Dog Hip Dysplasia – Hip Replacement


Key Points

Careful selection of candidates for total hip replacement is critical to ensure a successful outcome

Prognosis following hip replacement is usually very good

If a complication of hip replacement occurs it usually is not a small problem….it is major and usually requires reversional surgery

 

Hip Dysplasia

  • Hip dysplasia is a very common disease that affects larger breed dogs. This disease is caused by the abnormal development of the hip as a puppy grows. Bad genetics are a major contributing factor. Sometimes the mother and father of the affected puppy are negative for the disease. If this is the case, the parents may have hidden genes for the disease.
  • Hip dysplasia results in looseness of the hip joints. Because the joints are loose the head and socket of the hip become deformed. The socket becomes shallow and the head of the femur gets flattened. Arthritis develops in the joint and causes pain.
  • Clinical signs of hip dysplasia can be seen as early as 4 months of age, however, many dogs are 8 to 12 months of age. Some dogs seem to experience signs of hip dysplasia when they are a couple of years old and others in the geriatric years. The clinical signs of a problem may first start out as exercise intolerance. Bunny hopping, stiffness on rising after a rest, lameness on a limb, and atrophy of the muscles of the hind limbs are typical clinical signs. Occasionally the hip joint will be very loose and it will become dislocated with minimal trauma. This usually causes the pet to become suddenly lame. Replacement of the hip back in the joint is generally unsuccessful as the geometry of the joint is so abnormal.
  • The diagnosis of hip dysplasia is made based on a combination of history, clinical signs, physical examination findings, and radiographs. We do not base a decision to perform a total hip replacement solely on the radiographs. A dog may have very degenerate hips and does not show any clinical signs. Another dog may have profound clinical signs of hip dysplasia and have milder degenerative changes as seen on a radiograph.
  • Selection of the patient to do a hip replacement must therefore be done carefully. Dogs that are not candidates for hip replacement include
    • dogs less than 10 months of age (we usually wait until the dog matures)
    • successful medical therapy
    • chronic infections of the bladder, skin or elsewhere
    • concurrent significant neurological disease
    • diseases that increase the risk of blood clots (nephrotic syndrome and Cushing’s disease)
    • bone cancer
    • Dogs that are totally spastic and uncontrollable, may also be less desirable candidates as the complication rates after surgery will be increased.
  • Fig 1 shows a dog’s pelvis afflicted with hip dysplasia of the left hip joint (your right)  Note the extensive bone spurs that are surrounding the joint in comparison to the opposite normal hip joint.

Fig 1

 

Total Hip Replacement Surgery

  • Total hip replacement requires a preoperative evaluation. Blood work is generally done to ensure health of the internal organs. Urine testing is done to ensure that no bladder infection is present. The body is checked over for obvious infections such as skin infection. Two radiographs of the hips are taken in order to determine the size of the femoral implant and plastic cup that will be needed for your pet. Your pet should be bathed at home and completely dried the day before surgery. Your pet should not be allowed to go outside except for elimination purposes so that he/she does not get dirty.
  • Just before surgery the entire leg will be shaved. An epidural will be given for pain control after anesthesia is induced. Once in the operating room, special sterile plastic drapes are glued to the limb. An incision is made over the region of the hip. The ball of the femur is removed and the marrow cavity is cleaned out. The acetabulum (socket) is reamed out and a plastic cup is cemented in placed. A cobalt-chrome femoral implant is cemented into the femur bone and the hip is put back in place. We use the BioMedtrix hip prosthesis to perform a total hip replacement (most surgeons in the USA use this type of hip as it is an adjustable system).
  • Below in Fig 2 hip dysplasia is found on only one side (your right – which is the dog’s left hip); note that the hip does not fit nicely in the joint like the opposite one does; in Fig 3 total hip replacement has been performed to correct the problem.

Fig 2

Fig 3

 

After Care and Convalescence

  • After surgery has been completed intensive care is provided.
  • Pain control after surgery is maintained with an epidural at the time of the surgery and morphine is given in the postop period as needed. While at home, oral pain medication may be needed and a prescription of Tylenol #4 will be given to you at the time of discharge of your pet.
  • The incision is covered with a bandage for about 1-2 days. The bandage should be kept clean and dry if still in place at home.
  • It is important to support the hind limbs with a sling to prevent slipping and falling. The SupportRx Harness by TopDog Rehabilitation is an affordable and effective option. (link to http://topdoghealth.com/therapy-support-products/support-rx/)
  • Antibiotics must be given after surgery to help prevent against infection.
  • Exercise restriction must be continued for 3 months. During the first 2 months the pet should be kept in the house on good footing (avoid slippery flooring). During the third month exercise is gradually increased.
  • Rehabilitation therapy is very important after surgery to maintain muscle mass and range of motion of the operated hip.
  • Most dogs will start to bear some weight on the limb within a couple of days after the surgery. Within 2 weeks your pet should bear a moderate amount of weight on the limb. By 2 months after surgery full weight-bearing resumes.
  • Your pet should be examined 2 weeks and 6 weeks after surgery to ensure that the hip is healing well. At 4 months after surgery and annually, examinations and radiographs should be done to ensure that the hip is still stable and the implants are not loosening.

 

Potential Complications

  • As with any surgery, complications may arise. Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oxymetry, inspiratory and expiratory carbon dioxide levels, and respiration rate), the risk of problems with anesthesia is minimal.
  • Infection is an unusual complication, as strict sterile technique is used during the surgery and antibiotics are administered. When infection occurs it usually is very devastating, as it is usually impossible to clear the infection with antibiotics. This is because bacteria migrate into the bone cement and the antibiotics cannot penetrate the cement very well. If infection occurs removal of the implants is usually needed. Infection of the hip prosthesis can also take place if the dog develops an infection elsewhere in the body. The infection from another site may enter into the blood stream and migrate to the hip. Therefore skin, mouth, bladder, and other types of infections must be treated as soon as possible.
  • Another unusual, but reported complication is sciatic nerve damage. If this occurs it usually is temporary.
  • Excessive activity or exercise within the first 2 months can also lead to complications. The femoral prosthesis could dislocate from the acetabular cup. Another complication is loosening of the cement from the bone or loosening of the implants from the cement. Both of these conditions require surgery to correct the problem.

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