Shoulder Osteochondrosis

Shoulder osteochondrosis and secondary osteoarthritis is a condition that uncommonly affects medium and large breed dogs. The condition has a hereditary component, but inheritance is not simple and the condition is otherwise poorly understood. It is a condition whereby an area of cartilage and underlying bone on the back of the humeral head (the “ball” of the “ball and socket” shoulder joint) do not develop normally. The abnormal tissue detaches from the underlying bone, creating a loose flap which causes pain and inflammation.

It is typically diagnosed in young dogs around 6 to 10 months of age; signs include forelimb lameness and stiffness. Some dogs are affected severely, others only very mildly. Diagnostic tests include X-rays or CT scan; CT scan is much more accurate and gives much more information, so is preferred.

Management options depend on the severity of the condition:

• Conservative (non-surgical) management — in some dogs it is thought that with time the flap will detach and the lameness will self-resolve. However, if this has not happened within a 4 to 8 week period, it is unlikely to do so by itself.
• Surgery (standard) — the purpose of surgery is to remove the loose flap of cartilage and bone. It can be done by arthroscopy (key-hole) surgery, or by a small surgical incision into the shoulder joint; each has advantages and disadvantages.

For dogs that do not respond well, other options include implants to fill the defect in the humeral head — though these are not easy to place, are expensive, carry various possible complications, and the evidence supporting their use is limited. For dogs that respond poorly to all other options, arthrodesis (fusion) of the shoulder joint is performed; this is a complex procedure so is performed only rarely in dogs that are otherwise not coping.

Most dogs respond extremely well to surgery to remove the flap, with rapid resolution of the lameness and only minimal problems of minor stiffness and lameness in the future. It is important to understand that surgery is not a complete cure, as the underlying lesion / defect in the humeral head is not addressed and remains untreated. In the vast majority of dogs this has minimal consequence, but in a minority a residual or more obvious lameness is apparent.

Dogs that undergo a successful shoulder fusion (arthrodesis) do very well and are minimally to not lame.