The annual number of total hip arthroplasty (THA) procedures performed in the United States is expected to reach approximately 572,000 by 2030¹⁾. THA can provide pain relief and improved quality of life for patients with end stage osteoarthritis²⁾. Other indications for THA include fractured neck of the femur, dysplasia, avascular necrosis, and inflammatory arthritis³⁾. Surgical approaches used in performance of THA can vary on the initial incision site and subsequent manipulation of the muscles may be required to reach the hip joint. Three prevalent surgical approaches have been employed in performance of THA: the direct anterior approach (DAA), anterolateral approach (ALA), and posterior approach (PA). Ongoing discussions regarding their relative merits persist⁴⁾.

The popularity of DAA has increased in recent years. The gluteal muscles can be avoided when using the DAA by making an incision over and through the fascia covering the tensor fascia latae muscle (TFL), during the interval between the TFL and the sartorius muscle⁵⁾. Faster time to mobilization and reduced early postoperative pain have been reported for DAA THA patients compared to ALA and PA. These findings suggest that the DAA may have an advantage for outpatient procedures⁶⁾. Decisions regarding the preferred approach are based on surgeon preferences, experience, and specific characteristics of each patient⁷⁾.

This study was conducted for the purpose of analyzing trends, global contributors, journals, authors, and articles in the literature on direct anterior total hip arthroplasty (DA THA). The findings of this study will also demonstrate the impact of DA THA research, geographical contributions, publication patterns, collaborations, and evolving research themes. Finally, it will provide a comprehensive overview of the current literature on DA THA research and highlight current and emerging hotspots.

1. Sources of Data and Search Strategy

The Web of Science (WoS) Core Collection of Clarivate Analytics was used due to its popularity as a data source for conduct of bibliometric research and its accessibility to comprehensive information. The Social Science Citation Index (SSCI) and the Science Citation Index (SCI) Expanded were used in conducting a literature search. The keyword query included “hip replacement” OR “hip arthroplasty” OR “total hip” OR “THA” (all fields) AND “anterior” OR “direct anterior approach” OR “DA” OR “DAA” OR “anterior based” (topic) AND 1982-2022 (year published) AND Article (document type). To minimize the risk of omission, this study focused on articles as the document type and indexes of SCI Expanded and SSCI spanning from 1993 to 2022 were utilized. The selection of search terms was based on previously published articles on anterior hip approaches.

2. Data Extraction

Data collection was performed by two authors. After screening the database, acquisition and examination of pertinent data required for the analysis was performed. Specific details including the year of publication, the title, the institutions, the nations, the journal of publishing, the abstracts, the references, the citations, and the impact factor were examined in this bibliometric study.

3. Bibliometric Analysis

Excel files containing the bibliometric indicators were extracted from the WoS database and then imported for further examination. Omitted data was cross-referenced using the WoS database. Data from different areas of interest were grouped using a country-specific classification. Data visualizations including co-authorship, topic trends, co-citation, dual-map overlay, thematic map, knowledge maps of scientific production, and thematic evolution were created using VOSviewer (ver. 1.6.19.0) (Leiden University, Leiden, Netherlands) and Bibliometrix (University of Naples Federico, Naples, Italy).

1. Publication Data

A search of the WoS database retrieved 743 articles related to DA THA published between 1993 and 2022, with an average of 18.34 citations per document. Fig. 1 shows an upward trend in global scientific production with an annual growth rate of 17.71%. The highest number of annual publications was reported in 2021 with 120 articles, followed by 2022 with 113 articles, 2020 with 104 articles, and 2018 with 69 articles.

Figure 1. Annual scientific production showing an increase in global production of articles.

2. Countries

Table 1 shows the country’s scientific production with literature originating from 41 countries. The US was the most significant contributor with 34.1%. The top 10 producing countries after the USA were Japan at 7.1%, Germany at 6.8%, Switzerland at 5.7%, France at 5.4%, Canada at 5.3%, China at 5.2%, Australia at 5.0%, Netherlands at 5.0%, Austria at 4.0%, and Belgium at 2.7%. Fig. 2 show that the US generated the highest number of citations with a total of 6,501 citations and had the highest yearly production from 2003 to 2022.

Figure 2. (A) Most cited countries over time. (B) Country production over time.

Table 1 . Country Scientific Production.

Region	No. of published papers
USA	612
Japan	128
Germany	122
Switzerland	102
France	96
Canada	95
China	94
Australia	89
Netherlands	89
Austria	71
Belgium	48
Italy	45
Norway	34
United Kingdom	28
Türkiye	22
Greece	15
South Korea	11
Spain	11
Hungary	8
Thailand	8
Israel	7
Colombia	6
Iran	6
India	5
Poland	5
Sweden	5
Czech Republic	4
Ireland	4
Singapore	4
Brazil	3
Romania	3
Denmark	2
Portugal	2
South Africa	2
Bahrain	1
Bulgaria	1
Egypt	1
Lebanon	1
New Zealand	1
Russia	1
Serbia	1

3. Institutions

A total of 732 institutions published at least one article with the top eight institutions from the USA, Austria, Canada, France, and Japan as shown in Fig. 3. The Medical University of Innsbruck made the most significant contribution with 263 articles, followed by the University of Ottawa with 229, Rothman Institute with 143, Udice-French Research Universities with 131, Ottawa Hospital Research Institute with 120, Jefferson University with 101, Juntendo University with 86, and University of Western Ontario with 61 articles. The Medical University of Innsbruck and the University of Ottawa had the highest annual production in 2022 with 44 and 41 articles, respectively. This was followed by Ottawa Hospital Research Institute in 2022 with 26 articles and Rothman Institute in 2022 with 24 articles as shown in Fig. 3.

Figure 3. Affiliations’ production over time in direct anterior total hip arthroplasty research.

4. Journals

DA THA specific manuscripts were published in 116 journals. The most relevant and impactful journals were the Journal of Arthroplasty with 903 articles and 4,571 citations, followed by Hip International with 267 articles and 501 citations, and Archives of Orthopaedic and Trauma Surgery with 114 articles and 366 citations as shown in Fig. 4A. As shown in Fig. 4B, the greatest annual production for the Journal of Arthroplasty was between 2020 and 2021 with 30 articles. The most impactful journals according to H-index were the Journal of Arthroplasty at 35, Clinical Orthopaedics and Related Research at 21, International Orthopaedics at 17, Journal of Bone and Joint Surgery – American Volume at 14, and the Bone and Joint Journal at 12 as shown in Fig. 4C.

Figure 4. (A) Most local cited sources. (B) Sources’ production over time. (C) Sources’ local impact by H-index.

5. Most Influential Articles

The 10 most cited articles are shown in Fig. 5, and the most influential article was authored by Matta et al.⁸⁾ in 2005 with 393 citations, followed by Barrett et al.⁹⁾ in 2013 with 267 citations.

Figure 5. Most global cited documents.

6. Keywords

Of the 1,070 authors’ keywords, 47 keywords appeared at least 10 times, with the term “replacement” appearing 1,551 times (Fig. 6). Fig. 7A shows the co-occurrence visualization depicting the interrelation of keywords. Fig. 7C shows the density clusters of topics. The size of each circle corresponds to the frequency of its appearance. A burst in utilization of keywords including “dislocation,” “posterior approach,” and “revision” occurred during the period from 2015 to 2020. Fig. 7B shows a visual depiction of clusters along with their corresponding time frames. The thematic evolution depicted in Fig. 7D shows keywords used during the time period from 1993 to 2019 including “mortality,” “approach,” and “muscle damage” to 2020-2022 with notable keywords that include “quality of life,” “clinical outcomes,” “dislocation,” “revision arthroplasty,” and “postoperative pain.” Fig. 7E shows the thematic map arranged according to centrality and density. Centrality is defined as the association strength of keywords linkage while density indicates the strength of the topic or cluster development. Niche themes characterized by low centrality and high density are considered developed clusters but have yet to impact literature on DAA. Motor themes characterized by high centrality and density are the current trending themes showing high linkage between keywords. Basic themes characterized by high centrality and low density are considered keywords with a significant impact, but lack further development. Fig. 8 shows the evolution in topics from 2008 to 2022. In particular, the most trending keywords were as follows: “posterior” in 2018, “dislocation” and “outcomes” in 2019, “direct anterior approach” in 2020, and “revision,” and “quality of life” in 2021.

Figure 6. Words’ frequency over time.

Figure 7. (A) Keywords co-occurrence overlay. (B) Co-occurrence overlay showing the thematic keywords evolution. (C) Density clusters of topics. (D) Thematic evolution. (E) Thematic map.

Figure 8. Trend topics.

This bibliometric analysis was conducted for identification of previous, current, and trending topics within the field of DA THA research. Analysis of relevant journals, countries, affiliated institutions, authors, articles, and keywords was performed for identification of developing hotspots in the literature.

1. Articles

Recognizing these publications is critical for assessing trends in themes and predicting potential areas of interest in the future¹⁰⁾. The randomized controlled trial “Otto Aufranc Award: a multicenter, randomized study of outpatient versus inpatient total hip arthroplasty” reported by Goyal et al.¹¹⁾ included the highest number of citations (137 citations). Higher pain levels were observed for outpatients on the first day; however, no significant differences in reoperations, readmissions, or follow-up interactions were observed between outpatient and inpatient THA patients¹¹⁾. The second most cited article was “A prospective randomized assessment of earlier functional recovery in THA patients treated by minimally invasive direct anterior approach: a gait analysis study” reported by Mayr et al.¹²⁾ that included 128 citations. The findings of the study indicated that patients undergoing minimally invasive DAA showed superior improvements in gait parameters compared to those using the traditional ALA, particularly between six and 12 weeks post-surgery¹²⁾. The third most cited article with 122 citations was “Incidence of lateral femoral cutaneous nerve neuropraxia after anterior approach hip arthroplasty” by Goulding et al.¹³⁾. The objective of the study was to determine the frequency and impact of lateral femoral cutaneous nerve (LFCN) neuropraxia following the use of an anterior hip approach for hip resurfacing and primary THA. Among 107 patients, development of LFCN neuropraxia was reported in 81%, with greater prevalence in patients who underwent hip resurfacing (91%) compared with THA (67%). In a subgroup of 60 patients followed for 12 months, 88% of patients initially experienced neuropraxia, with only 6% achieving full recovery. Despite its common occurrence after DA THA, and LFCN neuropraxia did not restrict functionality, and symptoms decreased over time, although complete resolution was infrequent¹³⁾.

2. Keywords and Clusters

Clusters and their associated keywords are depicted in both the co-occurrence overlay shown in Fig. 7A and the density map shown in Fig. 7C. Keywords including “dislocation,” “posterior approach,” and “revision” were used frequently from 2015 to 2020, in agreement with the increasing emphasis on perioperative complications and comparing different approaches. A visual representation of clusters and their respective time frames is shown in Fig. 7B. The critical issues cluster gained prominence in 2018, featuring keywords such as “failure,” “fixation,” and “fractures,” with node links extending to “mortality” in 2020. A comprehensive keyword search identified six clusters. The identified clusters were compared with other surgical approaches, acetabular component placement, and a comprehensive assessment of complications. This comprehensive assessment of complications consisted of the following clusters: ALA complications, nerve damage considerations, critical issues, osteotomy and quality of life, and dislocations. The critical issues clusters included failure, femur fixation, and fractures while examining their impact on overall mortality.

1) Comparison with other approaches

The cluster keywords included “incision,” “complications,” “direct lateral,” “experience,” “gait,” “lateral approach,” “learning curve,” “mini-incision,” “muscle damage,” “posterior approach,” “posterolateral approach,” and “wound complications.” There are multiple surgical approaches for gaining access to the hip when performing THA including DAA, ALA, lateral approach, and posterolateral approach (PLA)¹⁴⁾. Decisions regarding the surgical approach in performance of primary and revision THA are based on surgeon experience and patient preferences with individual patient factors and history^15,16).

Low revision rates for dislocations and other causes have been reported for the DAA¹⁷⁾, while a reduction in postoperative drainage, incision length, estimated blood loss, bedrest duration, length of stay, and surgery duration has been reported¹⁸⁾ . When compared with PLA for THA, the DAA is considered a minimally invasive approach that can offer notable advantages, particularly for geriatric patients who often present with medical comorbidities. PLA is a commonly used approach for reasons of simplicity in execution and favorable intraoperative exposure⁴⁾. According to the study by Jin et al.¹⁸⁾ comparing the PLA and DAA groups, PLA patients had longer skin incisions with increased levels of blood loss and postoperative drainage, suggesting the advantages of DAA in minimizing soft tissue damage and blood transfusion. A meta-analysis by Putananon et al.¹⁹⁾ reported that the lateral approach was the most effective for improving the visual analog scale score, followed by the anterior approach. However, when performing an assessment based on function using the Harris hip score, the anterior approach was the most effective, followed by the lateral approach¹³⁾. DAA is not without inherent disadvantages including a higher revision rate for aseptic stem loosening, potentially due to a tendency to utilize a smaller metaphyseal stem^10,20). A meta-analysis conducted by Awad et al.²¹⁾ comparing DAA and PLA reported increased complication rates, nerve injuries, peri-prosthetic femur fractures, revision rates, and surgical wound complications, but lower rates of dislocations and venous thromboembolism for DAA. In addition, there is a significant learning curve when using the DAA, and 50 or more procedures are required to achieve a complication plateau^10,22).

2) Acetabular component placement

Keywords for the acetabular component placement clusters included “accuracy,” “acetabular component,” “anteversion,” “dislocation,” “fluoroscopy,” “motion,” “orientation,” “placement,” “polyethylene wear,” “safe zone,” and “revision.”

The acetabulum and proximal femur orientations differ significantly between DAA and PLA. The hip is surgically dislocated anteriorly in performance of DAA compared to PLA, resulting in a different intraoperative exposure of the acetabulum^23-25). This variance in exposure can lead to different perspectives with regard to intraoperative landmarks. In addition, the minimally invasive nature of this procedure allows limited exposure of the proximal femur when using the DAA, which increases the risk of component malpositioning²⁶⁾. The DAA offers the benefit of performing surgery in a supine position, with the disadvantage of using intraoperative fluoroscopy radiation^27,28).

Incorrect placement of a component can be a cause of functional issues and complications including impingement, dislocation, and accelerated wear²⁹⁾. Excessive anteversion of the acetabulum can cause anterior dislocation or impingement, whereas retroversion may result in posterior dislocation or iliopsoas impingement with excessive acetabular prominence³⁰⁾. In a similar manner, excessive inclination may lead to lateral dislocation²⁰⁾. A study conducted by Callanan et al.³¹⁾ reported an elevated risk of acetabular malpositioning when using a minimally invasive approach, low-volume surgeons, and obese patients.

3) Complications assessment

(1) Anterolateral approach

Keywords used for the ALA cluster included “anterolateral approach,” “damage,” “femoral cutaneous nerve,” “posterior,” and “superior gluteal nerve.” Anterolateral approach has been associated with complications including femur fracture, abductor muscle damage, and femoral nerve palsy (FNP). FNP has been reported to occur in 0.6% to 5% of cases with risk factors including hematoma formation, traction, ischemia, laceration, and retractor-induced injury³²⁾. Placement of an anterior wall retractor with excessive traction and compression through the iliopsoas has been hypothesized as the most significant risk factor for FNP³³⁾. The incision for ALA is made further from the fascia to gain access to the hip joint located between the tensor fasciae latae and gluteus medius. However, as both muscles receive innervation from the superior gluteal nerve, ALA may be a reason for reduced muscular strength if the nerve is damaged³⁴⁾. In contrast to the lateral hip approach, ALA can preserve soft tissue, minimize the risk of dislocation, and promote rapid recovery of muscular strength³⁵⁾. By contrast, results from use of the minimally invasive DAA indicated improvements in a broader range of gait parameters, including cadence, stride time and length, walking speed, and others, when compared to the ALA¹²⁾.

(2) Critical issues

The keywords for the critical issues cluster included “failure,” “femur,” “fixation,” “fractures,” and “mortality.” In a study analyzing data from the New Zealand Joint Registry, patients between 46 to 50 years of age at the time of the initial THA had a lifetime risk of revision of 27.6%, compared to a rate of 1.1% for patients aged 90 to 95 years³⁶⁾. The leading causes for revision following primary THA were aseptic loosening, infection, periprosthetic fracture, and dislocation³⁶⁾. In addition, in a series of 198 cases, Jayasinghe et al.³⁷⁾ reported a five year and overall mortality rate of 22% and 33% , respectively. When examining mortality rates per indication for revision, variations in the 5-year mortality rates were observed across different scenarios: revision of hemiarthroplasty (51%), periprosthetic fracture (28%), infection (14%), and aseptic loosening (13%)³⁷⁾.

(3) Osteotomy and quality of life

Keywords for the osteotomy and quality of life cluster included “osteotomy” and “quality of life.” Osteotomy can be regarded as an initial operative option for joint preservation for avascular osteonecrosis of the femoral head for prevention of necrotic bone collapse and to promote repair for dispersal of weight-bearing forces³⁸⁾. THA is the typical treatment for advanced femoral head collapse or end stage osteoarthritis of the hip³⁸⁾. Osteotomy for joint preservation can modify the native alignment for achievement of outcomes similar to those reported for regenerative therapy, such as intraarticular injection with platelet-rich plasma, mesenchymal stem cells, and bone marrow aspirate concentrate³⁹⁾. Nakai et al.⁴⁰⁾ reported that THA was more reliable than osteotomy transtrochanteric rotational osteotomy for improving the quality of life for 37 patients with necrosis of the femoral head.

(4) Dislocation

Use of the PLA was associated with revision due to dislocation, when compared with the DAA, straight lateral approach, and ALA¹⁷⁾. Several patient-related factors including advanced age, white ethnicity, high body mass index, low income, drug use disorder, and social deprivation were identified as risk factors for dislocation⁴¹⁾. In addition, comorbidities including a previous history of spinal fusion surgery, hip surgery, or patients undergoing THA for management of avascular necrosis, rheumatoid arthritis, inflammatory arthritis, or osteonecrosis were associated with an elevated risk of dislocation^41-43). Selection of a surgical approach may be helpful in efforts to mitigate the risk of dislocation in performance of primary THA. Prophylactic interventions that can be considered for patients at high risk of dislocation include cemented fixations, larger femoral head sizes, elevated acetabular liners, or dual mobility bearings⁴¹⁾. In addition, perioperative optimization of modifiable risk factors and comorbidities may be helpful in further reducing the risk⁴¹⁾.

This bibliometric analysis examined past, current, and emerging trends in large databases, providing insights for predicting potential focal points for conduct of future research. In fact, a noteworthy interest and traction with use of the DAA for THA has been observed in the literature. In addition, the results of cluster analysis revealed predominant themes including comparisons of the DAA to other approaches, assessment of acetabular component placement, ALA, critical issues, osteotomy and quality of life, and dislocations. All of these clusters and trends emphasize the focus of joint surgeons around the world on optimizing THA, with potentially promising postoperative improvements in patient reported outcome measures.

No funding to declare.

No potential conflict of interest relevant to this article was reported.