Avulsion fracture of the origin of the extensor digitorum longus muscle in a foal.

This study examined a case of a young horse which was treated for lameness in its right hind limb due to an unusual type of fracture – an avulsion fracture in a muscle connected to the knees. The fracture was treated surgically and the horse made a successful recovery.

About the Case

• The research focuses on a particular veterinary case, where a 9-week-old Thoroughbred x Holsteiner colt, or young male horse, was referred for evaluation and treatment due to lameness, or inability to normally move or flex its right hind limb.
• Radiography, or the use of X-rays to view the affected part, revealed some unusual findings. There were multiple bone fragments in the lateral part of the femorotibial joint, a significant joint of the horse’s leg where the major bones of the thigh and the calf meet.

Diagnosis and Findings

• Among the radiography findings was also a radiolucency, or area of increased radiability that appears darker on the images, on the distolateral (situated away and to the side from the center) part of the femur in the area known as the extensor fossa.
• These findings were consistent with an avulsion of the origin of the extensor digitorum longus muscle. Avulsion means that the muscle has been torn off from the point where it was attached to the bone. The extensor digitorum longus is a muscle that runs along the back of the leg and helps in extending or raising the digits, or digits-like part.

Treatment and Outcome

• An arthroscopy, or an invasive examination technique that uses an arthroscope to view inside a joint, was performed on the lateral part of the horse’s femorotibial joint. It confirmed that the bone underneath the cartilage layer in the area of the extensor fossa was exposed and the origin of the extensor digitorum longus muscle was found to have been torn off.
• The joint was cleaned out, known as lavage, and fibrin (a clotting protein in the blood) and fragments of cartilage and bone were removed.
• Following the surgical intervention, the horse was monitored and after six months, the horse appeared to be physically normal while it was trotting and cantering, thus indicating a successful treatment and recovery process.