Advanced imaging shows extra-articular abscesses in two out of three adult patients with septic arthritis of the native hip joint.

Background: Septic arthritis (SA) of the native adult hip is a rare orthopaedic emergency requiring prompt diagnosis and treatment. As clinical presentation and laboratory findings are frequently atypical, advanced imaging is often requested. This retrospective study aimed to investigate the prevalence and pattern of extra-articular infectious manifestations and their implications for pre-operative advanced imaging in patients with proven SA of the native hip joint. Methods: Out of 41 patients treated surgically for SA of the native hip during a 16-year period at our tertiary referral hospital, 25 received advanced imaging (computed tomography (CT), magnetic resonance imaging (MRI), or fluorodeoxyglucose positron emission tomography (FDG PET-CT)) prior to initial intervention. For each investigation, a specific set of variables was systematically interpreted, and the most suitable surgical approach was determined. The prognostic value was evaluated by comparing specific outcome measures and the extent of extra-articular involvement. Results: It was found that 32 % of patients had an abscess in one anatomical region, 32 % of patients had abscesses in multiple anatomical regions, and only 36 % of patients had no substantial abscess. Gluteal abscesses were especially common in patients with SA due to contiguous spread. Abscesses in the iliopsoas region were more common in patients with SA due to hematogenous seeding. A combination of several different surgical approaches was deemed necessary to adequately deal with the various presentations. No significant prognostic factors could be identified. Conclusion: We recommend performing advanced imaging in patients with suspected or proven septic arthritis of the native hip joint, as extra-articular abscesses are present in 64 % and might require varying anatomical approaches.

Laboratory workflow for optimizing leukocyte count and differential in synovial fluids on Sysmex XN-1000.

INTRODUCTION: Falsely elevated synovial white blood cell (WBC) counts using automated hematology analyzers have been reported particularly in the setting of joint arthroplasty. We evaluated the implementation of a laboratory workflow based on Sysmex XN-1000-automated cell counting and scattergram interpretation. METHODS: WBC and differential were measured for 76 synovial fluid samples (29 native joints and 47 with joint arthroplasties) with Sysmex XN-1000 and manual methods. All scattergrams were evaluated for possible incorrect WBC and/or differential according to our implemented workflow. A specific finding was the "banana-shape" scattergram, which indicates possible interferences. The European Bone & Joint Infection Society (EBJIS) criteria were applied to identify possible prosthetic joint infections (PJIs) in patients with joint arthroplasties. RESULTS: Correlation between automated and manual WBC counts, calculated for samples with WBC count <50 000/µL, was higher for native joints (r = 0.938) compared with patients known with arthroplasty (r = 0.906). Scattergrams classified as OK showed overall a higher correlation compared with scattergrams, which were interpreted as NOT OK. "Banana-shape" scattergrams (n = 19) showed falsely elevated automated WBC count, and the patterns were mainly seen in prosthesis patients (17/19 [89%]). Six of 47 (13%) patients with joint arthroplasties were reclassified from "confirmed" to "unlikely" PJI according to the EBJIS criteria. CONCLUSION: Our workflow based on scattergram interpretation resulted in accurate WBC counts in synovial fluid using automated/and or manual methods. It is important to identify the presence of "banana-shape" scattergrams to avoid overestimated automated WBC counts. Overall, automated synovial WBC count can be used, even for patients with arthroplasty, but after visual inspection of the scattergram to exclude possible interferences.

Ureaplasma urealyticum osteomyelitis of the greater trochanter in a patient with multiple sclerosis using ocrelizumab - a case report.

Ocrelizumab - a monoclonal anti-CD20 antibody used in treatment of multiple sclerosis (MS) - marks significant progress in treating autoimmune diseases but raises susceptibility to opportunistic infections due to hypogammaglobulinemia. A young MS patient developed osteomyelitis from persistent Ureaplasma urealyticum urethritis, which was diagnosed with specialized polymerase chain reaction and resolved with targeted antibiotics. A multidisciplinary approach is crucial for managing such infections.