Hip Impingement / Femoroacetabular Impingement (FAI)

Femoroacetabular impingement (FAI) happens when extra bone on the ball of the hip, the rim of the socket, or both, causes them to pinch together during movement. Over time this pinching can tear the labrum and damage cartilage. FAI is a common cause of groin pain in athletes and active adults.

Types of FAI

• Cam impingement: a bump on the femoral head-neck junction makes the ball less round. It’s more common in young athletes.
• Pincer impingement: the socket rim over-covers the ball.
• Combined: both are present, which is common.

Symptoms

Deep groin or front-of-hip pain with hip flexion and rotation, such as squatting, sitting in low chairs, getting out of a car, or cutting and pivoting in sport. Some patients also notice stiffness, clicking or reduced hip rotation. Many people have FAI shapes on X-ray with no pain at all, so treatment is based on symptoms, not X-rays alone.

Diagnosis

Dr. Dold uses specific exam tests and specialized hip X-rays to measure the bone shape. An MRI or MR arthrogram shows the labrum and cartilage, and a diagnostic injection can confirm that the joint is the pain source.

Non-surgical treatment

• Physical therapy for hip and core strength, and to avoid pinching positions
• Activity and training changes, such as limiting deep squats
• Anti-inflammatory medicine
• An image-guided joint injection

Hip arthroscopy for FAI

When pain persists despite non-surgical care, hip arthroscopy is performed as outpatient surgery through small incisions. Dr. Dold:

• Reshapes the cam bump (femoroplasty) and/or trims the pincer rim (acetabuloplasty)
• Repairs the labrum with suture anchors, or reconstructs it when needed
• Addresses cartilage damage where possible

Results are generally better in hips without significant arthritis, which is why early evaluation matters.

Recovery and return to sport

Most patients use crutches with protected (toe-touch) weight bearing and a hip brace for about 4 weeks, then progress through a structured physical therapy program. Return to running and sport usually takes about 3 to 6 months, based on strength and movement testing.

Does FAI cause arthritis?

FAI is recognized as one contributor to hip arthritis over time, particularly when it has caused labral and cartilage damage. Not everyone with an FAI hip shape develops arthritis. Surgery is recommended to relieve symptoms, not only to prevent arthritis.

Watch Dr. Dold: FAI surgery

Some of these videos show real surgery, so some viewers may prefer not to watch.

More videos on Dr. Dold’s YouTube channel.

What the research shows

FAI has been studied in several large randomized trials. Here is what they show.

A hip shape is not a diagnosis

Cam and pincer shapes are common in people with no pain, especially athletes. That is why international consensus defines FAI syndrome as the combination of symptoms, exam findings and imaging, and why treatment is based on the whole picture, not an X-ray alone. Larger cam deformities have been linked to a higher risk of arthritis later in life.

Arthroscopy compared with physiotherapy

In the UK FASHIoN and FAIT randomized trials, patients improved with both approaches, but hip arthroscopy led to greater improvement in pain, function and quality of life. Meta-analyses of these trials reach similar conclusions. Not every trial agrees: a smaller military trial found no significant difference at 2 years. For this reason, a structured trial of physiotherapy is a reasonable first step for many patients.

What happens during surgery matters

Repairing the labrum has produced better function than removing torn labral tissue in comparative studies, including a randomized trial. Studies of routine capsular closure show mixed results, but an insufficient capsule has been linked to hip instability after surgery.

Return to sport and long-term results

Most athletes return to sport after arthroscopy for FAI, and improvements have lasted 5 years or more in follow-up studies. Older age, arthritis on X-rays and advanced cartilage damage have been linked to a higher chance of a later hip replacement.

Why see Dr. Dold

• Hip arthroscopy research in AJSM and JBJS Reviews; Stryker Advanced Hip Arthroscopy Course (2018)
• Board certified by the American Board of Orthopaedic Surgery, with subspecialty certification in Sports Medicine
• Fellow of the American Orthopaedic Association (FAOA), the American Academy of Orthopaedic Surgeons (FAAOS), the American College of Surgeons (FACS) and the Royal College of Surgeons of Canada (FRCSC)
• Sports medicine and arthroscopy fellowship at NYU Langone / Hospital for Joint Diseases; orthopedic residency at the University of Toronto
• Member of the International Society for Hip Arthroscopy (ISHA)
• D Magazine Best Doctors (Collin County), 2019–2026 · Rated 4.9 on Google

Frequently asked questions

Research cited on this page

1. Griffin DR, Dickenson EJ, O’Donnell J, et al. The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. Br J Sports Med. 2016;50(19):1169-1176. PubMed
   International consensus: a diagnosis of FAI syndrome requires the right symptoms, positive exam findings and imaging findings together. Suitable treatments include conservative care, rehabilitation and surgery.
2. Griffin DR, Dickenson EJ, Wall PDH, et al. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. Lancet. 2018;391(10136):2225-2235. PubMed
   In a randomized trial of 348 patients, hip arthroscopy improved hip-related quality of life more than a personalized physical therapy program at 12 months.
3. Palmer AJR, Ayyar Gupta V, Fernquest S, et al. Arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of symptomatic femoroacetabular impingement: multicentre randomised controlled trial. BMJ. 2019;364:l185. PubMed
   In a second randomized trial, patients treated with arthroscopic surgery reported better hip function at 8 months than those treated with physiotherapy and activity modification.
4. Agricola R, Heijboer MP, Bierma-Zeinstra SM, et al. Cam impingement causes osteoarthritis of the hip: a nationwide prospective cohort study (CHECK). Ann Rheum Dis. 2013;72(6):918-923. PubMed
   Over 5 years, hips with a cam-type deformity were more likely to develop end-stage arthritis, especially when hip rotation was also reduced.
5. Ramos N, Dold A, Youm T. Postoperative considerations following hip arthroscopy. JBJS Rev. 2017;5(7):e3. PubMed
   A review of recovery and rehabilitation after hip arthroscopy, co-authored by Dr. Dold.
6. Reiman MP, Agricola R, Kemp JL, et al. Consensus recommendations on the classification, definition and diagnostic criteria of hip-related pain in young and middle-aged active adults from the International Hip-related Pain Research Network, Zurich 2018. Br J Sports Med. 2020;54(11):631-641. PubMed
   The Warwick consensus distinguishes FAI syndrome (symptoms, exam findings and imaging together) from FAI shapes seen on imaging in people without pain.
7. Frank JM, Harris JD, Erickson BJ, et al. Prevalence of Femoroacetabular Impingement Imaging Findings in Asymptomatic Volunteers: A Systematic Review. Arthroscopy. 2015;31(6):1199-204. PubMed
   A review of 2,114 hips in people without symptoms found cam morphology in about 37% overall, and in more than half of athletes.
8. Mascarenhas VV, Rego P, Dantas P, et al. Imaging prevalence of femoroacetabular impingement in symptomatic patients, athletes, and asymptomatic individuals: A systematic review. Eur J Radiol. 2016;85(1):73-95. PubMed
   FAI imaging findings were common in athletes and people without symptoms, but differed in type from those in patients with symptoms.
9. Thomas GE, Palmer AJ, Batra RN, et al. Subclinical deformities of the hip are significant predictors of radiographic osteoarthritis and joint replacement in women. A 20 year longitudinal cohort study. Osteoarthritis Cartilage. 2014;22(10):1504-10. PubMed
   In a large cohort of women, larger cam deformities predicted later hip arthritis and hip replacement.
10. Ahedi H, Winzenberg T, Bierma-Zeinstra S, et al. A prospective cohort study on cam morphology and its role in progression of osteoarthritis. Int J Rheum Dis. 2022;25(5):601-612. PubMed
    A prospective cohort found cam morphology was linked to later bone marrow lesions and joint swelling in the hip.
11. Griffin DR, Dickenson EJ, Achana F, et al. Arthroscopic hip surgery compared with personalised hip therapy in people over 16 years old with femoroacetabular impingement syndrome: UK FASHIoN RCT. Health Technol Assess. 2022;26(16):1-236. PubMed
    In the UK FASHIoN trial, hip arthroscopy improved hip-related quality of life more than personalized physiotherapy, though both groups improved.
12. Palmer A, Fernquest S, Rombach I, et al. Medium-term results of arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of femoroacetabular impingement syndrome: a multi-centre randomised controlled trial. Br J Sports Med. 2025;59(2):109-117. PubMed
    Medium-term follow-up of the FAIT trial found better function and less cartilage damage on MRI after arthroscopy, with no difference in X-ray joint space at about 3 years.
13. Mansell NS, Rhon DI, Meyer J, et al. Arthroscopic Surgery or Physical Therapy for Patients With Femoroacetabular Impingement Syndrome: A Randomized Controlled Trial With 2-Year Follow-up. Am J Sports Med. 2018;46(6):1306-1314. PubMed
    A military trial found no significant 2-year difference between arthroscopy and physical therapy, and many patients in both groups had limited improvement.
14. Dwyer T, Whelan D, Shah PS, et al. Operative Versus Nonoperative Treatment of Femoroacetabular Impingement Syndrome: A Meta-analysis of Short-Term Outcomes. Arthroscopy. 2020;36(1):263-273. PubMed
    A meta-analysis of randomized trials found arthroscopy gave better short-term hip outcomes than physical therapy alone.
15. Gatz M, Driessen A, Eschweiler J, et al. Arthroscopic surgery versus physiotherapy for femoroacetabular impingement: a meta-analysis study. Eur J Orthop Surg Traumatol. 2020;30(7):1151-1162. PubMed
    A meta-analysis of 3 high-quality randomized trials found arthroscopic surgery more effective than physiotherapy.
16. Kim CH, Moon JK, Yoon JY, et al. Arthroscopy versus nonoperative treatment of symptomatic femoroacetabular impingement syndrome: A systematic review and meta-analysis. Medicine (Baltimore). 2020;99(49):e23247. PubMed
    A meta-analysis found arthroscopy gave better hip quality-of-life scores at 12 months, but other outcome scores did not clearly differ.
17. Ramadanov N, Lettner J, Voss M, et al. Minimal Clinically Important Differences in Conservative Treatment Versus Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Frequentist Meta-Analysis of RCTs. Orthop Surg. 2025;17(9):2514-2528. PubMed
    A 2025 meta-analysis found arthroscopy improved function compared with conservative care, though differences in some measures were not significant at 8 months or less.
18. Wu ZX, Ren WX, Ren YM, et al. Arthroscopic labral debridement versus labral repair for patients with femoroacetabular impingement: A meta-analysis. Medicine (Baltimore). 2020;99(19):e20141. PubMed
    A meta-analysis found labral repair gave better function, pain and satisfaction scores than labral debridement.
19. Krych AJ, Thompson M, Knutson Z, et al. Arthroscopic labral repair versus selective labral debridement in female patients with femoroacetabular impingement: a prospective randomized study. Arthroscopy. 2013;29(1):46-53. PubMed
    In a randomized trial of women with FAI, labral repair gave better function than debridement.
20. Savoye-Laurens T, Verdier N, Wettstein M, et al. Labral tears in hip dysplasia and femoroacetabular impingement: A systematic review. Orthop Traumatol Surg Res. 2023;109(4):103539. PubMed
    A review found labral tears in most hips with impingement, and one study reported better 10-year survival after repair than debridement.
21. Liu L, Zhang Y, Gui Q, et al. Effect of Capsular Closure on Outcomes of Hip Arthroscopy for Femoracetabular Impingement: A Systematic Review and Meta-analysis. Orthop Surg. 2020;12(4):1153-1163. PubMed
    A meta-analysis of capsular closure after hip arthroscopy found no significant differences in function, satisfaction or complications.
22. Duplantier NL, McCulloch PC, Nho SJ, et al. Hip Dislocation or Subluxation After Hip Arthroscopy: A Systematic Review. Arthroscopy. 2016;32(7):1428-34. PubMed
    Hip dislocation after arthroscopy was linked to undercoverage of the socket, capsular insufficiency and some soft-tissue releases.
23. Minkara AA, Westermann RW, Rosneck J, et al. Systematic Review and Meta-analysis of Outcomes After Hip Arthroscopy in Femoroacetabular Impingement. Am J Sports Med. 2019;47(2):488-500. PubMed
    A high percentage of patients returned to sport after hip arthroscopy for FAI, with low complication and reoperation rates.
24. Weber AE, Bolia IK, Mayfield CK, et al. Can We Identify Why Athletes Fail to Return to Sport After Hip Arthroscopy for Femoroacetabular Impingement Syndrome? A Systematic Review and Meta-analysis. Am J Sports Med. 2021;49(6):1651-1658. PubMed
    About 12% of athletes did not return to sport after hip arthroscopy for FAI, most often because of persistent pain.
25. O’Connor M, Minkara AA, Westermann RW, et al. Return to Play After Hip Arthroscopy: A Systematic Review and Meta-analysis. Am J Sports Med. 2018;46(11):2780-2788. PubMed
    Return-to-play rates after hip arthroscopy were high, but rehabilitation protocols varied widely between centers.
26. Kyin C, Maldonado DR, Go CC, et al. Mid- to Long-Term Outcomes of Hip Arthroscopy: A Systematic Review. Arthroscopy. 2021;37(3):1011-1025. PubMed
    A review of mid- to long-term follow-up (5 to 20 years) found lasting improvement after hip arthroscopy, with variable rates of later hip replacement.
27. Griffin DW, Kinnard MJ, Formby PM, et al. Outcomes of Hip Arthroscopy in the Older Adult: A Systematic Review of the Literature. Am J Sports Med. 2017;45(8):1928-1936. PubMed
    Hip arthroscopy in older adults without significant arthritis gave favorable results, though some later needed hip replacement.
28. Uzun E, Ferrer-Rivero J, Lizano X, et al. High satisfaction and low conversion rate to total hip arthroplasty after hip arthroscopy for femoroacetabular impingement syndrome and risk factors affecting survival at long-term follow-up. Knee Surg Sports Traumatol Arthrosc. 2025;33(4):1507-1514. PubMed
    Older age, more arthritis on X-ray and full-thickness cartilage damage were linked to conversion to hip replacement after arthroscopy for FAI.

Medically reviewed by Andrew P. Dold, MD, FAOA, FAAOS, FACS, FRCSC. Last reviewed September 30, 2026. This page is general information, not medical advice.