Rupture of the Ligament of Head of Femur
A partial tear or rupture of the ligament of the head of the Femur bone (round ligament) of the coxofemoral joint is a relatively rare condition that can affect any age or breed of horse. Nevertheless, it appears to be more common in small breed horses (miniatures and ponies) and young horses. The hip joint is usually very stable but occasionally a partial tear or complete rupture of ligament of the head of the femur can occur without a complete joint luxation. In these cases, the head of the femur may have greater range of motion within the joint, contributing to synovitis, joint effusion, and lameness.
Subsequent degenerative changes within the joint often lead to Osteoarthritis. Definitive diagnosis of a ruptured ligament of the head of the femur can be difficult.
Etiology
Trauma is the cause of the Rupture of the Ligament of Head of Femur in horses.
Clinical sign
- Acute onset of lameness
- Swelling over the hip difficult to observe
- Gluteal atrophy, if condition is chronic
- Horses often stand with a toe-out, stifle-out, and hock-in appearance of the affected hindlimb that is typical of problems in the coxofemoral region
- Firm intermittent pressure applied over the greater trochanter usually elicits a painful response.
- Limb manipulation, flexion of the hip joint, and upper limb flexion tests may also be painful.
- Crepitation over the joint may be present because of the excessive motion of the femur, but can be difficult to document
- Although the clinical signs often localize the problem to the hip region, intrasynovial anesthesia may be required to prove that the joint is affected.
- The clinical signs associated with partial tearing of the ligament of the head of the femur are not as clear as those seen with complete rupture of the ligament
Diagnosis
- History and clinical signs indicative of hip related condition
- Radiography – ventro-dorsal or oblique radiography under general anaesthesia
- Ultrasonography
- Osteoarthritis changes noticed in the case chronic luxation. These include osteophytes on the cranial and caudal rim of the acetabulum and at the capsular attachment on the femoral neck.
- Arthroscopy
- Scintigraphy
Treatment
There is no effective treatment for complete rupture of the ligament of the head of the femur of the hip joint. Affected horses often develop osteoarthritis and remain lame.
However, arthroscopy of the hip joint has been used successfully to debride partial tears of the round ligament and to perform a synovectomy.
Ligament tearing in small breeds of horses, particularly miniature horses, can be adequately debrided and a return to soundness is possible.
Prognosis
The prognosis is poor for horses with complete rupture of round ligament, regardless of treatment. Secondary osteoarthritis of the hip joint appears to be a likely sequela. However, the response to debridement of partial tears in small-breed horses has been favorable in a limited number of cases.