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Aims Methicillin-resistant Staphylococcus aureus (MRSA) can cause wound infections via a ‘Trojan Horse’ mechanism, in which neutrophils engulf intestinal MRSA and travel to the wound, releasing MRSA after apoptosis. The possible role of intestinal MRSA in prosthetic joint infection (PJI) is unknown. Methods Rats underwent intestinal colonization with green fluorescent protein (GFP)-tagged MRSA by gavage and an intra-articular wire was then surgically implanted. After ten days, the presence of PJI was determined by bacterial cultures of the distal femur, joint capsule, and implant. We excluded several other possibilities for PJI development. Intraoperative contamination was excluded by culturing the specimen obtained from surgical site. Extracellular bacteraemia-associated PJI was excluded by comparing with the infection rate after intravenous injection of MRSA or MRSA-carrying neutrophils. To further support this theory, we tested the efficacy of prophylactic membrane-permeable and non-membrane-permeable antibiotics in this model. Results After undergoing knee surgery eight or 72 hours after colonization, five out of 20 rats (25.0%) and two out of 20 rats (10.0%) developed PJI, respectively. Strikingly, 11 out of 20 rats (55.0%) developed PJI after intravenous injection of MRSA-carrying neutrophils that were isolated from rats with intestinal MRSA colonization. None of the rats receiving intravenous injections of MRSA developed PJI. These results suggest that intestinal MRSA carried by neutrophils could cause PJI in our rat model. Ten out of 20 (50.0%) rats treated with non-membrane-permeable gentamicin developed PJI, whereas only one out of 20 (5.0%) rats treated with membrane-permeable linezolid developed PJI. Conclusion Neutrophils as carriers of intestinal MRSA may play an important role in PJI development. Cite this article: Bone Joint Res. 2020;9(4):152–161.

Background Previous studies have demonstrated that age, smoking, Tamai's level of amputation, causes of injury and ischemia time were associated with the success rate of digit replantation. The primary objective of this study is to investigate whether mental status including anxiety and depression is associated with the rate of digit replant failure. Methods This study included 134 digits from 102 patients who received digital replantation after complete amputation from 1 September 2013 to 1 September 2015. The Zung self-rating anxiety scale (SAS) and the Zung self-rating depression scale (SDS) were used to assess the pre-injury level of anxiety and depression for each patient. All participants were followed up for at least 1 month. Failure was defined as necrosis of replanted finger which required revision amputation or flap cover of the skeleton. Results Multivariate logistic regression analysis showed that increased level of pre-injury anxiety was an independent risk factor correlated with success rate (odds ratios [OR] = 7.69, 95% confidence interval [CI]: 1.93–30.30) in this series. The relative risk of anxiety group was 4.48 (95% CI: 1.38–14.49) compared to normal group. Digits with double arterial anastomosis in anxiety patients showed a higher survival rate while the number of veins repaired showed no significant effect on survival rate. Conclusions Increased level of pre-injury anxiety was an independent risk factors for digit replantation failure. Double arterial anastomosis increased the success rate of replanted digits in anxiety patients.

Highlights • Preoperative CT images of GCTBs have value in prognostic prediction. • Certain features of GCTBs on CT images are related to local recurrence. • Our models’ predictions for GCTB patients accepting extensive curettage are good.