Osteochondrosis (OC) / Osteochondritis Dissecans (OCD)
This condition occurs when cartilage does not transition to bone as part of the normal growth and development of bones and joints. The primary location is on the head of the humerus (the ball part of the shoulder joint). It causes mild to severe forelimb lameness in dogs that are 6 to 12 months of age. Both shoulder joints are often affected, but one is usually more lame and painful than the other. A key diagnostic test is pain with extension of the shoulder joint in a young dog. Confirmation of the diagnosis is a radiograph with a characteristic lesion seen. Surgical removal of the cartilage flap generally results in significant improvement. This can be performed with and incision and small opening in the shoulder joint, or by arthroscopy
Shoulder OCD lesion. Note the flattening of the head of the humerus, with mineralized fragment located over the flattened area.
The biceps muscle crosses both the shoulder and elbow joints. Sometimes it becomes inflamed, stretched, and in advanced cases, partially or completely torn. Middle aged to older active dogs are most frequently affected. Lameness may be intermittently mild to severe, continuous non weight-bearing lameness. The test that is usually performed is to simultaneously flex the shoulder and extend the elbow to put maximum tension on the muscle-tendon unit; this results in pain. Palpation directly over the upper part of the biceps tendon also creates pain. A diagnostic test to more completely characterize the condition is ultrasound of the tendon and muscle. Treatment options include conservative management with rest and nonsteroidal anti-inflammatory medications, extracorporeal shockwave treatment, therapeutic laser, therapeutic ultrasound, biologic therapy with stem cells or platelet rich plasma, and surgery.
This muscle runs along the front of the scapula and inserts on the upper part of the humerus (greater tubercle). The tendon insertion of this muscle may become inflamed, stretched, or torn. Chronic cases often have some calcification of the tendon insertion. Diagnostic ultrasound can more completely characterize the problem. Dogs generally have a mild to moderate forelimb lameness that progressively worsens if not treated. Pain may also be present when the area is palpated. Treatment options include conservative management with rest and nonsteroidal anti-inflammatory medications, extracorporeal shockwave treatment, therapeutic laser, therapeutic ultrasound, biologic therapy with stem cells or platelet rich plasma, and surgery.
This muscle runs along the back of the scapula and inserts on the upper part of the humerus below the supraspinatus muscle. The tendon/muscle may become damaged with fibrosis. Initially, owners may remember some degree of lameness, but as the muscle and tendon undergo fibrosis, the front limb assumes the characteristic position with the elbow rotated in to the chest, and the foot and forelimb externally rotated. Diagnostic ultrasound can more completely characterize the problem. Dogs generally have a mild to moderate forelimb lameness with inability to completely extend the shoulder joint. Treatment is generally very effective, and consists of completely releasing the scar tissue with rehabilitation after surgery to help prevent recurrence.
Characteristic posture of infraspinatus muscle contracture. With damage and fibrosis of the muscle, it causes the elbow to be carried near the body and the lower limb to be externally rotated.
Medial Shoulder Instability (MSI)
Dogs are engaging in more sporting events that result in much torsion of the shoulder joint while turning sharply or turning while landing after a jump. The medial glenohumeral ligament (medial collateral ligament) and/or subscapularis muscle may be stretched or torn. Lameness varies from mild intermittent to continuous severe lameness. A physical exam test that is frequently performed is to fully extend, and then abduct (pull the lower limb away from the body); dogs with MSI will have increased abduction and pain at the end of abduction. Magnetic resonance imaging may be useful in identifying damaged tissues, but it often underestimates the degree of damage. Diagnostic arthroscopy is currently the gold standard in identifying the problem. Although some claim that diagnostic ultrasound may be useful in diagnosing the condition, board-certified radiologists have stated that is is not possible to properly examine the area with ultrasound because too many artifacts are present while trying to image the area. Conservative treatment consists of rest and hobbles to prevent abduction while the damaged tissues heal. Extracorporeal shockwave treatment may help to speed the healing process. Conservative management is generally effective in improving the lameness if the degree of damage is relatively mild. Careful rehabilitation is important to strengthen the area, but alterations in activity may be necessary because dogs will be prone to re-injury. Surgical reconstruction of the tissues may be necessary if the injury is severe or recurrent. Older methods, such as thermal or capsular shrinkage have fallen out of favor, and may actually further damage tissues.