The association between patellar height and anterior cruciate ligament injury: a systematic review and meta-analysis patellar height

Introduction Anterior cruciate ligament (ACL) injuries have become a significant public health burden. Recent evidence suggests a potential association between patellar height and ACL injury, though existing studies show inconsistent results. This study aimed to synthesise evidence about this association through systematic review and meta-analysis. Material and methods Comprehensive searches across seven databases through October 2025 identified observational studies comparing patellar height (Insall-Salvati Index, [ISI]) between ACL-injured patients and controls. Two reviewers independently performed selection, extraction and quality assessment (Newcastle–Ottawa Scale [NOS]). Random-effects meta-analysis was used to calculate the standardised mean differences (SMDs) and 95% confidence intervals (CIs). Subgroup analyses were performed based on age (≤16 vs >16 years), measurement method and timing. Results Four studies (891 participants: 460 ACL injury, 431 controls) were included. The overall analysis showed marginal ISI elevation (SMD = 0.250; 95% CI [0.116, 0.384]) with substantial heterogeneity ( I 2 = 93.9%). Adults >16 years demonstrated a significant association (SMD = 0.453; 95% CI [0.289, 0.617]; I 2 = 0%), while adolescents ≤16 years showed no clear association ( I 2 = 96.8%). Modified ISI (MIS) measurements showed stronger associations (SMD = 0.514) than traditional methods. Evidence certainty was low to very low. Conclusions Elevated patellar height shows a consistent association with ACL injury in adults but not in adolescents. This suggests that patellar height modifies knee biomechanics, potentially increasing ACL loading in adult athletes. Patellar height may serve as a screening component for ACL injury alongside other factors. Large prospective cohort studies with standardised protocols are needed.