Knee Malalignment and Thigh Muscle Strengthening in Individuals With Medial Knee Arthritis

Although quadriceps strengthening is the cornerstone of physiotherapy management, recent evidence suggests that high quadriceps strength in patients with malaligned knees may increase OA progression.

This study investigates the effects of quadriceps strengthening on the adduction moment in patients with medial knee OA with and without malalignment. 107 participants with and without varus knee malalignment were recruited and randomised into an exercise or a control group. Participants in the exercise group were taught five quadriceps strengthening exercises by a project physiotherapist to be performed five days a week for twelve weeks at home. The exercises were:

• Quadriceps exercise over fulcrum using ankle weight
• Straight leg raise exercise using ankle weight
• Long arc knee extension exercise in sitting using ankle weight
• Knee extension exercise with isometric hold at 60° knee flexion using ankle weight
• Knee extension exercise with isometric hold at 60° knee flexion using an elastic band.

Each exercise was performed at 2x10 repetitions for the first 2 weeks and 3x10 repetitions thereafter.

Participants visited the physiotherapist 7 times at Week 1, 2, 3, 4, 5, 7 and 10. They were given the ankle weights and elastic band to bring home and instructed about the repetitions and weights to use by the physiotherapist, who also checked and progressed their exercises. The average duration of the physiotherapy sessions was 30 minutes. To monitor compliance, each participant was given an exercise instructions sheet and kept a training diary to record the exercises they had done.

The control group received no intervention.

Inclusion criteria

• Pain in the knee
• Osteophytes on knee x-ray
• Self-reported pain on the inner aspect of the study knee
• Osteophytes in the medial compartment of the knee joint and
• Medial joint space narrowing greater than lateral joint space narrowing on x-ray

Exclusion criteria

• Knee surgery within the previous 6 months
• History of lower limb joint replacements
• Systemic arthritic conditions such as rheumatic or psoriatic arthritis
• Valgus knee deformity (> 5º)
• Inability to walk without the use of walking aids
• Intending to start a lower limb strengthening program in the next 3 months
• Seeking or currently receiving physiotherapy for OA knee