Introduction / Anatomy
The hip is one of the largest joints in the body and is often subjected to large forces, especially with running and jumping, or when significant trauma is involved. The ball (femoral head) and socket (acetabulum) are normally covered with a 3 – 4 mm layer of firm cartilage which permits smooth gliding of the two surfaces over each other. With and injury or degeneration, the articular cartilage may crack, fissure, or even shed loose segments into the joint. These “loose bodies” may cause additional damage if they get caught between the ball and socket surfaces. A firm, fibrocartilaginous rim (labrum) encircles the cup to help confine and distribute loads across the joint evenly. This labrum may tear and if it becomes unstable, can become periodically entrapped between the femoral head (ball) and acetabulum (cup). If this happens, it can lead to degenerative arthritic changes with increased pain and stiffness.
Hip pain may be secondary to inflammation of the synovial or “lining” tissues, degenerative arthritis with “bone-on-bone” wear and impinging spurs, entrapment of the cartilage labrum, or catching of loose bodies. There may also be an accompanying progressive stiffness or catching / locking. Depending on the severity of the symptoms, a limp is not uncommon.
Examination findings include a restriction of motion, especially rotation when the hip is flexed. Popping or snapping may occasionally be heard or felt with motion. Pain is often worsened when the hip is flexed and then brought across the midline of the body. Routine X-rays reveal a variable degree of arthritis with loss of joint space between the ball and socket or acetabulum, bone spurs, or cavities. It is also possible to detect a misshapen neck of the femur or acetabular rim overgrowth, both of which can lead to bony impingement and labral tearing. MRI studies, often with contrast dye, are much more sensitive in detecting labral tears and defects of the cartilage surface of the joint.
Hip arthroscopy offers the opportunity to treat many hip disorders with a minimally-invasive approach. During the surgery, the leg of the involved hip is placed in traction to separate the hip approximately 1/4 of an inch which improves access to the entire hip joint and minimizes the chance of instruments scuffing the articular cartilage. Tubular cannulas (fig. 1) are introduced into the joint permitting the introduction of the arthroscope and various instruments including shavers, punch baskets, graspers and heat probes (fig. 2). Loose bone or cartilage bodies (fig. 3) can be removed and damaged cartilage shaved to a more stable surface.
Labral tears (fig. 4) are shaved or repaired with anchors and sutures if amenable. When the neck of the femur and rim of the acetabulum impinge, the abnormal surfaces can be reshaped with a small burr (fig. 5). If the joint lining or synovium is intensely inflammed, it can be removed with a shaver (fig. 6).
Following most hip arthroscopies, crutches are used for a period of 3 – 5 days. If significant bone removal is necessary, protected weight-bearing is continued for 4 weeks to prevent the possibility of an inadvertent fracture. Physical therapy can assist in regaining full range-of-motion and restoring normal strength of the muscles about the hip. Most activities can be resumed by 6 weeks unless tissues are repaired in which case a longer period,
up to 4 months may be necessary.