Healthy joints and cartilage are exposed to mechanical loads during everyday motion and activity. While normal joint loading can help maintain joint tissues, high loading due to obesity, or abnormal loading due to anatomy or trauma can contribute to microfractures, bone thickening, and cartilage degradation. Many osteoarthritis (OA) therapies only provide short-term pain relief or repair focal cartilage damage. When the biomechanics behind joint overload are left untreated, however, the patient may suffer through several rounds of unsuccessful therapies until he or she is a candidate for knee replacement surgery.

Fig. 1 – The implantable spring system maintains a patient’s natural kinematics. (©2013 Moximed, Inc.)
A new partial load absorber device that reduces knee joint load is designed to be a first surgical option for patients with OA of the medial compartment of the knee. The absorber is implanted in the extra-capsular space along the medial side of the joint. By lightening the load on the knee, the system cushions and protects the affected cartilage while maintaining natural knee motion and structural integrity.

The KineSpring System, by Moximed Inc., consists of two modular bases and a load absorber spring. In a standard orthopaedic procedure, it is implanted alongside the joint through two incisions near the medial femoral and tibial condyles. (See Figure 1) Bone screws anchor the bases to the femur and tibia. The spring is able to reduce load on the medial knee compartment by up to 13kg when the foot is on the ground. All parts are made of titanium or cobalt chrome. Unlike joint replacement procedures, no bone, ligament, or cartilage is removed during the procedure. Xray images ensure that the device is in place and functioning properly. The diameter of the absorber is roughly the size of a pencil.

This represents a new class of therapy that bridges the gap in knee OA treatment between conservative care and joint-modifying surgical procedures. The device has been implanted in patients in Australia since 2008 and in Europe since 2010. As of June 2013, more than 400 people have successfully had this procedure. It has CE mark approval. The effectiveness of the device has been demonstrated in three completed clinical studies. A fourth prospective clinical study in Europe recently started in Belgium, France, Germany, Luxembourg, and the Netherlands. The first clinical study in the US is currently enrolling patients.

The article was based on information supplied by Moximed, Inc., Hayward, CA. For more information, Click Here .