Implantation of a shock or load absorber for mild to moderate symptomatic medial knee osteoarthritis

The aim of this procedure is to lighten the load on the knee when the person is standing by inserting a load absorber. This reduces pain and potentially delays the need for further surgery. The device is implanted subcutaneously outside the knee joint, along its medial aspect. It is secured to the femur and tibia. It is intended to keep surrounding structures including bone, muscle and ligaments intact, allowing subsequent surgery to be performed if necessary. The device can be removed at a later date.

The procedure is performed with the patient under general anaesthesia and supine. Fluoroscopy is used to confirm alignment of the knee joint. Two incisions, over the medial aspects of the femoral and tibial condyles, are made. A femoral base plate is inserted through the proximal incision and attached to the medial femoral cortex using surgical screws; a tibial base plate is similarly attached to the medial tibial cortex. A tunnel is created between the 2 incisions beneath the skin using blunt dissection and the load absorber is implanted in this tunnel. The load absorber is attached to the 2 base plates. Its function is checked and the wounds are closed.