Developmental Dysplasia of the Hip (DDH)
What is hip dysplasia (DDH)?
A spectrum of presentations (dependent on age) that all result from the cup of the hip (acetabulum) not being deep enough. The end result if left untreated is that the child may develop early arthritis of the hip with associated pain and limitation of movement.
Questions and Answers
How do I know if my baby has hip dysplasia?
1) Does your child have risk factors for DDH? These include: a family history of hip dysplasia; breech presentation at birth; low weight gain during pregnancy (oligohydramnious); other packaging conditions (torticollis, metatarsus adductus)
2) Are there abnormal signs on my baby’s examination? These include an unstable hip; decreased abduction (pulling the legs apart); asymmetric skin creases around the hip/thigh
Ask your doctor to order an ultrasound of the hips
Depending on the child’s hips it will be one of
- Normal: nothing more needs to be done if the clinical exam is normal
- Not quite developed enough (immature): this might be entirely normal or it might be a sign that there is actually true hip dysplasia. Another ultrasound needs to be done 6-8 weeks after the first one to determine how the hips are developing
- Hip dysplasia: the hip(s) is (are) seen to truly dysplastic and not developing in the manner needed- treatment is needed
We know that all babies at birth have hips that on ultrasound are not fully developed. In general the hip will reach a certain standard on ultrasound by age 6 weeks. The reality though is that there is a great variability in just “how fast” the hip actually develops. As such at the 6-week ultrasound some hips, which are entirely normal, appear “dysplastic””. If there is a normal clinical exam there may well be progression of the hip that will end up being entirely normal. As such your doctor may order another ultrasound to be done in 6-8 weeks to assess the development of the hip to determine that it is truly normal (“physiologic immaturity”) vs. being dysplastic and needing treatment.
This can be confusing, as many articles do not differentiate between the two. Hip dislocation is the extreme form of hip dysplasia whereby the femoral head is not actually in the joint. I.e. All dislocated hips are dysplastic but not all dysplastic hips are dislocated.
- If the hips are in the joint then in general the child will go on a course of bracing and the treatment monitored with serial ultrasounds
- If the hip is dislocated:
- If the child is less than 5 months in general a brace will be tried to get the hip back in the joint
- If the child is over 5 months of age it is oftentimes necessary to take them to theatre to examine and treat the h
Your Paediatric Orthopaedic Surgeon will review your baby clinically along with further ultrasounds at 6-8 week intervals to ensure the hip is developing appropriately. As the hip improves in general the surgeon will decrease the amount of time needed in the brace.
The surgeon will carefully examine the hips with the baby asleep. He will then put dye into the hip and assess whether it is possible to get the hip fully back into the joint. If the hip goes in nicely then the child will go into a “Hip Spica” – a plaster that goes from the chest to the ankles and keeps both hips in the desired position. INSERT PIC OF BABY IN HIP SPICA
If the hip does not go into place then the surgeon will need to do a “medial open reduction” of the hips whereby the structures that are stopping the hip from going back into place are removed. The child then goes into a hip spica.
In general ultrasound is done up to six months as the hip is all cartilage and has not started to turn into bone. As the child matures the hip turns into bone and the ultrasound is not able to assess what is going on so an x-ray is needed
We know that in DDH whilst the child will hopefully respond to the original management of bracing / plaster that as the child matures they are at risk of still developing a dysplastic hip. In general we follow the kids up to the age of 10.
Some children who are treated successfully early on with their DDH will not continue to properly develop their hips so follow up necessary. Unfortunately the hip can become quite dysplastic and the yet the child will appear normal. By knowing early that there is a problem this can be dealt with surgically before the child has a hip that cannot be improved.
- Unfortunately no. A hip can be very dysplastic and doomed to eventually become degenerative and painful and yet in person they appear normal.
- Child (insert picture)
This age group is harder to diagnose than the neonate. In general the child themselves will NOT complain as any issues. You may notice there is an asymmetry to walking and that one side appears shorter than the other.
See your family doctor who can order an x-ray if indicated – the child is too late for an ultrasound. If there is dysplasia on the x-ray the child should see a Paediatric Orthopaedic Surgeon for management.
Usually there will be further imaging which might include:
- Further x-rays to see how the hip looks when held in different positions
- MRI to assess the structure of the hip including how much cartilage is there that might eventually turn into bone
- Arthrogram: this is a study done in theatre under a general anaesthetic whereby the Paediatric Orthopaedic Surgeons puts dye into the joint which then shows the outline of the of both the acetabulum (cup) and the femoral head (ball) and how the two dynamically relate to each other. The surgeon can then tell you whether the main issue is in the cup, the head or both. From this the surgeon can tell you an operative plan. Sometimes the arthrogram shows that there is enough cartilage present that may turn into bone so that the hip develops normally on its own. In that situation no surgery needs to be done at the time and you would continue to follow up in the future.
The surgery can either redirect the femoral head (ball) more into the center of the cup to stimulate development of the acetabulum (proximal femoral osteotomy) or can involve redirecting the acetabulum itself (pelvic osteotomy).
- Proximal femoral osteotomy; an incision is made along the outside of the upper part of the femur bone and then the femur redirected by cutting the bone (osteotomy) and then redirecting the head. The bone is then held in its new position with a plate that is directly on the bone. Usually no plaster is used after the operation Insert picture of femoral osteotomy with blade plate.
- Pelvic osteotomy: a skin incision is made along the front and side of the pelvis and the pelvic bone (ilium) is cut so that the acetabulum can be rotated “around” the femoral head to correct the dysplasia of the hip and give the femoral head more support. Depending on the age of the patient and stability of the osteotomy the child may need to go into a hip spica.
Insert picture of pelvic osteotomy
In general you will have noticed an asymmetry in your child’s gait or they will have been complaining of pain
Your child needs a standing x-ray of their pelvis
Usually in this age group if a child has symptoms or abnormal signs on examination they will need an operative procedure. Most often this is done by redirecting the acetabulum- occasionally the femur also needs to be dealt
- Triple Pelvic Osteotomy INSERT PICTURE
- Peri-Acetabular Ostotomy (PAO) INSERT PICTURE
The type of operation used depends on the surgeon’s training and experience. In practical terms there is no difference to the patient. The patient will start ambulating on crutches immediacy aft ether operation. A plaster cast is NOT used.