to the teardrop. The anatomic hip centre falls at the centre of the hypotenuse that is drawn. More recent studies have described different formulas for determining COR and maintain that their accuracy is greater than that of previous methods. Fujii et al.26), who formulated two new methods, the Modified Ranawat method and the pelvic height ratio method, reported that these methods are more accurate than the Ranawat triangle method. Pierchon et al.25) developed a method for calculating the hip centre using the teardrops and sacro-iliac joint. However, the COR migrates superomedially and requires inferiorization and lateralization. Baghdadi et al. detected a 24% risk of aseptic loosening with every 1 mm shift of the COR from the native COR. However, no difference was observed with a shift of COR on the vertical axis2). Lee et al.16) reported that implant stability and good outcomes were achieved with a press fit of cups and was not related to the restoration of the COR.
Filling the acetabular cavity secondary to lateralization of the cup with morselized bone graft is the best option. Ranawat and Zahn27) presented the first guidelines for bone grafting in patients with protrusion. Grafting is not recommended in cases of protrusion <5 mm with a strong medial wall; grafting is required for protrusion >5 mm with a thin medial wall; use of additional fixation devices is required in the case of a grossly deficient medial wall. Autogenous morcellised femoral head graft was used in most studies for restoration of the COR. Additional grafts from the iliac crest or trochanter can be used in cases where the femoral head is inadequate. Although allogenic graft and synthetic graft substitutes have also been used, Dutka et al.10) reported that a relatively poorer outcome was observed with use of a mixed graft as compared to an autogenous graft in 12-year follow-up. Histological studies have demonstrated complete graft incorporation after eight months followed by remodeling to the point that conversion of the graft into normal trabecular bone can be observed at 15 months post-surgery28). All studies included in the review reported that good incorporation of the bone graft was observed in almost all patients, which was achieved within approximately 3-6 months followed by consolidation and trabeculation of the graft. Kondo et al.14) reported a higher rate of loosening in hips that underwent surgery without a bone graft and placed emphasis on the importance of bone grafting. The majority of authors preferred to fill the medial acetabular cavity with bone graft and only 72 THAs were performed without bone grafting. Further progression of protrusion post THA can also be prevented with bone grafting. In the series reported by Baghdadi et al.2) poorer clinical scores were observed in hips that underwent surgery without bone grafting.
Commercially available bone mills, reamers, or rongeurs can be used in preparation of bone graft. Mullaji and Marawar20) reported that use of commercial bone mills can result in production of a graft size that is too small for use; however, Yun et al.22), who exclusively used a commercial mill, reported that there were no poor outcomes in terms of ingrowth or consolidation. A review by Mirza and Sadiq29) maintained that larger bone chips of 8 mm are the ideal size to provide stability for acetabular bone grafting. Some authors used only morselized bone graft while others used smaller pieces of bone impacted into the acetabulum while the gaps were filled with morselized graft. Kondo et al.14) reported on use of femoral neck slices when filling the bone defect. Good results were achieved with use of various methods of impaction, from the use of smaller trial heads to specialized impactors for reversal of reaming. Figueras Coll et al.9) reported on use of a titanium mesh in 25 patients while Rosenberg et al.21) used a vitallium mesh over the impacted bone graft to contain it in 27 patients. They reported that bone grafting with mesh is an effective and simple method for arresting progression of protrusion9,21).
Historically, cemented cups have been used routinely with good results11,13,14,21). However, in more recent studies the dynamics have shifted towards the use of uncemented cups based on achieving a peripheral rim fit. Proper acetabular preparation for use of a cementless cup is required in order to avoid overreaming the medial wall and consequent medialization of the cup. Smaller reamers or curettes can be used with care in preparation of the acetabular floor in order to create only a bleeding bed, not to enlarge the cavity. Reaming must be anatomical, with the goal of obtaining an equatorial press-fit fixation while avoiding the process described as “reaming-related medialization”, in order to avoid compromise of the acetabular offset30). Previous studies have reported on several techniques for achieving an adequate press-fit when using cementless cups, from a 2-mm underreaming to 1-mm line-to-line reaming23,31). Most authors have reported avoiding the use of additional screws for fixation until and unless considered necessary. A screw augmentation was used in only 148 out of 436 uncemented cups. Acetabular support rings were also used in two studies. Matsuno et al.18) reported on use of a Harris Galante porous coated cup with an MC ring supporter. The COR was restored within 4 mm of normal18). A study by Mibe et al.19) evaluated use of two cemented rings, the TACT Cup supporter and the Kerboul plate, and two uncemented rings, the Ganz ring and the Müller ring, with all cemented cups. They reported a survival rate of 72% when using both failure and death as end points. Better maintenance of acetabular thickness was achieved with use of uncemented rings as compared to cemented support rings19).
The studies included in this review do not provide adequate evaluation of the choice of femoral stem. Cementless stems were used primarily. The choice of femoral stem, which is based on the patient’s bone quality, should be individualized. The majority of patients with protrusio are females in the age group 65-70 years, many of whom are on chronic steroid therapy. These findings suggest the use of cemented stems in the majority of patients30). Dorr classification based on the cortical thickness of the proximal femur can provide guidance in the selection of a stem. According to a review by Bengoa et al.30), a low femoral neck osteotomy to avoid limb lengthening and use of femoral stems with collodiaphyseal angle in varus are recommended (<125°). Lateralization and posteriorization of the initial box osteotome are required in order to avoid placing a stem in varus, which is highly likely with the overhand of the greater trochanter. However, none of the studies included in the review have offered any rationale regarding the types of femoral stem or the type of fixation that should be used.
Baghdadi et al.2) performed surgery on 162 hips (107 uncemented vs. 55 cemented) and compared survival rates; the 10-year survival rate was 95% and the 15-year survival rate was 89% in the uncemented group and 92% and 85%, respectively, in the cemented group. In another study, they reported acetabular cup revision free survival of 94.3% at 10 years and 85.4% at 15 years for all uncemented cups8). Rosenberg et al.21) reported a survival rate of 90% at 12-year follow-up with use of cemented acetabular cups in rheumatoid patients with protrusion. The most common complications were aseptic loosening (n=55) and heterotopic ossification (n=21). While the former required revision, conservative management was administered for the latter. Other common complications included recurrent dislocations, polyethylene wear, and deep vein thrombosis. The incidence of infection and wound complications was relatively low. However, awareness of such complications is required, particularly in cases of inflammatory arthritis where the patient is on immunomodulatory and biological drugs30).
Our review has limitations. First, the review includes a mix of study types, many of which were retrospective, with no control groups for comparison of the outcome of THA in treatment of PA with that of THA for other indications. Identification of prospective comparative studies would be ideal. Second, in most studies the sample size was less than 50. However, due to the paucity of literature, we needed to utilize all available studies. Third, larger studies on this topic, such as studies utilizing registry data, are currently missing and interest will perhaps increase in the near future.
However, the large number of studies included in the review for analysis is a major strength of our study. To the best of our knowledge, this is the first systematic review reported in recent years that provides details on the various aspects of THA in the cohort of patients with PA. Performance of THA in this subset of patients is technically more difficult compared with other indications for a primary THA, as is the difference in outcome and complications. Therefore, this article would be helpful in assessing the outlook for such patients as it integrates all of the current evidence regarding the outcome of THA in patients with acetabular protrusio.
Performance of THA in patients with PA presents a greater challenge as compared to other routine indications. However, the results of the surgery are promising and, if done properly, survivorship may be comparable with that of THA for other indications. This review supports the use of an uncemented cup with a morselized autograft for filling the medial acetabular defect. Restoration of the anatomic hip centre of rotation and achieving a good press fit is extremely important. Screws or rings can be used to augment the fixation when considered necessary. Selection of the femoral stem should be decided on an individual basis according to anatomy and bone quality. However, there is a lack of good quality case-control studies comparing outcomes in patients undergoing THA for treatment of PA and other indications. Such studies are needed in order to attain a higher quality of evidence on this topic.
No funding to declare.
No potential conflict of interest relevant to this article was reported.
Table 1 . Quality Assessment of Studies according to New Castle–Ottawa Score.
Cohort studies | Representativeness of cohort | Ascertainment of exposure | Ascertainment of outcome (functional) | Adjustment for confounder | Follow-up mentioned |
---|---|---|---|---|---|
Zhen et al.3) (2018) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.8) (2015) | Yes | Yes | Yes | Yes | Yes |
Dutka et al.10) (2011) | Yes | Yes | Yes | Yes | Yes |
Mullaji and Marawar20) (2007) | Yes | Yes | Yes | Yes | Yes |
Krushell et al.15) (2008) | Yes | Yes | Yes | Yes | Yes |
Baghdadi et al.2) (2013) | Yes | Yes | Yes | Yes | Yes |
Hansen and Ries12) (2006) | Yes | Yes | Yes | Yes | Yes |
Rosenberg et al.21) (2000) | Yes | Yes | No | Yes | Yes |
Matsuno et al.18) (2000) | Yes | Yes | Yes | Yes | Yes |
Gates et al.11) (1989) | Yes | Yes | No | Yes | Yes |
Kondo et al.14) (2002) | Yes | Yes | Yes | Yes | Yes |
Liu et al.17) (2023) | Yes | Yes | Yes | Yes | Yes |
Zuh et al.23) (2015) | Yes | Yes | Yes | Yes | Yes |
Yun et al.22) (2021) | Yes | Yes | Yes | Yes | Yes |
Mibe et al.19) (2005) | Yes | Yes | Yes | Yes | Yes |
Lee et al.16) (2022) | Yes | Yes | Yes | Yes | Yes |
Figueras Coll et al.9) (2008) | Yes | Yes | Yes | Yes | Yes |
Johnsson et al.13) (1984) | Yes | Yes | No | Yes | Yes |
Table 2 . Study Characteristics and Demographic Details.
Study | Country | Inclusion/exclusion criteria | Etiology | Total hips | Study design | Mean age (yr) | Sex (F:M) | Extension of protrucio from Kohler’s line/Sotelo-Garza classification | Intervention | Approach | Implant | Follow-up |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | China | Protrusio in RA | RA | 20 hips (18 patients) | Prospective cohort | 45.8±8.3 | 12:6 | 12.7 mm | Uncemented with bone grafting | Posterolateral approach | Porous tantalum cups, 16 hips; titanium porous coated cups, 4; 4th generation ceramic-ceramic implantations, 8; polyethylene-lined ceramic implantations, 12 | 4.5±1.7 yr |
Baghdadi et al.8) (2015) | USA | THA done in protrusio | OA, 48 hips; RA, 15; sequele of septic arthritis, 2 | 65 hips (53 patients) | Retrospective cohort | 66 | 53:12 | 7±4 mm | Uncemented 58 hips, impacted with morselized bone graft; 26 hips, supplementary screw fixation | Anterolateral, 34 procedures; posterior, 28; transtrochanteric, 3 | Harris-Galante (HG)-I, 6 hips; Harris-Galante (HG)-II, 13; Omnifit, 17; Reflection™, 7; Porous-Coated Anatomic (PCA), 4; Press-Fit Condylar (PFC), 2; Elliptical, 1; Bi-Articular, 1; Trilogy®, 11; Hedrocel®, 3 | 15.4 yr |
Dutka et al.10) (2011) | Poland | 1. THA done in patients with protrusion acetabuli with any etiology 2. Minimum 4-year follow-up 3. Full medical records available | RA, 122 hips; Otto’s disease, 6; psoriatic arthritis, 3; SLE, 2; acetabular fracture, 1; radiation damage, 1 | 135 hips (127 patients) | Retrospective cohort | 55.2 | 119:8 | Grade 1, 48; grade 2, 36; grade 3, 21 | 128 hips, cemented; 7 hips, uncemented Autogenous grafts, 97 hips; mixed grafts, 38 | NA | NA | 12.7 yr |
Mullaji et al.20) (2007) | India | 1. Primary THAs in significant protrusio acetabuli 2. Minimum follow-up of 2 years | RA, 14 patients; ankylosing spondylitis, 5; Idiopathic, 4 | 30 hips (23 patients) | Prospective cohort | 46 | 17:6 | Grade 1, 8; grade 2, 10; grade 3, 12 | Uncemented THR with morselized BG | Anterolateral approach | Duraloc porous-coated cups, 17 cases; Bicontact cups, 13 One screw used to augment, 15 cases; 2 screws used, 12; no screw used, 3 A porous-coated stem used 21 cases: Bicontact, 13; Summit, 8 Cemented Charnley stems used, 9 cases | 4.2 yr |
Krushell et al.15) (2008) | England | Primary THA of any cause with acetabular protrusio | Inflammatory arthritis in 22 cases and OA in 7 cases | 29 hips (27 patients) | Retrospective cohort | 66 | 20:7 | Mean, 4.1 mm protrucio medial to Kohler’s line | Uncemented, Autologous BG in all cases Additional synthetic grafts, 3 cases | Posterolateral approach | Beaded dual-geometry acetabular shell design with multilayer titanium MicroStructured porous ingrowth surface | 4 yr |
Baghdadi et al.2) (2013) | USA | All patients with protrusio acetabuli who had undergone primary THR with a minimum follow-up of 2 years | Idiopathic, 117 hips; underlying inflammatory component, 38; genetic - 2, post infectious - 2, post radiation - 1, metabolic - 2 | 162 hips (127 patients) | Retrospective cohort | 66±13 | 112:15 | 7±5 mm | Cemented, 55 hips (14/55 cemented hips, bone grafting) Uncemented, 107 hips (83/107 uncemented hips, bone grafting done) | First-generation designs: Charnley, Aufranc Turner, Elliptical, Ti-Bac Cups Second-generation designs: Harris-Galante (HG)-I, Harris-Galante (HG)-II, Omnifit, Reflection, Porous-Coated Anatomic, PressFit Condylar Third-generation designs: Pinnacle, Trilogy, Hedrocel, Trident, Trabecular Metal Modular, Tritanium Hemispherical Cluster | 10±6 yr | |
Hansen and Ries12) (2006) | USA | 1. Revision surgeries 2. Large medial defect with at least 50% radiographic projected acetabular bone loss 3. Minimum 2-year follow-up | OA in 9 patients, RA in 3, posttraumatic arthritis in 2, avascular necrosis in 1, PVNS in 1, and DDH in 1 | 19 hips (17 patients) | Prospective cohort | 66 | 13:9 | 10.5 mm | Uncemented porous coated acetabular cup and morselized allograft | Posterior approach+ extended trochanteric osteotomy if necessary | Cementless hemispherical component with a widened peripheral rim | 2.8 yr |
Rosenberg et al.21) (2000) | Netherlands | 1. Patients diagnosed as RA with protrusio hip who under goes THA 2. Patients with minimum 8-year follow-up | RA | 20 hips (16 patients) | Prospective cohort | 53 | 13:3 | NA | Cemented cups with Morselized allograft | Posterolateral approach | 32 mm polyethylene Mueller or Allopro cup | 11.7 yr |
Matsuno et al.18) (2000) | Japan | Patients diagnosed to have RA with protrusio hip | RA | 15 hips (13 patients) | Prospective cohort | 61.9 | 9:4 | NA | Uncemented with iliac crest and morsellised femoral head graft | Aposterior approach | MC cup supporter | 53.6 mo |
Gates et al.11) (1989) | USA | Painful progressive protrusio acetabuli | RA, hemiarthroplasty, THA, OA | 48 hips (40 patients) | Prospective cohort | 57.8 | 29:11 | 8.6 mm | Cemented THA with medial acetabular reinforcement with BG Autologous BG, 39 hips; Allograft, 9 | NA | NA | 12.3 yr |
Kondo et al.14) (2002) | Japan | RA with protrusion acetabuli treated with THA Minimum 9-year follow-up | RA | 25 hips (19 patients) | Prospective cohort | 56.7 | 16:3 | Grade 1, 8; grade 2, 13; grade 3, 4 | Cemented with autologous graft | NA | NA | 129.6 mo |
Liu et al.17) (2023) | China | 1. RA 2. Moderate and severe in patients with acetabular protrusions in which the bottom of the acetabulum exceeded Kohler’s line in the pelvic AP radiography | RA | 56 hips (45 patients) | Prospective cohort | 55.64±5.38 | 28:17 | 10.97±3.08 mm | Uncemented THA with impacted bone grafting | Posterolateral approach | Biological total hip prostheses: A porous tantalum cup, 42 hips; sintered, three-dimensional, asymmetric, titanium, and porous-coated cups, 14; weight-bearing interfaces, 24; fourth-generation ceramic-on-ceramic implantations, and ceramic-on-highly cross-linked polyethylene, 32 | 5.20±1.20 yr |
Zuh et al.23) (2015) | Romania | THA in protrusio | Protrusion of unknown aetiology, 16 hips; RA, 6; protrusion secondary to tuberculous arthritis, 3; post-traumatic protrusion, 2; hip arthritis with thin medial acetabular wall, 12 | 39 hips (32 patients) | Retrospective study | 58.3±8.9 | 15:17 | I, 15 hips; II, 9; III, 3; thin medial wall, 12 | Medial acetabular wall – augmented by impaction bone grafting Uncemented cup – all cases | Direct lateral approach | 4.5 yr | |
Yun et al.22) (2021) | USA | THA in protrusio | 5 patients, RA; 18 patients, idiopathic PA | 23 THAs in 21 patients | Retrospective study | 68±9 | 19:2 | Mild, 7 patients; moderate, 13; severe, 3 | Morcellized femoral head autograft using Bone Mill, cementless acetabular cups | Direct anterior approach | 5.3 yr | |
Mibe et al.19) (2005) | Japan | Protrusio in RA | RA | 19 hips of 15 patients | Retrospective | 60.2 (48-75) | All F | 12 hips, grade 1; 3 hips, grade 2; 1 hip, grade 3 Medial-proximal type, 3 hips | THA using a support ring All cups- cemented | Not mentioned | 4 hips, TACT cup supporter; 1 hip, Kerboull plate; 6 hips, a Ganz ring; 5 hips, Müller ring | 38 mo |
Lee et al.16) (2022) | Korea | THA in protrusio | RA, 14 hips; post-traumatic arthritis, 7; ankylosing spondylitis, 4; previous infection, 1 | 26 cementless THAs of 22 patients | Retrospective study | 59.9 | 17:5 | Mild, 5 hips; moderate, 19; severe, 2 | Uncemented THA, reinforcement acetabular components in 2 hips | Kocher-Langenbeck approach | PLASMACUP SC, 9 hips; Bencox cup, 7; Pinnacle cup, 5; G7 cup, 1; ABT cup, 1; Delta TT cup, 1 SPH reinforcement cups, 2 hips with defective rim of the acetabulum | 5.1 yr |
Figueras Coll et al.9) (2008) | Spain | THA in protrusio | Severe arthrosis (50% of cases), protrusio due to hemiarthroplasties (15%), and rheumathoid arthritis (15%) Aseptic loosening of the acetabular cup in THA, and some other causes- less common diagnoses | 25 hips (25 patients) | Retrospective study | 71.1 | 16:9 | Paproski’s classification – 20 type IIa cases, 4 type IIb and 1 type IIc | Cemented acetabular cup, autogenous morcellized bone-graft and acetabular wiremesh | Anterolateral | Charnley stem and cemented cup (7 right and 18 left hips) | 8.6 yr |
Johnsson et al.13) (1984) | Sweden | Protrusio in RA | RA | 27 hips (25 patients) | Retrospective study | 56 (29-76) | 21:4 | Joint destruction according to Larsen and Larsen et al. 12 hips, grade IV; 15 hips, grade V Mean acetabular protrusion, 6 mm | Spongious bone chips from the trochanter and/or the femoral head, and iliac crest, 10 cases – thin titanium net A high density polyethylene (HDPE) protrusion cup – last 5 cases | 26 hips, postero-lateral; 1 hip, anterior approach without trochanteric osteotomy | Lubinus (25) and McKee-Arden (2) types | 2 yr |
Values are presented as mean±standard deviation or mean (range)..
F: female, M: male, RA: rheumatoid arthritis, THA: total hip arthroplasty, OA: osteoarthritis, SLE: systemic lupus erythematosus, NA: not available, THR: total hip replacement, BG: bone graft, PVNS: pigmented villonodular synovitis, DDH: developmental dysplasia of hip, AP: anteroposterior, PA: protrusio acetabuli..
Table 3 . Evaluation and Follow-up.
Study | Outcome measure | Preop | Postop | Revisions | Complications | Radiological evaluation | Conclusion/remarks | Follow-up mentioned? |
---|---|---|---|---|---|---|---|---|
Zhen et al.3) (2018) | HHS | 55.3±9.5 | 92.5±12.7 | Nil | Nil | Distance from center of femoral head to Kohler’s line increased from 19.87±3.9 mm to 21.5±3.5 mm after the operation. | For patients with PA secondary to RA cementless, trabecular, metal modular cup allowing peripheral press fitting and restoration of bone stock by impacted bone graft - satisfactory short-term results | Yes |
Baghdadi et al.8) (2015) | HHS | 55 | 82 | Revision, 15 hips; aseptic loosening, 12; polyethylene liner failure, 2; recurrent instability, 1 | Aseptic loosening, liner wear, recurrent instability | 5 unrevised acetabular components and 3 unrevised femoral components - non-progressive radiolucency | Satisfactory results for a median follow-up of 15 years for uncemented acetabular component in THR with PA | Yes |
Dutka et al.10) (2011) | HHS | NA | Mean, 86.6; cemented, 84.2; uncemented, 92.6 | Revision in 10 hips Both component loosening, 6; acetabular component loosening, 4 | 10 hips, loosening; HO Brooker II in 15 cases, DVT in 6, and wear of the acetabular component in 4 | The radiographic outcomes: excellent in 47 hips (34.8%), good in 60 (44.5%), fair in 18 (13.3%), and poor in 10 (7.4%) | At 12-year follow-up, better outcomes seen with patients operated with autogenous bone grafting than mixed bone grafting. No significant difference in type of prosthesis, aetiology and severity of PA in final outcome. | Yes |
Mullaji et al.20) (2007) | HHS | 52 | 85 | Nil | 1 postoperative hematoma 1 secondary suturing owing to necrosis of the superficial edges of the wound | All bone grafts united by the 6th month. Several small radiolucencies seen around the screw in 3 cases. | Uncemented porous coated hemispheric cups with peripheral press fit fixation and restoration of bone stock with impacted autologous bone grafting appears to give satisfactory medium-term results. | Yes |
Krushell et al.15) (2008) | HHS Hip centre to Kohler’s line distance | 41 24 mm | 84.6 30.9 mm | 1 case - secondary osteolysis due to polyethylene wear after 8 years | 1 peroneal nerve palsy and 1 case of recurrent dislocation. 1 case of late reoperation for polyethylene wear and secondary osteolysis. | At follow-up, mean protrusion medial to Kohler’s line was 1.0 mm, mean vertical distance 12.5 mm, mean horizontal distance 30.9 mm. | Excellent results obtained in 29 hips both clinically | Yes |
Baghdadi et al.2) (2013) | HHS | 51±12 | 77±18 | 11 revised - 9 asepic loosening, 1 linear wear and liner exchange, 1 instability | 9 - asepic loosening 1 - linear wear and liner exchange 1 - instability | Femoral offset decreased by 4±9 mm Hip COR improved by 11±6 mm | 10-year survival rate is 95% (95% CI). 15-year survival rate is 89% (95% CI) in uncemented. 10-year survival rate is 92% (95% CI). 15-year survival rate is 85% (95% CI) in cemented. | Yes |
Hansen and Ries12) (2006) | HHS | 32.3 | 71.7 | Revision - 1 due to recurrent dislocation | 5 - dislocation, 1 - developed a transient lateral femoral cutaneous neuropraxia, 1 - perioperative cardiac event | Mean protrusio position of the acetabular prostheses medial to Kohler’s line was 10.5 mm. | Uncontained medial acetabular defects can be successfully augmented with morselized bone graft , oversized rim fit acetabular component if good quality peripheral bone exists and integrity of acetabular rim is maintained. | Yes |
Rosenberg et al.21) (2000) | Long-term survival rate for primary THA | NA | NA | 2 revisions due to aseptic loosening | Aseptic loosening - 2 | In all cases, radiographs - the impacted morsellized bone grafts had become incorporated with the surrounding bone. | Long-term survival rate for primary THA in RA patients having protrusio acetabuli and acetabular reconstruction with impacted morselized bone graft is 90% (95% CI) at an average 12-year follow-up. | Yes |
Matsuno et al.18) (2000) | JOA score | 20.6 | 70.4 | Nil | One patient - transient sciatic nerve palsy | The COR of the hips was improved to within 4 mm of normal. | All grafts appeared to heal radiologically with no radiolucent line between graft and acetabulum. | Yes |
Gates et al.11) (1989) | Central edge angle Protrusion medial to Kohler’s line | 80.3° +8.6 mm | 57.7° –10.5 mm | 5 revisions -progressive protrusion | Loosening, 8; trochanteric non-union, 2 | Postoperatively-average distance of migration of the femoral head medial to Kohler’s line 10.5 mm, vertical migration average 5.3 mm. | Vertical migration and horizontal distance, two measurements utilizing a x-y coordinate system based on the tear drop-most useful radiographic measurements for determining the presence of PA and in following postoperative progression | Yes |
Kondo et al.14) (2002) | JOA score | 19.6 | 35.2 | Nil | 6 acetabular component loosening | Acetabular component loosening | The rate of loosening of THA without bone grafting was higher than that of THA with bone grafting. | Yes |
Liu et al.17) (2023) | 1. Range of flexion motion of the hip joint 2. Range of abduction motion 3. HHS | 39.48°±8.36° 10.86°±4.34° 37.84±4.74 | 103.07°±7.64° 36.75°±3.99° 89.55±4.05 | Nil | Reduction of the hip joint was extremely difficult in three patients (4 hips) | The horizontal distance of the hip rotation center increased from preoperative 10.40±2.50 mm to postoperative 24.03±1.77 mm, and the vertical distance increased from preoperative 72.36±3.10 mm to postoperative 92.48±5.31 mm. | Uncemented THA combined with impacted grafting granule bone of the autogenous femoral head and biological acetabular cup-reconstruct the acetabulum, restore the COR of hip joint, and achieve good medium-term outcomes in the treatment of moderate to severe PA secondary to RA. | Yes |
Zuh et al.23) (2015) | HHS | 42.3±3.9 | 85.2±3.0 | Nil | HO, 6 cases | Hip COR was restored close to the ideal values on the vertical axis, while on the horizontal axis the COR obtained was lateral to the ideal point. | Impaction bone grafting for acetabuloplasty, associated with the implantation of an uncemented cup, yields good midterm clinical and radiological results in patients with PA or primary hip arthrosis with a thinned medial acetabular wall. | Yes |
Yun et al.22) (2021) | Hip disability and osteoarthritis outcome score | Not done | 91±10.4 | 1 revision - stem subsidence | 1 case - Meckel’s diverticulum required 20 days of inpatient care for small bowel obstruction and acute pyelonephritis | Preoperative AK distance (mm): 8±4.5; range, 1-16 Postoperative AK distance (mm): 0±2.2; range, -4 to 3 | Anterior approach may decrease the significant risks of dislocation by avoiding posterior dissection. | Yes |
Mibe et al.19) (2005) | JOA score | 25.2±8.6 | 55.6±8.7 | 2 revisions owing to loosening of the Ganz ring | Loosening of the Ganz ring - 2 patients | The mean depth of the protrusio acetabuli was 3.6 mm before operation, and 3.1 mm just after the operation. | With THA for protrusio acetabuli in RA - no loosening, and bone stock maintained by a bone graft using a support ring. It suppresses progression of the PA in the short-term. | Yes |
Lee et al.16) (2022) | Modified HHS | NA | Restored group: 83.6±12.1, Medialized group: 83.8±10.4 | One patient - periprosthetic femoral fracture | No other complications | The mean abduction and anteversion angles (in degrees) of the acetabular component were 37.4 and 23.7 in the medialized group and 43.8 and 24.9 in the restored group, respectively. | Implant stability and favorable results were obtained by press-fitted cups, irrespective of hip center restoration. THA in PA patients-promising clinical and radiological results. | Yes |
Figueras Coll et al.9) (2008) | HHS | 42.3 | 90.6 | Nil | 4 DVT, 3 posterior hip dislocations, 3 wound infection | One had radiolucent lines >2 mm - zone 2, which did not progress. | Bone-grafting and acetabular wiremesh - effective and simple method to arrest the progresion of PA | Yes |
Johnsson et al.13) (1984) | NA | NA | NA | One hip revised - deep infection Recurrent dislocations occurred in one - re-operation planned | Recurrent dislocations, 1 hip; deep infection, 1 | Progressive radiolucent zone of 4-5 mm at the bone- cement interface - 2 hips Calcar resorption of 4-10 mm - 2 hips with 10 mm distal migration of the femoral component in the latter case | THA with the use of autogenous spongious bone graft reinforcement to the medial acetabular wall-successful surgical procedure in patients with RA and PA | Yes |
Values are presented as mean±standard deviation..
Preop: preoperative, Postop: postoperative, HHS: Harris hip score, Nil: nothing, PA: protrusio acetabuli, RA: rheumatoid arthritis, THR: total hip replacement, NA: not available, HO: heterotopic ossification, DVT: deep vein thrombosis, COR: centre of rotation, CI: confidence interval, THA: total hip arthroplasty, JOA: Japanese Orthopaedic Association, AK distance: medial acetabular border to kohler line distance..
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