Ultrasonographic diagnosis of coxofemoral subluxation in horses.

The study investigates the use of ultrasonography to detect coxofemoral subluxation, a condition involving displacement of the hip joint, in horses, with the results indicating its effectiveness in diagnosis and establishing prognosis based on related complications such as acetabular rim fractures.

Study Overview

• The research examined seven horses found to have coxofemoral subluxation, a condition where the femoral head (the ball part of the hip’s ball-and-socket joint) is displaced from its usual spot within the acetabulum (the socket).
• The affected horses varied in age and gender, and all showed signs of lameness, with the severity ranging from mild to acute. Some horses showed improvement initially, but their condition worsened over time.

Ultrasonographic Diagnosis

• The diagnosis of subluxation was confirmed via the use of ultrasonography, an imaging technique that uses sound waves to produce images of the interior of the body.
• The ultrasonographic examination involved observing the displacement of the femoral head from the acetabulum when the horse was bearing weight on the affected limb. The femoral head was then seen to return to the acetabulum when the horse’s limb was at rest.

Additional Findings

• Other notable findings included visible acetabular rim fractures and joint effusion, or buildup of excess fluid around the joint, observed in six of the horses, regardless of weight bearing status.
• The only horse not exhibiting these complications was the one that eventually showed a good outcome.

Outcome and Prognosis

• The outcome for most of the horses was poor, with six suffering from severe chronic lameness. This led to euthanasia for four of the horses.
• Postmortem examinations revealed subluxation and acetabular rim fractures in the horses. Subluxation was found to be the result of an elongated but intact femur head ligament.
• Signs of osteoarthrosis, a type of arthritis caused by inflammation, breakdown, and eventual loss of cartilage in the joints, were also found upon ultrasonographic, radiographic analyses, and necropsy.

Implications

• The investigation confirmed the effectiveness of dynamic ultrasonography performed on standing horses for producing diagnostic images and identifying coxofemoral subluxation.
• The study affirms the critical role of this imaging technique in helping to identify affected horses and determine prognosis, given the typically poor outcome for those with subluxation and associated complications like acetabular fracture.