Hip pain is a common complaint among athletes. A particular area of recent focus is Femoroacetabular impingement (FAI). FAI typically affects young athletes. FAI is a specific hip or groin pain caused by anatomic abnormalities that affect the normal range of motion of the hip. This mechanical mismatch can injure the surrounding tissue of the hip joint, specifically, the labrum. Initial injury to the labrum can then progress in degenerative joint disease that has the potential to lead to arthritis. These abnormalities in anatomy and mechanics are now thought to be a cause of hip osteoarthritis. The prevention of injury is a priority of sports medicine physicians leading to in-depth research in FAI. Advances in FAI management hope to aid in the prevention of osteoarthritis, which has the possibilities of prolonging pain-free athletic careers.

Understanding femoroacetabular impingement begins with basic anatomy. The hip is a ball and socket joint made up of the femur (thigh bone) and the pelvic bone called the acetabulum. The acetabulum is then surrounded by cartilage called the labrum which acts as a gasket for the hip joint. Normally, this ball and socket engineering allows for a wide range of motion seen in extremes in athletes playing hockey, gymnastics and dancing.

Any changes in the normal anatomy in the hip can cause pathology. Patients with FAI will complain of pain, usually worsened with prolonged sitting or standing as well as activities that require deep bending at the hip. Another complaint will be clicking, locking or catching of the hip. Subtle changes in the normal anatomy of the hip’s ball and socket joint can result in pain and chronic hip problems that can be on-going for those patients and athletes with FAI.

FAI can have specific findings during a physical exam. Patients and athletes will complain of chronic on-going, deep, groin or side of the leg to buttock pain. Pain during provocative testing often occurs. One common position is bending at the hip, adduction and internal rotation of the hip joint. Another sign affected patients will show is when the patient cups his or her hand around the outside of the hip forming a C-shape which is commonly called the “C-sign”.

Two proposed causes of FAI are changes in the bones themselves: cam impingement and pincer impingement. The cam lesion is defined as an abnormal shape of the femur bone going into the socket. The cam lesion is most commonly present in young males. It can present as vague hip pain with hip bending, adduction and internal rotation. The lesion causes a mechanical pressure to the hip’s labrum, which then also affects the articular cartilage. Cam lesions are initially diagnosed on a plain X-ray film, seen below. Findings can be obvious or subtle.

Pincer impingement is an abnormal shape of the acetabulum or hip socket. This impingement is more common in active, middle aged women. Pincer impingement occurs because additional bone extends over the normal edge of the acetabulum causing over-coverage of the hip joint. The labrum can be pinched under the prominent rim of the acetabulum which then affects the articular cartilage. Two deformities may also be present in cases in which the FAI would be termed mixed and defined as a combined form of impingement.

After the diagnosis of FAI is made, the proper treatment plan is set into place. Most commonly, treatment begins with physical therapy and medications for inflammation and pain control. It is important that physical therapy focuses on strengthening and range of motion of the hips. Improving strength in the hips and muscles surrounding the joint will help to alleviate stress in the already abnormal areas of the hip ball and socket joint. Another recommendation can be simply lifestyle modification. These changes in a daily routine can also help limit stress to the hip areas.

For more severe cases or if the mechanical problems of FAI do not improve, a physician may recommend injection and/or surgical intervention. Two options of surgery are open incision and arthroscopy. Research continues to grow in the field of hip arthroscopy or minimally invasive surgery. Hip arthroscopy could be a possibility for patients with the diagnosis of FAI in the hands of a skilled surgeon. The focus of surgical treatment is to correct the mechanical abnormalities of the bones called osteotomy, as well as consideration for repair to the labrum based on the surgeon’s findings.

Non-surgical and surgical treatments of femoroacetabular impingement continue to be an evolving field of study in sports medicine. As research studies continue in the diagnosis and treatment of FAI, patients and their physicians will be able to address this issue even more effectively and help patients with FAI stay in the game.

AMSSM Member Authors
Ryan Schreiter, DO and Mark Sakr, DO