[Illustration: $1] =Diagnosis.= The condition can only be confused with luxation of the patella; but manual examination of the affected parts revealing the presence of a rigid cord below the trochanter at once removes any doubt. =Prognosis.= The prognosis is only grave in working animals. Moreover, the accident is now much rarer than formerly, if only because animals are better looked after and better fed. =Treatment.= If the accident results simply from the formation of a depression in the musculo-aponeurotic layer which replaces the muscle at the point where it passes over the trochanter, there is nothing to be done. Reduction will occur spontaneously, and entire liberty of action will be regained. Cruzel states that it is sometimes sufficient to force the animal to move down a slope, in order to withdraw the trochanter from the depression in which it has been lodged, and to restore its normal mobility. Rest and good feeding favour the deposition of fat, and soon alter the conditions responsible for the accident; the muscles of the quarter become surrounded with fat, the external ischio-tibial muscle (biceps femoris) is thrust outwards on account of its superficial position, and then cannot be ruptured by the summit of the trochanter. If, on the other hand, the musculo-aponeurotic layer is fissured and the summit of the trochanter firmly fixed in the opening, operation becomes necessary. This consists in incising the anterior margin of the muscle over the afore-mentioned rigid cord. The margins of the wound retract, the tension of the cord is diminished, the trochanter released, and the normal play of the limb restored. Numerous methods of operation have been described and a number of special instruments invented. The earlier methods consisted in simple subcutaneous section of the rigid cord formed by the musculo-aponeurotic layer and the muscle. Subcutaneous section is carried out exactly like tenotomy, using straight and curved tenotomes. The seat of operation is about three inches below the summit of the trochanter. In the absence of tenotomes, section may be performed with a bistoury introduced from below the muscle by means of a grooved director, which has been inserted through a cutaneous puncture made at the point indicated over the anterior margin of the prominent cord. In better nourished subjects, in which this cord is less prominent, the operator may, to ensure greater accuracy, make a vertical incision an inch or two in length at the point selected over the anterior margin of the muscle, isolate this muscle by means of the director, and afterwards perform the section. Considerable hæmorrhage occasionally follows division of some small muscular vessel, but is of no consequence unless the wound has been infected. RUPTURE OF THE FLEXOR METATARSI.