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Challenging forelimb lameness: The shoulder (Proceedings)

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Apr 01, 2010

Diagnosing and treating forelimb conditions in dogs can be very challenging. Many dogs present with a similar history including minimal responsive to rest and non-steroidal anti-inflammatory drugs and increased lameness following exercise and heavy activity. It can be difficult to localize the lesion on palpation as many dogs may show increased sensitivity in the shoulder and elbow from referred pain and compensation. To further challenge the veterinarian it is not uncommon for diagnostics such as radiology to be within normal limits due to the soft tissue nature of these injuries (tendon, ligament, and cartilage). Fortunately, with the availability of advanced diagnostics (arthroscopy, MRI, CT scan, ultrasound, etc) the definitive diagnosis can be determined and an appropriate treatment plan created. Depending on the diagnosis (tendon, ligament, cartilage lesions, etc) treatment options may include arthroscopic treatments, stem cell therapy (SCT), platelet rich plasma (PRP), rehabilitation therapy and medical management.

Supraspinatus Tendinopathy

In humans and dogs, several degenerative disorders in the insertion of the supraspinatus tendon have been identified, including rotator cuff tears, calcifying tendonitis or tendinosis, and tendinosis as a result of overuse. Degeneration of the supraspinatus tendon has been suggested to be a factor in the development of rotator cuff tears in humans. Overuse injury has been suggested as the cause of this disorder, and the role of overuse in the pathogenesis has been supported by findings of experimental studies. Histologically, affected tendons contain discontinuous and disorganized collage fibers. Typically, no inflammatory cells are detected. In chronic cases, a proliferative nodule develops which can cause biceps brachii tendon displacement and pain.

Dogs commonly present with a history of a chronic unilateral weight-bearing lameness that is exacerbated with activity and often refractory to treatments. Supraspinatus atrophy may be noted and discomfort may be elicited by direct palpation over the tendon and during flexion of the shoulder. It is not uncommon to identify concurrent BT or medial shoulder instability (MSI), therefore a thorough shoulder exam including biceps test and abduction angles are required.

Enhanced imaging using MRI is able to readily visualize the condition in the acute phase. Plain radiography and CT Scan may reveal mineralization just cranial to the greater tubercle in chronic cases. Ultrasound may also a useful modality for diagnosing this condition. Arthroscopic exploration may identify "impingement" of the biceps tendon secondary to supraspinatus tendon swelling as well as possible MSI pathology.

Depending on the severity, treatment options may include rehabilitation therapy (manual therapy, modalities, therapeutic exercise, etc), platelet rich plasma (PRP), and stem cell therapy. In chronic cases, it is necessary to re-initiate the inflammatory process to stimulate the healing response.

Surgical treatment is warranted for those that do not respond to conservative medical management and rehabilitation therapy. Surgical treatment should include arthroscopic exploration to identify and treat concurrent BT and/or MSI if noted, or resection of abnormal tissue through an open approach. Surgery has been considered the treatment of last resort in humans with tendinosis because of the small reported difference in treatment success between surgical intervention and conservative management.