Faculty Bibliography

Infecting microorganism is a strong predictor of treatment success for periprosthetic joint infection (PJI). The purpose of this study was to compare the infecting pathogens causing PJI at two large infection referral centers in the United States and in Europe. In this study, 898 consecutive cases of PJI were identified at the HELIOS ENDO-Klinik Hamburg in Europe and 772 cases were identified at the Rothman Institute in the United States. The incidence of organisms at the HELIOS ENDO-Klinik Hamburg versus the Rothman Institute was: coagulase-negative Staphylococcus (39.3 vs. 20.2%), S. aureus (13.0 vs. 31.0%), Streptococcus (6.5 vs. 5.8%), Enterococcus (7.0 vs. 3.9%), anaerobic (9.0 vs. 0.9%), fungal (0.3 vs. 2.3%), mycobacterial (0 vs. 0.6%), polymicrobial (3.4 vs. 7.4%), culture negative (16.1 vs. 15.8%), and other organisms (0.9 vs. 5.4%). The percentage of methicillin-resistant S. aureus was significantly higher at the American center than at the European center (48.1 vs. 12.8%; p < 0.0001). Our findings show higher virulence and resistance organisms are more prevalent at a referral center in the United States compared with one in Europe.

BACKGROUND:The volume of total knee arthroplasties, including revisions, in young patients is expected to rise. The objective of this study was to compare the reasons for revision and re-revision total knee arthroplasties between younger and older patients, to determine the survivorship of revision total knee arthroplasties, and to identify risk factors associated with failure of revision in patients fifty years of age or younger. METHODS:Perioperative data were collected for all total knee arthroplasty revisions performed from August 1999 to December 2009. A cohort of eighty-four patients who were fifty years of age or younger and a cohort of eighty-four patients who were sixty to seventy years of age were matched for the date of surgery, sex, and body mass index (BMI). The etiology of failure of the index total knee arthroplasty and all subsequent revision total knee arthroplasties was determined. Kaplan-Meier survival curves were used to evaluate the timing of the primary failure and the survivorship of revision knee procedures. Finally, multivariate Cox regression was used to calculate risk ratios for the influence of age, sex, BMI, and the reason for the initial revision on survival of the revision total knee arthroplasty. RESULTS:The most common reason for the initial revision was aseptic loosening (27%; 95% confidence interval [CI] = 19% to 38%) in the younger cohort and infection (30%; 95% CI = 21% to 40%) in the older cohort. Of the twenty-five second revisions in younger patients, 32% (95% CI = 17% to 52%) were for infection, whereas 50% (95% CI = 32% to 68%) of the twenty-six second revisions in the older cohort were for infection. Cumulative six-year survival rates were 71.0% (95% CI = 60.7% to 83.0%) and 66.1% (95% CI = 54.5% to 80.2%) for revisions in the younger and older cohorts, respectively. Infection and a BMI of ≥ 40 kg/m(2) posed the greatest risk of failure of revision procedures, with risk ratios of 2.731 (p = 0.006) and 2.934 (p = 0.009), respectively. CONCLUSIONS:The survivorship of knee revisions in younger patients is a cause of concern, and the higher rates of aseptic failure in these patients may be related to unique demands that they place on the reconstruction. Improvement in implant fixation and treatment of infection when these patients undergo revision total knee arthroplasty is needed.

BACKGROUND:Preoperative antibiotics are known to be critical for decreasing the risk of periprosthetic joint infection (PJI) in primary THA and TKA. However, antibiotics often are withheld before revision surgery, as there is concern that even a single dose of prophylactic antibiotics may affect intraoperative cultures. QUESTIONS/PURPOSES/OBJECTIVE:In this prospective randomized controlled trial, we determined the effect of a single dose of prophylactic antibiotics on cultures obtained at the time of revision arthroplasty. METHODS:We randomized 65 patients with known PJI after 37 TKAs and 28 THAs at three centers. Patients were included in the trial if they had a culture-positive aspiration and had not taken antibiotics within 2 weeks of the procedure. Patients were randomized to receive prophylactic antibiotics either before the skin incision or after a minimum of three sets of intraoperative cultures were obtained. Preoperative and intraoperative cultures were then compared. Results between patients who did and did not receive antibiotics were compared using an equivalence test for proportion differences (two one-sided t-tests [TOST]) with a 0.2 margin. RESULTS:Intraoperative cultures yielded the same organisms as preoperative cultures in 28 of 34 patients (82%) randomized to receive antibiotics before the skin incision compared to 25 of 31 patients (81%) randomized to receive antibiotics after obtaining operative cultures (statistically equivalent by TOST estimate: p = 0.0290). CONCLUSIONS:In this randomized controlled trial, there was no effect on the results of cultures obtained intraoperatively when prophylactic antibiotics were administered before skin incision. Given the known benefits of prophylactic antibiotics in preventing PJI, preoperative prophylaxis should not be withheld in revision surgery for fear of affecting cultures.

BACKGROUND:While it is accepted accurate identification of infecting organisms is crucial in guiding treatment of periprosthetic joint infection (PJI), there remains no consensus regarding the best method for obtaining cultures. QUESTIONS/PURPOSES/OBJECTIVE:We compared the yield of intraoperative tissue samples versus swab cultures in diagnosing PJI. METHODS:Tissue and swab cultures (three each) were collected prospectively during a consecutive series of 156 aseptic and septic revision arthroplasties from October 2011 to April 2012. The tissues and swabs were taken from standardized regions of the joint. After excluding 39 reimplantation procedures, we included 117 cases (74 hip, 43 knee; 30 septic, 87 aseptic) for analysis. We used a modified version of the Musculoskeletal Infection Society criteria for defining PJI, requiring three of five rather than four of six criteria. Tissue and swab cultures from septic and aseptic cases were used to calculate their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying PJI. RESULTS:Tissue cultures were positive in a higher percentage of septic cases than swab cultures: 28 of 30 (93%) versus 21 of 30 (70%). Tissue cultures were positive in two of 87 aseptic cases (2%), while swab cultures were positive in 10 of 87 (12%). The sensitivity, specificity, PPV, and NPV were 93%, 98%, 93%, and 98%, respectively, for tissue cultures and 70%, 89%, 68%, and 90%, respectively, for swab cultures. CONCLUSIONS:Tissue cultures demonstrated higher sensitivity, specificity, PPV, and NPV for diagnosing PJI than swab cultures. Swab cultures had more false-negative and false-positive results than tissue cultures. Because swab cultures pose a higher risk of not identifying or incorrectly identifying infecting organisms in PJI, we believe their use in obtaining intraoperative culture specimens should be discouraged. LEVEL OF EVIDENCE/METHODS:Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND:More than 3 million people in the United States have atrial fibrillation, most of whom are being managed with anticoagulation therapy for life. The goal of the present study was to examine the effect of chronic anticoagulation therapy on patients with atrial fibrillation who undergo total joint arthroplasty. METHODS:We retrospectively reviewed all patients undergoing aseptic primary or revision total joint arthroplasty at our facility from March 2007 to August 2011. One hundred and sixty-one patients with atrial fibrillation (Group A) were compared with 161 matched controls (Group B). A total of 112 hips and 210 knees underwent 239 primary arthroplasties and eighty-three revisions. The groups were compared with use of conditional logistic regression (with matching on the basis of the involved joint [hip or knee], type of procedure [revision or primary], age, and sex) with regard to the length of hospital stay, postoperative hemoglobin levels, transfusion requirements, and readmissions. RESULTS:The preoperative length of stay (1.7 versus 0.2 days; p < 0.0001), postoperative length of stay (4.6 versus 3.2 days; p = 0.0002), and total length of stay (6.3 versus 3.4 days; p < 0.0001) were significantly longer for patients with atrial fibrillation (Group A). Hemoglobin levels were lower (but not significantly so) for Group A at baseline (13.1 versus 13.8 mg/dL), on Postoperative Day 2 (10.1 versus 10.6 mg/dL), on Postoperative Day 3 (9.8 versus 10.2 mg/dL), on Postoperative Day 4 (9.6 versus 10.1 mg/dL), on Postoperative Day 5 (9.7 versus 9.9 mg/dL), and at discharge (9.9 versus 10.3 mg/dL). Group A had a significantly higher prevalence of blood transfusion (15.5% versus 3.7%; p = 0.0005) and periprosthetic joint infection (5.6% versus 0.62%; p = 0.0196). A diagnosis of atrial fibrillation (odds ratio, 4.09; 95% confidence interval, 2.05 to 8.18; p < 0.0001) significantly increased the odds of total joint arthroplasty complication and the need for hospital readmission. CONCLUSIONS:Patients with preoperative atrial fibrillation undergoing total joint arthroplasty had an increased length of hospital stay, increased transfusion requirements, and an increased risk of periprosthetic joint infection and unplanned hospital readmission.

We assessed the utility of culturing draining wounds or sinuses in evaluating periprosthetic joint infection (PJI). Fifty-five patients with a draining wound or sinus after total joint arthroplasty (28 knees, 27 hips) who had not received antibiotics for at least two weeks were prospectively studied. Superficial wound cultures were compared to intra-articular cultures to determine accuracy in isolating infecting organism(s). The superficial cultures were concordant with deep cultures in 26 of 55 cases (47.3%) and were more likely to generate polymicrobial results (27.3% vs. 10.9%; P=0.023). In 23 cases (41.8%), the superficial cultures would have led to a change in antibiotic regimen. Superficial cultures yielded bacterial growth in 8 of the 10 cases (80%) when deep cultures and further work-up suggested the absence of deep infection. Given the potential to misguide diagnosis and treatment, we recommend against obtainment of superficial cultures in patients with a draining wound or sinus following hip or knee arthroplasty.

Accurate and efficient diagnosis of periprosthetic joint infection remains one of the most challenging tasks for orthopedic surgeons. Currently, no widely used diagnostic test allows for quick and efficient performance, low cost, and high sensitivity and specificity. Aspiration of synovial fluid from a patient's joint can be done in the clinic both quickly and easily; oftentimes, the aspirate obtained is bloody, thus rendering the use of colorimetric strip testing impractical. We describe a simple, inexpensive, and effective protocol using centrifugation to allow for leukocyte esterase (LE) testing after bloody joint aspirations. In all cases, both septic and aseptic, there was a 100% concordance in LE enzyme test results. Although further validation may be necessary, these initial results demonstrate that accuracy of LE testing is not affected by centrifugation.

Periprosthetic joint infection (PJI) is one of the most devastating and costly complications following total joint arthroplasty (TJA). Diagnosis and management of PJI is challenging for surgeons. There is no "gold standard" for diagnosis of PJI, making distinction between septic and aseptic failures difficult. Additionally, some of the greatest difficulties and controversies involve choosing the optimal method to treat the infected joint. Currently, there is significant debate as to the ideal treatment strategy for PJI, and this has led to considerable international variation in both surgical and nonsurgical management of PJI. In this review, we will discuss diagnosis and management of PJI following TJA and highlight some recent advances in this field.