Prevalence of Concurrent Trochlear Dysplasia in Patients with Anterior Cruciate Ligament Tear: A Cross-Sectional Study

Abstract Trochlear dysplasia (TD) is an anatomical abnormality wherein the trochlear groove (TG) is shallow, flat, or convex, and this disrupts the biomechanics of the patellofemoral joint (PFJ). This alteration may increase the risk of anterior cruciate ligament (ACL) injury, due to aberrant patellar tracking and elevated anterior tibial translation force. Despite growing interest in this subject, data on TD prevalence in Indian populations are lacking. This study aims to estimate the prevalence of TD in Indian patients with magnetic resonance imaging (MRI)-confirmed ACL tears, alongside associated chondromalacia patellae and retinacular injuries, to elucidate the potential biomechanical relationship between the two. A cross-sectional study was conducted at a tertiary care institute for a duration of 18 months. A total of 147 patients with MRI-confirmed ACL tears were enrolled in this study. MRI was used to assess TD through three validated metrics: a. Trochlear depth (TD < 3 mm), b. Lateral trochlear inclination (LTI < 11°), and c. Facet asymmetry ratio (FAR < 40%). TD was classified as low-grade (Type A) or high-grade (Types B–D) using the Dejour classification, simplified per Lippacher et al. Chondromalacia patellae and retinacular injuries were also evaluated. Data was analyzed using descriptive statistics and the Chi-square test in SPSS v27.0, with significance set at p < 0.05. TD was identified in 14.3% of patients (21/147), with 71.4% classified as low-grade (Type A) and 28.6% classified as high-grade (Types B to D). TD < 3 mm was observed in 10.9%, FAR < 40% in 9.5%, and LTI < 11° in 0.7%. Complete ACL tear accounted for 73.5% of patients, while partial ACL tear accounted for 26.5% of patients. Chondromalacia patellae was present in 15.6% (23/147) of patients, with 14.3% (3/21) among TD patients. No retinacular injury was observed. Statistical analysis revealed no significant association between TD and ACL tear type (p = 0.195) or chondromalacia patellae (p = 0.644), suggesting that TD may contribute to the ACL injury risk without directly influencing tear severity or associated cartilage damage. The 14.3% prevalence of TD in patients with ACL tears underscores its potential role as a biomechanical risk factor in the Indian population. The predominance of low-grade TD suggests that subtle trochlear anomalies may contribute to ACL strain through altered PFJ mechanics. The low incidence of chondromalacia patellae, and the absence of retinacular injuries may reflect milder TD grades, and specific injury mechanisms. Routine MRI-based TD assessment is recommended to inform personalized ACL injury management and preventive strategies. Further research is needed to explore the causal relationship, and to optimize clinical outcomes.