Which muscle groups show decreased strength in knee OA?

Which muscle groups show decreased strength in knee OA?

• A. Glutes and quadriceps
• B. Hamstrings and gastrocnemius
• C. Quadriceps and gastrocnemius
• D. Tibialis anterior and peroneals

Answer: (C)

Knee OA commonly weakens muscles that directly stabilize the knee during weight-bearing. The two groups most consistently weaker are the quadriceps and the gastrocnemius. The quadriceps are essential for controlling knee extension and patellar tracking. Pain, swelling, and reflexive inhibition (arthrogenic inhibition) reduce their force output, leading to slower, less controlled knee motion during walking and activities like stair climbing. This weakness increases joint loading and contributes to functional limitation. The gastrocnemius crosses the knee and helps with knee flexion and ankle plantarflexion, aiding push-off and knee stabilization in late stance. When it’s weak, knee control during gait is compromised, which also alters joint loading patterns. Tibialis anterior and peroneals are primarily ankle-related muscles, so their weakness is less specifically associated with knee OA. Gluteal weakness can influence knee mechanics, but the most characteristic pattern described in knee OA is weakening of the quadriceps and gastrocnemius.

Knee OA commonly weakens muscles that directly stabilize the knee during weight-bearing. The two groups most consistently weaker are the quadriceps and the gastrocnemius.

The quadriceps are essential for controlling knee extension and patellar tracking. Pain, swelling, and reflexive inhibition (arthrogenic inhibition) reduce their force output, leading to slower, less controlled knee motion during walking and activities like stair climbing. This weakness increases joint loading and contributes to functional limitation.

The gastrocnemius crosses the knee and helps with knee flexion and ankle plantarflexion, aiding push-off and knee stabilization in late stance. When it’s weak, knee control during gait is compromised, which also alters joint loading patterns.

Tibialis anterior and peroneals are primarily ankle-related muscles, so their weakness is less specifically associated with knee OA. Gluteal weakness can influence knee mechanics, but the most characteristic pattern described in knee OA is weakening of the quadriceps and gastrocnemius.