Scapulohumeral Luxation

Chapter 103 Scapulohumeral Luxation



Robert A. Taylor


Scapulohumeral luxation is an uncommon clinical condition. Both congenital and traumatic luxations occur; the latter is more common.


Medial luxation of the humeral head is most common, especially in smaller-breed dogs. Lateral luxation of the humeral head, while less common, usually occurs in larger dogs (Fig. 103-1). Cranial and caudal luxations are rare.


image

Figure 103-1 Medial (left) and lateral (right) luxations of the scapulohumeral joint.



ANATOMY



• The shoulder joint is a ball-and-socket joint. The articular surface of the scapula forms the concave glenoid, and the convex humeral head articulates within it. Although the joint is capable of movement in any direction, its major actions are flexion and extension.

• The joint capsule is continuous and blends with the medial and lateral glenohumeral ligaments (Fig. 103-2). These ligaments help to support the joint and may be 2.0 mm or greater in thickness.

• The subscapularis, supraspinatus, infraspinatus, and teres minor muscles provide periarticular support.

• The tendon of origin of the biceps brachii and its sheath join with the joint capsule on its cranial medial aspect and provide additional stability. The bicipital tendon is held in the bicipital groove by the small but sturdy transverse humeral ligament.

• Luxation is not possible unless the glenohumeral ligaments and joint capsule have been ruptured.

image

Figure 103-2 The glenohumeral ligaments.



CLINICAL SIGNS



• The principal signs are varying degrees of lameness, depending on the severity of the luxation.


DIAGNOSIS



• Diagnosis is made by physical examination and confirmed by radiography.

• Careful palpation of the area between the acromion of the scapula and greater tubercle can be helpful.

• In medial luxations, hold the elbow in a flexed position and abduct the lower limb.

• In lateral luxations, hold the elbow in a flexed position and adduct the lower limb.

• Examine both shoulders simultaneously and use the normal limb for comparison.


PREOPERATIVE CONSIDERATIONS



• Radiograph the shoulder to rule out intra-articular fractures.

• Use general anesthesia for all shoulder reduction procedures, whether open or closed.

• Closed reduction is a non-surgical treatment.


PROCEDURES FOR CLOSED REDUCTION



Procedure for Medial Luxation



1. Flex the elbow and pull the limb laterally while exerting digital pressure on the scapular spine.

2. Gently rotate the limb downward to reduce the luxation.

3. Place the limb in a Velpeau sling for 10 to 14 days.

4. If the joint is stable on removal of the sling, begin passive range-of-motion exercises. When possible, encourage swimming as an adjunct to physical therapy, but restrict exercise for 1 month.

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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Scapulohumeral Luxation

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