Evaluation of pelvic obliquity, trunk lean, hip angle, and hip adduction moments effect on knee adduction moment in a young, healthy population

Abstract

Purpose Knee adduction moment (KAM) is recognized as a major contributor to medial knee joint loads with hip adduction moment (HAM) previously linked to KAM in the pathological population. However, HAM is affected by motion at the femur, pelvis, and trunk; therefore, the contributions of frontal plane pelvic obliquity, trunk lean, and hip angle on HAM and KAM were examined. Methods Three-dimensional gait analysis at self-selected walking velocity was performed for nine female and nine male subjects during a single session. A regression analysis model was used to compare contributions of proximal joint motions on HAM and KAM. Results Females walked with higher HAM and KAM compared to males. Individual variables contributing to first peak HAM included trunk lean and pelvic obliquity in females (R2=0.55) and males (R2=0.62). Hip angle and pelvic obliquity in females (R2=0.50) and pelvic obliquity in males (R2=0.38) were related to first peak KAM while HAM alone contributed to 5% and 70% in females and males respectively. Second peak HAM was related to frontal plane hip angle in females (R2=0.45) and pelvic obliquity and trunk lean in males (R2=0.35). Second peak KAM was attributable to trunk lean and hip angle in females (R2=0.56) while only to trunk lean in males (R2=0.36). Hip adduction moment contributed to 34% and 14% of second peak KAM, in females and males respectively. Conclusion The combination of pelvic obliquity, trunk lean, and hip angle, as well as HAM only, explain the substantial variability in KAM during normal walking gait. While previous studies have used only HAM to explain KAM, differences in proximal contributions to both HAM and KAM in the current study suggest this relationship is not as clear as previously thought and proximal variables should be considered individually instead of as a combined hip moment for future research.