Calve Legg-Perthe's Disease

Also known as: Avascular Necrosis of the Femoral Head — Femoral Head Necrosis — Legg Perthes disease — Osteochondritis juvenilis — Coxa plana

Introduction

This condition describes the avascular aseptic necrosis of the femoral head and neck in dogs, which leads to collapse of the coxofemoral joint and osteoarthritis.

The precise cause is unknown and a specific vascular lesion has not been identified.

Pathophysiology of the disease, is that interruption of the blood to the femoral head leads to death of osteocytes and collapse and deformation of the femoral head during normal loading. The articular cartilage becomes thickened, clefts develop and there is fraying of the superficial layers.

It occurs most commonly in small and miniature breeds of dogs such as the Yorkshire Terrier, Chihuahua and miniature Poodle, between 4 and 11 months of age.

The condition is usually unilateral but can be bilateral.

Clinical Signs

There is usually a gradual-onset pelvic limb lameness which is usually weight-bearing.

There may be muscle atrophy in the affected limb.

Pain on palpation and manipulation of the hip joint is severe and crepitation may be noted.

The animal is usually otherwise normal.

Diagnosis

History and clinical signs are suggestive.

Radiography allows a definitive diagnosis to be made, and findings include:

Irregular areas of lysis at the femoral head and neck

Irregular density of the head and neck

Widening of the articular space

Flattening and collapse of the subchondral bone of the head

Evidence of degenerative joint disease around the femoral head and acetabular rim such as osteophytes

Histological findings include: Aseptic ischaemic necrosis in central parts of femoral head, fragmentation of trabecular bone.

Treatment

Conservative treatment involving cage confinement and analgesia may be successful in a minority of patients.

Femoral head and neck excision is the treatment of choice and is tolerated very well by small dogs. Passive physiotherapy should be started 3 days after surgery, and swimming can be helpful once the sutures have been removed. Analgesic and anti-inflammatories can help in the post-operative period.

If the disease occurs in a large dog, total hip replacement can be considered.

Prognosis

Prognosis is good to excellent for full recovery in small dog breeds as they respond well to surgery.

Affected animals should not be used for breeding as a heritable component is suspected.

Calve Legg-Perthe's Disease Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Orthopaedics Q&A 13

References

Pasquini, C. (1999) Tschauner's Guide to Small Animal Clinics Sudz Publishing

Shires, P. (2005) The 5-minute veterinary consult: muscoloskeletal disorders Wiley-Blackwell