Hip dysplasia is a congenital defect in which the ball and socket joint of the hip is abnormally formed. The hip joint is comprised of two bony components: the acetabulum (socket) and the femoral head (ball). Hip dysplasia describes the condition of having a socket that does not fully cover the ball, leading to partial or complete dislocation of the hip socket. If left untreated, hip dysplasia will lead to the gradual degradation of the cartilage, oversized labrum, and the soft tissues lining the hip and ultimately cause the joint to become arthritic.
The vast majority of people who suffer from hip dysplasia are born with it, even if it only appears later in life. At birth, the hip joint is almost entirely comprised of cartilage that hardens into bone over time. If the ball of the femoral head is not properly seated in the socket at birth, it can lead to hip dysplasia as the cartilage turns to bone. There are a number of predisposing risk factors for the condition, including genetics, birth weight, birth position, and first pregnancies. It is also more common in women than men, for reasons we do not fully understand.
The symptoms of hip dysplasia vary based on the age of onset and the severity of the condition. In infants, the most common sign of dysplasia is one leg that’s longer than the other, while teenagers and young adults will present with pain, limping and a clicking or popping in the joint. Most patients with hip dysplasia have painless or painful snapping hip from the iliopsoas tendon. Adults will generally present with more severe pain that extends to the groin or buttocks, catching or locking, and instability in the joint. Interestingly, one of the telltale signs of hip dysplasia is extreme flexibility, which many people would consider a good thing. However, in this case, it is a sign that the hip is able to move far beyond its normal range of motion due to a shallow acetabulum. Dysplasia can ultimately lead to hip instability, labral damage, and early-onset arthritis if left untreated.
Diagnosis and Treatment
Infants are generally assessed for hip dysplasia by a pediatrician within the first few weeks of their life. They will likely conduct a physical examination of the joint, followed by an ultrasound if they feel it is warranted by their examination findings. Later in life, your doctor will likely rely on advanced imaging techniques to diagnose hip dysplasia. An x-ray will help them visualize any abnormal bony prominences in the hip, while magnetic resonance imaging (MRI) will help them understand what is happening with the soft tissues, including the labrum and the cartilage that holds the socket in place.
If you have been diagnosed with hip dysplasia, treatment will largely depend on your age. Infants can generally be treated non-operatively, but older children and adults will likely require surgery to correct their deformity. Mild dysplasia can often be treated arthroscopically with a labral repair and a tightening of the capsule surrounding the joint. Moderate to severe dysplasia requires correction of the mechanical and bony deformity with a surgical procedure called a peri-acetabular osteotomy (PAO).