OSTEOCHONDRITIS DISSECANS (OCD)
Dr. Bud Siemering

Osteochondritis dissecans can result in permanent lameness if not treated early.  This condition can occur in the shoulder (caudal humeral head), elbow (medial humeral condyle), stifle (medial femoral condyle) and the hock.

The most common clinical sign is persistent lameness involving one limb in dogs less than 12 months of age.  If OCD is present in both shoulders lameness may be more difficult to detect, especially if both joints are equally painful.

Upon physical exam the affected shoulder will be painful upon hyperextension.  The elbow will be painful upon hyperextension.  Sometimes joint effusion will be seen protruding as a small "pouch of fluid" between the olecranon and the lateral humeral epicondyle.  The stifle will not be painful upon extension or flexion.  However, joint effusion can be detected just medial and lateral to the straight patellar ligament.  Be sure to compare the right and left stifles.  Often just looking at the hock will help you immensely in diagnosing OCD of this joint.  The hock is always thickened due to a large amount of joint effusion, fibrosis, and inflammation of the synovial membrane.  The hock will be painful upon hyperextension.

Radiography can usually help confirm the diagnosis. Proper radiographic positioning for each joint is essential.  If the suspected humeral head lesion is not seen on a standard lateral radiograph then additional internal and external rotation radiographs will often times reveal the lesion.  Very mild cases of OCD cannot be detected radiographically. 

Treatment for confirmed OCD is surgical removal of the cartilage flap, curretage of the subchondral bone and microfracture of the subchondral bone bed.  Microfracture is simply making multiple small holes approximately 2 to 3 mm deep in the subchondral bone bed.  It has been show that this stimulates the formation of islands of fibrocartilage and shortens healing time.  The microfractures can be made with a kirshner wire that has been bent at the tip.  It has been reported that resting patients with very mild OCD will result in healing of the lesion.  Arthroscopy can also be used to assist in both the diagnosis and treatment of OCD in the shoulder, elbow and stifle.  The arthroscopic shaver can be used to "curette" the lesion.

The prognosis for OCD varies widely.  The earlier the detection and surgical intervention, the better the prognosis.  Because of this, persistence on our part in diagnosing lameness is young dogs is essential.  Shoulder OCD has the best prognosis followed by the stifle, then the elbow and finally the hock.  Patients with OCD of the shoulder and no degenerative joint disease return to normal function and have an excellent long-term prognosis.  There is some controversy as to whether OCD of the hock should be corrected surgically.  I believe that if OCD of the hock is diagnosed before osteoarthritis is present the prognosis is better if surgery is performed.  Patients who have OCD of the hock with concurrent osteoarthritis are not candidates for surgery.