Fractures of the neck of the scapula are recognized by crepitation, by passively moving the leg, but it is necessary to exclude fractures of the humerus when one depends upon the finding of crepitation by this means. However, unless undue swelling exists, the exact location of the crepitation is recognized without serious difficulty.
Treatment.—The treatment of compound fractures of the scapular spine consists in the removal of the broken piece of bone by way of a cutaneous incision so situated that good drainage of the wound will follow.
Simple fractures of the body of the scapula are best treated by placing the subject in a sling, if the animal is halter broken, and enforcing absolute quiet for a period of from three to six weeks. Splints or similar appliances are not of practical value in scapular fractures.
Compound fractures of the scapula usually result from violence, which at the same time does serious injury to adjacent structures, and it then becomes necessary to administer an expectant treatment, observing general surgical principles and providing in so far as possible for the comfort of the patient.
Scapulohumeral Arthritis.
Anatomy.—The scapulohumeral joint is an enarthrodial (ball and socket) joint wherein the ball or humeral articulating head greatly exceeds in size the socket or glenoid cavity of the scapula. The capsular ligament surrounding this joint is very large and admits of free and extensive movement of the articulation. There exist no lateral or common ligaments jointing the scapula and humerus as in other joints, but instead the tendinous portions of muscles perform this function. The principal ones which are attached to the scapula and humerus that act as ligaments are the supraspinatus (antea-spinatus), infraspinatus (postea-spinatus) biceps-brachii (flexor brachii) and subscapularis muscles.
Etiology and Occurrence.—Inflammation of the scapulohumeral articulation results from injuries of various kinds, including punctures which perforate the joint capsule, bruises from collars, metastatic infections and involvement as a result of direct extension of infectious conditions situated near the joint.
Classification.—Acute arthritis may be septic or aseptic, and there seems to be a remarkable tendency for recovery in cases of septic arthritis involving this joint in the horse.
Chronic arthritis with destruction of articular surfaces and ankylosis, is seldom observed. It is only in cases of severe injury, where the articular portions of the bones are damaged at the time of infliction of the injury, and where the articulation remains exposed for weeks at a time, together with immobility of the parts because of attending pain, that permanent ankylosis results.
Scapulohumeral arthritis may result then from infections, local or metastatic; from injuries, such as contusions of various kinds; from wounds, which break the surface structure or perforate the joint capsule; or from luxations.