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Background: Several demographic and clinical risk factors for recurrent ankle instability have been described. The main objective of this study was to investigate the potential influence of morphologic characteristics of the ankle joint on the occurrence of recurrent instability and the functional outcomes following a modified Broström-Gould procedure for chronic lateral ankle instability., Methods: Fifty-eight ankles from 58 patients (28 males and 30 females) undergoing a modified Broström-Gould procedure for chronic lateral ankle instability between January 2014 and July 2021 were available for clinical and radiological evaluation. Based on the preoperative radiographs, the following radiographic parameters were measured: talar width (TW), tibial anterior surface (TAS) angle, talar height (TH), talar radius (TR), tibiotalar sector (TTS), and tibial lateral surface (TLS) angle. The history of recurrent ankle instability and the functional outcome using the Karlsson Score were assessed after a minimum follow-up of 2 years., Results: Recurrent ankle instability was reported in 14 patients (24%). The TTS was significantly lower in patients with recurrent ankle instability (69.8 degrees vs 79.3 degrees) ( P  < .00001). The multivariate logistic regression model confirmed the TTS as an independent risk factor for recurrent ankle instability (OR = 1.64) ( P  = .003). The receiver operating characteristic curve analysis revealed that patients with a TTS lower than 72 degrees (=low-TTS group) had an 82-fold increased risk for recurrent ankle instability ( P  = .001). The low-TTS group showed a significantly higher rate of recurrent instability (58% vs 8%; P  = .0001) and a significantly lower Karlsson score (65 points vs 85 points; P  < .00001)., Conclusion: A smaller TTS was found to be an independent risk factor for recurrent ankle instability and led to poorer functional outcomes after a modified Broström-Gould procedure., Level of Evidence: Level IV, retrospective cohort study., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: The asymmetry of the medial and lateral knee compartments contributes significantly to femorotibial biomechanics and pivoting, and it is reported to be a relevant risk factor for an anterior cruciate ligament (ACL) injury., Purpose: (1) To assess the role of femoral condyle sphericity as a risk factor for an ACL rupture and rerupture. (2) To compare the new risk factor with existing bony morphological risk factors via magnetic resonance imaging (MRI) and to assess the most predictive risk factor for an ACL rupture., Study Design: Cohort study; Level of evidence, 3., Methods: A retrospective case-control study of 60 patients was conducted. Three age- and sex-matched cohorts (each n = 20) were analyzed: ACL reruptures, primary ACL ruptures, and a control group consisting of isolated meniscal tears or patients with anterior knee pain without signs of trochlear dysplasia. The lateral femoral condyle index (LFCI) as a novel MRI measurement was developed to quantify femoral sphericity. In addition, previously known MRI risk factors associated with ACL injury were analyzed (notch width index, medial tibial slope, lateral tibial slope, medial tibial depth, and lateral tibial height). Differences among groups were compared; cutoff values were defined; and diagnostic performance of the risk factors was assessed. The risk factors were subsequently analyzed with multiple logistic regression., Results: The LFCI was significantly smaller in knees with ACL reruptures (median, 0.67; range, 0.59-0.75) and primary ACL ruptures (0.67; range, 0.60-0.75) than in the control group (0.76; range, 0.6-0.81; P < .01). The LFCI yielded the highest area under the curve among the analyzed risk factors: 0.82 (95% CI, 0.7-0.9). A cutoff of 0.70 yielded a sensitivity of 78% and a specificity of 80% to predict an ACL rupture or rerupture (odds ratio, 13.79; 95% CI, 3.67-51.75). In combination with lateral tibial height (cutoff, 3.8 mm) and lateral tibial slope (cutoff, 2.9°), the diagnostic performance was improved. The area under the curve was 0.86 (95% CI, 0.75-0.94), with a sensitivity of 90% and a specificity of 70% (odds ratio, 21.00; 95% CI, 5.10-85.80)., Conclusion: A decreased LFCI is associated with an ACL injury. The LFCI, lateral tibial height, and lateral tibial slope are the most predictive risk factors for an ACL injury. These findings might aid clinicians in identifying patients at risk for an ACL injury and inform the patient after reconstruction for a higher risk of rerupture.