HIP DYSPLASIA OR DEVELOPMENTAL DYSPLASIA OF THE HIP (DDH)
Overview
The hip is a ball-and-socket joint that normally sees the femoral head (“ball”) seated firmly in the acetabulum (“socket”). There are a number of different conditions that can greatly impact proper development of the hip joint in children, greatly impacting their potential to lead active, healthy and pain-free lives.
One of the most common hip conditions in children is Developmental dysplasia of the hip (DDH), affecting 1-3% of all newborns. DDH encompasses a range of hip joint abnormalities, from mild instability to complete hip dislocations at birth.
Our bones develop over time from soft cartilage, and the hip joint is particularly underdeveloped at birth. DDH is when a baby has a hip joint that is abnormally loose (the “ball” can move around too much in the “socket”), or completely out of the socket altogether (dislocated). DDH in infancy can cause children to later develop arthritis in the hip joint at a young age, and/or require a hip replacement in young adulthood. This is particularly true if DDH is not caught and treated as early as possible in life.
1-3%
DDH is the most common paediatric hip condition, affecting approximately 1-3% of infants
Approximately
1-3 infants/1000 live births are diagnosed with a dislocated hip, and a further
15-20/1000 are affected by some degree of hip instability.
Risk Factors
According to the American Academy of Orthopaedic Surgeons (AAOS) guidelines, risk factors warranting selective ultrasound screening for DDH include:
Breech presentation
Family history of DDH
History of clinical hip instability
History of swaddling
Other risk factors that have potentially been implicated in past studies include:
Female sex
First born
High birth weight
Oligohydramnios
Symptoms
DDH can be difficult to diagnose in infants because it does not usually cause babies pain, and may not have many overt symptoms. Diagnoses should be confirmed by either ultrasound or x-ray imaging. Potential symptoms in babies can include asymmetric buttock creases, hip clicks or pops, or limited range of motion in the hip joint that a parent may notice if they have difficulty diapering. In older children, pain, limping/waddling gait and/or a swayback may suggest hip dysplasia.
Treatment
In most mild cases of DDH, and/or in infants diagnosed early, non-operative treatment by a harness or brace can often be effective at stabilizing the hip and promoting normal, healthy development of the hip joint. The Pavlik harness is most commonly used in infants under six months of age. It is a dynamic, or flexible, harness that allows for movement while keeping the baby’s hips in a flexed and abducted position. More rigid braces, hip abduction braces, may also be used to keep the baby’s hips in position.
Surgical treatment options may include either closed or open reduction of the hip.
Closed reduction: With the baby under anesthesia, the femoral head (“ball”) is physically manipulated back into the acetabulum (“socket”) by the surgeon. Usually, the surgeon will also perform an adductor tenotomy at the same time. This involves making a small incision near the hip joint and releasing the adductor tendon to relieve pressure on the hip joint and making it easier for the femoral head to stay in the correct position.
Open reduction: This surgical approach involves opening the hip joint capsule to remove any tissues or other barriers preventing the femoral head from sitting properly in the acetabulum. Once any barriers are removed, the femoral head can be positioned correctly in the acetabulum.
Open reduction may also be accompanied by either a femoral or pelvic osteotomy if any reshaping of the hip joint is needed to properly position the ball in the socket. Femoral osteotomy involves cutting the bones of the femur to realign the joint. Pelvic osteotomy involves cutting the pelvic bones to deepen/reshape the acetabulum to allow the femoral head to sit firmly in the socket.
After surgery, the baby is usually placed in a hip spica cast for 1-3 months to keep the hips properly aligned while healing. After removal of the hip spica cast, they may be transitioned into a brace for a period of time to ensure proper hip joint development.