Medial Compartment Disease of the Elbow (previously referred to as the catch all term of Elbow Dysplasia) is the most common cause of front limb lameness in the young dog, especially of the larger breeds.
Dysplasia comes from the Greek dys, (abnormal) and plassein (to form). Therefore, dysplasia refers to abnormal development, in this case of the elbow joint.
The elbow is formed from the meeting of three bones:
the humerus, which is the bony support of the upper limb from the shoulder to the elbow; the ulna, which runs from the elbow to the paw along the back of the limb; and the radius, which supports the major weight-bearing along the front of the lower limb.
All three of these bones need to grow and develop normally and at the same rate such that they fit perfectly at the elbow. If there are any abnormalities along these lines or if the cartilage lining the elbow joint does not form properly then “dysplasia” or abnormal formation is the result.
Elbow dysplasia can take several different forms.
Ununited anconeal process (UAP), fragmented medial coronoid process (FMCP), osteochondritis dessicans of the medial humeral condyle (OCD), ununited medial epicondyle (UME) and elbow incongruity all qualify as types of elbow dysplasia that can be present individually or in combination. While all of the variations are distinct and probably develop in different ways, they have in common that they produce loose pieces of bone and/or cartilage within the joint that act as irritants much as a pebble does in your shoe! All of these variations also have in common that they are primary problems that invariably lead to the secondary development of arthritis within the elbow. The term “arthritis” simply describes inflammation within a joint. The longer an elbow joint is ill-fitting or irregular, the more arthritis forms. While traumatic episodes may affect the development of the elbow joint, the vast majority of elbow dysplasia cases are genetic in origin.
The first sign of a problem is a mild to moderate front limb lameness in a young dog between the ages of 4 to 10 months. If the problem is not diagnosed at this stage, more marked lameness may be noted as severe arthritis sets in. Large breed dogs predominate in the following list of commonly affected breeds:
- Bernese Mountain Dog
- Chow Chow
- German Shepherd
- Golden Retriever
- Labrador Retriever
- St. Bernard
- Bassett Hound
Diagnosis and treatment
The history of front limb lameness in a young, large breed dog is suggestive of elbow dysplasia. Examination of the elbow may show pain, thickening or swelling, and restricted movement.
Radiographs of the elbow will usually confirm the diagnosis although FMCP and OCD might not be clearly demonstrated. Even in these cases there are usually radiographic signs that suggest the diagnosis. Advanced imaging studies, particularly computed tomography (CT), may also be
helpful. Ultimately, surgical exploration of the joint may be needed to provide a complete diagnosis. In recent years, such exploration is most often done with an arthroscope, a camera that is inserted in the joint without the need of major open surgery.
This is the preferred means of diagnosis and treatment for cases of elbow dysplasia. Some cases may be managed with open joint surgery and still others may do well with medications alone such as anti-inflammatories. Early surgical management of these problems provides the best chance for minimizing arthritic changes in these elbows, but
all dysplastic elbows will develop some degree of arthritis. Older dogs, where arthritis is well established, may still benefit to some degree from arthroscopic surgery but the benefits are less predictable. The newest generation of canine anti-inflammatory drugs along with chondroprotectives such as glucosamine and diets high in omega-3 fatty acids can also provide
Elbow replacement is an exciting new treatment that has been developed in the last couple of years and, although not widely available, holds great promise for the future.