Legg-Perthes disease

Key Points A disease of the hip joint that results in abnormal deformity of the ball of the hip joint This is a disease primarily seen in small breed dogs Treatment is femoral head and neck excision Prognosis is very good, providing that rehabilitation therapy is done after surgery

Same disease but different names (synonyms) Calve-Perthes disease Legg-Perthes disease Avascular necrosis of the femoral head Coxa plana Osteochondritis juvenilis What is it? A disease of the hip joint that results in abnormal deformity of the ball of the hip joint The disease starts with an insult to the blood supply to the head of the femur bone As the blood supply is damaged, the bone dies off The bone in the femoral head collapses and the cartilage coating of the femoral head becomes cracked and deformed Arthritis or inflammation of the hip joint results, which causes pain and lameness Cause Not completely understood Genetics - can be autosomal recessive gene in some dogs Injury - compression of the vessels of in the femoral head Abnormal sex hormone activity - preconcious Because of the potential heritability of this disease, affected dogs should not be bred Signalment Typically dogs that are less than 1 year of age (5 to 8 months of age is most common with peak incidence around 7 months of age) Breeds commonly affected Yorkshire Terriers - most common breed Westies Many other small breed dogs Equal risk for males versus females Clinical signs Irritability Chewing at hip of flank region Progressive lameness (may take about 2 months until dog is not bearing any weight on limb) Stiffness of affected limb (85 to 90% of dogs have only one hip affected) Atrophy of muscles of affected limb Pain when moving the hip - especially when extending the limb backward and also to the side Crepitus or crunchy feel of the hip joint on range of motion Diagnosis Physical examination - hip pain Radiographs flattening of femoral head lucencies of femoral head bone spurs - arthritic degeneration increased joint space Below is a radiograph of the hips of a Yorkie that has the disease; take note of the moth-eaten appearance of the femoral head (below left and right) Treatment Conservative treatment with strict cage rest and physical therapy could be successful only if the femoral head is still has its normal shape and is is tightly seated in the socket; monthly radiographs should be made until the pet is 1 year of age Surgery - femoral head and neck excision is the treatment of choice if the radiographs show deformity of the femoral head or looseness of the hip joint; this surgery involves removing the femoral head and neck Below is a photo as the femoral head is being removed from the hip joint shown above; take note of the deformed head of the femur and the cracks in the cartilage. The radiograph below demonstrates a femoral head and neck excision (arrow) Prognosis Femoral head and neck excision usually gives a satisfactory result - the pet is greatly improved; some dogs may have residual lameness, especially with heavy exercise or weather changes Postop care After Care and Convalescence A prescribed analgesic medication should be administered in the postop period at home. Nonsteroidal anti-inflammatory medications are very beneficial to reduce pain at the surgical site and encourage weight bearing. In some cases, antibiotics may be prescribed. Activity is not limited after surgery. In fact, exercise will help to maintain a good range of motion of the hip joint. The owner should do rehabilitation therapy using the TopDog Home Rehabilitation guide for FHO Surgery found at www.fhoguide.com until the pet is using the limb normally. Flexion and extension of the hip joint is essential in the recovery period. Rehabilitation therapy will help prevent adhesions from forming, thus maintaining a good range of motion of the hip region. If possible, swimming should be started after the incision has healed. It is also highly recommended that rehabilitation therapy sessions be scheduled with a professionally trained therapist. Most dogs will start to bear a small amount of weight on the limb within 2 weeks after surgery. Within 4 to 6 weeks the pet should bear a moderate amount of weight on the limb. By 2 to 3 months after surgery, recovery is complete. The pet should be examined 2 weeks and 2 months after surgery to ensure that the hip region is healing well. Most small pets do well following femoral head and neck excision surgery. Larger dogs can also do well, but some weakness on that limb frequently can be seen. This is due to the muscles supporting the region of the hip instead of the actual joint. As a result, heavy exercise can cause the pet to become stiff or lame. Anti-inflammatory medication can be given to give your pet relief if needed. If your pet is a medium to large breed dog, total hip replacement is the preferred technique over the femoral head and neck excision surgery. Complications As with any surgery, complications may arise. Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oximetry, inspiratory and expiratory carbon dioxide levels, and respiration rate), the risk of problems with anesthesia is minimal. Infection is also an unusual complication, as strict sterile technique is used during the surgery. Poor range of motion of the hip joint can occur and is usually due to a lack of rehabilitation therapy. If your pet is not using the limb very well after 2 to 3 weeks, anti-inflammatory therapy should be continued for another 2 to 4 weeks. Sciatic nerve damage is a rare complication of FHO surgery, but frequently is a transient problem.