Hip impingement is a mechanical disorder of the hip. It is a common cause of stiffness and pain in the hip, and can eventually lead to arthritis. Impingement refers to the thighbone pinching against the pelvis bone, which happens when the mechanics or bone structure of the hip are not perfect.
Children can be born with this problem, or it can result from repetitive stress to the hip from athletics. When the two bones impinge, they trap the labrum (a cartilage bumper that nearly fully encircles the socket [pelvis] side of the hip joint). Repeated impingement can cause a labral tear – and eventually a cartilage tear – that leads to arthritis.
Symptoms of hip impingement include:
- Pain in the hip (groin), especially when flexing the hip.
- Stiffness in the hip.
The diagnosis of hip impingement can be made with a physical exam and X-rays. Often, the X-rays will show the imperfections in bone structure that can cause impingement. A torn labrum cannot be seen on X-ray, but an MRI can show a tear. The MRI should be done with dye having been injected into the hip joint to give a clearer picture of the labrum.
Treatment of hip impingement should begin with rest from painful activities, such as running, jumping and dancing. Physical therapy can be beneficial to restore better joint mechanics and improve flexibility and strength.
If conservative management fails to improve hip motion and pain after six weeks, an MRI should be done. If the MRI shows a labral tear and bone problems have been identified, surgery can be done to repair the labrum and change the bone problems so that the hip impingement is improved. The child should return to sports only when he or she has full motion and strength, and has no pain.