Treatment of a coxofemoral luxation secondary to upward fixation of the patella in a Shetland pony

Abstract

A nine-year-old Shetland pony gelding, with a history of recurrent upward fixation of the patella, suddenly developed severe lameness in its right hindlimb. A luxation of the coxofemoral joint was diagnosed by a clinical and radiographic examination. The initial treatment of the luxation by closed reduction was not maintained, and the limb was placed in an Ehmer sling for four days after a second closed reduction. This allowed the femoral head to remain in the acetabulum, although a persistent subluxation remained, presumably owing to a rupture of the round ligament. The pony remained comfortable at pasture for over two years after the reduction, until osteoarthritis of the coxofemoral joint caused it to become severely lame and it had to be euthanased.

Aspects of coxofemoral luxations in the horse

“…). Nonetheless the projection has been successfully deployed, even in small ponies, to demonstrate coxofemoral luxations (Clegg and Butson ).…”

Medial Patellar Desmotomy

“…2,4,6,14 Although most cases of upward patellar fixation are primary, upward patellar fixation can occur secondary to neurologic disease and to stifle pathology and in horses with coxofemoral joint luxation. 4,[14][15][16][17] If necessary, these conditions should be ruled out before performing surgery.…”

Femoral head ostectomy following osteotomy of the greater trochanter in a pony with chronic coxofermoral luxation

“…Coxofemoral luxation is frequently seen in combination with upward fixation of the patella (Nyack et al 1982, Foerner 1992, Malark et al 1992, Clegg and Butson 1996. Platt et al (1990) describe a case of upward fixation of the patella secondary to coxofemoral luxation, presumably as a result of the altered position of the limb following luxation (exorotation of stifle and toe and endorotation of the hock) and atrophy of the quadriceps muscle.…”

“…Successful closed reduction resulted in persistent lameness in one case (Malark et al 1992) and osteoarthritis in another case (Clegg and Butson 1996) in which reduction was maintained using an Ehmer sling. Reluxation occurs because the round and accessory ligaments rupture at the time of luxation and subsequent filling of the acetabulum with blood clots or granulation tissue.…”