THE RELATIONSHIP BETWEEN GLUTEUS MEDIUS ACTIVATION AND FRONTAL PLANE KNEE STABILITY

Excessive knee abduction moment and knee valgus in a weight bearing limb are well known biomechanical risk factors of chronic knee pain such as patellofemoral pain (PFP) or knee osteoarthritis (OA). Neuromuscular control of the hip abductors is important to prevent excessive knee abduction moment and knee valgus. Potential associations between altered neuromuscular control of gluteus medius (GMED) and PFP has been frequently suggested; however, there is limited literature on how neuromuscular control of the GMED is related to the knee abduction moment or knee valgus. The primary objective of the present study was to examine whether GMED onset and activation magnitude are related to the knee abduction moment and knee valgus. The secondary objective was to investigate the relationship between hip abductor strength and knee abduction moment and valgus. 20 healthy females (22.6 ± 2.5 yrs) performed 15 Single Limb Mini Squats (SLMS) on each leg. Correlations between the GMED activation parameters, hip abductor strength, and frontal plane knee angle and moment were examined separately for each limb in three different phases of the SLMS: Double to single limb transition, single limb stabilization, and descending phase. As secondary analyses, the relationships among frontal plane hip kinematics, kinetics, pelvic obliquity, and frontal plane knee angle and moment were examined separately for each limb in the specific movement phases. Greater GMED activation magnitude was significantly correlated with a decrease of the knee abduction moment during the single limb stabilization phase in the non-dominant limb only. The non-dominant limbs experienced significantly greater reduction of the knee abduction moment than the dominant limbs during the single limb stabilization phase. Greater hip abduction strength was correlated with less knee valgus only in the dominant limb during the double to single limb transition phase. Limb dominance may be an important factor when considering the neuromuscular control of GMED for controlling knee abduction moment. These results can provide useful insights for developing strategies for preventing chronic knee pain