Dr. Clive Clutton
What FAI is
FAI describes a mismatch in the shape of the ball (the top of the thigh bone) and the socket of the hip. When the hip bends deeply or rotates, the two can meet earlier than usual, which can irritate the cartilage and the labrum, the rim of tissue around the socket.1 It is called FAI syndrome when that shape comes with symptoms and matching exam findings. Many people have the shape on imaging and no pain at all.
The three types
- Cam. Extra bone on the ball, so it is less round. More common in young, active men.
- Pincer. The socket covers more of the ball than usual.
- Mixed. Features of both, and very common.
Common symptoms
- Pain in the groin or front of the hip, sometimes felt at the side
- Pain in deep squats, getting in and out of a car, or after sitting for a while
- Pain with pivoting, kicking or sprinting
- A pinching feeling when the knee is pulled toward the chest
Does it lead to arthritis?
A large cohort study found that people with a more pronounced cam shape (an alpha angle over 60°) had a higher risk of developing end-stage hip arthritis over five years.2 That is an association, not a guarantee. Many people with a cam shape never develop arthritis, and the study does not show that treating the shape prevents it.
Conservative care first
Exercise-based care is commonly recommended as a first approach for FAI syndrome.1 A 2025 meta-analysis of 21 randomised trials compared it with hip arthroscopy. Surgery scored slightly better on two hip-function scores in the short term, but neither difference reached the size patients would notice as meaningful, and pain scores did not differ significantly.3
Surgery can still be the right choice for some people, especially when symptoms persist despite a good rehabilitation programme. A surgeon can help you weigh that.
What exercise-based care can include
- Changing squat depth, stance and hip position so training continues with less pain
- Strengthening the hip muscles, for example lateral band walks and Romanian deadlifts
- Hip control at end range, for example PAILs and RAILs from Functional Range Conditioning®
- Mobility work such as 90/90 drills, within a comfortable range
- A gradual return to deeper positions and heavier loads
Get medical care promptly if hip pain follows a fall or injury and you cannot bear weight, if it comes with fever or feeling unwell, or if it is severe at night and not eased by rest.
Sources
- Fortier LM, et al. An updated review of femoroacetabular impingement syndrome. Orthop Rev 2022;14(3):37513. Narrative review. Link
- Agricola R, et al. Cam impingement causes osteoarthritis of the hip: a nationwide prospective cohort study (CHECK). Ann Rheum Dis 2013;72(6):918-923. Prospective cohort study. Link
- Ramadanov N, et al. Conservative treatment versus hip arthroscopy in patients with femoroacetabular impingement: a multilevel meta-analysis of randomized controlled trials. Bone Jt Open 2025;6(4):480-498. Meta-analysis of randomised trials. Link
This article is general education. It does not replace advice from a clinician who has examined you.