Hip impingement (FAI): the groin pain of the young and active hip
Last updated September 3, 2026.
Hip impingement (femoroacetabular impingement, FAI) is when the ball or socket of the hip is shaped such that they collide at the movement extremes: causing groin pain in young and middle-aged active adults, worst with deep hip bending, twisting, and sport. It shows on the X-ray and the examination together (the shape alone on a scan is common in pain-free people), it is managed physio-first (the strengthening and the movement retraining genuinely work for many), and the keyhole surgery (reshaping the bone, repairing the labrum) is reserved for the cases that fail the conservative course.
What does it feel like?
The pattern: a deep groin (or side-of-hip) pain, often sharp on the twist or the deep bend (the squat, the low car seat, the football kick, the long drive), a catching or clicking sensation, stiffness after sitting (the first steps after the cinema), and the aching after sport. It builds in the teens-to-forties, in the active (the footballers, the dancers, the gym-squatters), and it masquerades for years as a groin strain or a flexor pull. The examination move (knee to chest and rolled inward, the FADIR) reproduces it.
Why does it happen?
The shapes: the cam type (the ball not perfectly round: a bump jamming the socket rim), the pincer type (the socket overcoverage gripping the neck), or both, mostly developmental (the hip grew that way, sometimes shaped by the adolescent sport years), and symptomatic when the collision load (the deep flexion sports) meets the shape. The labrum (the socket's seal) tears under the repeated collision, and over years the impingement associates with early hip arthritis in some, which is part of why the symptomatic kind is managed actively.
How is it treated?
- Physiotherapy first: the structured program (the hip and core strengthening, the movement-pattern retraining away from the impinging extremes): genuinely effective for many, and the trials support the conservative-first path.
- The activity modification: the deep-flexion extremes temporarily avoided (the full-depth squat, the prolonged low sitting), while keeping the fitness with the modified training.
- Pain relief: the ordinary painkillers and the anti-inflammatories for the flares.
- Injection: the image-guided joint injection as a diagnostic-and-therapeutic tool in the assessment.
- Arthroscopic surgery for the right cases: the keyhole reshaping of the cam or pincer and the labral repair: good outcomes in the genuinely-failed-conservative, well-selected patients.
When is it an emergency?
FAI is clinic medicine; the jump-the-queue hip items: the hip that will not bear weight after an injury, the red hot hip with fever, the night pain unrelenting and positional-independent, the leg length or shape changing in a child, and the numbness or weakness below: these are the different doors. The young athlete with the chronic groin pain is the routine referral worth making early, because the physio works best before years of compensation pile up. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
My X-ray shows the impingement shape. Do I need surgery?
The shape is not the sentence: cam and pincer shapes are surprisingly common on scans of people with no hip pain at all (in the imaging studies of pain-free volunteers, a large minority have the shapes), so the diagnosis of FAI as your pain's cause needs the three-way match (the symptoms, the examination reproducing them, and the shape on imaging), and even the confirmed diagnosis starts physio-first: the strengthening and movement-retraining programs genuinely resolve or control the symptoms for a good share of patients without any operation. The surgery (the keyhole reshaping) is for the genuinely-failed-structured-physio cases with the matching picture, where its outcomes are good. The X-ray finding alone, without the story, is a note for the file, not a booking for the theatre.
Why did it take two years to find this?
Because FAI is young-medicine's great mimic: the pain is deep and vague (the groin ache without a wound to point at), it imitates the flexor strain, the groin strain, and the hernia (each diagnosed, treated, and failed, in the classic patient story), it lives at the intersection of specialties (physio, GP, sports medicine, orthopedics), and the telltale details (the pain on rising from the low seat, the catching on the twist, the young sporty patient) only assemble when someone thinks of the hip joint itself. The condition was barely named twenty years ago (the arthroscopy era revealed it), so the two-year path you walked is the ordinary one. The footballers, dancers, and deep-squatters are its population, and you are now at the right door.
Do I have to give up football and squatting?
Modify rather than surrender, in the main: the management is not sport-abstinence but load-and-pattern management (the deep-flexion extremes get temporarily tamed: the squat depth limited above the impinging range during the rehab, the prolonged low sitting broken up), while the strengthening rebuilds the hip's control, and many patients return to full sport (the physio-managed and, where needed, the post-arthroscopy patients both play again: the professional footballers who have had the surgery are the public evidence). The football itself is not the enemy (the movement variety is good for hips); the unmanaged symptoms are. The rare hard conversation (the advanced joint damage found early) changes the advice, and that is what the X-ray exists to catch.
Will this give me arthritis?
The association is real and the management exists because of it: long-standing impingement collision (the cam type especially) is associated with earlier hip osteoarthritis in some patients, which is precisely why the symptomatic kind is treated actively rather than shrugged at: the physio and the surgery both aim partly at protecting the joint's future. The honest caveats: many people with the shapes never develop arthritis (the shape alone is a weak predictor, the symptoms plus the shape a stronger one), the arthritis question takes decades to answer, and the research on whether treatment prevents it is still maturing. The actionable summary: the diagnosis you are getting is the protective kind of knowledge: managed early, the risk is the one being minimized; ignored, it is the one accumulating.
What does the physio actually do for a bony shape problem?
The shape is fixed but the collision is functional, and that is the treatment surface: the physio strengthens the muscles that control the hip's position (the deep rotators, the glutes, the core: a strong, well-controlled hip spends less time jamming its extremes), re-trains the movement patterns (the squat and lunge mechanics that avoid the pinch: genuine skill work), restores the range the guarding has stolen, and paces the loads back up to the sport. The outcomes justify the order: the structured programs improve pain and function in the majority of committed patients, which is why the guidelines and the trials put the operation after the program. The bone does not change; everything about how you load it does.
What is the surgery like, if it comes to that?
Hip arthroscopy: keyhole surgery through two or three small portals (the cam bump reshaped, the pincer rim trimmed, the labrum repaired or tidied), day-case or one night, on crutches for two to four weeks, and the rehab program over months (the protected range first, then the strengthening ladder back to sport, with the full sport typically at four to six months). The outcomes in the well-selected (the failed-conservative, shape-matching, minimal-arthritis patients) are genuinely good (the majority return to sport and report substantial improvement), and the honest caveats: it is real surgery with real recovery, the results are best in the young with intact cartilage, and it does not guarantee the arthritis-free future. The surgeons who do it well are the high-volume hip specialists: the center matters, and the referral is worth steering.