Hip Dysplasia

The image above shows A) Normal hip B) Dyslpasia C) Subluxation D) Luxation

Hip dysplasia is also known as developmental dysplasia (DDH) and was previously called congenital dysplasia.

Who does it affect?

Causes and Risks

• Gender - 80% of cases are female. This is probably due to the production of oestrogen which makes the ligaments more stretchy giving the bones more room to move around.
• First born - 60% of cases occur with the first child possibly because the uterus is tighter allowing the foetus less room to move.
• Culture and Race - There is strong variation of the incidence of this condition in certain ethnic groups. Native Americans tend to have a higher rate, possibly as a consequence of their traditional way of swaddling infants. Chinese and African Americans are also reported to have a higher incidence.
• Breech birth - being "upside-down" in the womb may force the foetus into a position which increases risk.
• Oligohydramnios - which is a condition where there is only a small amount of fluid in the womb, which restricts the amount the foetus can move about.
• Other conditions - any other condition that may hamper movement or prevent the child from standing or walking may increase the risk of hip dysplasia.

Hip Dysplasia Symptoms

Hip Dysplasia Diagnosis

Checks include: -

• manoeuvring the hip
• checking to see if the skin folds on both sides are the same
• checking that the length of both femurs are equal

If the condition is not picked up at this stage it may be evidenced later if a child limps when they start to walk.

Hip Dysplasia Treatment

The earlier treatment is started the better the outcome and the greater chance of avoiding long term damage such as osteoarthritis.

The aim of any treatment is to establish a good stable, contact between the femoral head and the acetabulum which should allow the joint to develop normally. This is done by keeping the hip in a flexed position for sufficient time.

Non-surgical interventions
If the condition is diagnosed early enough then a "nappy splint" may be used. If this isn't sufficient then the infant may need to wear a Pavlik harness for about six weeks full-time and a further six weeks part-time. The harness keeps the child's legs bent in the correct position. The harness works well solving the problem for 90% of children with milder hip dysplasia and 80% of those with a more severe problem.

One possible, though not common, complication of this method is avascular necrosis (loss of blood flow to the femoral head which may result in bone death.).

Surgical interventions
If the infant does not respond to these interventions or the condition is not diagnosed till later then surgical treatment may be needed to position the head of the femur correctly. Prior to surgery the child may be placed in traction to loosen the tissue around the joint. Following surgery a plaster cast, known as a hip spica, will be applied. This encloses both hips and keeps the legs apart and may be used for several months. This process is known as closed reduction.

An open reduction is usually carried out only on children over 2 years. This involves cutting any tendons, ligaments or muscle that is preventing the femur from fitting inside the acetabulum (the cup part of the joint). The hip joint can then be put in place. It is usual for the child to be put into a hip spica following surgery.

In some cases it may be necessary to perform an osteotomy. This involves cutting and rotating the femur so that it is in the best position for a snug fit with the acetabulum. With some older children it may be necessary to also alter the positioning of the acetabulum.

All children who undergo surgery for hip dysplasia are at increased risk of developing osteoarthritis during their 40s and 50s.

Hip Dysplasia is also common in dogs where the cause is known to be genetic. Over 82 breeds are affected with larger breeds having the highest incident.