The relationship between morphological characteristics of the hip capsule and patient symptoms in the setting of femoroacetabular impingement (FAI) is undefined. In this study, patients with symptomatic FAI prospectively underwent 3T magnetic resonance (MR) imaging of the affected hip and completed the hip disability and osteoarthritis outcome score (HOOS) to determine the correlation between hip capsule anatomy and patient symptoms. Anterior hip capsule volume, posterior capsule volume, anterior‐posterior capsule volume ratio, and proximal‐distal volume ratio in the anterior capsule were quantified and measured using axial‐oblique intermediate‐weighted 3D fast spin echo MR images. A total of 35 patients (35 hips) were included for analysis (mean age: 30.6 years; mean body mass index [BMI]: 24.9 kg/m2; 57% male). The mean alpha angle was 62.2° ± 4.7°, the mean anterior hip capsule volume was 1705.1 ± 450.3 mm3, the mean posterior hip capsule volume was 1284.8 ± 268.5 mm3, the mean anterior to posterior capsule volume ratio was 1.1 ± 0.39, and the mean proximal to distal volume ratio of the anterior capsule was 0.65 ± 0.28. There was no correlation between age, gender, or BMI, and any hip capsule characteristics. Worse scores on the HOOS pain scale were correlated with increased anterior to posterior volume ratio (r = −.38; 95% confidence interval: −0.06 to −0.63). In conclusion, hip capsule morphology correlates with patient symptoms in the setting of FAI as increased anterior capsular volume, relative to posterior capsular volume, is associated with greater patient pain.

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Introduction: There is no consensus on whether articulating or static spacers are superior during two-stage exchange arthroplasty for periprosthetic joint infection. We aimed to compare surgical time, need for extensile exposure, surgical costs, and treatment success for articulating and static spacers. Methods: This was a retrospective review of 229 periprosthetic joint infections treated with two-stage exchange with a minimum of one-year follow-up. For articulating and static spacers, we compared the need for extensile exposure during reimplantation and treatment failure based on an updated definition. Surgical time and costs at both stages were also compared. Subgroup analysis was performed for total knee and hip arthroplasties.Results: There was no difference in the surgical time for spacer insertion; however, articulating spacers demonstrated reduced surgical time during reimplantation (181 vs. 234 minutes, P , 0.001). In multivariate analysis, there was no difference in extensile exposures (odds ratio 2.20, P = 0.081), but treatment failure was more likely for static spacers (odds ratio 2.17, P = 0.009). Overall surgical costs for two-stage exchange were similar between groups (23,782 vs. 23,766, P = 0.495). Conclusion: Articulating spacers demonstrated shorter surgical times and a trend toward decreased extensile exposures during reimplantation. They also had higher treatment success rates and similar surgical costs for overall two-stage exchange. P eriprosthetic joint infection (PJI) remains one of the most devastating complications after total joint arthroplasty. 1,2 The preferred treatment of chronic PJI in the United States is two-stage exchange arthroplasty. 3 This involves removal of all components and insertion of an antibiotic-impregnated spacer, followed by an interim period of antibiotics and reimplantation of components at a later date. The reported success rate of two-stage exchange varies, ranging from 65% to 100% depending on inclusion criteria and definition of treatment success. 2,[4][5][6][7] Recent studies suggest that we