Canine hip dysplasia and its treatment

Hip Dysplasia is a common developmental disease of the hind legs in dogs. It can affect dogs of all breeds and sizes and even cats. It is believed to have a genetic basis but other factors such as nutrition and activity level may affect how or when it will show itself. Some dogs will show clinical signs quite early (4-10 months of age) and other dogs will appear to be normal. However, if the disease is not treated arthritis will eventually set in and clinical signs develop. Early recognition by your veterinarian will allow different options for treatment to be discussed.

Screening x-rays may be taken at the time of neutering (6 months of age) and are recommended.

Clinical signs of hip dysplasia:

• Stiffness getting up
• Sitting with legs off to the side
• Lameness in one hind leg
• A "waddling" or "rolling" gait in the hind end
• A "bunny hopping" gait during running (placing both hind legs on the ground together during running)
• In severe cases, the dog may be reluctant to get up and the ability to run/play may be reduced

Hip dysplasia and its relationship to hip arthritis

Hip dysplasia describes the abnormal development of the hip joint as the dog grows. This abnormal development means that the hip joint is unstable and leads to excessive wear and tear on the cartilage surfaces of the hip joint resulting in arthritis. The age at which clinical signs of arthritis develop after hip dysplasia is diagnosed is quite variable and unpredictable. It may be as young as 2 years old or may not surface until your pet is getting older (8-10 years old).

Clinical signs of hip arthritis:

• Loss of muscle mass in one or both hind legs
• Slow or stiff getting up
• Lameness in one or other hind leg
• Reluctance to go for a long walk or a run – may sit down or refuse to go further
• Reluctance to jump up or go upstairs
• Flopping down rather than a controlled sit
• Difficulty posturing to urinate/defecate
• Shifting from leg to leg during eating.

What are my options to treat hip dysplasia and arthritis?

These clinical signs can be quite subtle and if both hind legs are affected at the same time can be even more difficult to distinguish. If you are concerned that your pet is exhibiting any or all of these signs consult your veterinarian and x-rays of the hips may be suggested to confirm the presence of hip dysplasia/arthritis.

Medical vs surgical management:

Medical management is essentially the same for any dog with arthritis and consists of one or all of the following:

• Regular gentle exercise
• Weight loss
• Physical Therapy – warmth, passive range of motion exercises, etc.
• Chondroprotective products such as glucosamine, chondroitin sulphate, MSM, etc
• NSAIDs – anti-inflammatory, pain relieving drugs such as Metacam, Deramaxx or Rimadyl are commonly used drugs.

Surgical Procedures for Hip Dysplasia and Hip Arthritis are broken down as follows:

Hip Dysplasia Treatments:

• 1. Triple Pelvic Osteotomy
• 2. Pubic Symphysiodesis

Hip Arthritis Treatments:

• 1. Total Hip Replacement
• 2. Femoral Head Removal
• 3. Hip Denervation

Whether to choose medical or surgical management is quite a complicated and lengthy discussion based on the age, intended use and size of your pet and other factors. A thorough history, orthopedic and neurological exam and review of pelvic x-rays are necessary so that we can best advise you as to the appropriate management for your pet. Treatment outcomes vary and it is important that if you want your pet to be fully functional and comfortable that you understand all options available.

In the young dog (under 1 year old), medical management can be used to relieve pain during the early phase of hip dysplasia. This approach will get some dogs over the “remodeling pain” associated with their abnormally developing hips. However, it is important to understand that hip dysplasia does not heal itself and medical management is simply masking the disease in the hips. Untreated, the long-term result will be hip arthritis and surgery could be considered in the young dog to try to prevent that. However, this treatment must be done early before the cartilage in the hips deteriorates too much.

In the older dog, once the signs of hip arthritis surface, medical management can be started with good results. However, there are some potential side effects of some of the drugs used and also significant costs if treatment is expected to go on for a long time.

Also, as the breakdown of the hips progresses, medical management may become unsuccessful in managing your pet’s pain. Again, surgery may be a more appropriate option in the long run.

Surgical procedures for hip dysplasia

1. Triple pelvic osteotomy:

Why perform a triple pelvic osteotomy?

In puppies, the joint instability associated with hip dysplasia can be painful and disrupts normal development of the hip joint. A triple pelvic osteotomy (tpo) is performed to relieve pain, restore function, and stabilize the hip joint so it will develop more normally. It is important to realize that the objective is to stabilize the hip joint to prevent the development of debilitating arthritis. The emphasis must be on early detection and intervention before severe joint damage occurs. Studies in humans and in dogs show that if the abnormal weight-bearing forces across the joint are corrected early in the course of hip dysplasia, a more "normal" articulation will develop

What is a triple pelvic osteotomy?

Triple pelvic osteotomy means cutting the pelvis in three places (see fig. 3). The osteotomies, or cuts, are performed to allow rotation of the acetabulum (or hip socket) to a better position over the femoral head. Thus, the femoral head is "captured" within the acetabulum to stabilize the hip joint. A stainless steel plate specifically designed for this procedure holds the repositioned acetabulum while the osteotomies heal. (See fig. 5)

Is your dog a candidate for a triple pelvic osteotomy?

A triple pelvic osteotomy must be performed before arthritic changes become too advanced. Ideal candidates are usually 5 to 8 months of age. Your veterinarian can easily evaluate your pet with an x-ray while he/she is under anesthetic for neutering. Occasionally, dogs less than 8 months old are not candidates if their hip dysplasia is severe. Some dogs may be a candidate in one hip but not the other. It is vital that the socket is in good condition for a TPO to work long term. If the socket is shallow, the cartilage or acetabular rim is badly damaged then TPO is not advised and a total hip replacement would be preferred. If both hips require reconstruction, surgery can be performed on both sides at the same time using a modified technique. Otherwise surgery can be performed on the second side 4-6 weeks after the first side. However, the opportunity to do the second side may be lost even within 4-6 weeks.

Are there any risks?

Yes. The incidence of complications is very low, but risks exist just as they would for surgery on people. Complications from infection, technical problems, and anesthesia can never be totally eliminated. The bone of young dogs is quite soft and young dogs can be very rambunctious so proper exercise control postoperatively is important. With owner and patient compliance, complications rarely occur.

When should the surgery be performed?

Surgery options must be considered as soon as early hip dysplasia is detected. Unless dysplasia is exceptionally severe, patients are allowed to reach an age of 6 months to improve bone quality (young puppies have very soft bone). It is important to realize that some patients are candidates at age 6 or 7 months, but may not be at age 9 or 10 months due to the advancement of the dysplastic process. In general, surgery should be performed as early as possible.

How do we get started?

Schedule an appointment for a consultation and examination of your dog. If available, bring radiographs and copies of recent lab work performed by your veterinarian. It is important that the skin is healthy before surgery. If superficial skin infection is present, treatment may be required before surgery can be performed.

Your surgeon will perform a complete orthopedic and neurologic evaluation to confirm the diagnosis and to make sure other less common conditions are not present. Radiographs (if available) will be reviewed. General anesthesia may be required, so food should be withheld for 12 hours prior to the appointment.

Pubic symphysiodesis

Pubic symphysiodesis is a procedure that is best performed at approximately 16 weeks of age and before 20 weeks of age. The goal of the procedure is to stop growth of the pubis in order to cause increased angulation of the hip socket. This may prevent the development of hip dysplasia.

Surgical procedures for hip arthritis/dysplasia

Once hip arthritis develops from either hip dysplasia or other injury to the hip joint the joint can become more and more painful and hind leg function impaired. The muscle of the affected leg starts to deteriorate and decrease in size. The main source of hip pain appears to be from pain fibers within the joint capsule around the hip joint but there is also pain from within the subchondral bone in the femur and pelvis. As cartilage continues to deteriorate bone on bone contact between the femur and hip socket contribute to the patient’s discomfort. For many dogs surgery is a good option at, or before this point, before too much muscle is lost.

1. Femoral head ostectomy (fho)

This procedure is aimed at relieving pain from hip arthritis by doing away with the hip joint. Pain fibers are highly concentrated in the joint capsule and so removing the femoral head and reducing the pull and stimulation of these pain fibers can relieve some of the pain from the hip. This procedure involves removing the femoral head and neck to obtain a smooth femoral surface to glide over the side of the pelvis. The ball and socket hip joint is effectively done away with and a “false joint” is created which allows the leg to move back and forth as fibrous tissue fills in between the femur and pelvis.

Postoperative physical therapy:

Postoperative recovery from an FHO is quite painful for 2-10 weeks as the false joint is formed and your pet adjusts to the new reality of not having a ball and socket hip joint. Physical therapy is essential after an FHO to keep the leg moving while healing takes place. Initially, dogs and cats do not use the leg after this procedure is performed and will get around on three legs. If the patient is left to carry the leg for too long with out using it the scar tissue that is forming the “false joint” will become restrictive and impair function. The owner is instructed how to flex and extend the hip in a rotary fashion so that the scar remains flexible until leg use resumes. This can take anywhere from 2 to 10 weeks.

Long term outcome:

How well the patient will use the leg once healing has taken place is quite variable. Smaller dogs and cats can appear to be quite functional but the larger the patient is the less predictable the outcome. Objective force plate assessment of dogs after an FHO has shown that they do not regain full use of the leg. Considering that the fulcrum of the femoral head has been removed this is not surprising. Instead of the body weight being carried by the ball and socket joint the femur will ride higher and has to be restrained by the muscles of the hip. Whether it is the decreased mechanical advantage or painful stretching of the hip muscles, or both, that leads to a less than satisfactory outcome is uncertain.

Muscle mass is generally not rebuilt after an FHO which is an indication of how much weight is being born on the operated leg. If the objective is to relieve pain then an FHO can be quite effective. If the objective is to return the pet to full function then an FHO can be less than ideal. The postoperative discomfort, need for physical therapy and often protracted recovery are also a consideration in whether this is your best choice of surgery.

2. Total hip replacement -universal bfx/cfx system

In the same way that hips are replaced in people with hip arthritis and other hip conditions we perform total hip replacement (THR) in the dog. We use the Biomedtrix Universal Hip System, which includes both cementless (BFX) and cemented (CFX) systems. Biomedtrix is well established as the leading THR system in the dog and we have been using the CFX system for many years. The newer BFX system promotes the in-growth of bone into the implant, which secures it for the life of the pet. The Universal System allows us to implant hips into a wide variety of dog breeds and sizes and even cats, and for various conditions. In certain situations we may combine both the CFX and BFX implants. As the name suggests we are replacing the entire hip joint – both femoral and pelvic side – with a prosthetic hip.

THR Technique

In THR the femoral head side of the hip joint is replaced with a stainless steel stem and femoral head. This steel ball articulates with a polyethylene pelvic cup that is implanted on the pelvic side of the hip joint with either a cemented (CFX) or boney ingrowth (BFX) prosthesis.

THR Indications:

THR is most frequently indicated for relief of chronic hip arthritis and can be performed in young or old dogs. The BFX system can be used early in the dog’s life when hip dysplasia has been first diagnosed and the hip has deteriorated beyond the indications for a triple pelvic osteotomy. This allows the dog to live a normal life and rebuild muscle in the hind legs. This, in turn, helps to prevent additional future orthopedic issues such as a ruptured cranial cruciate ligament, which can often affect dogs with untreated hip dysplasia.

THR is also indicated for malunion of pelvic fractures, chronic hip dislocaton and revision of failed triple pelvic osteotomy or FHO.

BFX Technology

The BFX system has been developed in parallel to the CFX system and is designed to allow bone in-growth into the porous surface of both the femoral stem and acetabular cup. Bone in-growth results in the long-term security of the implants. Once incorporated by the bone the BFX system is extremely secure and expected to last for the rest of the dog’s life. This long-term security is part of the technical advantage of the BFX over the CFX. The BFX can be implanted into dog’s as young as 6 months of age (although the average is 10 months of age) and once in-growth is complete the patient can return to any activity desired, including agility, hunting and even field- trialing.

Patient size, hybrid THR and CFX

The smallest BFX stem and cup allows implantation into dogs as small as 15-20kg depending on bone size. Our assessment of a THR candidate includes a series of 4 x-rays of the hips and femur with a special magnification marker in place. This allows us to accurately assess the patient’s bones for the right sized implants preoperatively. While it is preferred to implant a BFX implant if possible, the Universal System allows us to combine a cemented stem (CFX) with a BFX cup or vice versa where indicated. A so-called “hybrid” implant.

The CFX system alone is still indicated in certain situations where bone anatomy or size dictate. The shape and quality of bone in some dogs warrants the use of the CFX system. In addition, the CFX system gives immediate security of the implants and may be a better choice in some of the giant breeds. Finally, there is a micro system available, which allows implantation into very small dogs and even cats. The micro system is a cemented only system. The Universal BFX/CFX system allows us to address all of the variety of needs we see in our very diverse pet population.

Postoperative care:

As for all surgery at AVAH a regimen of postoperative pain relief is determined for each individual pet. Most pets recover quickly after THR surgery and will start using the leg within a few days of surgery, sometimes even the next day. Exercise must be strictly confined to leash walks only and slippery surfaces must be avoided. Stairs should be avoided in the first 2 weeks and then only under strict control and with a protective sling at first. Leash walks can be slowly increased in length but no running for 3 months. Follow-up xrays will be taken at 3 months and annual rechecks are recommended. After the three month x-rays exercise should be slowly returned to normal over a 1-2 month period. Dental hygiene should be maintained and antibiotics given quickly for signs of skin or bladder infection.

Complications:

THR is a highly technical surgery that requires experience and a dedicated team of knowledgeable doctors and veterinary nurses. Like all surgeries the outcome is never 100% successful. However, the success rate with THR is very high and complication rate is low (5-10%). In addition, most complications can usually be resolved but some may require further surgery. Overall, failure rate is less than 2%.

Complications can include the following:

• Hip dislocation – this can occur most often in the immediate 6 weeks after surgery during the period that the hip muscles are adapting to the new reality of a prosthetic hip. Resolution can involve closed or surgical reduction depending on the cause. Strict confinement after surgery is therefore very important.
• Femur fracture – fissure fractures can occur during implantation of a BFX stem and are usually resolved with cerclage wire fixation. Full femur fractures can occur at any time after surgery and trauma is usually involved. Like for other fractures internal fixation is required.
• Subsidence – until boney ingrowth of BFX implants occurs (3 months) movement of the implants (subsidence) can occur. If minor this may require no further treatment but major subsidence may require intervention.
• Aseptic loosening of implants – loosening of the BFX implants after in-growth is very unlikely. However, long term wear can result in some implant loosening of CFX implants , but less than 1%. Revision surgery may be performed.
• Neuropraxia – bruising of the sciatic nerve can occur infrequently during surgical manipulation of the femur and may result in dragging of the leg after surgery. These symptoms are usually temporary and will resolve in a few days to a few weeks.
• Infection – can occur in the immediate postoperative period or even years later. Infection rates are fortunately low and in line with the human field at about 1%. It is a tough problem to deal with in a CFX implant and may result in having to remove the implants. While infection can still occur in the BFX implants the consequence of removal of the implant may be avoided. Infection can get in to the blood stream from a variety of sources (dirty teeth, skin or bladder infection) and so antibiotic therapy is advised if any of these conditions arise in a pet after a THR.

How do we get started?

If you are concerned that your pet may be suffering from hip dysplasia/arthritis and you would like to consult with one of our Board-certified Surgeons to have your pet evaluated and to discuss your options, please call the surgery department at 613 520 2213 and set up an appointment. Your pet will be given a thorough general, orthopedic and neurologic exam and x-rays will need to be taken under sedation (please bring your pet in a fasted condition – no food for 12 hours).

3. Hip denervation

Hip denervation is a procedure that can be done on both hips at the same time. It involves cutting the nerve supply to the hip joint capsule to relieve some of the pain from hip arthritis. Subjectively, this can provide some relief for a dog. However, there are no objective and no long term follow-up studies available.