The Effect of Short-Term Instrument-Assisted Soft Tissue Mobilization on Lower Limb Muscle Strength and Sit-to-Stand Kinetics in Patients with Knee Osteoarthritis: A Randomized Controlled Trial

Background: Knee osteoarthritis (KOA) is a prevalent musculoskeletal condition, particularly among the elderly, characterized by joint pain, stiffness, and reduced functional capacity. These impairments significantly affect daily activities, including the sit-to-stand (STS) task, a fundamental functional movement. Instrument-assisted soft tissue mobilization (IASTM) has demonstrated potential for reducing pain and improving mobility; however, its impact on functional biomechanics during STS remains underexplored. Objectives: This study aimed to evaluate the effects of IASTM on lower limb muscle strength and STS kinetic parameters, including vertical ground reaction force (vGRF) and center of pressure (COP), in KOA patients. Methods: A double-blind, randomized controlled trial was conducted with 30 participants diagnosed with moderate KOA. Participants were randomly assigned to either an IASTM plus exercise therapy group or a sham IASTM plus exercise therapy group. The intervention consisted of four sessions over two weeks. Lower limb strength (knee extensors, flexors, plantar flexors, and dorsiflexors) was measured using a hand-held dynamometer. Biomechanical performance during the STS task was assessed using a force platform. Measurements were taken at baseline and 48 hours post-intervention. Results: A significant main effect of time was observed for knee extensor (P < 0.001, ηp2 = 0.553), knee flexor (P < 0.001, ηp2 = 0.455), and ankle plantar flexor strength (P < 0.001, ηp2 = 0.448). Additionally, a significant time × group interaction was found for knee extensor (P = 0.001, ηp2 = 0.332), knee flexor (P = 0.046, ηp2 = 0.105), and ankle plantar flexor strength (P = 0.011, ηp2 = 0.211). While both groups showed post-treatment improvement, the IASTM group exhibited significantly greater gains compared to the sham group. No significant changes were observed in vGRF or COP parameters during the STS task. Conclusions: Instrument-assisted soft tissue mobilization effectively enhances knee extensor, flexor, and plantar flexor strength in KOA patients but does not significantly influence STS biomechanics within the short intervention period. Although these strength improvements are promising, they may not be sufficient to alter the complex biomechanical demands of the STS task. Future research should explore longer intervention durations or the integration of IASTM with complementary physiotherapy modalities to achieve broader functional benefits.