Diseases of the Hip Joint

Background
The most common conditions affecting the hip joint of dogs and cats are hip dysplasia, hip dislocation and hip fractures. In general, hip disease results in hindlimb weakness or lameness. Surgical and non-surgical treatments exist for each of these conditions. Hip problems must be distinguished from disorders of the spine and knees which can cause similar symptoms.
 

Anatomy The hip (coxofemoral joint) is basically composed of the pelvis, the pelvic socket (acetabulum) and the ball (head) and neck of the femur (thigh bone). The fibrous joint capsule, groups of muscles, tendons and ligaments keep the femoral head in the acetabulum.

Hip Disease
Hip Dysplasia is a congenital condition of dogs and cats which results in laxity (looseness) of the hip joint. This condition typically occurs in both hips and leads to deformation of the pelvic socket and femoral head (osteoarthritis). In certain instances, osteoarthritis leads to hip pain and hindlimb lameness. Hip Dysplasia can be diagnosed by X-rays as early as four months of age with a PennHip® evaluation and at 2 years of age with an OFA evaluation. Fortunately, 85% of dogs with symptoms of hip dysplasia can be treated medically. However, 15% require surgical treatment to alleviate the pain and lameness. Some surgeons advocate procedures which are performed during puppyhood - prior to the onset of symptoms (such as lameness) – in an effort to avoid symptoms which may or may not develop later in life. Many surgeons only recommend surgery when symptomatic pets fail to respond to medical treatment.

Hip Luxation (Dislocation) is usually the result of trauma, such as a high fall or being struck by an automobile. Occasionally, it results from severe hip dysplasia. In many instances, the hip can be returned to the socket under anesthesia and a sling utilized to keep it in place while healing occurs. If the hip cannot be returned to the socket, or if it dislocates again when the sling is removed, surgery is indicated.

Hip Fractures are also the result of trauma. They can involve the pelvis, acetabulum, femoral head, femoral neck, or a combination of these structures. Many fractures of the pelvis can heal with strict cage rest. However, some fractures of the pelvis, most fractures of the acetabulum, and almost all fractures of the femoral head and neck require surgery for appropriate healing.

Legg-Calvé-Perthes Disease is a poorly understood congenital disease of small breed dogs which results in breakdown of the femoral neck. Fracture of the neck typically follows, resulting in severe hip pain and lameness. Many dogs require surgery for this condition.

Hip Dysplasia
Surgery for hip dysplasia can either be preventative or therapeutic:
Preventative procedures are performed early in a pets’ life, prior to the onset of symptoms of osteoarthritis. Examples include Triple Pelvic Osteotomy (TPO) and Juvenile Pubic Symphysiodesis (JPS). I do not advocate or perform these procedures.
Therapeutic procedures are performed when symptoms of osteoarthritis no longer respond to medical treatment. Total Hip Replacement (THR) and Femoral Head Ostectomy (FHO) are performed in this instance. A comparison of the therapeutic procedures follows:
 
 

Hip Luxation
When manual replacement and slinging fail, hip luxation is treated with Femoral Head Ostectomy (FHO), Total Hip Replacement (THR) and several methods of joint reconstruction. I recommend and perform FHO and refer pets to appropriate facilities for THR and joint reconstruction when indicated.

Hip Fractures can be surgically treated with pins, wire, screws and plates. The method of repair chosen depends on the location and severity of the fracture, the size of the pet and the presence of other orthopedic injuries.

Legg-Calvé-Perthes Disease is usually treated with Femoral Head Ostectomy because the pets affected are typically too small for Total Hip Replacement.