60 DISEASES OF THE SYNOVIAL MEMBRANES AND ARTICULATIONS. 



Diagnosis. The position of the limb and the displacement of the 

 patella are sufficiently distinctive to render dia.gnosis fairly easy, and to 

 allow of this accident being differentiated from luxation of the femoro- 

 tibial joint or hooking of the patella in the ischio-tibial muscle. 



Prognosis. The prognosis varies greatly. If the luxation is of 

 traumatic origin and the accompanying symptoms are not grave, reduc- 

 tion may be followed by permanent recovery. On the other hand, in 

 spontaneous luxation recurrence is almost inevitable. 



Treatment. The indications for treatment may be comprised in a 

 single phrase: reduction, with immobilisation of the parts for a suffi- 

 cient time. To effect reduction, a strip of webbing is fixed around the 

 pastern of the affected limb, passed over the withers, in front of the 

 shoulder of the opposite side, and brought round in froilt of the neck or 

 between the front limbs. By means of this an assistant exercises strong 

 traction on the limb until the fetlock is raised as high as the elbow of the 

 same side. The operator then applies strong inward pressure to the 



Fig. 22. — Bandage for luxation of the patella. 



patella, which usually slips back on to the gliding surface of the trochlea 

 at the first or second effort. 



After-treatment comprises the application of a smart blister, produc- 

 ing oedematous infiltration of all the tissues around the joint, and thus 

 impeding movement and recurrence of luxation. For this purpose various 

 preparations are used — e.g., cantharides, biniodide of mercury, croton 

 oil, etc. It is also advisable to fix the animal so that for a time it cannot 

 lie down, and to secure the pastern to the neck by means of a side-line. 



As an experiment, cases of simple fixation of the patella on the summit 

 of the internal lip of the trochlea might be treated by Bassi's method — 

 i.e., subcutaneous division of the internal lateral ligament of the patella 

 which holds the bone in its abnormal position. 



Finally, in spontaneous luxation, occurring in young animals in which 

 blisters have been ineffectually tried after reduction, Benard's bandage 

 may be used, though it is not generally regarded as very practical. It 

 consists of a piece of cloth of elongated lozenge form about four feet 

 in length, six inches in breadth at its centre and two inches at its ends. 

 Its centre is pierced by a transverse opening intended to surround 

 the patella, and carries a loop for the purpose of supporting the turns of 

 bandage. A second longitudinal opening is situated about eight inches 

 from the centre. 



