Prosthetic joint infection (PJI) is one of the major complications following arthroplasty. Optimal management of PJI is not limited to the treatment of joint infection alone, but also includes the maintenance of normal joint function along with improving quality of life.

Unlike other focal infections, PJI is particularly difficult to treat. Microorganisms form a biofilm on the metal surface of the implant, which interferes with antibiotic penetration and promotes resistance. The success of PJI treatment is dependent on the elimination of these biofilm-dwelling microorganisms¹,2). The primary surgical interventions performed to manage PJI are, either removal of the prosthesis to eliminate the biofilm, which may be followed up with a revision surgery later, or retaining the prosthesis and administration of biofilm active antibiotics along with radical debridement3).

Compared to other treatment options for early PJI, debridement with prosthesis retention is relatively simpler and has lesser morbidity, shorter hospital stay, and lower costs compared to revision surgery4). However, the reported success rates of debridement with prosthesis retention and long-term antibiotics is highly variable (21-89%)^4,5,6,7,8,9,10). Hence, in the current study, we evaluated the outcome of radical debridement with retention of prosthesis for early PJI after hip arthroplasty.

The Coventry classification modified by Senthi et al. for postoperative infections in hip arthroplasty describes the following general stages¹⁴,15). The first and second stage comprises acute infections occurring within 6 weeks and delayed chronic presentations, respectively. The third stage refers to infections on prosthesis with previously well-maintained function and the fourth stage is a positive for microbiological isolate during the aseptic revision of arthroplasty.

Our study shows that radical debridement with prosthesis retention and long-term antibiotics had a high success rate (100%) for early PJI. The HHS was 91 points (82-98 points) at the last follow-up. No robust treatment guidelines currently exist for early PJI after arthroplasty. Antibiotic therapy alone does not have favorable results and are reserved for patients in very poor health and surgical treatment is not a viable option3). Clinical outcomes of other treatment options such as early joint centesis are questionable²⁵,26).

The surgical treatments that are available include centesis of the joint, debridement, one, and two-stage reimplantation3). Two-stage reimplantation is a commonly performed procedure in chronic infection with favorable success rates. However, it requires 1) long-term treatment; 2) two complicated surgeries (removal of well-fixed prosthesis and reimplantation), which increases the risk of complications such as loss of bone stock, soft tissue deformation, and perioperative fractures; and 3) long-term hospitalization, which places considerable burden on both the patient and the hospital⁴,27).

The effectiveness of radical debridement with retention of prosthesis in patients with early PJI has been questioned due to its variable success rates across studies28). Brandt et al.5), Koyonos et al.29), and Odum et al.30) reported low rates (36.3%, 31% and 36% success rate respectively) of infection control and hence suggested that radical debridement has limited utility and should be performed only in certain situations. In contrast, Meehan el al.31) reported a high success rate of 89% in 19 cases of streptococcal infection. Vilchez et al.32), Tsukayama et al.6), Barberán et al.33), van Kleunen et al.34), Bassetti et al.35), and Choong et al.9) have reported success rates of 75.5%, 71%, 83%, 72%, 80% and 78% respectively.

Several factors influence the course of postoperative infection including host conditions, type of pathogen, antibiotics sensitivity, and surgical approach. Signs of infection, longer duration of symptoms, poor status of soft tissues and antibiotic resistance of pathogens are known to play a major role in failure^5,33,36,37).

The timing of radical debridement in relation to outcome is a commonly discussed factor. It has been reported that early radical debridement is important to ensure good treatment outcomes. Brandt et al.5) reported a higher risk of failure if radical debridement was performed after 2 days of infection. In another study, Tattevin et al.36) reported that the treatment was successful when the surgery was performed within an average of 4.85 days and failed if it was after 54.2 days. Marculescu et al.37) reported overall 60% success rate and when the surgery was done after 8 days of infection, the success rate dropped to 49%. In another study, Crockarell et al.8) concluded that the debridement with retention of prosthesis is successful treatment when performed within 2 weeks. Barberán et al.33) showed that the success rate of radical debridement performed within a month after the onset of infection was as high as 84.5%, but significantly lower (33.4%) if it was after 6 months. Other studies including Vilchez et al.32), van Kleunen et al.34), and Tsukayama et al.6) have also claimed favorable success rates for treatments implemented within 4 weeks. Therefore, it was suggested that radical debridement be performed within a month from arthroplasty⁵,33). But, it is difficult to determine the actual duration of onset of infection symptoms. Clinical symptoms like pain and elevated inflammatory biomarkers during the recovery period after surgery, making it hard to recognize the infection. Meehan et al.31) reported a high success rate of 89% in 19 cases of streptococcal infection with all of the cases of prosthetic infection occurred >30 days after implantation of prosthesis. In our study, we were unable to secure specific information regarding the duration of infection; however, the average time taken to implement radical debridement was 31.3 days (18-48 days). We had favorable clinical outcomes regardless of the time of surgery.

It is well-documented that the type of infective pathogen and treatment outcome are closely related¹⁰,38). Gram positive infections are considered easier to treat. However, novel antibiotics show favorable results for gram negative infections also6). Brandt et al.5) and Azzam et al.10) reported that PJI due to Staphylococcus aureus is associated with treatment failure. However, Odum et al.30), and Barberán et al.33) reported that a similar failure rate was found with both types of Staphylococci (Staphylococcus aureus and coagulase-negative staphylococci); this is contrary to previous reports of a significantly higher failure rate among MRSA isolates as compared to MSSA isolates.

Zimmerli et al.7) reported a 100% cure rate (12/12) with ciprofloxacin-rifampin therapy for orthopedic device-related staphylococcal infection in a randomized controlled study and concluded that orthopedic devicerelated infection due to rifampin and ciprofloxacin susceptible staphylococcal infection can be cured without removal of the device. Meehan et al.31) reported that only 11% of cases (streptococcal infection after arthroplasty) had failed treatment when patients after radical debridement were treated with intravenous penicillin/ampicillin or ceftriaxone or cefazolin for an average of 4 weeks followed by long-term oral cephalosporins. In our study, we were unable to isolate pathogens in nine patients (45%). The low rate of pathogen isolation could be due to a four-day prophylactic antibiotic regimen post-surgery, which was continued for 7-10 days if the CRP levels were high. We proceeded with early active radical debridement without hesitation if clinical symptoms and blood tests suggested an infection, without performing joint aspiration or other measures for culture.

Although several factors such as age, rheumatoid arthritis and diabetes make patients vulnerable to infection, no study has reported such associations in patients with early infection following hip arthroplasty⁹,37). In our study, most patients had good overall health although a few had unrelated medical disorders (Table 1).

It has been reported that presence of a sinus tract37), low levels of CRP at the time of infection (15-22 mg/L or lower)32) and continuous drainage after radical debridement10) are important factors influencing the clinical outcome. In our study, we found sinus tracts or persistent wound discharge in three patients while the averages of preoperative CRP and ESR were 21.1 mg/L (range 1-72 mg/L) and 49.85 mm/h (range 3-118 mm/h), respectively. No statistically significant association was found between the duration of antibiotic administration and CRP level before radical debridement (P=0.146).

Although there are several antibiotic treatment protocols for early PJI, no specific guideline for duration of antibiotic treatment has been established. Zimmerli et al.39) recommended 2-4 weeks of intravenous therapy followed by oral antibiotics for 3 months. Vilchez et al.32), on the other hand, used intravenous administration of antibiotics for 10.6±6.7 days and oral administration was continued for 88±45.9 days. In another study, Choong et al.9) used vancomycin until pathogen identification before radical debridement and thereafter, relevant antibiotics were administrated for 2 weeks. Oral antibiotics (e.g., rifampin) were given for 4-24 months. Marculescu et al.37) administered intravenous antibiotics for an average of 28 days and oral antibiotics for an average of 541 days. Barberán et al.33) used levofloxacin and rifampin after radical debridement for six weeks. We treated our patients with intravenous antibiotics for at least 4-6 weeks after radical debridement or until normal CRP levels were regained. Nine patients who had no microbiological isolate were treated solely with vancomycin while combinations of vancomycin/aminoglycoside were given to three, vancomycin/levofloxacin to two, vancomycin/ertapenem to two and vancomycin/tazocin to one. The average duration of antibiotic administration was 43.5 days (28-62 days) and CRP levels recovered within 8 weeks in most cases. We found that the duration of antibiotics administration was significantly longer in patients with isolated pathogens. This could be due to the isolated pathogens in our patients being either methicillin-resistant strains or Gram-negative strains, which are more virulent.

We had favorable outcomes with early debridement with prosthesis retention in early PJI. We recommend this procedure not only because of favorable outcomes, but also due to less physical and economic burden on patients and physicians. The isolated pathogens in our study were antibiotic resistant and virulent (e.g., Enterococcus) strains. Early radical debridement was implemented as soon as postoperative infective symptoms were noted. Furthermore, hip joint membranes were completely washed during radical debridement and all possible infection sites were packed for 5-10 minutes with gauze soaked in povidone-iodine solution. These could have contributed to our favorable surgical outcomes. However, radical debridement is not recommended for patients who are elderly, have significant medical comorbidities (e.g., advanced diabetes), or are transferred from other hospitals with infection after arthroplasty.

Being a retrospective study there was no control group. However, patients had follow-up for at least one year and we included all patients who met the diagnostic criteria. Certain details such as infective symptoms and duration were lacking, but we tried to verify patients' conditions using available medical records. The sample size of 20 is small, which is a limitation for statistical analysis of treatment outcomes. However, the results herein are significant as they describe the clinical outcome of surgeries performed by the same surgeon using established diagnostic criteria and surgical procedures.

We found that a combination of radical debridement with retention of prosthesis and administration of antibiotics could be an effective treatment option for early PJI after hip arthroplasty. The outcome of radical debridement can be significantly improved through careful patient selection, optimal timing of intervention, and thorough debridement. Long-term studies with more number of patients are required to validate our study findings.

Table 1. Patient Information (n=20)

Table 2. Type of Total Hip Replacement Arthroplasty (THRA)

Table 3. Treatment Outcome

Table 4. Isolated Pathogen, Antibiotics Used and Treatment Duration