Comparing selective and general hamstring stretching and strengthening for pain, disability, and quality of life in patients with primary knee osteoarthritis and varus deformity: A randomized clinical trial

A combination of hamstring stretching and strengthening exercises may benefit patients with knee osteoarthritis by promoting pain relief and disability improvement.
The current study aimed to compare the effects of lateral hamstring strengthening and medial hamstring stretching with general hamstring stretching and general hamstring strengthening on pain, disability, and quality of life in patients with primary knee osteoarthritis and varus deformity.
Forty patients with knee osteoarthritis were randomly assigned to two groups: a general hamstring strengthening group (14 women, 6 men) and a selective hamstring strengthening group (16 women, 4 men). In the general hamstring strengthening group, participants performed hamstring stretching and strengthening exercises broadly. In contrast, the selective hamstring strengthening group specifically targeted lateral hamstring strengthening and medial hamstring stretching. The treatment program was conducted three times a week for 4 weeks. Pain and disability levels were evaluated before and after treatment using the Knee Injury and Osteoarthritis Outcome Score (KOOS), quality of life was assessed using the Osteoarthritis Knee and Hip Quality of Life (OAKHQOL) questionnaire, and physical activity levels were determined using the Tegner activity scale.
Both groups demonstrated significant improvement in all outcomes except for the quality of life subscale of the KOOS questionnaire (p = .98) in the general hamstring strengthening group. However, the selective hamstring strengthening group exhibited greater improvements in symptoms (p = .02, effect size (d) = 0.92) and pain subscales (p = .01, d = 0.80) according to the KOOS questionnaire. Additionally, the pain subscale (p = .02, d = 0.79) of the OAKHQOL questionnaire exhibited greater improvements in the selective hamstring strengthening group. Tegner activity scale scores significantly improved in both groups.
Strengthening the lateral hamstring and stretching the medial hamstring muscles seem to be beneficial for reducing pain in patients with primary knee osteoarthritis and varus deformity. Attention to stabilization in frontal and horizontal planes in the knee joint might be better than simply evaluating the joint in the sagittal plane.