Loss of knee flexion can be a big problem after knee surgery or a knee injury. Loss of flexion is usually caused by scar tissue formation, called fibrosis. Fibrosis spreads over or replaces normal tissue during the healing process.
Fibrosis occurs most often after a knee fracture or injury to knee ligaments. Sometimes, the surgery to repair a torn ligament results in more loss of knee flexion. In some cases, the natural shape of the bones becomes flat or distorted from injury or disease. This can also cause a loss of knee flexion.
In this study, patients with loss of knee flexion had physical therapy (PT). The goal was to improve knee motion without further surgery or injury. If PT alone didn’t work, home mechanical therapy was added. A special machine was used to provide mechanical therapy. The program is called a patient-activated serial stretch (PASS). While sitting in a chair, the patient places a foot in a holder. The machine loads the knee through the foot using a hydraulic device. The patient controls the load and the stretching.
The device is used for 15 minutes, four to eight times each day. The knee is bent into full flexion for one to five minutes. Then the joint is straightened (extended) for the same amount of time. Finally, the knee is stretched back into full flexion again for another one to five minutes.
The authors report that patients using PASS regained knee flexion without further damaging tissue. When used often, this form of stretching seems easier on the knee joint. In cases where knee flexion hasn’t improved, patients may benefit from the use of mechanical therapy to regain functional range of motion.