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Hip

Femoroacetabular Impingement (FAI)

The hip is a ball-and-socket joint and the largest weight-bearing joint in the body. The upper end of the thigh bone (femur) is the ball that fits into the socket (the acetabulum) in the pelvis. Both sides of the hip joint are lined with articular cartilage, which allows the joint to glide easily and offers a wide range of motion.

The acetabular labrum is a circular ring of cartilage on the edge of the acetabulum that deepens the hip joint. The labrum also tightens the seal between the bones for joint stability, allowing for a wide range of motion in a normal, healthy joint.

Femoroacetabular impingement (FAI) is characterized by bony abnormalities that cause abnormal contact between the femoral head (ball) and the acetabulum (socket) of the hip joint, and the hip moves through its range of motion.

This irregular contact alters normal biomechanics and causes friction, creating bony prominences that damage the joint over time. If left untreated, this can cause labral tears and articular cartilage injury, contributing to hip pain and potentially leading to hip osteoarthritis.

FAI is generally categorized into three types based on the shape of the hip structures involved:

  • Cam Impingement occurs when the femoral head is not perfectly round, which typically develops during late adolescence/early adulthood. This can cause impingement during hip movements, particularly in flexion and internal rotation.
  • Pincer Impingement: This type of impingement involves an extra-deep acetabulum or hip socket. With hip movement, the labrum can be pinched under the prominent rim of the acetabulum.
  • Mixed Impingement: A combination of both cam and pincer types. This is the most common type of FAI.

Genetics, developmental factors, and repetitive stress on the hip joint from high-intensity activities at a young age, such as running and kicking, contribute to the development of FAI.

FAI can be seen in athletes participating in sports such as soccer, basketball, baseball, ice hockey, skiing, golf, and dance. FAI is a common cause of hip and groin pain in adolescents and young, active individuals.

It is important to note that FAI can also be seen in those without any hip pain or symptoms.

  • Patients with FAI typically present with intermittent, deep groin pain or pain located at the front of the hip.
  • The pain is often aggravated by activities that involve hip flexion and rotation, such as squatting, running, or sitting for prolonged periods.
  • Pain can occur with subtle decreases in certain hip ranges of motion, specifically flexion and internal rotation.
  • Some may sense a clicking or popping sensation in the hip.

The diagnosis of FAI involves a combination of clinical examination, patient history, and imaging studies. Your UCSF Women’s Sports Medicine expert will assess your hip symptoms, range of motion, and strength to comprehensively evaluate your hip condition. X-rays will identify abnormalities in the hip joint structure and allow for measurements necessary to diagnose FAI. At the same time, magnetic resonance imaging (MRI) can help assess the labrum, cartilage, and surrounding bone.

If you are diagnosed with FAI, our team will develop a comprehensive treatment plan tailored to your needs.

Treatment options for FAI range from conservative management to surgical intervention, depending on the severity of symptoms and the degree of joint damage.

  • A trial of conservative treatment is the gold standard in initial care for FAI, as the majority of patients see improvement. This includes physical therapy focused on core and gluteal muscle strengthening, improving range of motion, activity modifications to avoid movements that exacerbate symptoms, and non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain. Intra-articular injections can decrease inflammation, improve function, and be a diagnostic tool.
  • Surgical treatment, called hip arthroscopy, is an option when conservative measures fail to relieve symptoms. Hip arthroscopy surgery corrects the abnormal hip anatomy by removing excess bone to prevent further impingement and repair the damaged labrum. In certain circumstances, the labrum may be trimmed or reconstructed with a graft, depending on the individual patient’s condition.

When you or a loved one experiences hip pain, it is important to seek professional care. The UCSF Women’s Sports Medicine Center is here to support female athletes of all ages and abilities, from recreational to elite, with our team of sports medicine and orthopaedic specialists. Contact us to schedule a consultation and learn more.

References

  • Wong SE, Cogan CJ, Zhang AL. Physical Examination of the Hip: Assessment of Femoroacetabular Impingement, Labral Pathology, and Microinstability. Curr Rev Musculoskelet Med. 2022;15(2):38-52. doi:10.1007/s12178-022-09745-8
  • APathy R, Sink EL. Femoroacetabular impingement in children and adolescents. Curr Opin Pediatr. 2016 Feb;28(1):68-78. doi: 10.1097/MOP.0000000000000301. PMID: 26709682.
  • Lorenzon P, Scalvi A, Scalco E. The Painful Hip in Young Adults Between Impingement and Mild Dysplasia: Clinical and Instrumental Diagnostical Criteria. Acta Biomed. 2020 May 30;91(4-S):11-20. doi: 10.23750/abm.v91i4-S.9666. PMID: 32555072; PMCID: PMC7944806.
  • Joanna L Langner, Marianne S Black, James W MacKay, Kimberly E Hall, Marc R Safran, Feliks Kogan, Garry E-Gold, The prevalence of femoroacetabular impingement anatomy in Division 1 aquatic athletes who tread water, Journal of Hip Preservation Surgery, Volume 7, Issue 2, July 2020, Pages 233–241.
  • Hale RF, Melugin HP, Zhou J, et al. Incidence of Femoroacetabular Impingement and Surgical Management Trends Over Time. The American Journal of Sports Medicine. 2021;49(1):35-41. doi:10.1177/0363546520970914
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