Biomechanical mechanisms behind the reduction of knee adduction moment in medial knee thrust gait

Medial knee osteoarthritis (OA) is the most common OA subtype, and its progression has been strongly linked to increased knee adduction moment (KAM). Among various gait modification strategies, medial knee-thrust gait has emerged to be promising to attenuate KAM. This study aimed to clarify the biomechanical mechanism through which knee-thrust gait reduces KAM. Fourteen healthy young adults were recruited as a first step to understanding the mechanism. KAM was reduced by 21% in the first peak and 36% in the second peak during the knee-thrust gait compared to the normal gait. Stepwise multiple regression indicated that the moment arm (MA) was the primary contributor to both KAM peaks (adj. R² = 0.9, respectively). Furthermore, the reduction in MA was caused by the lateral deviation of the center of pressure relative to the knee joint center (C[Formula: see text]P) which outweighed the increase in medial tilting of the ground reaction force observed in knee-thrust gait (adj. R² > 0.80). These findings suggest that the reduction in KAM peaks is predominantly due to a shortened MA, affected by increased C[Formula: see text]P accompanied by wider step width. Understanding this mechanism may offer insights into enhancing gait modification strategies to reduce medial knee loading and potentially slow the progression of medial knee OA. However, since this study was conducted on healthy participants, caution is warranted when generalizing the findings to patients with knee OA.