Background This study aimed to investigate the risk factors for mechanical failure of cement spacers and the impact on hip function after two-stage exchange arthroplasty for periprosthetic joint infection (PJI). Methods Thirty-one patients (19 males and 12 females) with hip PJIs underwent resection arthroplasty and implantation of cement spacers from January 2014 to December 2015. Patients who encountered spacer-associated mechanical complications in the interim period (14 of 31) were compared with those without complications (17 of 31). Complications were defined as spacer dislocation, spacer fracture, spacer fracture with dislocation, and femoral fracture during or following spacer implantation. Hip functional outcome was assessed using the Harris hip score (HHS). Treatment success was defined according to the following criteria: (1) no symptoms or signs indicative of infection; (2) no PJI-related mortality; and (3) no subsequent surgical intervention for infection after reimplantation surgery. Multivariate logistic regression and Kaplan-Meier survival curves were used for analysis. Results Fourteen patients (14/31 = 45%) suffered at least one spacer-related complication within the interim period. The development of spacer complications was associated with a younger age (odds ratio [OR] 0.91, 95% confidence interval [CI] 0.83–1.00, p = 0.045) and chronic PJI (OR 14.7, 95% CI 1.19–182, p = 0.036). Patients with spacer complications also had a lower median HHS (37 vs. 60, p < 0.001) before reimplantation in comparison to those without spacer complications. After reimplantation, the two groups had a similar median HHS (90 vs. 89, p = 0.945). Two patients did not undergo reimplantation due to extensive comorbidities, and subsequently retained the antibiotic spacer for definitive treatment. The 2-year treatment success rate was 84.6% in the spacer-complication group and 87.5% in the non-spacer-complication group ( p = 0.81). Conclusion There was a high complication rate for articulating PMMA spacers during the interim period of two-stage revision total hip arthroplasty. A young age and chronic infection were the primary risk factors associated with mechanical complications. Patients at high risk of spacer-related mechanical complications should be advised accordingly by surgeons. Knowing the possible risk factors, surgeons should educate patients thoroughly to avoid spacer complications, thereby increasing patient satisfaction in the interim stage. Level of evidence Prognostic Level III.

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Purpose: Femoral head fracture dislocations are serious articular fractures that are associated with soft tissue injuries and are challenging to treat. Arthroscopic surgery may be a way to treat fracture reduction and fixation, thereby avoiding the need for extensive arthrotomy. Methods: We followed up a consecutive series of seven patients with femoral head fracture dislocation via a scope-assisted percutaneous headless screw fixation between 2016 and 2017. The clinical and radiological results were assessed. Results: The locations of the fracture were all involving infra-foveal area. The mean follow-up duration was 18 (range 12–24) months. The mean Harris hip score was 90.8 (range 88–93) at the latest follow-up. None of the patients showed early osteoarthritis, heterotopic ossification, or avascular necrosis. The average maximal displacement of the fracture site was improved from preoperative 6.79 mm (range 4.21–12.32) to postoperative 2.76 mm (range 0.97–3.97). Concomitant intra-articular hip lesions secondary to traumatic hip dislocation can also be treated. Conclusion: Managing the infra-foveal fracture of the femoral head using arthroscopic reduction and fixation with headless screws can be a safe and minimally invasive option. More patients and longer follow-up are needed for a definite conclusion.