Quadriceps-strengthening exercise and quadriceps and knee biomechanics during walking in knee osteoarthritis: A two-centre randomized controlled trial.

Objective: To assess the effect of quadriceps strengthening on quadriceps muscle force, power, and work and tibio-femoral compressive loads during walking in adults with knee osteoarthritis.
Methods: Study design: Two-center, randomized, controlled trial.
Intervention: Patients with knee osteoarthritis were randomly allocated to quadriceps strengthening program (3 times weekly) or no attention control group.
Main Outcome Measures: Primary outcome was change from baseline in peak quadriceps force during walking at 12 weeks. Secondary outcomes included quadriceps power and work, knee compression forces during walking estimated with musculoskeletal modeling, muscle strength and pain and function. Outcomes were measured at baseline and 12 weeks.
Results: 30 patients were randomized to receive either training (n = 15) or no attention (n = 15). At follow-up, there were no statistical differences between groups for maximum quadriceps force, quadriceps positive power, negative work, and positive work, and knee compressive force. Maximum negative quadriceps power in early stance was statistically significantly increased 36% in the training group compared to the control group which was most likely partially a response to faster walking velocity at follow-up. Muscle strength and patient reported pain and function were improved in the training group compared to the control group.
Conclusions: Quadriceps strength training leads to increased muscle strength and improved symptomatic and functional outcomes but does not change quadriceps or knee joint biomechanics during walking. The biomechanical mechanism of improved health with strength training in knee osteoarthritis patients remains unknown. ClinicalTrials.gov Identifier: NCT01538407.
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