What Is Hip Dysplasia?
Hip dysplasia means abnormal development of the hip joint and represents a complex genetic condition. The hip is a ball and socket joint formed from the femoral head and the acetabulum. Pets are born with normal hips. But within the first few months of life the joint capsule and ligament that stabilise the joint become loose. This results in hip laxity where the femoral head will not stay within the socket during movement. Abnormal forces develop which cause the femoral head to flatten and the acetabular socket to become shallow. This sets-up an ongoing vicious cycle resulting in cartilage damage and secondary arthritis develops.
Pain develops due to hip laxity in early life or secondary arthritis in later life. It was thought to be uncommon in cats but may be more common in cats than previously thought. It usually affects larger breed dogs.
What are the signs of hip dysplasia?
Pets may show signs before they reach 1 year of age and include difficulty getting up/lying down; difficulty with stairs, limping and a bunny-hopping walk to trot. In some patients the signs were too mild or subtle to be seen when they were younger. They may present later in life as young adults with signs of arthritis. The signs may be similar but stiffness after rest or inability to exercise as long as before may also be seen.
How Is Hip Dysplasia diagnosed?
Whenever a pet has signs like lameness, pain or stiffness your local vet will perform an orthopaedic examination to localise the issue to the correct joint. This is especially important because many dogs with hip pain may not show obvious signs of discomfort unless specific movements are carried out. If hip pain is detected your local vet will perform a number of tests to identify if hip dysplasia is the cause. These will include:
Blood tests: they will assess general health which is important before sedations or anaesthetics are performed. They will also help make future treatment recommendations.
X-Rays: in most cases this will diagnose hip dysplasia and the level of secondary arthritis that is present.
Ortolani test: this is a hip manipuation performed under sedation or anasthetic. By moving the hip a certain way it tests for laxity and together with X-rays will confirm dysplasia.
How Is Hip Dysplasia Treated?
Your vet will discuss the diagnosis with you and the treatment options. They may ask a member of specialist surgical team to speak to you or you can see them directly to discuss the options. There are many options for treatment and we would treat each pet as an individual taking into all the factors to make the right decision.
This involves weight and exercise management, anti-inflammatory pain killers and hydrotherapy. A plan is created and the success of this is carefully monitored with regular checks with your local practice. For example, we wouldn’t want a young pet to need drugs for life so this would not be counted as successful. Non surgical treatment is appropriate for mild cases. Even if it was successful at young age many dogs will go on to develop arthritis requiring treatment in the future.
Surgery is either aimed at modifying the hip anatomy or surgeries that salvage the hip.
Juvenile pubic symphysiodesis
This surgery fuses a part of the pelvis so as to improve the coverage of the femoral head by the acetabulum. Fusion is achieved by use of electrical cauterisation of the pubis. This surgery is only suitable for dogs under 5 months of age but because may pets present a bit later than this it is not often applicable. It can be used as a prophylactic surgery in very select cases.
Double pelvic osteotomy (DPO)
If there is no arthritis, just laxity, it may be possible to make two cuts into the pelvis to free up the acetabular segment and rotate it to cover the hip joint better. The new position of this segment is held in place with a special type of plate. The Ortlani test and X-rays are very important in selecting the right candidates for this surgery. With successful realignment patients may not develop arthritis in the operated joint.
You may see and hear vets refer to a surgery called the TPO (triple pelvic osteotomy). This is the same type of surgery but it is more invasive because three cuts were made. The DPO represents a refinement in the technique.
Total hip replacement (THR)
Like in humans it is possible to replace the femoral head and the acetabulum with new, better functioning implants. The femoral head is replaced with a metal implant that is attached to the rest of the bone with cement or a system can be used where the bone grows into the implant. The socket is replaced with a plastic and metal cup. Following surgery pets are rested really well to ensure a complication free recovery. The major issues with this surgery are infections and dislocation. Pets should be free of infection before surgery is undertaken and they are kept in the hospital for rehabilitation before they go home. This generally takes a week. They need complete rest for 2 months and at this point post operative X-rays are taken. If everything has healed your pet will slowly return to normal exercise 1 month later.
The success rate of the surgery is high with many patients returning to normal activity. But the surgery is the most expensive option and has greater, more serious complications than the other surgeries. Overall the complication rate has fallen over the years which is helped by the experience of our orthopaedic team.
Femoral head and neck excision
The femoral head and neck can be completely removed to eliminate pain. It converts the ball and socket hip joint to more of a hinge joint. By eliminating the bone on bone contact the joint is more comfortable with good function. It is less expensive in comparison to a total hip replacement and the post-operative rest requirements are less. Postoperative physiotherapy and rehabilitation is key to longterm success. After surgery your pet will stay with us for a couple of days to make sure mobility is restored and your pet is sent home with appropriate pain relief. The exercise levels and mobility are reviewed every two weeks and recommendations are made to ensure a smooth recovery. We usually see that most pets are back to normal after 8 weeks. The surgery is more suitable in smaller dogs and it is imperative that the excision is performed a certain way to minimise any spurs or sharp edges. Our experience, coupled with our equipment will ensure the highest standard of surgery to ensure everything is done to obtain the best outcome possible.