The hip joint is a ball-and-socket joint that is comprised of the head of the femur (ball) and the acetabulum (socket). Sometimes during development, the acetabulum fails to fully cover the femoral head. The shallow socket of the acetabulum results in partial or complete dislocation of the femoral head, which can have devastating effects on the cartilage over time.
What is hip dysplasia?
Hip dysplasia is a disorder of the hip joint in which the femoral head (ball) does not fit correctly within the acetabulum (socket). The femoral head either does not line up properly with the contour of the socket, or in other cases the socket is too shallow to support the femoral head in place. Most people with hip dysplasia are born with the condition. Hips with dysplasia tend to wear out faster than normal shaped hips, leading to progressive destruction of the articular cartilage and arthritis.
What are the symptoms of hip dysplasia?
Symptoms of hip dysplasia may present at different stages of life. In infancy, hip dysplasia may present with unequal leg lengths. The affected hip may also be less flexible than the other during diaper changes. Once the child learns to walk, they may develop a limp on the affected hip.
In young adults, hip dysplasia may cause tears to the labrum or early stages of arthritis. These will present with new onset activity-related groin pain. In severe cases, a sensation of hip instability and/or dislocation may be present.
Who has hip dysplasia?
Most individuals with hip dysplasia are born with the condition. Approximately 1 in 10,000 babies are born with hip dysplasia and females and first-born children are more likely to have it. Hip dysplasia can be caused while in the womb by increased pressure on the hips during development. First pregnancy, large baby, and breech position (abnormal baby position in the womb) are all risk factors that reduce the amount of space and increase the pressure within the womb. Hip dysplasia may also be genetic, or passed down in families.
How is hip dysplasia diagnosed?
Hip dysplasia is initially screened in infancy during well-baby visits. A special physical exam maneuver that moves the hip in a variety of directions can indicate if the ball fits properly within the socket. In babies older than 6 months old, an x-ray, ultrasound, or CT scan is used to confirm the diagnosis.
In mild cases, it may be more difficult to diagnose in infancy with the physical exam and it may not be diagnosed until young adulthood when the hip begins to start causing problems.
How is hip dysplasia treated?
In infancy, hip dysplasia may be treated non-surgically with braces and/or casting depending on the age of the child. However, in young adults and severe cases, surgery may be required to properly align the hip joint and prevent the progression of debilitating cartilage damage and arthritis.
Hip-preserving surgery to correct hip dysplasia is possible in young adults who have not yet developed severe arthritis. This includes an osteotomy procedure, which entails cutting the bone and shifting it to a better location. Periacetabular osteotomy (PAO) is the term used for an osteotomy of the hip socket most commonly used for this condition. It involves removing a segment of bone from the socket and positioning it in a location that will better support the femoral head during walking and activities of daily living. The bone is secured in place with screws until the bone fully heals. It takes about 3 months after surgery for the patient to be able to fully weight bear on the operated hip.
In older patients with end-stage arthritis, a hip replacement is the most appropriate treatment option. This procedure involves removing the damaged femoral head (ball) and part of the acetabulum (socket) and replacing it with prosthetic implants that restore the function of the joint.