Treatment options for hip laxity (Proceedings)

It is important to understand that when a dog presents with a dog with hip laxity (hip dysplasia) with or without secondary degenerative changes, that there is not one single way to manage every patient. Initially, one must decide if a particular patient is better suited for medical or surgical options. Medical management is identical to management of any other joint OA. If it is determined that surgery is a potential option, then many other factors about the case must be included in the decision of which surgical procedure is best for that particular animal. The goal of this lecture is to give you guidelines which will help you determine which surgical procedure may best suit a given dog in your practice. For ease of description and clarity, I will divide the discussion into immature and mature patients, with subdivisions depending on the degree of secondary degenerative joint disease. It must be stressed that concurrent orthopedic or neurologic disorders usually will preclude them from any of these procedures. Once those concurrent problems have been addressed, then possibly the dog may be considered for further coxofemoral joint surgery.

Patients

Immature Dogs

Dogs presented to your practice with pain and dysfunction caused by hip laxity can initially be divided into two groups: those which radiographically have degenerative joint disease(DJD)/Osteoarthritis(OA) present and those who don't. This differentiation is important as most surgeons feel that the presence of DJD/OA severely diminishes the positive long term effects of the pelvic or femoral osteotomy procedures.

Dogs without secondary DJD/OA:

In this group of animals, the possible surgical procedures include a pelvic osteotomy (most common is the triple pelvic osteotomy), the intertrochanteric osteotomy, femoral head and neck excision (FHO), and for the temporary relief of pain, the pectineus tendon/muscle transection.

Dogs with secondary DJD/OA:

In this group of animals, the possible surgical procedures include the FHO, and the pectineus transection for the relief of pain. Another approach is to manage these dogs with medical management until they are skeletally mature (10-12 months) and perform a total hip replacement.

Mature Dogs

This group of animals usually already has DJD/OA, and thus the potential use of the pelvic or femoral osteotomies is limited. However, there is the occasional 1 to 1.5 yr old dog that will fit the criterium for one of these procedures. In this group, the most common procedures recommended are the total hip replacement, and the FHO.

Procedures

Pelvic Osteotomies

The procedures in which osteotomies of the pelvis are performed are designed to improve the congruity of the coxofemoral joint. The most common of these procedures is the triple pelvic osteotomy (TPO) and more recently the juvenile pubic symphysiodesis (JPS). As previously stated, the TPO is best suited for treating the young, growing dog with clinical and radiographic signs of hip dysplasia and no radiographic evidence of DJD/OA. Thus candidates are usually under 10 months of age, medium to large size dogs with coxofemoral joint laxity. Once a patient has been identified as a potential candidate, surgery should be done as soon as possible to prevent further deterioration of the hip and appearance of radiographic evidence of DJD. Whether staged unilateral procedures (2 to 4 weeks apart) or bilateral procedures should be done is currently an area of debate with some surgeons on each side of the issue. The goal of these procedures is to improve clinical function (reduce pain, and stabilize the joint) and to slow the progression of DJD over the life of the patient.

Although published data is limited on the results of this procedure, that data is available is very positive with improvements in subjective and objective measurements of gait function. Also there is some evidence that there is a slowing of progression of DJD in dogs which have had the procedure. However, more data needs to be collected prior to the wholesale use or recommendation of any of these procedures.

Femoral head and neck excision

This procedure, also know as an excision arthroplasty is a salvage procedure that relies on the formation of a scar tissue (or false) joint. The main goals of this procedure are to relieve pain and improve limb function. It is commonly used by many practitioners as their "surgical" management of hip dysplasia, however many people do not always consider which dogs are the best candidates for this procedure. The following is a list of criteria that most surgeons consider when selecting potential candidates. Body size is the most consistent determinant, with dogs and cats under 40 to 50 pounds having the best potential for an excellent result. It is not that an FHO will not work on large dogs, it is simply that it is not as predictable in the large animal. Active, younger animals are more likely to rehabilitate from this surgery than an obese more sedentary animal. Also, in cases of chronic disease and severe disuse atrophy, rehabilitation and extensive physical therapy may be far more difficult, resulting in a less than favorable outcome. Finally, the owner must understand and be willing to actively participate in the rehabilitation of their pet.

Technical precision and attention to detail in the complete removal of the head and neck, and active aggressive physical therapy are the most important points that can be stressed in the success or failure of this procedure.

Total hip replacement

This procedure is continuing to grow in acceptance and use in veterinary orthopedics. With over 20 years of experience in clinical use, there are many surgeons who are trained and currently doing this procedure. The procedure is most appropriate for dogs who have severe hip joint dysfunction without evidence of infection or neoplasia. The dog must be skeletally mature and most candidates are over 15 kgs. There is no upper age or weight limit if the dog is in good overall health. However, do not wait until there is severe disuse atrophy in the limb as this may substantially affect the long term outcome of the case. Bilateral hip replacement is not required if both hips are diseased. Most surgeons will replace the most clinically affected hip and then wait for clinical signs to appear in the opposite hip. There are currently a couple of different hip systems currently being used in the field. However the pros and cons of these different component systems will not be extensively discussed here.

Other procedures

Currently, there are a few other procedures which are performed on the diseased hip. The previously mentioned pectineus tendon/muscle transection is currently not in favor by most surgeons. It will relieve pain in the short term, but it does not alter the progression of the degenerative changes in the hip. More recently, procedures such as femoral neck lengthening have been proposed. At the present time, however none of these procedures is currently widely accepted.

Conservative "Medical Management" Treatment Plan

Management of Hip Laxity and subsequent OA should be thought of as a multi-step approach with four to five important components. While some clinicians tend to reach for pharmacologic management alone, this is usually unsuccessful without concurrent management of exercise and weight reduction. Thus, starting to treat a patient with OA requires a lengthy discussion of all aspects of management with the client. Our discussion will follow the typical pattern we use in our practice. Remember, one must examine each case differently, assessing the age, normal activity levels, and, most importantly, the owner's expectant activity levels of the animal. Success largely depends on the accurate assessment of the client's expectations for the pet.

Management Components

     1. Weight Reduction

          • -Weight control is a must when dealing with OA. The vast majority of our patients seen with clinical manifestations of OA are obese. Owner education and proper dietary management must be considered in every case. In many cases, the implementation of weight reduction with rest and exercise modification diminishes or completely alleviates the clinical signs of OA.

     2. Nutritional Support

          • -The recent influx of diets on the market with a high N3:N6 fatty acid ratio is adding a whole new area of intervention. It is important to understand that there is an increase in N3 fatty acids in the diet and that specific N3 fatty acids are elevated (EPA and DHA).

     3. Exercise modification/Physical Therapy

          • -Protecting the osteoarthritic joint from excessive mechanical stress may limit clinical signs. Most patients with OA are comfortable with light to moderate exercise regimens that do not vary significantly. Enforced rest and exercise modification is different for each animal, but exercise extremes tend to exacerbate clinical signs. Swimming is a wonderful minimal load exercise, and in many parts of the country is available nearly year round to our patients.

     4. Pharmacologic Management

          • -Analgesic and antiinflammatory agents are the most common final component in the management of OA.

     5. Other modalities

          • -Included here are stem cell therapy, lasers, and acupuncture to name a few. However there is limited clinical data to support their use.