Knee instability

Abstract

Over 125,000 anterior cruciate ligament (ACL) injuries occur each year in the United States. External loads on the knee in coronal plane, specifically knee abduction moment (KAM), predict ACL injury risk with high sensitivity and specificity. The purpose of this randomized controlled trial was to determine if biomechanical and neuromuscular risk factors could place athletes into distinct risk profiles, if neuromuscular training (NMT) would affect these risk variables and if risk groups would react differentially to NMT. The hypotheses tested were that these factors would: (1) place subjects into 3 distinct risk profiles, (2) decrease with NMT and (3) would decrease to a greater extent in higher risk (III > II > I) profiles. A total of 624 female athletes from 52 basketball, soccer and volleyball teams were screened prior to their competitive season. During the screening, the athletes were asked to perform two different types of tasks for which biomechanical measures were taken: DVJ and SCD. For each task, 3 trials were performed. Validation of profile group involved examination as an independent predictor of KAM. and used the latent profile analysis (LPA). Statistical analyses were conducted using Analysis of Variance (ANOVA). Differences were considered statistically significant at P < 0.05. The LPA resulted in three profiles. The three profiles are significantly different in most of the pair wise comparisons of the means for these variables studies. The RCT analysis showed that the NMT decreased specific biomechanical and neuromuscular risk factors. The RCT analysis also showed that profile group was significantly associated with alterations in risk factors III = II > I. Profiles II and III had a significant greater decrease than Profile I, both with and without adjustment for age and pubertal stage. To the investigators’ knowledge, this is the first study to use LPA analysis of biomechanical landing data to create KAM and potentially ACL injury risk profiles using an RCT approach. LPA provided greater group separation using multiple combined movement analyses and three distinct profiles were observed using peak measures. Group differences in peak KAM across the profiles were significant (II > I and III > I), whether unadjusted or adjusted for age and pubertal stage. The RCT analysis showed that NMT decreased specific biomechanical and neuromuscular risk factors. The RCT analysis also showed that profile group was significantly associated with alterations in risk factors. These findings begin to explain the clinical incidence of LPA groups; yet, further study is needed to investigate this phenomenon. We continue to examine LPA models and will validate them post-intervention to determine potential emergent profiles that result from neuromuscular training. Further large cohort multicenter studies of prediction of biomechanical and neuromuscular risk factors, combined with ACL injury risk, with measured and demonstrably high validity and reliability will be the focus of future analyses.