Faculty Bibliography

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.

Infections with methicillin-resistant Staphylococcus aureus (MRSA) are an ever growing problem in the community, hospitals, and for orthopedic surgeons in particular. A conscious effort must be made to deal with this pathogen prior to total joint arthroplasty procedures. The drastic increase in prevalence of surgical-site infections (SSIs) after total joint replacement surgery has proved to be a major health care burden for both patients and surgeons from both a medical and financial standpoint. The development of screening techniques for detection of MRSA colonization in patients being admitted to hospitals is steadily increasing popularity. Particularly nasal swab rapid polymerase chain reaction detection of MRSA allows surgeons to identify patients at high risk for postoperative SSI. A variety of treatment regimens for eradication of MRSA colonization from the nares of surgical patients have surfaced, such as topical mupirocin prior to undergoing surgery. Decolonization of MRSA in patients undergoing joint arthroplasty procedures has demonstrated encouraging initial results in preventing SSIs and should be a serious focus of the future for orthopedic surgeons.