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TOTAL HIP REPLACEMENT IN DOGS
Overview
Total hip replacement is a surgery to replace a painful and dysfunctional hip joint with artificial (metal and plastic) prostheses, in order to provide a pain-free, fully functional joint for an active lifestyle. This surgery is typically performed on a dog with severe hip pain due to conditions called “hip dysplasia” and osteoarthritis. Total hip replacement can also be considered for a dog with painful and abnormal hip due to fracture, luxation (dislocation), and necrosis (severe degeneration).
Treatment Options for Hip Dysplasia
“Hip dysplasia”, meaning abnormal growth of the hip, is a common problem in dogs. Dysplastic hips are painful and lack smooth movements; therefore quality of life of the dog can be severely affected. Selection of the appropriate treatment option for this condition is dependent on many factors such as: age, severity of hip dysplasia, development of osteoarthritis, degree of pain/discomfort, and owner’s expectation and financial constraint.
Many dogs with pain and lameness associated with hip dysplasia can be effectively managed with conservative methods (i.e., without surgical intervention). Conservative methods include weight management (extremely important), moderation of excessive exercise/activity, providing warm comfortable bedding, and the use of non-steroidal anti-inflammatory drugs, physical rehabilitation, and oral supplement/agent as needed.
Total Hip Replacement or Other Options?
Several preventive surgical options can be considered for young growing puppies with hip dysplasia; however clinical efficacy of these procedures remains controversial.
If the dog has severe hip pain and the quality of life is decreased, and if conservative methods are not effective, surgical treatment should be considered. For these dogs, there are two surgical options available in North America:
(1) Total hip replacement, and
(2) Femoral head and neck ostectomy (FHO).
Total Hip Replacement Surgery
The hip joint is an important structure in dog’s body. The normal hip is a tightly joined “ball and socket” joint (Figure 1). This specialized structure enables a hind leg to move smoothly in full range of motion, and allows a dog to rise, walk, run, jump, and turn effectively. In the diseased hip, the “ball and socket” become irregular, rough, and deformed, causing pain and decreased range of motion (Figure 1).
In total hip replacement, the acetabulum (socket) and the femoral head (ball) are replaced with prosthetic implants (Figure 1). These components are fixated in place with cement or other methods. This surgery provides your pet with a nearly frictionless joint to replace the painfully arthritic joint, resulting in a clinically normal range of motion and limb function with routine exercise and activity.
FHO is a simpler surgery, which removes painful portion of the joint (Figure 2). These two surgical procedures are both good options to improve quality of life of the dog, and the owner has to make an ultimate decision whether to choose total hip replacement or FHO.
Figure 1. Normal hip (left) and abnormal hip (arrow). Total hip replacement can restore normal structure and function of “ball and socket” joint with artificial implants (color picture).
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Figure 2. Femoral head and neck ostectomy (FHO) removes abnormal portion (arrow) which is a major source of pain (see arrow in Figure 1).
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Which is Better Option for my Dog?
It depends. The decision can be made based on the following factors:
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Total Hip Replacement
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FHO
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1. Function after recovery
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excellent, almost normal
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good for normal life, decreased joint motion
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2. Cost
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expensive*
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moderate
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3. Post-operative care
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strict rest for 1-2 months
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no restriction, physical therapy required
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4. Potential complication
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can be serious**
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rare
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Total hip replacement should be considered for a healthy dog. In other words, total hip replacement should not be performed on a dog with infection anywhere in the body (skin, bladder), any neurological (spinal) problems, knee problems, cancer, or other medical conditions.
*Total hip replacement is an expensive surgery, however only 25-30% of the dogs need total hip replacement on both hips. Bilateral total hip replacement can be performed, but many dogs do so well following one total hip replacement that the owners decide not to pursue surgery on the other side.
**It should be noted that complications can be serious enough to require revision surgeries.
When Should Total Hip Replacement be Performed?
The decision to perform a total hip replacement should be made only after consultation with your dog’s veterinarian and an ACVS board-certified veterinary surgeon. They can best determine if your dog is a good candidate for the procedure and when it should be performed. Find an ACVS Veterinary Surgeon.
Types of Total Hip Replacement
There are several different types of total hip replacement available in North America. They are roughly classified as “cemented” and “cementless”. The choice of which technique is used is based on primarily the surgeon’s preference and experience, and the patient’s age and quality of bone.
“Cemented” total hip replacement has been performed in the dog for over 30 years. In this procedure, special medical-grade cement is used to fix the implants to the bones (Figures 3 and 4). Over the years, we have had about a 90-95% success rate. There is also a special system available for small dogs and cats, although it is not commonly performed (Figure 5).
Due to concerns regarding cement-related complications (as discussed later), there is a recent trend to avoid the use of cement in total hip replacement. There are a few “cementless” total hip replacement systems available in North America (Figures 4, 6, and 7). Compared with the cemented systems, we have less experience with cementless systems. There have not been long-term follow-up studies; however, short-term results appear promising.
Figure 3. Conventional cemented total hip system. Different sizes of modular implants are assembled and fixed in bones using cement (arrows) (New Generation Devices).
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Figure 4. Cemented (right side) and cementless (left side) total hip system (Biomedtrix universal hip system). Implants can be either stabilized with cement (arrows) or with tight fit “press-fit” cementless mechanism (left). With this cementless system, bone can grow into the implants overtime to further stabilize the implants.
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Figure 5. Cemented total hip system for small dogs and cats (Biomedtrix micro hip system).
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Figure 6. Cementless total hip system (Kyon “Zurich cementless”, Kyon Technoparkstr). Implants are stabilized with screws.
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Figure 7. Cementless total hip system (Helica screw prosthesis, Innoplant). Implants are secured to bones by the screw-in design.
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Post-Operative Care and Complications
Post-operative care is extremely important for success of the surgery, and consists of 6 -8
weeks of strict rest; keeping the dog on a leash to urinate/defecate. The following 6-8 weeks can include a gradual increase in walking to trotting while still on a leash.
Post-operative complications can occur (5-30%) and are most commonly due to luxation (Figure 8), fracture of the bone (Figure 9), infection, or loosening of the implants (Figure 10). If a post-operative complication does occur, it almost always requires additional surgery.
Figure 8. Luxation of total hip replacement. Femoral head (arrow) is displaced out of the socket.
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Figure 9. Fracture of femur (arrows) occurred 7 days after cementless total hip replacement.
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Figure 10. Loosening around the cement (arrows) can occur 7-10 years after cemented total hip replacement.
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Summary
Total hip replacement is a salvage procedure that is designed to remove a diseased/degenerated hip joint and replace with a prosthesis that provides good range of motion, limb use and improves quality of life. While total hip replacement is a difficult and expensive option that may have postoperative complications, results are usually excellent.
—Kei Hayashi, DVM, MS, PhD
Diplomate ACVS, Small Animal Surgery
Posted 5/29/2009
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