Therapeutic potential of a supine straight-leg thrust in managing knee joint dysfunction in knee osteoarthritis: A biomechanical study.

Abstract

Rehabilitation of knee osteoarthritis is often constrained by limited understanding of muscle activation patterns and active joint mobilization mechanisms. The supine straight-leg thrust (SST) exercise, previously introduced by our team, has shown promising clinical effects, yet its neuromuscular and kinematic mechanisms remain unclear. This study aims to investigate quadriceps-hamstring activation and knee joint kinematics during SST using synchronized surface electromyography and three-dimensional motion capture, and to compare its biomechanical effects with walking, squatting, and supine air cycling (SAC). Fifteen healthy adults performed walking, squatting, SST, and SAC exercises. Surface electromyography data of the quadriceps and hamstrings, and three-dimensional kinematic data of the tibiofemoral and patellofemoral joints were collected. Comparisons were made across tasks to evaluate muscle activation levels and multi-planar joint range of motion. SST elicited significantly greater activation of the rectus femoris, vastus medialis, and vastus lateralis compared to walking (P < 0.05), with levels comparable to squatting. SST also produced significantly larger ranges of motion in both tibiofemoral and patellofemoral joints than walking and squatting (P < 0.05). Compared to SAC, SST resulted in higher thigh muscle activation and more favorable joint mobility (P < 0.05). SST effectively activates key quadriceps muscles and enhances multi-planar knee joint mobility, outperforming walking, squatting, and SAC. These findings support the biomechanical rationale for SST as a targeted exercise for addressing joint dysfunction in knee osteoarthritis rehabilitation.