Orthopedics
Total Hip Replacement
What is total hip replacement?
In this procedure, a veterinary orthopedic surgeon replaces a painful or damaged hip joint with an artificial one, called a prosthesis. This eliminates the cause of pain and stiffness, and the patient can return to most of the activities they enjoy. When compared to femoral head and neck ostectomy (FHO), total hip replacement provides the best return to normal function in the limb.
Why is total hip replacement necessary?
The most frequent reason for performing a total hip replacement is relief of pain and disability caused by severe degenerative joint disease secondary to hip dysplasia or fracture. Other reasons include chronic dislocation of the hip and acute dislocation of the hip that cannot be reduced because of hip dysplasia or soft tissue damage. Many dogs with arthritic hip joints seem to function normally. But, when a painful joint is replaced with an artificial joint, there is often a dramatic change in the dog's personality as well as a change in activity levels.
What are other options to Total Hip Replacement?
Many dogs with hip arthritis can be comfortable and active with medical management. It is important to keep the patient thin and to provide regular, controlled activity. Nutritional supplements such as glucosamine and omega-3 fatty acids may reduce inflammation. Analgesic medications can be used occasionally, or continuously, depending on the patients need.
If hip pain persists, surgical options include femoral head and neck ostectomy (FHO) or total hip replacement. An FHO removes the ball portion of the hip so that there is no longer bone rubbing on bone in the diseased joint. While this can relieve much of the pain, the loss of the ball-and-socket structure of the hip usually means that the limb will not function normally. Small, light-weight dogs do better with an FHO. The advantages of FHO include easier recovery, less risky complications, and less expense.
How will I know if my dog needs this procedure?
Complete patient evaluation by your veterinarian and by a veterinary orthopedic surgeon will determine if total hip replacement can help your dog.
- History: Includes questions about your dog's hip pain, medications, prior injury and current vaccinations. Also included are questions related to which leg is causing your dog the most problems, your dog's ability to walk, exercise, climb stairs, rise and sit.
- Physical Examination: Includes a complete assessment of your dog's general health and skin condition, the range of motion in your dog's hips, and observation of how your dog walks, sits, rises and moves.
- X-rays: Provide the surgeon with information about your dog's hip bones and hip joints. They also help in the precise fit of your dog's new hip.
- Laboratory Analysis: Blood and urine samples will be analyzed to help determine the state of your dog's health, and if heartworms are present.
Are there reasons why my dog should not have a total hip replacement?
Yes. If your dog has healing wounds, inflammation or infection of the skin, ears, or teeth, poor nutritional status or laboratory evidence of metabolic disease or infection, a total hip replacement will not be performed at that time. When the problems are resolved, total hip replacement can again be considered.
Other problems such as stifle joint injury, prostatic disease and spinal disorders can mimic hip joint problems. In this case, total hip replacement will not improve the condition.
If a femoral head and neck excision was performed previously, the results of total hip replacement are generally not as rewarding as cases receiving hip replacement initially.
Are there size and age limits to total hip replacement?
Total hip replacement has historically been used in medium, large and giant breed dogs. There is now a much wider range of implant sizes, so it is available for small dogs as well.
In the past, total hip replacement was only considered in older dogs. This was due to concerns with how long the implants would remain stable. With the uncemented implants that we now use, break-down of the interface is unlikely, and the high quality of the plastic of the cup will help it last for the life of the dog. Implants can be placed in dogs as young as 7 – 10 months old with the expectation that they will provide a lifetime of pain-free function.
How is total hip replacement performed?
Under general anesthesia, the surgeon replaces the damaged parts of the joint with a prosthesis. The diseased femoral head in the hip joint is replaced by a metal ball on a stem that fits inside the femur. A metal and plastic cup is implanted into the pelvis to replace the damaged socket. The new prosthetic components are designed to allow the joint to move the same way as the normal hip.
The most commonly used prostheses at NCSU are called “uncemented”. “Cemented” implants are held in place with an acrylic, but there may be break down of the interface between the cement and bone over time. Porous-coated uncemented implants become stable by in-growth of bone into their beaded surface in the first few weeks after implantation. This bond is more likely to last the life of the dog. Because of this, we feel much more comfortable performing uncemented hip replacement in young dogs.
Will it take long for my dog to recover?
Most dogs are able to stand and walk on the new prosthesis within the first few days after surgery. While hospitalized, exercise is restricted to cage confinement with 10 to 15 minute walks under leash restraint twice daily. Most animals undergoing total hip replacement are hospitalized for a total of 3 to 4 days.
Management at home will require supervision, and activity must be restricted to walks under leash restraint for 4 weeks. During this time, care should be taken to avoid activity on slippery surfaces, and stairs should be climbed only while the dog is under the direct control of the owner. One month after surgery, supervised exercise can be gradually increased over the next 4 weeks. At the end of 8 weeks, more normal activity is allowed. Vigorous, rough play, or hard work is allowed after gaining strength and conditioning.
Radiographic evaluation and orthopedic examination are necessary at 3 and 6 months after surgery, and every 2 years thereafter. This provides a history of the patient's progress and may help to detect potential complications.
What are the risks and complications of total hip replacement?
There are risks inherent with any surgical procedure under anesthesia. You should discuss these risks with your veterinarian and/or the orthopedic surgeon. The current complication rate following total hip replacement is 2 to 5 percent. Complications are best treated when identified early. Significant complications include:
- Dislocation of the prosthetic joint is rare, and is most likely to occur in the first 4 weeks after surgery. It may be corrected manually, but another surgery is often necessary.
- Infection is a serious potential problem. If it occurs in the area of the wound, it is generally treated with antibiotics. If it occurs in the bone, removal of the prosthesis may be necessary.
- Subsidence or sinking of the stem – a small amount of settling of the stem has no effect on function of the prosthetic joint. A large amount of subsidence or stem rotation may require surgical revision of the stem.
- Fissure or Fracture of the femur – uncemented implants are hammered in to place. Fissures can develop. If they are seen during surgery, wire is placed to prevent them from expanding. If they develop after surgery, they may lead to subsidence of the stem, or fracture of the bone. Another surgery would be required to manage this issue.
- Loosening of the prosthesis is an uncommon problem with uncemented prostheses. If loosening is significant or progressive, the implant may need to be replaced or removed.
What are the benefits of a total hip replacement?
The main benefit of total hip replacement is relief of pain, and this is often quite dramatic. Some soreness in the leg and hip is to be expected for a few weeks because of the surgery and because muscles around the joint are weak from inactivity. Muscle strength and motion of the joint will improve with increased activity over the next few months.
Is total hip replacement permanent?
In most dogs, an uncemented total hip prothesis will last for the dog's life. It will provide years of pain-free activity that would not otherwise have been possible.