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What is Hip Impingement or FAI?

by | September 29, 2022

Hips work hard to bear our weight and support our movement. For that reason, problems affecting hips can take their toll on our overall quality of life and affect activities like running. Femoroacetabular impingement (FAI) or hip impingement is one of those problems. While this condition isn’t that frequently discussed, it can cause severe damage and limit a person’s range of motion. Learn more about hip impingement and how to treat it below.

What is Hip Impingement or FAI?

Femoroacetabular impingement (FAI) is a condition wherein the femoral head or ball of the hip joint pinches up against the cup of the hip, known as the acetabulum. In people with FAI, the hip joint isn’t shaped normally. The bones are too close and pinch tissue, thus causing a great deal of friction.

There are several types of hip impingement:

  • Pincer – happens when extra bone extends out of the normal rim of the cup of the hip. The prominent rim of the acetabulum can crush the labrum (fibrous cartilage) and cause damage
  • Cam – femoral head isn’t round and is unable to rotate smoothly. At the edge of the femoral head, the bump forms and grinds cartilage
  • Combined impingement – the presence of pincer and cam impingement at the same time
Femoroacetabular hip Impingement (fai)

The estimated prevalence of FAI is 10% to 15%, as numbers show (1). Around 86% of cases account for combined impingement, whereas 14% of cases include pincer or cam impingement alone. Damage to the cartilage, caused by FAI, can lead to stiffness and pain in the hip joint. Eventually, a person may develop osteoarthritis, one of the most common types of arthritis.

How Do You Know If You Have FAI?

Hip impingement can be asymptomatic, i.e. without noticeable signs and symptoms. When symptoms do appear, the affected person may experience the following:

  • Ache or pain in the groin area or inner hip
  • The pain usually occurs after walking or prolonged sitting
  • Low back pain
  • Clicking or locking within the hip joint
  • Difficulty putting on shoes or socks
  • Struggling to walk uphill
  • Pain at the sacroiliac joint or buttock
  • Limping
  • Stiffness of the hip

Pain associated with FAI is easy to confuse with other sources of pain, such as sports hernia, hip flexor tendinitis, and testicular pain, among others (2).

What Causes Hip Impingement?

The causes of hip impingement aren’t entirely clear. Sometimes abnormalities are present at birth, but people can also develop FAI later in life. The condition is caused by irregular development of hip bones. Deformity of cam or pincer bone spur causes joint damage.

Evidence shows FAI is a multifactorial condition. Possible factors involved in the development of hip impingement include repetitive athletic activity, prior hip surgery, and pediatric hip disease.

Sometimes a combination of genetic factors and sports activities such as those involving vigorous flexion and rotation during adolescence can alter the development of hip anatomy. Examples of sports that include vigorous flexion and rotation include football, basketball, and hockey (3).

Fortunately, hip impingement in runners is usually related to the soft tissues, which means that conservative care is frequently successful, especially when caught early.

Hip Impingement and FAI adjustment

How is FAI diagnosed?

Patients who experience the abovementioned symptoms should see a healthcare provider. The doctor may suspect hip impingement is the culprit, but they will order some tests to rule out other potential causes.

Diagnosis of FAI may involve patient history, physical exam, and imaging tests such as an X-ray, CT, and MRI. The doctor will also perform an impingement test by bringing your knee to the chest and rotating it toward the opposite shoulder. A person with FAI will feel pain during this movement.

How is FAI treated?

The first line of treatment for FAI includes rest, the use of non-steroidal anti-inflammatory (NSAID) medications, activity modification, and conservative treatments, like chiropractic and/or physical therapy. Stronger medications and injections are the next step and surgery is the final step.

Conservative Treatment for FAI

People with hip impingement  are advised to consider the following techniques to reduce their symptoms:

  • Resting by laying down in periods of acute pain
  • Avoiding triggering activities such as deep squats or extreme hip flexion
  • Applying hot and cold therapy on the buttocks and/or legs at home
  • Using over-the-counter painkillers to soothe the pain (limited effectiveness)

Exercises focused at improving glute strength and activation as well as improving hip joint range-of-motion can be effective treatments.

Other treatments that can be extremely effective at relieving piriformis syndrome include Graston Technique, chiropractic adjustments or mobilizations to the involved hip, Kinesio Taping and corrective exercises.

Hip Impingement and FAI adjustment

Hip Impingement Surgery

Surgical treatment of hip impingement has two goals. The first goal is to tackle damage to the hip joint by repairing or removing affected tissue. The second objective of surgery is to improve or correct the abnormal shape of the hip joint. Surgery may be recommended for young patients, e.g. adolescents, who want to reduce pain and stay active.

There are several surgical procedures for patients with FAI. They include:

  • Hip arthroscopy – allows surgeons to reach the hip joint through small incisions, thus minimizing damage to surrounding tissues. During the procedure, the surgeon performs osteoplasty i.e. reshapes the bone by removing excess bone growth.
  • Surgical hip dislocation – gives the surgeon open access to the entire hip joint to perform osteoplasty or fix damage to the bone.
  • Periacetabular osteotomy and femoral osteoplasty – procedures to reposition the hip socket and reshape the femur. The goal is to provide more stability.
  • Total hip replacement – necessary for people with chronic hip pain caused by osteoarthritis, especially if they have severe limitations in range of motion

A review from the Journal of Science and Medicine in Sport shows the surgical procedure for FAI was superior to non-operative treatments at 12 months but not 24 months of follow-up (4). Other studies also show surgical procedures for FAI are effective but emphasize the importance of evaluating its long-term effects (5).

Recovery time depends on the type of surgery. Minimally-invasive approaches require a few weeks of recovery, whereas more invasive procedures can involve recovery that lasts for months. The surgeon recommends the most suitable type of procedure depending on the severity of the condition and the patient’s needs.


Hip impingement can be congenital or acquired. When left unmanaged, it can cause major problems such as joint damage and lead to arthritis. Doctors usually start with conservative treatment and recommend surgery if they don’t work. You may need to modify your lifestyle to protect your hips, as well.


  • Lee WY, Kang C, Hwang DS, Jeon JH, Zheng L. Descriptive Epidemiology of Symptomatic Femoroacetabular Impingement in Young Athlete: Single Center Study. Hip Pelvis. 2016;28(1):29-34. doi:10.5371/hp.2016.28.1.29
  • Femoroacetabular impingement (FAI) symptoms. Stanford Medicine. https://stanfordhealthcare.org/medical-conditions/bones-joints-and-muscles/femoroacetabular-impingement/symptoms.html
  • Chaudhry H, Ayeni OR. The etiology of femoroacetabular impingement: what we know and what we don’t. Sports Health. 2014;6(2):157-161. doi:10.1177/1941738114521576
  • Ferreira GE, O’Keeffe M, Maher CG, et al. The effectiveness of hip arthroscopic surgery for the treatment of femoroacetabular impingement syndrome: A systematic review and meta-analysis. J Sci Med Sport. 2021;24(1):21-29. doi:10.1016/j.jsams.2020.06.013
  • Richardson RSF, Lothe K, Sturridge S. Is surgery effective in patients with femoroacetabular impingement syndrome? The BMJ. 2019;365:1359.

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