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Background: Several studies have confirmed a high rate of unexpected positive cultures (UPCs) after presumably aseptic revisions of shoulder arthroplasties; however, the impact on the outcome is still unclear. The purpose of this prospective study is to compare the patient-reported outcomes of standard revisions with and without the emergence of UPCs., Methods: During a 3-year period, we included all patients who were revised for reasons other than suspicion of infection from 2 orthopedic centers. Five biopsies were obtained from every revision, and only cultures with the same bacteria in at least 3 biopsy specimens were classified as UPCs. All patients were assessed using the Oxford Shoulder Score (OSS) and range of motion preoperatively and after at least a 2-year follow-up., Results: In this study, 124 patients were included, with a median follow-up of 29 months (range 29-32), and UPCs emerged after 27 revisions (22%), with Cutibacterium acnes accounting for 67% (18/27). At baseline, the OSS was 22 in both the culture-negative and UPC groups (P = .46). Then, at follow-up, the OSS was 37 in the culture-negative group and 35 in the UPC group (P = .91). The forward elevation increased significantly by 44° and 41°, respectively, in the 2 groups, but no statistically significant difference between the culture-negative group and the UPC group was found (P = .66). In contrast, the external rotation was unchanged after the revision, and again, no difference in the change between the culture-negative and UPC groups (P = .54) was observed. Subgroup analyses stratified by different implant designs revealed equal patterns with no statistical differences in outcome., Conclusion: We did not find a difference in outcome after a presumed aseptic revision regardless of the emergence of UPCs. Similarly, we could not demonstrate that patients with UPCs presented with poorer function at baseline compared with culture-negative patients. The clinical relevance of UPCs thus requires further evaluation, especially in the case of C acnes as a potential pathogenic versus a merely colonizing microbe., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Shoulder periprosthetic joint infections (PJI) caused by low-virulent bacteria pose a diagnostic challenge. Combined labeled leukocyte (WBC) and technetium 99m sulfur colloid bone marrow imaging (WBC/BM) is considered the radionuclide imaging gold standard for diagnosing lower limb PJI. However, it is laborious and expensive to perform, and documentation on shoulder arthroplasties is lacking. This study investigated WBC/BM single-photon emission computed tomography-computed tomography diagnostic performance in shoulder PJI., Method: All patients with a failed arthroplasty referred to a highly specialized shoulder department were scheduled for a diagnostic program including a WBC/BM. If an arthroplasty was revised, biopsy specimens were obtained and cultured for 14 days. The diagnostic performance of WBC/BM imaging was determined using biopsy specimens as a reference., Results: Of the 49 patients who underwent a WBC/BM scan, 29 (59%) were revised. Infection was present in 11 patients, in whom 2 WBC/BM scans were true positive. The WBC/BM scan in 9 patients was false negative. The remaining 18 patients all had a true negative WBC/BM scan. WBC/BM showed a sensitivity 0.18 (95% confidence interval [CI], 0.00-0.41) and specificity 1.00 (95% CI, 1.00-1.00) in detecting shoulder PJI. The positive predictive value was 1.00 (95% CI, 1.00-1.00), and negative predictive value was 0.67 (95% CI, 0.49-0.84). No patients infected with Cutibacterium (formerly Propionibacterium) acnes resulted in a positive WBC/BM, nor had they preoperative or perioperative signs of infection., Conclusion: A positive WBC/BM was found only in patients with obvious PJI. Hence, the scan added nothing to the preoperative diagnosis. The WBC/BM single-photon emission computed tomography-computed tomography scan cannot be recommended as a screening procedure when evaluating failed shoulder arthroplasties for possible infection., (Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)