The most common elbow disease of growing dogs is elbow dysplasia. Elbow dysplasia is manifested as a collection of different diseases including ununited anconeal process (UAP), osteochondritis dissecans (OCD) and fragmented medial coronoid process (FMCP). The most common elbow diseases seen in the adult dog are degenerative joint disease and medial compartment disease. Both are usually the long-term sequels of ED. Medial compartment disease is also seen in adult dogs that had previously no elbow dysplasia. Regardless the causes they all result in complete loss of cartilage on the medial coronoid and the medial aspect of the humeral condyle.

This presentation will focus primarily on the management of medial coronoid diseases of young and adult dogs, as this is the most controversial topic.

The ideal goal of any treatment of elbow disease should be to eliminate pain, to stop the progression of the disease and to prevent degenerative joint disease.

It is as difficult as it is to define the exact causes of the different manifestations of elbow dysplasia as it is to choose the optimal treatment regimen. Unfortunately, there is still a lack of good long-term studies comparing outcomes between surgical and conservative treatment regimens as well the different surgical treatments.

In the absence of sufficient evidence, treatment decisions remain largely empirical and subjective. Irrespective of this fact, treatment in young dogs should always be focused on prevention, while in older animals palliation will be the primary goal.

Independent of surgical procedures weight management, activity modifications, medical management, as well as physiotherapy should be included in every treatment plan.

It is not surprising that there are a variety of surgical treatment options to help dogs affected with elbow disease. The most commonly performed procedures are:

Fragment Removal (FR)

The arthroscopic removal of medial coronoid fragments has been the standard of care for years. Although the fragments are typically necrotic, they typically have strong joint capsule attachments or are squeezed between radius and ulna. The fragments act like a joint mouse causing synovitis, pain and osteoarthritis. Fragment removal alleviates synovial irritation and joint capsule tension during ambulation and this is thought to be the basis for treatment efficacy.

Subtotal Coronoid Ostectomy (SCO)

In many cases of FMCP, the remaining portion of the medial coronoid is diseased as well. Histological analysis has revealed extensive microcrack formation in the subchondral bone of the medial coronoid.³ As with stress fractures, this is a cause of significant pain. The SCO involves ostectomy of the diseased bone; i.e., removing the majority of the medial coronoid process.

Biceps Ulnar Release (BURP)

The biceps brachialis complex inserts on both the radius and the ulna at the medial aspect of the elbow joint. Contraction of the muscle complex leads to compression of the radial head into the radial incisure of the ulna. Recently the release of the ulna portion of the biceps tendon has been advocated to reduce the risk of fragmentation of the medial coronoid in dogs with synovitis and elbow pain or in those with small fragmentation of the medial coronoid and significant remaining portion of the coronoid that may be at risk to fragment in the future.⁶

Dynamic, Proximal Ulna Osteotomy

An oblique osteotomy of the proximal ulna should release the pressure on the joint caused by incongruence between radius and ulna. It is ideally performed in young growing dogs with a good healing potential, as the dynamic nature of the osteotomy does not allow for stabilization of the osteotomy. As the joint is destabilized and the bone ends loose, these dogs are quite painful until the osteotomy has healed.

Distal Ulna Osteotomy (DUO)

In the young dog less than 6–8 months of age, a partial osteotomy of the distal ulna might be preferred, as this is less painful for the dog than a proximal osteotomy. At that age, the interosseous ligament is not yet restricting motion between radius and ulna thus allowing shifting of the ulna in relationship to the radius. This procedure is primarily indicated if there is already obvious incongruence between radius and ulna at that age.

Proximal Abducting Ulnar Osteotomy (PAUL)

This technique was developed on the basis of several observations and biomechanical analysis of the canine elbow joint. A consequence of medial compartment syndrome is medial collapse of the joint. Medial collapse overloads the medial compartment, exacerbating existing lameness and joint pain. A slight abduction of the ulna of about 4 to 6 degrees seems to result in an unloading of the medial compartment alleviating pain and lameness. The PAUL procedure involves an osteotomy of the proximal ulna. A specially designed plate is applied to impose the desired modification of limb alignment aimed at unloading the medial compartment.

Sliding Humeral Osteotomy

A midshaft humeral transverse osteotomy is performed and the bones fixed with a special step plate that keeps the distal humerus in a medially shifted position. This unloads again the medial compartment and shifts the weight-bearing axis to the lateral compartment.

Canine Unicompartmental Elbow System (CUE)

This hemiarthroplasty is performed in joints of older dogs with medial compartment disease. The destroyed surface is restored with a small inlay prosthesis. This medial resurfacing procedure aims to reduce or to eliminate the pain and lameness that was caused by the bone-on-bone grinding while preserving the dog's own "good" cartilage in the lateral compartment.

Total Elbow Replacement (TER)

Total elbow replacement with a prosthesis has not yet really taken off. The main reason lies in the complexity of function of the elbow and the heavy loading, to which any prosthesis is exposed. The usually severe osteoarthritis with osteophytes, fibrosis of the joint capsule, makes the operation a demanding procedure and affect prognosis.

Most experience to date exists with the "TATE Elbow®". In this unique and patented system the artificial joint is inserted like a cartridge without opening the joint.

Both the system and the surgical technique are very sophisticated and well thought out. Nevertheless, the operation is very demanding and expensive.

The decision how to proceed depends not only on the patient's age at the time of diagnosis, but also (if present) on the type and severity of incongruence of the joint, on the condition of the cartilage and the extent of osteoarthritis already present at the time of diagnosis.^1,2,5,7 Elaborated algorithms have been postulated, intended to help in the decision process.⁴

If osteoarthritis is already severe, treatment options are limited, expensive and with questionable success. Thus our treatment efforts must focus on early intervention in the young dog to delay progression of the disease.

Early preventive surgical measures to consider are the BURP, the dynamic proximal ulna osteotomy, and a distal ulna osteotomy or may be a PAUL procedure

Already resulting fragments should always be removed, the risk of further fragmentations be prevented by a subtotal coronoid ostectomy. The earlier we intervene, the better the chances are to optimize the joint function and the more likely the patients remain pain free.

If the cartilage is already destroyed, as this is the case with medial compartment disease, preservation of a pain-free function becomes the primary goal.

Since most surgical interventions at this stage are expensive and not necessarily crowned with success, a conservative therapeutic trial should always be tried first. These include medical therapy with nonsteroidal anti-inflammatory drugs, intra-articular administration of steroids, platelet-rich plasma (PRP) or stem cells, laser therapy and physiotherapy. Many joints can be maintained quite successful at this stage. If this is not the case palliative surgery can be considered.

In spite of all our efforts and advancements in the treatment of dogs with ED, affected dogs have a poor long-term prognosis due to osteoarthritis.

References

1.  Bötcher P et al. Visual estimation of radioulnar incongruence in dogs using three dimensional image rendering. Vet Surg. 2009;39:199.

2.  Cuddy LC et al. Contact mechanism and three dimensional alignment of normal dogs elbows. Vet Surg. 2012;41:818.

3.  Danielson KC, Fitzpartick N, Muir P. Histomorphometry of fragmented medial coronoid process in dogs a comparison of affected and normal processes. Vet Surg. 2006;35:501.

4.  Fitzpatrick N, Yeadon R. Working algorithm for treatment decision making for developmental disease of the medial compartment of the elbow in dogs. Vet Surg. 2009;38:285.

5.  Gemmil T, Clements G. Fragmented coronoid process in the dog: is there a role for incongruency? J Small Anim Pract. 2007;48:361.

6.  Hulse D, Beale B, Kowaleski M, Vannini R. Relationship of the biceps brachialis complex to the medial coronoid process of the canine ulna. Vet Comp Orthop Traumatol. 2010;3:173–176.

7.  Samoy et al. Computed tomography finding in 32 joint affected with severe elbow incongruency and fragmented medial coronoid process. Vet Surg. 2012;41:486.

8.  Samoy et al. Arthroscopic findings in 32 joints affected with severe elbow incongruency and fragmented medial coronoid process. Vet Surg. 2012;41:355.