PERONEAL TENOTOMY 213 



especially around the superior extremities of the tibia and 

 fibula. 



Another very reasonable theory places the fault on the 

 loss of equilibrium in the action of that great mechanism that 

 automatically flexes the hock and the stifle simultaneously. 

 When one of these articulations flexes the other one also 

 flexes automatically. Flexion of one is physically impossible 

 without flexion of the other. The gastrocnemius posteriorly 

 extending from the femur to the calcaneum, and the tendi- 

 nous portion of the flexor matatarsi anteriorly extending 

 from the femur to the metatarsus, complete a mechanism op- 

 erating these great articulations with the aid of two groups of 

 muscles, one group anteriorly and one posteriorly. Normal 

 action of these two articulations depends upon an equili- 

 brium between these two groups. If this equilibrium is dis- 

 turbed by a decreased activity in the posterior group exces- 

 sive flexion of the hock and stifle results. This theory places 

 the lesion in the region of the gastrocnemius, and it is forti- 

 fied by the fact that exaggerated st.ringhalt always follows 

 either accidental or experimental division of this muscle. It 

 also explains much about the effect of peroneal tenotomy. By 

 dividing the peroneus (one of the anterior group) the dis- 

 turbed equilibrium is again balanced. The loss of this mus- 

 cle by surgical division of its tendon, equals the loss of mys- 

 terious origin posteriorly, and thus re-establishes the lost 

 equilibrium. Sometimes the defect posteriorly is too great 

 to be corrected by the division of so trivial a muscle as the 

 peroneus, hence the frequent failures. The cures effected by 

 partial or complete division of the flexor metatarsi still fur- 

 ther fortifies the hypothesis. 



That stringhalt is due to a definite lesion as uniform as 

 the symptom itself is the only reasonable hypothesis upon 

 which to base future investigation. 



EQUIPMENT. — The small curved bistoury recom- 

 mended for tenotomy of the metacarpal flexors is the only 

 special instrument required, and it may be supplanted^ with 

 any ordinary curved bistoury, either probe or sharp pointed. 

 A scalpel, local anaesthetic outfit, and antiseptics, complete 

 the equipment. If it is desired to resect a portion of the 

 tendon, as is often the case with some practitioners, a dis- 

 secting forcep and an elevator are added. 



RESTRAINT.— The operation can be performed in the 

 standing position with the aid of twitch, single side line to 

 lift the opposite leg and local anaesthesia. Recumbent re- 

 straint becomes necessary only in restive horses whose na- 



