Incidence of bacterial contamination in primary THA and combined hardware removal: analysis of preoperative aspiration and intraoperative biopsies

Conversion Birmingham Hip Resurfacing in Managing Post-traumatic Arthritis With Retained Femoral Hardware: A Case Report

CASE

A 70-year-old man with a year-long history of arthritic pain in his left hip presented to our clinic. He had a left intertrochanteric hip fracture 6 years ago, fixed with an open reduction internal fixation with a cephalomedullary nail. He underwent a conversion Birmingham Hip Resurfacing (BHR) with removal of the proximal helicoidal blade and retention of the intramedullary nail. At 7-year follow-up, the patient reported satisfactory clinical outcomes and excellent radiographic fixation.

CONCLUSION

This case highlights using conversion BHR in patients with post-traumatic arthritis with retained femoral hardware as an alternative to conventional total hip arthroplasty.

Dynamic hip screw in proximal femoral fractures followed by "single-stage" hip arthroplasty-retrospective analysis

The aim of this study is to present the results of single-stage total hip arthroplasty (THA) after Dynamic Hip Screw (DHS) failure, or secondary posttraumatic osteoarthrosis. From 2003 to 2020, 15 THAs were performed in group of 15 patients for the treatment of DHS failure, or for late complications following femoral neck and pertrochanteric fractures. The mean follow-up period after arthroplasty was 46.9 months (range 7-139). The patients were evaluated retrospectively-both clinically and radiographically, focussing on the demography, infection rate and other complications (revision surgery), during the year 2023. 9 males and 6 females were included in the study, with a mean age of 56.5 years (range 29-93) at the time of primary osteosynthesis. Each of them had proximal femoral fracture treated primarily with a DHS and then late one-stage revision surgery, with hardware removal and THA implantation. The median time between DHS osteosynthesis and THA was 41.2 months (range 4-114). Four patients (26.6%) had complications after THA, with the need for revision in two cases (13.3%). Dislocation rate was 6.6% (one case), with the need for repeated-revision of THA. The infection rate was 6.6% (one patient) with the need for revision of THA. Peroperative periprosthetic femoral fracture was observed in 13.3% (two patients) without any other problems. Six patients (40%) died during the follow-up period. Single-stage total hip arthroplasty with concomitant hardware removal bears a high- mortality rate, with a higher incidence of postoperative complications compared to elective THA.

Decreased Risk of Periprosthetic Joint Infection with Concurrent Hardware Removal During Conversion Total Hip Arthroplasty Compared to Staged Removal: A Matched Cohort Analysis

INTRODUCTION

Hardware removal before conversion total hip arthroplasty (cTHA) is a challenging task for the orthopaedic surgeon, although there is little consensus on the timing of hardware removal to mitigate risk of surgery-related complication following cTHA.

METHODS

Using a national insurance database, we evaluated patients who underwent hardware removal either on the same day or within 1 year before cTHA, resulting in a total of 7,756 patients. After matching based on demographic factors and comorbidities, both staged and concurrent groups consisted of 2,752 patients. The 90-day and 1-year risk of revision surgery, periprosthetic joint infection (PJI), periprosthetic fracture, and aseptic loosening were calculated and compared. Demographic factors and comorbidities were further evaluated as risk factors for PJI.

RESULTS

The rates of infection were 1.85% and 3.05% at 90 days postoperatively and 2.94% and 4.14% at 1 year postoperatively for concurrent versus staged cohorts, respectively (P = 0.004 and P = 0.02). No difference was observed at 90 days or 1 year between the two cohorts in risk of fracture, revision surgery, or aseptic loosening. Diabetes (P = 0.002 and P < 0.001), tobacco use (P < 0.001 and P < 0.001), and obesity (P = 0.026 and P = 0.025) were identified as risk factors for PJI at both 90 days and 1 year postoperatively.

DISCUSSION

The timing of hardware removal is associated with an increased risk of PJI, although no difference was observed in revision surgery, fracture, or loosening among staged versus concurrent cohorts. These findings are important to consider when surgeons are evaluating patients with periarticular implants surrounding their hip.

The direct anterior approach for conversion to total hip arthroplasty after acetabular fixation is safe and effective

INTRODUCTION

Total Hip Arthroplasty (THA) after prior acetabular fracture repair is known to be demanding as studies have shown inferior implant survival rates and higher infection rates for these procedures. The direct anterior (DA) approach might help mitigate some of these risks by utilizing a new surgical tissue plane. However, potential criticisms of the DA approach for these surgeries include the inability to access previous acetabular implants or heterotopic ossification (HO) if they were to inhibit implant placement. The goals of this study are to analyze the efficacy of the DA approach for conversion to hip arthroplasty surgery after previous acetabular fixation.

METHODS

After reviewing all records at our institution using current procedural terminology codes, we isolated patients with previous acetabular repair who underwent conversion to THA through the DA approach. Patient records were reviewed, and patients were contacted to obtain Harris Hip Scores.

RESULTS

23 patients (16 males and 7 females) were found with a mean follow-up time of 46 months (range 16-156 months). The mean age was 50 (range 28 - 83) and mean BMI was 28.5 (range 15.2 - 39.2). The average blood loss was 400 ml (range 200 - 900). The average operative time was 140 min (range 85-200 min). In 7 cases (32%) implants were encountered during acetabular reaming but the implants were either removed entirely or removed partially with a burr so that the acetabular cup could be positioned within acceptable parameters. In 2 cases pre-operative HO was encountered and was resected. The average Harris Hip Score at final follow-up was 92 (range 75 - 100). There were no deep infections and no neurovascular injuries encountered. 2 patients (9%) underwent revision surgery for aseptic femoral stem loosening. There was 1 anterior dislocation (4.5%) at 3 days post-operatively that was successfully treated with closed reduction and maintenance of hip precautions. Otherwise, the remaining 19 (86%) patients went on to uncomplicated recovery.

CONCLUSION

This is the largest known cohort analyzing the DA approach for conversion to hip arthroplasty after previous acetabular fixation. Overall, we demonstrate that the DAA is safe for conversion THA after acetabular fixation.

Clinical Outcomes and Complication Rate after Single-Stage Hardware Removal and Total Hip Arthroplasty: A Matched-Pair Controlled Study

BACKGROUND

Single-stage hardware removal and total hip arthroplasty is a complex surgical procedure, comparable to revision surgery. The purpose of the current study is to evaluate single-stage hardware removal and THA outcomes, compare this technique with a matched control group that has undergone primary THA and assess the risk of periprosthetic joint infection with a 24-month minimum follow-up.

METHODS

This study included all those cases treated with THA and concomitant hardware removal from 2008 to 2018. The control group was selected on a 1:1 ratio among patients who underwent THA for primary OA. The Harris Hip (HHS) and University of California at Los Angeles Activity (UCLA) scores, infection rate and early and delayed surgical complications were recorded.

RESULTS

One hundred and twenty-three consecutive patients (127 hips) were included, and the same number of patients was assigned to the control group. The final functional scores were comparable between the two groups; a longer operative time and transfusion rate were recorded in the study group. Finally, an increased incidence of overall complications was reported (13.8% versus 2.4%), but no cases of early or delayed infection were found.

CONCLUSIONS

Single-stage hardware removal and THA is a safe and effective but technically demanding technique, with a higher incidence of overall complications, making it more similar to revision THA than to primary THA.

Conversion total hip arthroplasty following proximal femur fracture: A retrospective analysis

BACKGROUND

The incidence of conversion total hip arthroplasty (cTHA) following reduction and fixation for proximal femur fractures will increase in parallel to the aging population worldwide.

OBJECTIVE

The goal of this study is to report the frequency of bacterial detection and the outcome of cTHA at the authors' institution and to analyze preoperative factors that correlate with higher rates of bacterial growth and septic revision.

METHODS

48 patients who had been converted to THA after osteosynthesis of a proximal femur fracture either by a one- or two-stage procedure were included. Septic failure rate and the frequency of bacterial detection at the time of fixation device removal were calculated. The influence of different preoperative factors was examined by the odds ratio. A receiver operating characteristic curve of c-reactive protein (CRP) for detection of bacterial growth at the time of fixation device removal was calculated.

RESULTS

18.8% patients showed positive bacterial cultures, with Staph. epidermidis being the most frequent pathogen (33.3%). Septic failure after cTHA occurred in 4.2%. Fixation with cephalomedullary nails and complications with the internal fixation showed higher odds for bacterial growth at time of cTHA. CRP for predicting bacterial growth had an area under the curve of 0.661. Implant survival was worse when temporary spacers were used.

CONCLUSION

Bacterial detection rate at the time of cTHA is high, whereas septic failure rates are low. Isolated evaluation of inflammatory blood markers without other diagnostic modalities for infection is not decisive and does not justify a two-stage approach with implantation of a temporary spacer.

Complications and survival of conversion to total hip arthroplasty after failed primary osteosynthesis compared to primary total hip arthroplasty in femoral neck fractures

INTRODUCTION

Surgical treatment options for patients with an intracapsular fracture of the femoral neck (FFN) are primary osteosynthesis as a femoral head-spearing technique or primary (hemi)arthroplasty. The most common complications after primary osteosynthesis, such as avascular necrosis (AVN) or non-union, can result in conversion to Total Hip Arthroplasty (cTHA). Data concerning complications and survival rates of cTHA in comparison to primary Total Hip Arthroplasty (pTHA) after FFN are limited due to the absence of well-designed studies.

METHODS

A multicentre retrospective cohort study was conducted in three Dutch hospitals comparing the rate of postoperative dislocations, periprosthetic fractures, prosthetic joint infections, blood loss during surgery (>1000 mL), postoperative cardiac- and pulmonary complications after pTHA and cTHA in the first year after surgery. As a secondary outcome implant survival of pTHA and cTHA in terms of revision rates was evaluated.

RESULTS

In total 548 patients were included (pTHA n = 264 and cTHA n = 284) with a mean follow-up of 5 years (±3.5 SD). No significant differences were found in postoperative complications rates. The revision rate in the pTHA group was 7.2% in comparison to 7.7% in the cTHA group (p = 0.81). No difference in the short-term implant survival was found between both groups (p = 0.81).

CONCLUSION

This study showed no significant differences in terms of postoperative complication rates in the first year after pTHA and cTHA in patients with FFN. Also, no significant difference in short-term implant survival of primary and conversion total hip arthroplasty was found.

Outcomes of hip arthroplasty with concomitant hardware removal: influence of the type of implant retrieved and impact of positive intraoperative cultures

INTRODUCTION

The impact of residual internal fixation devices on subsequent procedures about the hip has not been clearly well defined. The objective of the current study is to evaluate the outcome of hip arthroplasty after hardware retrieval as a one-stage replacement, to analyze possible differences related to the type of removed implant, and to assess the impact of unexpected intraoperative cultures during implant retrieval.

MATERIALS AND METHODS

We present a retrospective study including all those cases undergoing hip arthroplasty with concomitant hardware removal (cannulated screws, intramedullary nail, or dynamic hip screw) from 2005 to 2018. We evaluated demographics, intraoperative cultures, early infection rate, and other complications.

RESULTS

A total of 55 cases were included in the study. The median time between the implant surgery and the hip arthroplasty was 113 days. The removed devices included 6 cannulated screws, 34 intramedullary nails, and 15 dynamic hip screws. Up to 74.5% of the failed osteosynthesis belonged to intertrochanteric femoral fractures. Dislocation rate was 9.1% (1.8% requiring revision surgery), 25.5% of the cases needed further new surgeries after the hip arthroplasty, and 49.1% died during the follow-up period. Any-cause revision surgery and mortality rates were significantly increased after intramedullary nail removal. Intraoperative cultures were performed in 46 cases, and in 9 (16.4%), there was bacterial contamination: 6 cases (10.9%) presented one single positive culture and 3 (5.5%) presented ≥ 2 positive cultures for the same microorganism. A total of five cases (9.1%) presented early prosthetic joint infection that required debridement. None of these five cases had presented positive cultures at the implant removal.

CONCLUSION

According to our results, hip arthroplasty with concomitant hardware removal is related to a high 5-year mortality rate, mainly when intramedullary nail is retrieved. Whereas a high risk of early prosthetic joint infection is associated, it seems not to be related to the elevated presence of unexpected positive cultures.

Total Hip Arthroplasty After Prior Acetabular Fracture: Infection Is a Real Concern

BACKGROUND

Acetabular fractures often require surgical intervention for fracture fixation and can result in premature osteoarthritis of the hip joint. This study hypothesized that total hip arthroplasty (THA) in patients with a prior acetabular fracture who had undergone open reduction and internal fixation (ORIF) is associated with a higher rate of subsequent periprosthetic joint infection (PJI).

METHODS

About 72 patients with a history of acetabular fracture that required ORIF, undergoing conversion THA between 2000 and 2017 at our institution, were matched based on age, gender, body mass index, Charlson comorbidity index, and date of surgery in a 1:3 ratio with 215 patients receiving primary THA. The mean follow-up for the conversion THA cohort was 2.9 years (range, 1-12.15) and 3.06 years (range, 1-12.96) for the primary THA.

RESULTS

Patients with a previous acetabular fracture, compared with the primary THA patients, had longer operative times, greater operative blood loss, and an increased need for allogeneic blood transfusion (26.4% vs 4.7%). Most notably, PJI rate was significantly higher in acetabular fracture group at 6.9% compared with 0.5% in the control group. Complications, such as aseptic revision, venous thromboembolism, and mortality, were similar between both groups.

CONCLUSION

The present study demonstrates that conversion THA in patients with prior ORIF of acetabular fractures is associated with higher complication rate, in particular PJI, and less optimal outcome compared with patients undergoing primary THA. The latter findings compel us to seek and implement specific strategies that aim to reduce the risk of subsequent PJI in these patients.

High incidence of early periprosthetic joint infection following total hip arthroplasty with concomitant or previous hardware removal

INTRODUCTION

Hardware removal preceding total hip arthroplasty may increase the risk of prosthetic joint infection (PJI). Whether hardware removal and total hip arthroplasty (THA) should be performed in a single- or two-stage procedure remains controversial. In this comparative retrospective study, the incidence of PJI following either single- or two-stage THA with hardware removal was assessed in a consecutive series.

PATIENTS AND METHODS

All patients that underwent THA preceded by hardware removal from January 2006 until March 2018 were retrospectively reviewed and checked for the occurrence of early PJI. Recognized risk factors for PJI at the time of surgery were evaluated and the incidence of early PJI was compared between one- and two-stage THA regarding hardware removal.

RESULTS

145 patients underwent THA and hardware removal (52 two-stage surgery and 93 single-stage surgery). There were no significant differences between both groups regarding pre-operative hemoglobulin levels, time interval between internal fixation and THA, antibiotic-loaded-cement use, BMI and ASA classification. Overall the incidence of early PJI was 6.9%. The incidence of PJI was 8.6% in the single-stage group versus 3.8% in the two-stage group (P = 0.234).

CONCLUSION

Irrespective of single- or two-stage procedures, a high incidence of PJI was encountered. Despite non-significance, a trend towards a higher proportion of patients developing PJI after single-stage surgery was encountered. We recommend a two-stage surgical procedure regarding hardware removal and THA in patients that are expected to tolerate this surgical strategy. When considering a one-stage procedure, it should be preceded by a thorough pre-operative workup including joint aspiration and serum determination of inflammatory parameters. Multiple tissue samples should be obtained during hardware removal in either one- or two-stage procedures since the risk for development of PJI is relevant.

Diagnostic Accuracy of Serum, Synovial, and Tissue Testing for Chronic Periprosthetic Joint Infection After Hip and Knee Replacements: A Systematic Review

BACKGROUND

Chronic periprosthetic joint infection (PJI) is a devastating complication that can occur following total joint replacement. Patients with chronic PJI report a substantially lower quality of life and face a higher risk of short-term mortality. Establishing a diagnosis of chronic PJI is challenging because of conflicting guidelines, numerous tests, and limited evidence. Delays in diagnosing PJI are associated with poorer outcomes and morbid revision surgery. The purpose of this systematic review was to compare the diagnostic accuracy of serum, synovial, and tissue-based tests for chronic PJI.

METHODS

This review adheres to the Cochrane Collaboration's diagnostic test accuracy methods for evidence searching and syntheses. A detailed search of MEDLINE, Embase, the Cochrane Library, and the grey literature was performed to identify studies involving the diagnosis of chronic PJI in patients with hip or knee replacement. Eligible studies were assessed for quality and bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Meta-analyses were performed on tests with sufficient data points. Summary estimates and hierarchical summary receiver operating characteristic (HSROC) curves were obtained using a bivariate model.

RESULTS

A total of 12,616 citations were identified, and 203 studies met the inclusion criteria. Of these 203 studies, 170 had a high risk of bias. Eighty-three unique PJI diagnostic tests were identified, and 17 underwent meta-analyses. Laboratory-based synovial alpha-defensin tests and leukocyte esterase reagent (LER) strips (2+) had the best performance, followed by white blood-cell (WBC) count, measurement of synovial C-reactive protein (CRP) level, measurement of the polymorphonuclear neutrophil percentage (PMN%), and the alpha-defensin lateral flow test kit (Youden index ranging from 0.78 to 0.94). Tissue-based tests and 3 serum tests (measurement of interleukin-6 [IL-6] level, CRP level, and erythrocyte sedimentation rate [ESR]) had a Youden index between 0.61 to 0.75 but exhibited poorer performance compared with the synovial tests mentioned above.

CONCLUSIONS

The quality of the literature pertaining to chronic PJI diagnostic tests is heterogeneous, and the studies are at a high risk for bias. We believe that greater transparency and more complete reporting in studies of diagnostic test results should be mandated by peer-reviewed journals. The available literature suggests that several synovial fluid-based tests perform well for diagnosing chronic PJI and their use is recommended in the work-up of any suspected case of chronic PJI.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Alternative Payment Models Should Risk-Adjust for Conversion Total Hip Arthroplasty: A Propensity Score-Matched Study

BACKGROUND

For Medicare beneficiaries, hospital reimbursement for nonrevision hip arthroplasty is anchored to either diagnosis-related group code 469 or 470. Under alternative payment models, reimbursement for care episodes is not further risk-adjusted. This study's purpose was to compare outcomes of primary total hip arthroplasty (THA) vs conversion THA to explore the rationale for risk adjustment for conversion procedures.

METHODS

All primary and conversion THAs from 2007 to 2014, excluding acute hip fractures and cancer patients, were identified in the National Surgical Quality Improvement Program database. Conversion and primary THA patients were matched 1:1 using propensity scores, based on preoperative covariates. Multivariable logistic regressions evaluated associations between conversion THA and 30-day outcomes.

RESULTS

A total of 2018 conversions were matched to 2018 primaries. There were no differences in preoperative covariates. Conversions had longer operative times (148 vs 95 minutes, P < .001), more transfusions (37% vs 17%, P < .001), and longer length of stay (4.4 vs 3.1 days, P < .001). Conversion THA had increased odds of complications (odds ratio [OR] 1.75; 95% confidence interval [CI] 1.37-2.24), deep infection (OR 4.21; 95% CI 1.72-10.28), discharge to inpatient care (OR 1.52; 95% CI 1.34-1.72), and death (OR 2.39; 95% CI 1.04-5.47). Readmission odds were similar.

CONCLUSION

Compared with primary THA, conversion THA is associated with more complications, longer length of stay, and increased discharge to continued inpatient care, implying greater resource utilization for conversion patients. As reimbursement models shift toward bundled payment paradigms, conversion THA appears to be a procedure for which risk adjustment is appropriate.

False-positive Cultures After Native Knee Aspiration: True or False

BACKGROUND

Synovial fluid aspiration is a routine practice used by most orthopaedic surgeons to aid in the diagnosis of joint infection. In patients for whom there is a low pretest probability of infection, a positive culture-particularly if it is a broth-only culture-may be considered a contaminant, especially if the bacterial species are skin pathogens. To our knowledge no study has evaluated the incidence of contamination of aspirations from the native knee.

QUESTIONS/PURPOSES

What is the frequency of false-positive cultures among knee aspirations of the native knee?

METHODS

Two hundred patients, with a total of 200 knees, with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty (TKA) were identified for this study. None of these patients had symptoms, signs, or laboratory studies to suggest the presence of joint infection; a positive culture in this population therefore would be considered contaminated. Thirty-two (16%) patients were excluded secondary to a dry aspiration. One patient was enrolled in the study but did not have the knee aspirated and another patient's specimen was accidentally discarded. Each knee was aspirated under sterile conditions before performing the TKA. The fluid was sent for cell count and culture. If insufficient fluid was obtained for both cell count and culture, culture was performed rather than cell count.

RESULTS

There were no false-positive cultures (zero of 166 [0%]) in aspirations of native knees.

CONCLUSIONS

Our study would indicate that when done properly under sterile technique, cultures taken from knee arthrocentesis in patients without prosthetic joints should not be affected by perceived contaminant species. A positive specimen finding on culture should raise a strong suspicion of bacterial septic arthritis. Future studies should include more specimens as well as knees with prior TKA to help further identify the rate of false-positive cultures in knee arthrocentesis in both populations.

LEVEL OF EVIDENCE

Level I, diagnostic study.

High Rates of Occult Infection After Shoulder Fracture Fixation: Considerations for Conversion Shoulder Arthroplasty

BACKGROUND

Existing hardware may contribute to increased risk of bacterial contamination and subsequent periprosthetic joint infection (PJI) in conversion shoulder arthroplasty performed for failed fracture fixation.

QUESTIONS/PURPOSES

This study examined the incidence of positive pre-operative aspiration and inflammatory marker data, along with correlation of pre-operative positive aspiration or inflammatory markers and subsequent infection following conversion shoulder arthroplasty for failed open reduction and internal fixation (ORIF) and the need for re-operation at 4.6-year follow-up.

METHODS

Twenty-eight patients who underwent conversion to shoulder arthroplasty for any reason after fracture fixation were retrospectively reviewed in a single center. A pre-operative aspiration was done in 17 patients; all patients had intra-operative tissue sampling. All procedures were single-stage removal of hardware and performance of the arthroplasty. In cases of pre-operative positive bacterial growth, a single-stage procedure was performed according to the septic ENDO-Klinik protocol.

RESULTS

In 4 of 17 pre-operative joint aspirations, bacterial growth was detected; one pre-operative negative aspiration demonstrated bacterial growth in intra-operative sampling. In three of them, the infection has been validated through intra-operatively results. Pre-operative aspiration showed a sensitivity of 75% and specificity of 92% (p < 0.005) for infection. No post-operative PJIs were observed. Six revisions were performed, most commonly for aseptic loosening (two cases) and conversion of hemiarthroplasty to a reverse design (two cases).

CONCLUSIONS

In conclusion, the risk of low-grade shoulder infection after fracture osteosynthesis may be higher than in hip and knee joints, based on limited study data. Adequate pre-operative testing is recommended to rule out occult shoulder infection in this setting.

Increased release time of antibiotics from bone allografts through a novel biodegradable coating

The use of bone allografts is contraindicated in septic revision surgery due to the high risk of graft reinfection. Antibiotic release from the graft may solve the problem and these combinations can theoretically be used for prevention or even therapy of infection. The present study investigated whether amoxicillin, ciprofloxacin, and vancomycin alone or in combination with chitosan or alginate are suitable for short-term or long-term bone coating. Human bone allografts were prepared from femoral head and lyophilized. Antibiotic coating was achieved by incubating the grafts in antibiotic solution and freeze-drying again. Two biopolymers chitosan and alginate were used for creating sustained-release implantable coatings and the drug release profile was characterized in vitro by spectrophotometry. Using lyophilization with or without chitosan only resulted in short-term release that lasted up to 48 hours. Alginate coating enabled a sustained release that lasted for 8 days with amoxicillin, 28 days with ciprofloxacin coating, and 50 days with vancomycin coating. Using only implantable biodegradable allograft and polymers, a sustained release of antibiotics was achieved with ciprofloxacin and vancomycin for several weeks. Since the calculated daily release of the antibiotic was lower than the recommended IV dose, the calcium alginate coated bone graft can support endoprosthesis revision surgery.

Preoperative aspiration culture for preoperative diagnosis of infection in total hip or knee arthroplasty

This meta-analysis evaluated preoperative aspiration culture for diagnosing prosthetic joint infection (PJI) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). The pooled sensitivity and specificity were 0.72 (95% confidence interval, 0.65 to 0.78) and 0.95 (0.93 to 0.97), respectively. Subgroup analyses revealed nonsignificant worse diagnostic performance for THA than for TKA (sensitivity, 0.70 versus 0.78; specificity, 0.94 versus 0.96). Preoperative aspiration culture has moderate to high sensitivity and very high specificity for diagnosing PJI.