The elbow is a complex joint formed by the humerus, radius and ulna. For the elbow to function normally and comfortably, these three bones have to fit together perfectly and their surfaces have to be covered by healthy joint cartilage.
Elbow dysplasia is a term used to describe the abnormal development of the elbow. Traditionally, there are four conditions that result from abnormal development of the elbow:
Medial coronoid disease
Osteochondritis dissecans (OCD)
Ununited anconeal process (UAP)
These conditions may occur in isolation or in combination and affect the way the bones fit together and/or the quality of the joint cartilage. This ultimately results in elbow osteoarthritis and forelimb lameness (limping). The degree of osteoarthritis that a patient develops is variable and often unpredictable. Likewise, the degree to which the osteoarthritis affects an individual patient is often unpredictable. Unfortunately, osteoarthritis in any joint in the body is incurable, but with appropriate care, a good quality of life can be attained for your pet.
1. Medial coronoid disease
Concentration of forces in the medial compartment of the elbow joint can result in stress fractures forming within a peninsula of bone called the medial coronoid process of the ulna. These stress fractures can result in fragments forming within the joint (fragmented coronoid process). This ultimately leads to inflammation within the elbow (osteoarthritis).
That part of the elbow where the medial coronoid process and humerus come into contact is called the medial compartment. Commonly, there is severe wear and loss of cartilage in the medial compartment resulting in “bone on bone” contact. This condition is often referred to as medial compartment disease.
2. Osteochondritis dissecans (OCD)
Osteochondrosis occurs as a result of a problem with the way bone and cartilage form in a joint. In the elbow, this occurs in the medial trochlear ridge of the humerus. A flap of cartilage can peel away from the humerus resulting in osteochondritis dissecans (OCD), a painful condition resulting in osteoarthritis.
3. Ununited anconeal process (UAP)
Occasionally, a triangular process of bone and cartilage called the anconeal process doesn’t attach properly to the top part of the ulna during development. This loose piece of bone and cartilage results in discomfort and osteoarthritis.
4. Elbow incongruity
At times, the bones in the elbow don’t fit together properly. This can be as a result of a radius or ulna that is too short, or, as a result of an ulnar notch that is the wrong shape. These problems are thought to contribute to the development of medial compartment disease, fragmentation of the coronoid process, UAP and the resultant osteoarthritis.
Signs of elbow dysplasia
Regardless of the type, elbow dysplasia will often result in limping. This is usually most pronounced when rising from rest or after activity. During activity, the dog often “warms out of” the lameness and does not appear to be overtly lame.
Dogs with elbow dysplasia will often stand with their front paws turned outwards and there may be thickening or fluid swelling about the elbows.
How is elbow dysplasia diagnosed?
Diagnosing a patient with elbow dysplasia starts with an examination with our specialist surgeons. Watching your dog walk will often confirm a lameness that affects one or both front legs. Gently flexing and extending the elbows may result in discomfort that is localised to the elbows.
Ultimately, an accurate diagnosis will require imaging.
Plain radiographs (x-rays) may show evidence of elbow dysplasia (osteoarthritis, incongruity etc). However, usually, advanced imaging is required.
Computed tomography (CT) uses x-rays and a computer to produce images of the body. The images obtained using CT, can then be manipulated to produce images in three dimensions. This greatly improves the chances of an accurate diagnosis of elbow dysplasia.
Arthroscopy (inspection of joints using a camera) will allow direct, magnified visualisation of the internal workings of the elbows and is often very helpful for confirming and ultimately treating elbow dysplasia. The procedure is performed using a “keyhole” technique resulting in a rapid recovery.
How is elbow dysplasia treated?
Some dogs with elbow dysplasia may be determined to be best treated with non-surgical therapies. These usually include weight management, exercise adjustment, physiotherapy and supplements that may improve joint health.
Arthroscopic fragment removal and subtotal coronoidectomy
This treatment strategy involves using an arthroscope to guide the removal of fragments of cartilage/bone from the elbow joint or, the majority of the medial coronoid process. This procedure is performed minimally invasively, with the majority of dogs walking and able to be discharged the day after surgery. Removal of the OCD cartilage flap is also achieved using arthroscopy.
Proximal abducting ulnar osteotomy (PAUL)
This technique involves performing a cut in the ulna and stabilising it using a special titanium plate and screws. The aim is to reduce the load that is taken by the diseased part of the elbow joint resulting in a more comfortable joint.
Dynamic ulnar osteotomy
Sometimes, a type of ulnar osteotomy is performed that is not stabilised using a plate. These techniques are often used if there is joint incongruity present, that is, if the radius and ulna don’t align with the humerus properly. They allow the bone to move into a more congruent position such that the bones fit together better. Combined with an accurately placed screw, an ulnar osteotomy may specifically benefit patients with UAP.
What is the prognosis for elbow dysplasia?
The aim of treatment for dogs with elbow dysplasia, is to improve their comfort level. Unfortunately, it is impossible to cure the disease and the secondary osteoarthritis that results. However, with an appropriate assessment by the surgeons at Queensland Veterinary Specialists, a management regime can be tailored to achieve the best possible outcome for your pet.