The Articulations 355 



leg seeming shorter than its fellow. The humerus can be extended 

 and flexed only with the greatest difficulty. The position assumed 

 by the head of the humerus is indicated by an enlargement, a hollow 

 existing at the site of the joint, and the parts are painful. Partial 

 luxations generally get well with treatment, but the prognosis of 

 complete luxation is less favorable. Hertwig had one complete 

 recovery. 



Treatment. Reduction is effected by extension of the humerus 

 and pressure over its head in the direction of normal position. 



The Humero-Badio-Ulnar Articulation. This luxation may 

 take place either inwardly or outwardly. It may be complete or 

 partial between the humerus on the one hand and the radius and 

 ulna on the other. The head of the radius may also be displaced 

 alone and, as a rule, to the outside. In these cases the annular liga"- 

 ment uniting the heads of the radius and ulna is coincidently rup- 

 tured. Curiously enough, luxation of the head of the radius, and 

 sometimes of both radius and ulna, is often congenital in the Black- 

 and-tan Terrier breed, involving one or both elbows. When it 

 occurs under these circumstances the young are usually born in this 

 condition, but may also acquire it in the first few weeks of life. 

 I have also seen the congenital form in other breeds, and in one in- 

 stance there was an additional deformity in the shape of a club-foot. 



According to Carougeau, humero-radio-ulnar luxation may 

 arise from various traumatic influences, from extreme flexion of the 

 forearm with external displacement and rupture of the 

 internal lateral ligament, or from twisting of the joint 

 with slipping of the coronoid process from the trochlea of the 

 humerus, in which case all the ligaments are ruptured. Luxation of 

 the head of the radius with rupture of the annular ligament con- 

 necting this bone with the ulna is chiefly caused by leaping or falling 

 from great heights. 



Symptoms and Diagnosis. The symptoms of humero-radio- 

 ulnar luxation are depression on one side of the articulation and 

 enlargement on tbe opposite with infiltration of the neighboring 

 tissues and muscles. In addition to the change of contour may also 

 be noticed ; turning of the foot in the opposite direction to that in 

 which the displacement has taken place, shorter appearance of the 

 leg than its fellow, a limping gait, and expression of pain when the 

 seat of luxation is handled. 



