Knee Extension

By Ben Benjamin, PhD

Question: Does the medial patella retinaculum control the last five degrees of knee extension?

Answer: No.

The medial patella retinaculum is an extension of the patella tendon mechanism.

The medial vastus muscle functions to control the last five degrees of knee extension - the final tightening action that occurs when you straighten your knee. The vastus medialis muscle atrophies under particular circumstances. Knowledge of what these conditions will increase your assessment skills; help your clients get well more quickly; and save you considerable time and wasted effort.

When certain structures in the knee are injured (a torn meniscus, a loose body in the knee joint, or an inflamed coronary or collateral ligament, among others), the knee produces excess fluid and swells, making it painful to straighten the knee. All of these conditions cause the knee to swell as a protective measure.

Ligament injuries respond to hands-on treatment; other conditions, such as a torn meniscus or a loose body in the knee joint, only improve with medical intervention. When the conditions are addressed and eliminated, the swelling in the knee subsides. If straightening the knee is painful, the medial vastus muscle will not respond to exercise, and will not be able to regain its strength.