Luxation of the Scapulohumeral Joint.

Because of the large humeral head articulating as it does with a
glenoid cavity, scapulohumeral luxations are very rare in the horse.
According to Moller[7], luxation is generally due to excessive flexion
of the scapulohumeral joint. In such cases the head of the humerus is
displaced anterior to the articular portion of the scapula and remains
so fixed.

Symptoms.--Complete luxation of the scapula is recognized because of
immobility of the scapulohumeral joint and of the abnormal position of
the head of the humerus, which can be recognized by palpation, unless
the swelling be excessive. Immobility of the scapulohumeral joint is
noticeable when one attempts to passively move the parts.

Treatment.--Reduction of the luxation is effected by making use of the
same general principles that are employed in the reduction of all
luxations, and they are--the control of the animal so that the
manipulations of the operator are not antagonized by muscular
contraction, which is best accomplished by anesthesia; placing the
luxated bones in the position which they have taken to become unjointed;
and then making use of force which is directed in a manner opposite to
that which has effected the luxation.

In a forward luxation of this kind, the operator should further flex the
humerus, and while it is in this flexed position, force is exerted upon
the articular head of this bone, and it is pushed downward and backward
into its normal position.