What is it?
Osteochondritis dissecans (OCD) is a developmental disorder caused by disruption in the blood supply between the subchondral bone and articular cartilage of the joint . The result is micro-fissures across the cartilage which worsens with day-to-day activity. Over time these cartilage fissures worsen and loosen from the subchondral bone exposing it to synovial fluid. This causes pain, lameness and the associated muscle loss.
It is a disorder which is seen most commonly in young (less than 1 year) large and giant breed dogs such as Rottweilers, Mastiffs and Labradors.
Whilst the cause is not fully understood, it has been shown that rapid growth, nutrition and hormonal imbalances can increase the probability of development of an OCD lesion.
Diagnosis of OCD
OCD is usually diagnosed in juvenile patients often under a year of age. As the lesion can occur anywhere within the joint, severity of signs can be variable but typical presenting signs include lameness, stiff gait with joint swelling and pain on palpation.
Initially a clinical examination is performed which will localise the joint(s) affected. Radiographs are then taken under sedation or general anaesthesia of the affected and healthy contra-lateral (if applicable) joint. OCD lesions are usually seen on radiographs as an abnormal area of flattening of the joint surface with subchondral sclerosis. You may also see a ‘joint mouse’ if a calcified flap has detached completely. Occasionally CT may also be required.
What joints are affected by OCD?
Whilst any joint can be affected, we find it most often in the shoulder, stifle and hock joints.
What are the treatment options for OCD?
Typically the first approach would be arthroscopy, the OCD lesion excised and the subchondral bone debrided. On occasion the lesion is too large to remove arthroscopically and an arthrotomy is required.
In large lesions resurfacing techniques can be considered. The two options available are Osteochondral Autograft Transplant System (OATS) and Synacart, a synthetic plug to restore the integrity of the joint surface.
OATS uses a donor plug of cartilage and bone harvested from a non weight bearing portion of the joint that is transferred to the defect left by removal of the OCD lesion. Both of these systems have pros and cons, and their use will be discussed during the initial consultation.
Prognosis for dogs affected by OCD
While removal of the OCD flap will lead to short term clinical improvement, in the long term degenerative joint disease will occur leading to osteoarthritis. Of the commonly affected joints, shoulder OCD has the best outlook, and return to full exercise is common. Unfortunately the outlook is not so good for stifle and hock OCD, with chronic joint problems likely. In these cases, maintenance of a lean body weight, exercise moderation and judicious use of supplements and anti inflammatory medications may be required to get the best results. In cases where these measures do not give an adequate quality of life, salvage procedures such as Total Knee Replacement or arthrodesis can be considered.
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