Downeast Dog News
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“It’s Cool to be Hip”

TOTAL HIP REPLACEMENT
By Meghan Sullivan, DVM, DACVS | Feb 01, 2020

Hip dysplasia is the most common canine orthopedic condition. Despite the fact that is used as a “catchall” lameness phrase, it is a specific condition. It results in laxity (looseness) of the hip joint which consists of a ball (femoral head) and socket (acetabulum) joint. The femoral head can rub on the acetabulum which results in a shallow acetabulum and flattening of the femoral head. The sequela is pain, erosion of bone, loss of cartilage, swelling, and arthritis. It is most commonly found in large and giant breed dogs, though it can be seen in any breed. Just imagine the discomfort of “bone on bone” pain!

Symptoms of hip dysplasia usually present in two groups. Young dogs may have significant hip laxity but not yet have arthritis. They present with lameness in the hind end, bunny hopping, reluctance to exercise or jump, and pain on palpation of the hips. Older dogs have developed secondary hip arthritis due to the hip dysplasia. They usually show pain secondary to joint remodeling, loss of range of motion and the pain of arthritis. They can have chronic lameness, stiffened hind end, trouble walking or jumping, muscle atrophy and do not resolve despite medications. Symptoms can be intermittent at first, and typically worsen after “weekend warrior” activities. Remember that our “best friends” hide pain very well, so be vigilant for even subtle symptoms.

Hip dysplasia is diagnosed on physical exam and with radiographs. Commonly, affected dogs have a wide or narrow-based stance, “bunny hopping gait” and decreased muscle mass in the hind legs. They are painful manipulation of the hip joints and have decreased extension. An Ortolani is a physical test performed to examine for laxity of the joint. Radiographs (xrays) can confirm laxity, subluxation or luxation, arthritis, and muscle atrophy. Sedation is typically utilized to relax the patient and reduce pain so that the proper xray views can be evaluated. In breeds considered high risk, you may consider obtaining a survey xray hip when your dog is anesthetized for spay or neuter surgery.

In a previous article, we have described medical management of hip dysplasia and arthritis. But did you know that total hip replacement (THR) is a surgical option for dogs? It involves the replacement of the diseased acetabulum and femoral head with implants just as is performed in humans. This eliminates the pain by making a normal functional hip joint with no “bone on bone” pain and improved motion. The implants are titanium and polyethylene and fixed in place with cement, metal bolts, or “press-fit” (bone ingrowth) methods. There are several types of total hip replacements performed in dogs but Biomedtrix with either cemented (CFX) press bit biologic (BFX) or hybrid (combination of the two) are the most commonly performed.

The most common indication for a total hip replacement is osteoarthritis secondary to hip dysplasia in a mature dog, or laxity/pain and lameness from hip dysplasia in a young dog. Other reasons for performing a total hip replacement include a hip luxation which could be traumatic or chronic, and certain femoral head fractures which may not be fixable. Total hip replacements are most often performed in medium, large, and giant breed dogs older than 9 months. However, they can be performed in all sizes of dogs and even cats.

The outcome of a THR is excellent and restores dogs who have chronic lameness and pain to near-normal or normal function. THR dogs immediately bear weight postop on the surgical leg because they are in less pain. By two weeks postop, most dogs are to 90% of their normal function and studies have shown that dogs can return to improved activity as soon as 3 months postop. Radiographs to recheck healing are performed 6-12 weeks postoperatively. They are on leash only during that time and owners use a sling or harness when walking their pet to help prevent slipping/falling. If a pet needs both hips performed, the second side can be performed as soon as 6 weeks after the first. Clients are generally extremely pleased with their dog’s return to full life activities!

All dogs with hip dysplasia should be kept at very lean bodyweight for life. This alone, greatly enhances their movement, function, and activity. A severely overweight patient may not be accepted for a THR surgery due to a potential increased complication rate or make for a more challenging recovery.

It is preferable to have dogs (especially young ones) that are symptomatic from hip dysplasia evaluated in a timely manner if medical management has not been successful. A consultation with a surgical specialist can provide further information and options for long term treatment or THR surgery. Our goal with THR is to have our patients back to running, jumping, playing, and doing any physical exercise that they would like to do. Total hip replacement provides the most normal, pain free quality of life and best joint functionality of any of the treatments for hip dysplasia.

 

Meghan Sullivan, DVM, DACVS

Portland Veterinary Emergency and Specialty Care