Synovial Fluid Absolute Neutrophil Count and Neutrophil-To-Lymphocyte Ratio are not Superior to Polymorphonuclear Percentage in Detecting Periprosthetic Joint Infection

BackgroundSerum and synovial biomarkers are currently used to diagnose periprosthetic joint infection (PJI). Serum neutrophil-to-lymphocyte ratio (NLR) has shown promise as an inexpensive test in diagnosing infection, but there are no reports of synovial NLR or absolute neutrophil count (ANC) for diagnosing chronic PJI. The purpose of this study was to investigate the diagnostic potential of both markers.MethodsA retrospective review of 730 patients who underwent total joint arthroplasty and subsequent aspiration was conducted. Synovial white blood cell (WBC) count, synovial polymorphonuclear percentage (PMN%), synovial NLR, synovial ANC, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), serum WBC, serum PMN%, serum NLR, and serum ANC had their utility in diagnosing PJI examined by area-under-the-curve analyses (AUC). Pairwise comparisons of AUCs were performed.ResultsThe AUCs for synovial WBC, PMN%, NLR, and ANC were 0.84, 0.84, 0.83, and 0.85, respectively. Synovial fluid ANC was a superior marker to synovial NLR (P = .027) and synovial WBC (P = .003) but not PMN% (P = .365). Synovial NLR was inferior to PMN% (P = .006) but not different from synovial WBC (P > .05). The AUCs for serum ESR, CRP, WBC, PMN%, NLR, and ANC were 0.70, 0.79, 0.63, 0.72, 0.74, and 0.67, respectively. Serum CRP outperformed all other serum markers (P < .05) except for PMN% and NLR (P > .05). Serum PMN% and NLR were similar to serum ESR (P > .05).ConclusionSynovial ANC had similar performance to PMN% in diagnosing chronic PJI, whereas synovial NLR was a worse diagnostic marker. The lack of superiority to synovial PMN% limits the utility of these tests compared to established criteria.     

Utility of Synovial White Blood Cell Count and Differential Before Reimplantation Surgery

BackgroundDetermining optimal timing of reimplantation during 2-stage exchange for periprosthetic joint infection (PJI) remains elusive. Joint aspiration for synovial white blood cell (WBC) count and neutrophil percentage (PMN%) before reimplantation is widely performed; yet, the implications are rarely understood. Therefore, this study investigates (1) the diagnostic yield of synovial WBC count and differential analysis and (2) the calculated thresholds for persistent infection.MethodsInstitutional PJI databases identified 129 patients undergoing 2-stage exchange arthroplasty who had joint aspiration before reimplantation between February 2005 and May 2014. Persistent infection was defined as a positive aspirate culture, positive intraoperative cultures, or persistent symptoms of PJI—including subsequent PJI-related surgery. Receiver-operating characteristic curve was used to calculate thresholds maximizing sensitivity and specificity.ResultsThirty-three cases (33 of 129; 25.6%) were classified with persistent PJI. Compared with infection-free patients, these patients had significantly elevated PMN% (62.2% vs 48.9%; P = .03) and WBC count (1804 vs 954 cells/μL; P = .04). The receiver-operating characteristic curve provided thresholds of 62% and 640 cells/μL for synovial PMN% and WBC count, respectively. These thresholds provided sensitivity of 63% and 54.5% and specificity of 62% and 60.0%, respectively. The risk of persistent PJI for patients with PMN% >90% was 46.7% (7 of 15).ConclusionSynovial fluid analysis before reimplantation has unclear utility. Although statistically significant elevations in synovial WBC count and PMN% are observed for patients with persistent PJI, this did not translate into useful thresholds with clinical importance. However, with little other guidance regarding the timing of reimplantation, severely elevated WBC count and differential analysis may be of use.     

How Does a “Dry Tap” Impact the Accuracy of Preoperative Aspiration Results in Predicting Chronic Periprosthetic Joint Infection?

BackgroundPeriprosthetic joint infection (PJI) after total hip arthroplasty (THA) is challenging to diagnose. We aimed to evaluate the impact of dry taps requiring saline lavage during preoperative intra-articular hip aspiration on the accuracy of diagnosing PJI before revision surgery.MethodsA retrospective review was conducted for THA patients with suspected PJI who received an image-guided hip aspiration from May 2016 to February 2020. Musculoskeletal Infection Society (MSIS) diagnostic criteria for PJI were compared between patients who had dry tap (DT) vs successful tap (ST). Sensitivity and specificity of synovial markers were compared between the DT and ST groups. Concordance between preoperative and intraoperative cultures was determined for the 2 groups.ResultsIn total, 335 THA patients met inclusion criteria. A greater proportion of patients in the ST group met MSIS criteria preoperatively (30.2% vs 8.3%, P < .001). Patients in the ST group had higher rates of revision for PJI (28.4% vs 17.5%, P = .026) and for any indication (48.4% vs 36.7%, P = .039). MSIS synovial white blood cell count thresholds were more sensitive in the ST group (90.0% vs 66.7%). There was no difference in culture concordance (67.9% vs 65.9%, P = .709), though the DT group had a higher rate of negative preoperative cultures followed by positive intraoperative cultures (85.7% vs 41.1%, P = .047).ConclusionOur results indicate that approximately one third of patients have dry hip aspiration, and in these patients cultures are less predictive of intraoperative findings. This suggests that surgeons considering potential PJI after THA should apply extra scrutiny when interpreting negative results in patients who require saline lavage for hip joint aspiration.     

Normal CRP and WBC values in total hip arthroplasty (THA) with signs of loosening. Do we need a joint aspiration?

PurposeOverall Total hip arthroplasty (THA) is a very successful procedure. However, in case of complication dedicated management is required. Two major complications of THA failures are aseptic loosening (AL) and periprosthetic joint infection (PJI). The primary hypothesis of this study was that joint aspirations in patients with signs of loosening after THA are capable to detect PJI in suspected AL with negative serologic testing.MethodsIn this study a total of 108 symptomatic patients with radiographic signs of prosthetic loosening and hip pain in THA were included. Based on a standardized algorithm all patients underwent serological testing followed by joint aspiration preoperatively. Intraoperatively harvested samples were subjected to microbiological testing and served as the gold standard in differential diagnosis. Demographics, as well as the results of serologic and microbiological testing were collected from the medical records.ResultsOf the included patients 85 were finally diagnosed with an AL and 23 with PJI. Within the patients with PJI 13 (56%) patients demonstrated elevated CRP and WBC counts, as well as positive synovial cultures after joint aspiration. In ten patients (44%) diagnosed with PJI neither CRP nor WBC were abnormal.ConclusionThe diagnosis of PJI can be difficult in THA with radiographic signs of loosening. Clinical features including pain, fever, and local sings of infection are uncommon especially a long period after index operation. First-line screening testing relies on serological evaluation of CRP and WBC. However, normal CRP and WBC values cannot rule out a PJI. These cases can be detected by joint aspiration and synovial cultures reliably.     

Utility of Diagnostic Markers in Late Periprosthetic Joint Infection Workup for Total Knee Arthroplasty Patients Who Received Antibiotics 48 Hours Before Aspiration

BackgroundDiagnosing periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) remains challenging despite recent advancements in testing and evolving criteria over the last decade. Moreover, the effects of antibiotic use on diagnostic markers are not fully understood. Thus, this study sought to determine the influence of antibiotic use within 48 hours before knee aspiration on synovial and serum laboratory values for suspected late PJI.MethodsPatients who underwent a TKA and subsequent knee arthrocentesis for PJI workup at least 6 weeks after their index arthroplasty were reviewed across a single healthcare system from 2013 to 2020. Median synovial white blood cell (WBC) count, synovial polymorphonuclear (PMN) percentage, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), and serum WBC count were compared between immediate antibiotic and nonantibiotic PJI groups. Receiver operating characteristic (ROC) curves and Youden’s index were used to determine test performance and diagnostic cutoffs for the immediate antibiotics group.ResultsThe immediate antibiotics group had significantly more culture-negative PJIs than the no antibiotics group (38.1 versus 16.2%, P = .0124). Synovial WBC count demonstrated excellent discriminatory ability for late PJI in the immediate antibiotics group (area under curve, AUC = 0.97), followed by synovial PMN percentage (AUC = 0.88), serum CRP (AUC = 0.86), and serum ESR (AUC = 0.82).ConclusionAntibiotic use immediately preceding knee aspiration should not preclude the utility of synovial and serum lab values for the diagnosis of late PJI. Instead, these markers should be considered thoroughly during infection workup considering the high rate of culture-negative PJI in these patients.Level of EvidenceLevel III, retrospective comparative study.     

Dilute Betadine Lavage Reduces the Risk of Acute Postoperative Periprosthetic Joint Infection in Aseptic Revision Total Knee and Hip Arthroplasty: A Randomized Controlled Trial

BackgroundThe purpose of this randomized, controlled trial is to determine whether dilute betadine lavage compared to normal saline lavage reduces the rate of acute postoperative periprosthetic joint infection (PJI) in aseptic revision total knee (TKA) and hip arthroplasty (THA).MethodsA total of 478 patients undergoing aseptic revision TKA and THA were randomized to receive a 3-minute dilute betadine lavage (0.35%) or normal saline lavage before surgical wound closure. Fifteen patients were excluded following randomization (3.1%) and six were lost to follow-up (1.3%), leaving 457 patients available for study. Of them, 234 patients (153 knees, 81 hips) received normal saline lavage and 223 (144 knees, 79 hips) received dilute betadine lavage. The primary outcome was PJI within 90 days of surgery with a secondary assessment of 90-day wound complications. A priori power analysis determined that 285 patients per group were needed to detect a reduction in the rate of PJI from 5% to 1% with 80% power and alpha of 0.05.ResultsThere were eight infections in the saline group and 1 in the betadine group (3.4% vs 0.4%, P = .038). There was no difference in wound complications between groups (1.3% vs 0%, P = .248). There were no differences in any baseline demographics or type of revision procedure between groups, suggesting appropriate randomization.ConclusionDilute betadine lavage before surgical wound closure in aseptic revision TKA and THA appears to be a simple, safe, and effective measure to reduce the risk of acute postoperative PJI.Level of EvidenceLevel I.     

Reevaluating Current Cutoffs for Acute Periprosthetic Joint Infection: Current Thresholds Are Insensitive

BackgroundDiagnosing acute periprosthetic joint infection remains a challenge. Several studies have proposed different acute cutoffs resulting in the International Consensus Meeting recommending a cutoff of 100 mg/L, 10,000 cell/μL and 90% for serum C-reactive protein (CRP), synovial white blood cell count (WBC), and polymorphonuclear percentage (PMN%), respectively. However, establishing cutoffs are difficult as the control group is limited to rare early aseptic revisions, and performing aspiration in asymptomatic patients is difficult because of a fear of seeding a well-functioning joint arthroplasty. This study (1) assessed the sensitivity of current thresholds for acute periprosthetic joint infection (PJI) and (2) identified associated factors for false negatives.MethodsWe retrospectively reviewed patients with acute PJIs (n = 218), defined as less than 6 weeks from index arthroplasty, treated between 2000 and 2017. Diagnosis of PJI was based on 2 positive cultures of the same pathogen from the periprosthetic tissue or synovial fluid samples. Sensitivities of International Consensus Meeting cutoff values of CRP, synovial WBC, and PMN% were evaluated according to organism type. Multiple logistic regression analysis was performed to determine associated factors for false negatives.ResultsOverall, the sensitivity of CRP, synovial WBC, and PMN% for acute PJI was 55.3%, 59.6%, and 50.5%, respectively. Coagulase-negative Staphylococcus (CNS) demonstrated the lowest sensitivity for both CRP (37.5%) and WBC (55.6%). CNS infection was identified as an independent risk factor for false-negative CRP.ConclusionsCurrent thresholds for acute PJI may be missing approximately half of PJIs. Low virulent organisms, such as CNS, may be responsible for these false negatives. Current thresholds for acute PJI must be reexamined.     

Synovial White Blood Cell Count and Differential to Predict Successful Infection Management in a Two-Stage Revision

BackgroundAn array of synovial white blood cell (WBC) count and polymorphonuclear differential (PMN%) thresholds have been reported using 2013 Musculoskeletal Infection Society (MSIS) definition which has a poor accuracy to confirm infection control before reimplantation. The workgroup of MSIS recently developed a comprehensive definition of successful infection management. Our objectives were to determine optimal thresholds for WBC count and PMN% associated with reimplantation success based on this new MSIS definition and assess if values above these thresholds indicate decreased survival time.MethodsA retrospective review was conducted on a consecutive series of 133 two-stage hip/knee arthroplasties performed by 15 surgeons (2014-2020) at 2 institutions. All surgeries had a minimum follow-up of 1 year. The inclusion criteria included reporting of preoperative synovial fluid aspiration results. Thus, 88 were finally included. Surgical success was defined by MSIS outcome reporting tool (Tiers 1-4). Receiver operating characteristic curve analyses were performed to estimate optimal thresholds of WBC count and PMN%. A Kaplan-Meier survival analyses with log-rank test were performed.ResultsWith area under the curve of 0.65, synovial PMN% showed superior accuracy than WBC count (area under the curve = 0.52) in determining outcome of reimplantation. The optimal PMN% threshold (62%) demonstrated sensitivity of 57% and specificity of 77%. The calculated WBC count threshold (2,733/μL) showed poor sensitivity (21%) but high specificity (95%). There was a significant difference in failure-free survival (24 months) between the cases with WBC count higher vs lower than 2,733/μL (P = .002). This was also true for PMN% at 5 months postoperatively (P = .009).ConclusionWBC count (2,733/μL) shows very high specificity to confirm successful reimplantation. Both WBC count and PMN% (62%) thresholds can significantly determine reimplantation survival.     

Etiology and Complications of Early Aseptic Revision Total Hip Arthroplasty Within 90 Days

BackgroundThe etiology, complications, and rerevision risks of early aseptic revision total hip arthroplasty (THA) within 90 days are insufficiently documented.MethodsA national insurance claims database (PearlDiver Technologies, Fort Wayne, IN) was queried for patients who underwent unilateral aseptic revision THA within 90 days of the index procedure using administrative codes. Patients who underwent revision for infection, without minimum 2-year follow-up, and younger than 18 years were excluded. This cohort was matched based on gender, age, and Charlson Comorbidity Index to a control group of patients who underwent primary THA without revision within 90 days. Two-year rerevision and 90-day complication rates were recorded. Chi-square and Fisher exact tests were used as appropriate for statistical comparison.ResultsFour hundred two patients met the inclusion criteria for early aseptic revision within 90 days of the index procedure and were matched to the control group. The overall 2-year rerevision rate was higher in the early revision group compared with control group (14.9% vs 2.5%, P < .001). Complications within 90 days occurred more frequently in the early revision group, including blood transfusion (10.2% vs 3.2%, P < .001), deep vein thrombosis (9.0% vs 3.2%, P = .001), and pulmonary embolism (2.74% vs 0.75%, P = .031). The most common reasons for early aseptic revision were dislocation (41.5%), fracture (38.1%), and loosening (17.4%).ConclusionEarly aseptic revision THA is associated with significantly higher 90-day complication rates and 2-year rerevision rates compared with a control group of primary THA without revision. The most common reasons for acute early revision were dislocation, fracture, and mechanical loosening.Level of EvidenceLevel III.     

Higher 2-Year Cumulative Incidence of Mental Health Disorders Following Antibiotic Spacer Placement for Chronic Periprosthetic Joint Infection following Total Joint Arthroplasty

BackgroundThe relationship of chronic periprosthetic joint infection (PJI) treatment on the development and relapse of mood disorders remains largely unreported. This study aims to compare the incidence of different mental health disorders following antibiotic spacer placement for chronic PJI when compared to aseptic revisions and primary procedures.MethodsPatients who underwent antibiotic spacer for septic total hip and knee arthroplasty (PJI THA/TKA) were identified in the PearlDiver Database using Current Procedure Terminology (CPT) codes for hip and knee antibiotic spacers. Patients who underwent aseptic revision and primary-THA/TKA were also identified using CPT codes. The incidences of depressive, anxiety, bipolar, psychotic, and stress disorders were identified within 2 years following the index procedures via Kaplan–Meier Analysis.ResultsThe risk of depressive (hazard ratio (HR): 1.5; P < .001) and stress (HR: 1.5; P < .001) disorders were significantly higher in those who underwent PJI-THA when compared to aseptic revision, with the added risk of bipolar when compared to primary THA. The risk of depressive (HR: 1.6; P < .001), stress (HR: 1.4; P < .001), bipolar (HR: 1.3; P < .001), and psychotic disorders (HR: 1.5; P = .003) were significantly higher in those who underwent PJI-TKA when compared to aseptic revision, with the added risk of anxiety when compared to primary TKA.ConclusionPatients who undergo spacer placement for septic-THA/TKA have a disproportionately higher incidence of mental health disorders within 2 years following surgery when compared those undergoing aseptic revisions and primary procedures. Due to this higher risk, physicians should strongly consider collaborative care with psychiatrists or mental health professionals.Level of EvidenceIII.     

Laboratory Value Effectiveness in Predicting Early Postoperative Periprosthetic Joint Infection After Total Hip Arthroplasty

BackgroundDiagnosing early periprosthetic joint infection (PJI) after primary total hip arthroplasty (THA) remains challenging. We sought to validate optimal laboratory value cutoffs for detecting early PJIs in a series of primary THAs from one institution.MethodsWe retrospectively identified 22,795 primary THAs performed between 2000 and 2019. Within 12 weeks, 43 hips (43 patients) underwent arthrocentesis. Patients were divided into 2 groups: evaluation ≤6 weeks or 6-12 weeks following THA. The 2011 Musculoskeletal Infection Society major criteria for PJI diagnosed PJI in 15 patients. Mann-Whitney U-tests were used to compare median laboratory values and receiver operating characteristic curve analysis was used to evaluate optimal cutoff values.ResultsBoth within 6 weeks and between 6 and 12 weeks postoperatively, median C-reactive protein (CRP), erythrocyte sedimentation rate, synovial white blood cell (WBC) count, neutrophil percentage, and absolute neutrophil count (ANC) values were significantly higher in infected THAs. Optimal cutoffs within 6 weeks were: CRP ≥100 mg/L, synovial WBCs ≥4390 cells/μL, neutrophil percentage ≥74%, and ANC ≥3249 cells/μL. Between 6 and 12 weeks, optimal cutoffs were: CRP ≥33 mg/L, synovial WBCs ≥26,995 cells/μL, neutrophil percentage ≥93%, and ANC ≥25,645 cells/μL.ConclusionEarly PJI following THA should be suspected within 6 weeks with CRP ≥100 mg/L or synovial WBCs ≥4390 cells/μL. Between 6 and 12 weeks postoperatively, cutoffs of CRP ≥33 mg/L, synovial fluid WBC ≥26,995 cells/μL, and neutrophil percentage ≥93% diagnosed PJI with high accuracy.Level of EvidenceLevel IV Diagnostic.     

Risk of Prosthetic Joint Infection Increases Following Early Aseptic Revision Surgery of Total Hip and Knee Arthroplasty

BackgroundIt is important to identify risk factors for periprosthetic joint infection (PJI) following total joint arthroplasty in order to mitigate the substantial social and economic burden. The objective of this study is to evaluate early aseptic revision surgery as a potential risk factor for PJI following total hip (THA) and total knee arthroplasty (TKA).MethodsPatients who underwent primary THA or TKA with early aseptic revision were identified in 2 national insurance databases. Control groups of patients who did not undergo revision were identified and matched 10:1 to study patients. Rates of PJI at 1 and 2 years postoperatively following revision surgery were calculated and compared to controls using a logistic regression analysis.ResultsIn total, 328 Medicare and 222 Humana patients undergoing aseptic revision THA within 1 year of index THA were found to have significantly increased risk of PJI at 1 year (5.49% vs 0.91%, odds ratio [OR] 5.61, P < .001 for Medicare; 7.21% vs 0.68%, OR 11.34, P < .001 for Humana) and 2 years (5.79% vs 1.10%, OR 4.79, P < .001 for Medicare; 8.11% vs 1.04%, OR 9.05, P < .001 for Humana). Similarly for TKA, 190 Medicare and 226 Humana patients who underwent aseptic revision TKA within 1 year were found to have significantly higher rates of PJI at 1 year (6.48% vs 1.16%, OR 7.69, P < .001 for Medicare; 6.19% vs 1.28%, OR 4.89, P < .001 for Humana) and 2 years (8.42% vs 1.58%, OR 6.57, P < .001 for Medicare; 7.08% vs 1.50%, OR 4.50, P < .001 for Humana).ConclusionEarly aseptic revision surgery following THA and TKA is associated with significantly increased risks of subsequent PJI within 2 years.     

Diagnostic Utility and Thresholds for Commonly Obtained Serum and Synovial Markers Prior to Reimplantation in Periprosthetic Joint Infection

BackgroundAccurate diagnosis of persistent periprosthetic joint infection (PJI) during 2-stage exchange remains a challenge. This study evaluated the diagnostic performance and thresholds of several commonly obtained serum and synovial markers to better guide reimplantation timing.MethodsThis was a retrospective review of 249 patients who underwent 2-stage exchange with antibiotic spacers for PJI. Serum and synovial markers analyzed included white blood cell (WBC) count, polymorphonuclear percentage (PMN%), neutrophil-to-lymphocyte ratio (NLR), and absolute neutrophil count (ANC). Serum markers analyzed were erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), as well as percentage change in ESR and CRP from initial diagnosis to reimplantation. Area under the curve (AUC) analyses were performed to determine diagnostic accuracy of detecting PJI.ResultsIn TKAs, synovial ANC and WBC had the highest AUCs (0.76), with thresholds of 2,952 and 3,800 cells/μL, respectively. The next best marker was serum CRP (0.73) with a threshold of 5.2 mg/dL. In THAs, serum CRP had the highest AUC (0.84) with a threshold of 4.3 mg/dL, followed by synovial PMN% (0.80) with a threshold of 77%. Percentage change in serum ESR or CRP provided low diagnostic value overall.ConclusionRegarding serum markers, CRP consistently performed well in detecting persistent PJI in patients with antibiotic spacers. Absolute values of serum CRP and ESR had better diagnostic value than trends for guiding reimplantation timing. Diagnostic performance differed with joint type; however, synovial markers outperformed serum counterparts. No marker alone can be utilized to diagnose residual PJI in these patients, and further work is needed in this domain.     

A Comparison of Revision Rates for Dislocation and Aseptic Causes Between Dual Mobility and Large Femoral Head Bearings in Primary Total Hip Arthroplasty With Subanalysis by Acetabular Component Size: An Analysis of 106,163 Primary Total Hip Arthroplasties

BackgroundDual mobility (DM) and large femoral head bearings (≥36 mm) both decrease the risk of dislocation in total hip arthroplasty (THA). There is limited comparable data in primary THA. This study compared the revision rates for dislocation and aseptic causes between DM and large femoral heads and subanalyzed by acetabular component size.MethodsData from the Australian Orthopedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis from January 2008 (the year of first recorded DM use) to December 2019. All DM and large femoral head bearings were identified. The primary outcome measure was the cumulative percent revision (CPR) for dislocation and for all aseptic causes. The results were adjusted by age, sex, and femoral fixation. A subanalysis was performed stratifying acetabular component diameter <58 m and ≥58 mm.ResultsThere were 4942 DM and 101,221 large femoral head bearings recorded. There was no difference in the CPR for dislocation (HR = 0.69 (95% CI 0.42, 1.13), P = .138) or aseptic causes (HR = 0.91 (95% CI 0.70, 1.18), P = .457). When stratified by acetabular component size, DM reduced the CPR for dislocation in acetabular component diameter <58 mm (HR = 0.55 (95% CI 0.30, 1.00), P = .049). There was no difference for diameter ≥58 mm. There was no difference in aseptic revision when stratified by acetabular component diameter.ConclusionThere is no difference in revision rates for dislocation or aseptic causes between DM and large femoral heads in primary THA. When stratified by acetabular component size, DM reduces dislocation for acetabular component diameter <58 mm.Level of EvidenceLevel III.     

Extended Oral Antibiotic Prophylaxis After Aseptic Revision Total Hip Arthroplasty: Does It Decrease Infection Risk?

BackgroundExtended oral antibiotic prophylaxis (EOA) has been shown to reduce infection after high-risk primary total hip arthroplasties (THAs) and reimplantations. However, data are limited regarding EOA after aseptic revision THAs. This study evaluated the impact of EOA on infection-related outcomes after aseptic revision THAs.MethodsWe retrospectively identified 1,107 aseptic revision THAs performed between 2014 and 2019. Patients who received EOA >24 hours perioperatively (n = 370) were compared to those who did not (n = 737) using an inverse probability of treatment weighting model. Their mean age was 65 years (range, 19-98 years), mean body mass index was 30 kg/m² (range, 16-72), and 54% were women. Outcomes included cumulative probabilities of any infection, periprosthetic joint infection (PJI), and re-revision or reoperation for infection. Mean follow-up was 4 years (range, 2-8 years).ResultsThe cumulative probability of any infection after aseptic revision THA was 2.3% at 90 days, 2.7% at 1 year, and 3.5% at 5 years. The cumulative probability of PJI was 1.7% at 90 days, 2.1% at 1 year, and 2.8% at 5 years. There was a trend toward an increased risk of any infection (hazards ratio [HR] = 2.6; P = .058), PJI (HR = 2.6; P = .085), and re-revision (HR = 6.5; P = .077) or reoperation (HR = 2.3; P = .095) for infection in patients who did not have EOA at the final clinical follow-up.ConclusionsEOA after aseptic revision THA was not associated with a statistically significant decreased risk of any infection, PJI, or re-revision or reoperation for infection at all time points.Level of EvidenceLevel III.     

Ultrasound-Guided Periprosthetic Biopsy in Failed Total Hip Arthroplasty: A Novel Approach to Test Infection in Patients With Dry Joints

BackgroundTo diagnose periprosthetic joint infection (PJI) preoperatively, ultrasound-guided joint aspiration (US-JA) may not be performed when effusion is minimal or absent. We aimed to report and investigate the diagnostic performance of ultrasound-guided periprosthetic biopsy (US-PB) of synovial tissue to obtain joint samples in patients without fluid around the implants.MethodsOne-hundred nine patients (55 men; mean age: 68 ± 13 years) with failed total hip arthroplasty (THA) who underwent revision surgery performed preoperative US-JA or US-PB to rule out PJI.ResultsSixty-nine of 109 patients had joint effusion and underwent US-JA, while the remaining 40 with dry joint required US-PB. Thirty-five of 109 patients (32.1%) had PJI, while 74/109 (67.9%) had aseptic THA failure. No immediate complications were observed in both groups. Technical success of US-PB was 100%, as the procedure was carried on as planned in all cases. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of US-JA were 52.2%, 97.8%, 92.3%, 80.3%, and 82.6%, while for US-PB, they were 41.7%, 100%, 100%, 80%, and 82.5%, respectively, with no significant difference (P = .779). Using the final diagnosis as reference standard, we observed a moderate agreement with both US-JA (k = 0.56) and US-PB (k = 0.50).ConclusionWe present a novel US-guided technique to biopsy periprosthetic synovial tissue of failed THA to rule out PJI. We found similar diagnostic performance as compared with traditional US-JA. This supports future larger studies on this procedure that might be applied in patients without joint effusion.     

Periprosthetic joint infection diagnosis: a complete understanding of white blood cell count and differential

Recent research has raised doubts regarding the utility of serum white blood cell count (WBC) for diagnosis of periprosthetic joint infection (PJI). As synovial WBC and neutrophil (PMN) percentage have been adopted as accurate markers of PJI, this study investigated the correlation of WBC in serum versus joint fluid and diagnostic value of all WBC levels for failed arthroplasty patients. 153 patients (73 PJI) undergoing revision knee arthroplasty were identified. Weak correlations between joint fluid and serum for WBC (R = 0.19), PMN count (R = 0.31), and lymphocyte count (R = -0.22) were observed. Diagnostic accuracy of PMN (93%) and WBC (93%) synovial count relative to serum was similar to synovial WBC (93%) and PMN% (95%) alone. Serum WBC analysis does little to improve the accurate diagnosis of PJI.     

High Mortality After Total Knee Arthroplasty Periprosthetic Joint Infection is Related to Preoperative Morbidity and the Disease Process but Not Treatment

BackgroundPeriprosthetic joint infection (PJI) mortality rate is approximately 20%. The etiology for high mortality remains unknown. The objective of this study was to determine whether mortality was associated with preoperative morbidity (frailty), sequalae of treatment, or the PJI disease process itself.MethodsA multicenter observational study was completed comparing 184 patients treated with septic revision total knee arthroplasty (TKA) to a control group of 38 patients treated with aseptic revision TKA. Primary outcomes included time and the cause of death. Secondary outcomes included preoperative comorbidities and Charlson Comorbidity Index (CCMI) measured preoperatively and at various postoperative timepoints.ResultsThe septic revision TKA cohort experienced earlier mortality compared to the aseptic cohort, with a higher mortality rate at 90 days, 1, 2, and 3 years after index revision surgery (P = .01). There was no significant difference for any single cause of death (P > .05 for each). The mean preoperative CCMI was higher (P = .005) in the septic revision TKA cohort. Both septic and aseptic cohorts experienced a significant increase in CCMI from the preoperative to 3 years postoperative (P < .0001 and P = .002) and time of death (P < .0001 both) timepoints. The septic revision TKA cohort had a higher CCMI 3 years postoperatively (P = .001) and at time of death (P = .046), but not one year postoperatively (P = .119).ConclusionCompared to mortality from aseptic revision surgery, septic revision TKA is associated with earlier mortality, but there is no single specific etiology. As quantified by changes in CCMI, PJI mortality was associated with both frailty and the PJI disease process, but not treatment.     

Transverse posterior wall acetabular fracture pattern is associated with increased risk of periprosthetic joint infection after conversion total hip arthroplasty

IntroductionAcetabular fracture subtypes are associated with varying rates of subsequent conversion total hip arthroplasty (THA) after open reduction internal fixation (ORIF) with transverse posterior wall (TPW) patterns having a higher risk for early conversion. Conversion THA is fraught with complications including increased rates of revision and periprosthetic joint infections (PJI). We aimed to determine if TPW pattern is associated with higher rates of readmissions and complications including PJI after conversion compared to other subtypes.MethodsWe retrospectively reviewed 1,938 acetabular fractures treated with ORIF at our institution from 2005 to 2019, of which 170 underwent conversion that met inclusion criteria, including 80 TPW fracture pattern. Conversion THA outcomes were compared by initial fracture pattern. There was no difference between the TPW and other fracture patterns in age, BMI, comorbidities, surgical variables, length of stay, ICU stay, discharge disposition, or hospital acquired complications related to their initial ORIF procedure. Multivariable analysis was performed to identify independent risk factors for PJI at both 90-days and 1-year after conversion.ResultsTPW fracture had higher risk of PJI after conversion THA at 1-year (16.3% vs 5.6%, p = 0.027). Multivariable analysis revealed TPW independently carried increased risk of 90-day (OR 4.89; 95% CI 1.16–20.52; p = 0.03) and 1-year PJI (OR 6.51; 95% CI 1.56–27.16; p = 0.01) compared to the other acetabular fracture patterns. There was no difference between the fracture cohorts in 90-day or 1-year mechanical complications including dislocation, periprosthetic fracture and revision THA for aseptic etiologies, or 90-day all-cause readmission after the conversion procedure.ConclusionAlthough conversion THA after acetabular ORIF carry high rates of PJI overall, TPW fractures are associated with increased risk for PJI after conversion compared to other fracture patterns at 1-year follow-up. Novel management/treatment of these patients either at the time of ORIF and/or conversion THA procedure are needed to reduce PJI rates.Level of evidenceTherapeutic Level III (retrospective study of consecutive patients undergoing an intervention with analyses of outcomes).     

Less Than 1-Year Quiescent Period After Septic Arthritis of the Hip is Associated With High Risk of Periprosthetic Joint Infection Following Total Hip Arthroplasty

BackgroundApproximately 20,000 patients are diagnosed with septic arthritis annually, with 15% specifically affecting the hip joint. These cases exacerbate arthritic changes, often warranting a total hip arthroplasty (THA). Given their prior history of infection, these patients are predisposed to subsequent periprosthetic joint infections (PJIs). Multiple studies suggest delaying THA after a native septic hip, but no study utilizing a large cohort examined the specific timing to mitigate post-THA PJI risk within a short (<1 year) quiescent period after septic arthritis. We sought to compare patients who were diagnosed with septic hip arthritis at time intervals (0-6, or 6-12 months) prior to an ipsilateral primary THA to a cohort of THA patients who never had a septic hip history. Specifically, we assessed: from 90 days to 2 years (1) revisions due to PJI and (2) associated risk factors for PJI at 2-years.MethodsA national, all-payer database was queried to identify all patients who underwent a primary THA between 2010 and 2021 and patients who had prior ipsilateral septic hip arthritis were characterized using International Classification of Disease and Current Practice Terminology codes (n = 1,052). A randomized sample of patients who never had a history of septic arthritis prior to undergoing THA was used as a nonseptic group comparison (n = 5,000). The incidences of PJI at 90 days through two years were then identified and compared using bivariate chi-square analyses. Risk factors for post-THA PJIs were then analyzed using multivariate regression models.ResultsThe septic arthritis cohorts were more likely to require revisions due to PJIs, as compared to the non-septic group at 90 days, 1 year, and 2 years (all P < .0001). Patients who were diagnosed with septic arthritis between 0 and 6 months prior to THA were at greater PJI risk at both one-year (odds ratio (OR) of 43.1 versus 29.6, P < .0001) and two years (OR of 38.3 versus 22.1, P < .0001) compared to patients who had diagnoses between 6 and 12 months. Diabetes mellitus, obesity, and tobacco use were associated risk factors for PJIs at 2 years in the septic hip cohort in comparison to the cohort without a septic hip history.ConclusionLess than a 1-year quiescent period after septic arthritis is associated with a 38 times increased risk and a 22 times risk for post-THA PJI, at 0 and 6 months and 6 and 12 months, respectively. Though patients who undergo THA greater than 6 months after their septic arthritis treatment have a decreased risk compared to those between 0 and 6 months the risks are still high. Orthopaedic surgeons should be aware of the increased risks of PJIs when considering performing a THA in patients with a history of septic arthritis.