Evaluation of intra- and interobserver reliability in the assessment of the ‘critical trochanter angle’

Background: The recently described 'critical trochanter angle' (CTA) is a novel parameter in the preoperative risk assessment of stem malalignment in total hip arthroplasty. As its reproducibility needs to be evaluated, the given study aims to investigate intra- and interobserver reliability. It is hypothesized that both analyses justify the clinical use of the CTA. Methods: A total of 100 pelvic radiographs obtained prior to total hip arthroplasty were retrospectively reviewed by four observers with different levels of clinical experience. The CTA was measured twice by each observer at different occasions in the previously described technique. Intra- and interobserver reliability was evaluated using intraclass correlation coefficients (ICC) with confidence intervals (CI) and the Bland-Altman approach. Results: The mean CTA in both measuring sequences was 20.58° and 20.78°. The observers' means ranged from 17.76° to 25.23°. Intraobserver reliability showed a mean difference of less than 0.5° for all four observers (95% limit of agreement: - 7.70-6.70). Intraobserver ICCs ranged from 0.92 to 0.99 (CI 0.88-0.99). For interobserver variation analysis, ICCs of 0.83 (CI 0.67-0.90) and 0.85 (CI 0.68-0.92) were calculated. Conclusion: Analyses concerning intra- and interobserver reliability in the assessment of the CTA showed 'very good' and 'good' results, respectively. In view of these findings, the use of the CTA as an additional preoperative parameter to assess the risk of intraoperative stem malalignment seems to be justified

Parameters affecting baseline hip function in patients with cam-derived femoroacetabular impingement syndrome: data analysis from the German Cartilage Registry

Background Using the database of the German Cartilage Registry (KnorpelRegister DGOU), this study aims to present patient- and joint-related baseline data in a large cohort of patients with cam-derived femoroacetabular impingement syndrome (FAI) and to detect symptom-determining factors. Materials and methods Requiring cam morphology as the primary pathology, 362 patients were found to be eligible for inclusion in the study. The assessment of preoperative baseline data was performed using the patient-reported outcome measure—International Hip Outcome Tool (iHOT-33). Descriptive statistics were performed to present baseline data. Univariate and multiple regression with post hoc testing were used to identify patient- and joint-related factors that might affect the preoperative iHOT-33 and its subscores, respectively. Results The study collective’s mean age was 36.71 ± 10.89 years, with 246 (68%) of them being male. The preoperative mean iHOT-33 total was 46.31 ± 20.33 with the subsection “sports and recreational activities” presenting the strongest decline (26.49 ± 20.68). The parameters “age,” “sex,” “body mass index” (BMI), and the confirmation of “previous surgery on the affected hip” were identified to statistically affect the preoperative iHOT-33. In fact, a significantly lower mean baseline score was found in patients aged > 40 years (p < 0.001), female sex (p < 0.001), BMI ≥ 25 kg/m2 (p = 0.002) and in patients with previous surgery on the affected hip (p = 0.022). In contrast, the parameters defect grade and size, labral tears, and symptom duration delivered no significant results. Conclusions A distinct reduction in the baseline iHOT-33, with mean total scores being more than halved, was revealed. The parameters “age > 40 years,” “female sex,” “BMI ≥ 25,” and confirmation of “previous surgery on the affected hip” were detected as significantly associated with decreased preoperative iHOT-33 scores. These results help to identify symptom-defining baseline characteristics of cam-derived FAI syndrome. Trial registration: The German Cartilage Registry is conducted in accordance with the Declaration of Helsinki and registered at germanctr.de (DRKS00005617). Registered 3 January 2014—retrospectively registered. The registration of data was approved by the local ethics committees of every participating institution. Primary approval was given by the ethics committee at the University of Freiburg (No. 105/13). https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS0000561