EXAMINING THE RELATIONSHIP BETWEEN HIP STRENGTH MEASURES AND KNEE INJURY RISK FACTORS DURING SIDE-CUTTING

Abstract

Anterior cruciate ligament (ACL) injuries are prevalent throughout high school, collegiate and professional athletics, with females being 2-2.5 times more likely to sustain injury compared to males. A key risk factor for non-contact ACL injury has been identified as excessive dynamic knee valgus, consisting of detrimental amounts of hip adduction and internal rotation, tibial rotation in either direction, and knee abduction. Clinical assessment of lower extremity hip strength to quantify dynamic knee valgus is of great importance. Therefore, the purpose of this research study is to investigate the relationship between hip strength measurements and knee injury risk factors during a side-cutting maneuver in females. Forty six female soccer, basketball, and volleyball athletes (age, 16.3±3.6 years; height, 1.6±0.1 m; body mass, 58.3±11.9 kg) were recruited for the research study and split into two groups (Adolescents (AD), n=27, 12-16 years; Young adults (YA), n=17, 17-25 years) . A break test was performed to using a MicroFet2 HHD (Hoggan Health Industries Inc., West Jordan, UT) to assess strength. Non-weight bearing (NWB) strength assessments included: hip external rotation (HER), hip abduction (HAB), and hip extension (HEXT). Combined weight bearing (WB) hip abductor and external rotator strength was assessed in a double leg squat bilaterally (SqB), in a double leg squat unilaterally (SqU), and in a lunge (LNG) position. A three-dimensional motion capture system (Vicon, Inc., Centennial, Colorado, USA) with 18 cameras and software (Vicon Nexus, Version 2.2.3) was utilized to capture hip and knee biomechanics during the side-cutting task. Data revealed 7/22 (32%) and 8/22 (36%) of side-cutting biomechanical variables were significantly predicted by multiple models of non-weight bearing and weight bearing hip strength assessments. Knee IR moment/(BM*HT) had the highest r² value for the NWB regression model (p = 0.007, r² = 0.378) for the AD group and was predicted by HEXT (p = 0.001, r = 0.529). In the YA group, 43% of sagittal plane knee excursion was described by HABD (p = 0.029, r = -0.658) and was the lone significant NWB regression model. Raw knee FLX moment was the lone significant WB regression model for the AD group (p = 0.002, r² = 0.444) and was predicted by SqU (p = 0.035, r = -0.503) and LNG (p = 0.035, r = 0.571). Raw vGRF had the highest r² value for the WB regression model (p = 0.004, r² = 0.625) for the YA group and was predicted by LNG (p = 0.010, r = -0.777). No consistent pattern was found. Neither strength assessment method nor individual sub-positions were found to be superior to the other in terms of predicting commonly reported knee injury risk factors. This may suggest that clinical strength assessment techniques should be multimodal to successfully examine lower extremity strength relationships, dynamic movement, and injury risk.