BackgroundA key issue in the treatment of periprosthetic joint infection (PJI) is the correct diagnosis. The main problem is lack of diagnostic tools able to diagnose a PJI with high accuracy. Alpha-defensin has been proposed as a possible solution, but in the current literature, there is a lack of independent validation.Questions/purposesWe performed a prospective study to determine (1) what is the sensitivity, specificity, and positive and the negative predictive values of the alpha-defensin immunoassay test in diagnosing PJI; and (2) which clinical features may be responsible for false-positive and false-negative results?MethodsPreoperative aspiration was performed in all patients presenting with a painful hip/knee arthroplasty, including both primary and revision implants. Metallosis, other inflammatory comorbidities, and previous/concomitant antibiotic therapy were not considered as exclusion criteria. An inadequate amount of synovial fluid for culture was an exclusion criterion. A total of 156 patients (65 knees, 91 hips) were included in this prospective study. At the time of revision, synovial fluid samples were taken to perform the alpha-defensin assay. During surgical débridement of tissue, samples for cultures and histologic evaluation were taken, and samples were cultured until positive or until negative at 14 days. A diagnosis of PJI was confirmed in 29 patients according to the International Consensus Group on PJI.ResultsThe sensitivity of the alpha-defensin immunoassay was 97% (95% confidence interval [CI], 92%–99%), the specificity was 97% (95% CI, 92%–99%), the positive predictive value was 88% (95% CI, 81%–92%), and the negative predictive value was 99% (95% CI, 96%–99%). Among four false-positive patients, two had metallosis and one had polyethylene wear. The false-negative case presented with a draining sinus, and intraoperative cultures were also negative.ConclusionsAlpha-defensin assay appears to be a reliable test, but followup evaluation is needed to estimate longer term performance of the test. The authors believe that alpha-defensin has demonstrated itself to be sufficiently robust that PJI diagnostic criteria now should include this test. Future studies are needed to compare the differences among the diagnostic capability of the available tests, in particular when metallosis is present, because metallosis may predispose the test to a false-positive result.Level of EvidenceLevel I, diagnostic study.

To present two patients with Miller Fisher syndrome (MFS) recurrence after 35 and 44 years and review of the literature on recurring MFS. All identified cases with recurrent MFS were evaluated. Age, gender, clinical features of first and recurrent MFS, course of disease, laboratory findings, therapy and outcome were transformed into tables. Twenty-eight patients (16 men, 12 women; mean age at the first episode 34 years (range 13-57 years); mean age at the latest episode 47 years (range 21-66 years) with a total of 70 MFS episodes were identified. Twenty-one patients had a single recurrence, five patients had two recurrences, one patient had four recurrences and one patient had seven recurrences. The mean interval between attacks was 9.45 years (3 months to 44 years). In 76% of the initial episodes and in 81% of the recurrent episodes, an infectious disease preceded MFS. Additional facial and bulbar symptoms and autonomic disturbances were frequent findings. Cerebrospinal fluid (CSF) and electrodiagnostic findings were unspecific. If tested, autoantibodies against GQ1b had been positive in all episodes. In about half of the patients, immunotherapy was applied. The outcome was favourable in most patients. Recurrence of MFS is a rare quite uniform condition with a mostly favourable prognosis.

Within the past 5 years, the oral anticoagulants rivaroxaban, apixaban, and dabigatran etexilate have been approved for the prevention of venous thromboembolism in adult patients after elective hip or knee arthroplasty in the European Union and many other countries worldwide. These agents differ from the previously available anticoagulants because they selectively and directly inhibit a single factor in the coagulation cascade—rivaroxaban and apixaban inhibit Factor Xa, and dabigatran inhibits Factor IIa (thrombin)—potentially enhancing the predictability of their anticoagulant effect. Currently, although some guidelines provide recommendations for the use of rivaroxaban, dabigatran etexilate, and apixaban in clinical practice, there are still questions regarding the optimal practical management of patients receiving these agents. This article briefly reviews the practical limitations associated with conventional anticoagulants, discusses potential issues with the practical management of the newer oral anticoagulants, and provides clinical experience from a single institution where rivaroxaban and dabigatran etexilate have been used within their approved indications.