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1/20/13

Disorders of the shoulder joint

How can I tell if my dog has a shoulder joint problem?
There are many disorders affecting the shoulder joint that can affect all ages of dogs and which can occasionally also affect cats. Limping is the usual problem noted at home. There is usually no specific gait abnormality suggestive of a shoulder problem (as opposed to an elbow problem, for example). Some shoulder problems are developmental and affect young dogs that have not been subject to trauma. In some cases, problems can be associated with an external injury, whilst other shoulder conditions are the result of repetitive strain to the muscles around the shoulder joint.

Here is a list of some of the common conditions affecting the canine shoulder joint:
Osteochondrosis (OC) and osteochondritis dissecans (OCD)
In dogs that grow very quickly, the rapid cartilage growth can outstrip its own blood supply. This causes abnormal cartilage development and subsequent osteoarthritis. In some cases, flaps of diseased cartilage become separated from the remaining cartilage surface. This is called osteochondritis dissecans (OCD). Genetic factors are the most important cause of OC and OCD, with strong breed predispositions, particularly in Labradors and giant breed dogs. Different breeds appear to be predisposed to developing the condition in different joints. For example, the shoulder joint is most commonly affected in Border Collies, Great Danes and Irish Wolfhounds. Various other factors such as dietary or nutritional problems during the first few months of life, hormonal imbalances and joint trauma can also increase the risk of developing OC.


OC lesion
OC is typically diagnosed by a combination of examination by an experienced orthopaedic surgeon, radiography of the affected joints, and arthroscopy (examination of the joint by keyhole surgery). Because OC can occur at the same time as other developmental orthopaedic diseases (such as certain manifestations of elbow dysplasia), some dogs may require additional tests such as CT or MRI scans.

Various treatment options are available for shoulder OC/OCD. The best treatment option for each dog can only be recommended following thorough clinical, radiographic and arthroscopic assessment. Non-surgical management is occasionally appropriate for dogs with small cartilage defects and minimal discomfort. The majority of dogs are treated surgically. The following options are available:
Surgical removal of the cartilage flap: Certain types of small cartilage defects in specific locations are treated arthroscopically (keyhole surgery) by flap removal and debridement of the defect bed. This allows the cartilage defect to heal by scar cartilage formation over the course of several weeks. Scar cartilage (fibrocartilage) is less robust than healthy joint (hyaline) cartilage, so although this allows some of the joint inflammation to resolve in the short-term, the joint will remain abnormal, with ongoing development of osteoarthritis and cartilage wear. We currently recommend this surgery for very small or shallow disease lesions.
Principle of OATS and a synthetic graft in situ with preparation of an adjacent site for another synthetic graft.Osteochondral autograft transfer (OAT): Over recent years, we have adopted the OATS™ (Arthrex, Naples, FL) system for use in the canine shoulder joint. This system has been used for many years in human joints to resurface cartilage lesions including OCD, with positive long-term results. It involves collection of a cylinder of bone and cartilage from a non-contact area of a healthy joint (usually the knee) and transplanting it into a joint affected by OCD in order to resurface the cartilage defect with healthy hyaline cartilage. In some cases, it may be more appropriate to use a synthetic resurfacing graft instead of a cartilage graft.

Shoulder instability

There are several different forms of shoulder instability. Some dogs experience a low-grade repetitive sprain injury to the shoulder ligaments or a strain injury to the muscles of the rotator cuff. Affected animals are often middle-aged athletic large breed dogs. Lameness in affected dogs is often worse after exercise. Dogs affected by high-grade sprains and strains of the shoulder joint may experience an obvious permanent limp.

Prosthetic stabilization postoerative radiograph.
Diagnosis of shoulder instability is made using a physical examination test that is usually performed under sedation or general anaesthesia. We will often perform radiographs to check for the presence of osteoarthritis. Occasionally, advanced imaging using MRI can be helpful when assessing dogs with suspected strain injuries. Most dogs are assessed under general anaesthesia using arthroscopy. This is a keyhole technique whereby a fibre-optic camera is inserted into the shoulder joint.

Treatment of shoulder instability depends on the grade of sprain and strain, and the degree of instability. Low-grade injuries are often treated non-surgically with anti-inflammatory medication, exercise modification and physiotherapy. High-grade injuries can be treated using prosthetic stabilization, shoulder fusion, or total joint replacement.

Prosthetic stabilization: The surgical technique for shoulder stabilization is modeled on the techniques used for the management of rotator cuff tears in humans. We have pioneered the application of human implantation systems to dogs, with excellent success.


Post-op shoulder arthrodesis.Shoulder fusion (arthrodesis): In animals affected by the most severe problems affecting the shoulder, including severe instability, dislocation (luxation), articular fractures, and arthritis, arthrodesis may be the best option. This is called a “salvage” surgery because it is used as a last-resort where other techniques to save the joint would have a poor probability of success. We have excellent experience with shoulder arthrodesis, and have published the largest case series describing this technique in dogs.


Postoperative radiograph of a total shoulder replacement
Total shoulder replacement: The technology and implants for canine total shoulder joint replacement have been pioneered at Fitzpatrick Referrals. The first clinical cases were operated here, and we are currently the only veterinary hospital offering this procedure worldwide.
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