Preoperative Use of Clopidogrel Does Not Affect Outcomes for Femoral Neck Fractures Treated With Hemiarthroplasty.

BACKGROUND: The antiplatelet effect of clopidogrel on blood loss and perioperative complications after surgical intervention remains ambiguous. The purpose of this study was to determine if patients on clopidogrel before hemiarthroplasty for femoral neck fracture are predisposed to greater surgical bleeding and perioperative complications compared with those not taking clopidogrel before surgery. METHODS: We conducted a review of our electronic medical record from 2006-2013 and identified 602 patients who underwent 623 hemiarthroplasty procedures for displaced femoral neck fracture, of which 54 cases (9%) were taking clopidogrel before hospital admission. Patient demographics and comorbidities, operative and surgical variables, and perioperative complications at 90 days were compared between the clopidogrel and nonclopidogrel user groups. RESULTS: The 2 groups of patients had similar baseline characteristics, but patients taking clopidogrel preoperatively were sicker with higher American Society of Anesthesiologists scores (P = .049) and age-adjusted Charlson index (P = .001). They also had a greater incidence of cerebrovascular disease (P = .01), chronic obstructive pulmonary disease (P = .03), diabetes (0.03), and malignancy (P < .001). There was no significant difference between the 2 patient groups with respect to 90-day postoperative medical readmissions (P = .85), surgical readmissions (P = .26), infection (P = .99), and mortality (P = .89). CONCLUSION: Patients taking clopidogrel who present with a displaced femoral neck fracture can safely undergo a hemiarthroplasty while actively on clopidogrel without an increase in medical or surgical complications and mortality. We do not recommend delaying surgical intervention until the antiplatelet effects of clopidogrel subside.

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

BACKGROUND: Determining 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. METHODS: Institutional 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. RESULTS: Thirty-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). CONCLUSION: Synovial 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.

The ACS NSQIP Risk Calculator Is a Fair Predictor of Acute Periprosthetic Joint Infection.

BACKGROUND: Periprosthetic joint infection (PJI) is a severe complication from the patient's perspective and an expensive one in a value-driven healthcare model. Risk stratification can help identify those patients who may have risk factors for complications that can be mitigated in advance of elective surgery. Although numerous surgical risk calculators have been created, their accuracy in predicting outcomes, specifically PJI, has not been tested. QUESTIONS/PURPOSES: (1) How accurate is the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Surgical Site Infection Calculator in predicting 30-day postoperative infection? (2) How accurate is the calculator in predicting 90-day postoperative infection? METHODS: We isolated 1536 patients who underwent 1620 primary THAs and TKAs at our institution during 2011 to 2013. Minimum followup was 90 days. The ACS NSQIP Surgical Risk Calculator was assessed in its ability to predict acute PJI within 30 and 90 days postoperatively. Patients who underwent a repeat surgical procedure within 90 days of the index arthroplasty and in whom at least one positive intraoperative culture was obtained at time of reoperation were considered to have PJI. A total of 19 cases of PJI were identified, including 11 at 30 days and an additional eight instances by 90 days postoperatively. Patient-specific risk probabilities for PJI based on demographics and comorbidities were recorded from the ACS NSQIP Surgical Risk Calculator website. The area under the curve (AUC) for receiver operating characteristic (ROC) curves was calculated to determine the predictability of the risk probability for PJI. The AUC is an effective method for quantifying the discriminatory capacity of a diagnostic test to correctly classify patients with and without infection in which it is defined as excellent (AUC 0.9-1), good (AUC 0.8-0.89), fair (AUC 0.7-0.79), poor (AUC 0.6-0.69), or fail/no discriminatory capacity (AUC 0.5-0.59). A p value of < 0.05 was considered to be statistically significant. RESULTS: The ACS NSQIP Surgical Risk Calculator showed only fair accuracy in predicting 30-day PJI (AUC: 74.3% [confidence interval {CI}, 59.6%-89.0%]. For 90-day PJI, the risk calculator was also only fair in accuracy (AUC: 71.3% [CI, 59.9%-82.6%]). Conclusions The ACS NSQIP Surgical Risk Calculator is a fair predictor of acute PJI at the 30- and 90-day intervals after primary THA and TKA. Practitioners should exercise caution in using this tool as a predictive aid for PJI, because it demonstrates only fair value in this application. Existing predictive tools for PJI could potentially be made more robust by incorporating preoperative risk factors and including operative and early postoperative variables. LEVEL OF EVIDENCE: Level III, diagnostic study.

Lyme Disease: A Potential Source for Culture-negative Prosthetic Joint Infection.

The presentation of Lyme arthritis can mimic periprosthetic joint infection (PJI) caused by typical bacterial organisms. A patient with left total knee arthroplasty (TKA) and chronic Lyme disease presented to our institution with Lyme-associated PJI. He complained of pain, erythema, and fever for 3 days and met Musculoskeletal Infection Society criteria for PJI. Preoperative synovial fluid Lyme polymerase chain reaction (PCR) and serological tests were positive, whereas both preoperative aspiration and intraoperative cultures were negative. The patient underwent resection arthroplasty with insertion of an antibiotic spacer followed by intravenous ceftriaxone and oral doxycycline treatment for 6 weeks. He underwent reimplantation at 8 weeks after repeat synovial fluid PCR analysis was negative. At 1 year, the patient was asymptomatic with a painless, functional, revision TKA. It is essential to consider Lyme-associated PJI in the setting of culture-negative PJI, especially in regions with a high prevalence of Lyme disease.