Os femoris
The femur is the longest and heaviest bone in the horse. It extends from the hip joint to the stifle. The rounded femoral head articulates with the acetabulum of the pelvis to form the hip joint. The distal end has prominent trochlear ridges over which the patella glides, and the medial and lateral condyles form the femorotibial joints of the stifle. The entire bone is surrounded by the massive muscles of the thigh (quadriceps, biceps femoris, semitendinosus, etc.), which makes fractures difficult to image and stabilize. Its primary role is to transmit propulsive force from the hip to the stifle and lower limb while providing attachment for the largest muscles in the body. Because of its size and the surrounding musculature, adult femoral fractures generally carry a poor prognosis for return to athletic use.
Origin: N/A (bone)
Insertion: N/A (bone)
Action: Transmits propulsive force between hip and stifle; provides attachment for the largest muscles in the body
Fractures in adult horses are difficult to repair and often have a guarded to poor prognosis due to the bone’s size, the forces involved, and the difficulty of external coaptation. Foals have a better outlook with internal fixation. Imaging usually requires radiography or advanced modalities; the heavy muscle cover limits ultrasound utility.
## Overview Femoral fracture is a break of the thigh bone. In adult horses it usually results from severe trauma and carries a very poor prognosis. Most adult horses are euthanized. Foals have a some
## Overview Coxofemoral luxation is dislocation of the femoral head from the acetabulum. It is uncommon in horses because of strong ligamentous support, but occurs more often in ponies and miniature
Damage to the femoral nerve (for example after general anesthesia or from iliopsoas muscle injury) paralyzes the quadriceps, so the horse cannot lock the stifle.
Sudden non-weight-bearing lameness in the hind limb after a fall, kick, or traumatic event should be evaluated immediately. Do not force the horse to move. Femoral fractures are surgical emergencies when repair is attempted.
## Overview Femoral fracture is a break of the thigh bone. In adult horses it usually results from severe trauma and carries a very poor prognosis. Most adult horses are euthanized. Foals have a somewhat better chance with internal fixation in selected cases. ## Causes High-energy trauma (falls, kicks, collisions). ## Diagnosis Acute non-weight-bearing lameness, swelling, crepitus, and radiographic confirmation. The limb may appear shortened or rotated. ## Treatment Surgical repair is rarely successful in adults due to implant and opposite-limb limitations. Foals may be candidates for internal fixation. Most adults are euthanized. ## Recovery and Prognosis Poor in adults. Guarded in foals even with surgery. ## Prevention Trauma avoidance. Signs include: acute non-weight-bearing lameness; severe swelling; crepitus; limb shortening or rotation; recumbency
## Overview Coxofemoral luxation is dislocation of the femoral head from the acetabulum. It is uncommon in horses because of strong ligamentous support, but occurs more often in ponies and miniature horses, sometimes secondary to upward fixation of the patella. Trauma is the usual cause. The limb is typically non-weight-bearing with external rotation. ## Causes Severe trauma or, in small equids, violent contraction associated with locked patella. ## Diagnosis Characteristic stance (shortened limb, externally rotated, higher hock) plus radiographic confirmation. ## Treatment Closed reduction under general anesthesia is attempted early. Maintenance of reduction is difficult. Femoral head ostectomy is an option in small horses and ponies for chronic cases. Prognosis for athletic function is very guarded. ## Recovery and Prognosis Poor for return to work in large horses. Some ponies become pasture sound after reduction or ostectomy. ## Prevention Trauma avoidance; prompt treatment of upward patellar fixation in ponies. Signs include: non-weight-bearing hindlimb lameness; external rotation of the limb; asymmetrical pelvis; higher point of the hock
Damage to the femoral nerve (for example after general anesthesia or from iliopsoas muscle injury) paralyzes the quadriceps, so the horse cannot lock the stifle. Signs include: Inability to fix the stifle in extension; the stifle and hock collapse when weight is placed on the limb; the horse cannot support weight on the affected hindlimb.
Fractures in adult horses are difficult to repair and often have a guarded to poor prognosis due to the bone’s size, the forces involved, and the difficulty of external coaptation. Foals have a better outlook with internal fixation. Imaging usually requires radiography or advanced modalities; the heavy muscle cover limits ultrasound utility.
Sudden non-weight-bearing lameness in the hind limb after a fall, kick, or traumatic event should be evaluated immediately. Do not force the horse to move. Femoral fractures are surgical emergencies when repair is attempted.
See the Femur on our interactive 3D horse model. Open 3D Model