| What We Treat
Femoroacetabular Impingement
Groin pain when you squat deep, sit for long periods or twist on the leg? FAI is a common cause of hip pain in younger, active adults — and one where the shape of the joint and how you load it both matter.
Overview
What Is FAI?
Femoroacetabular impingement syndrome describes a combination of hip shape, symptoms and clinical findings. Extra bone at the head-neck junction of the thigh bone, or over-coverage of the socket, causes the two to make contact at the end of movement — particularly in deep flexion and rotation. The important word is syndrome: the bony shapes are common in people with no symptoms at all, so the diagnosis requires the shape, the symptoms and the clinical signs together.
Tap a structure, or use the buttons, to see the different types.
Cam Morphology
Extra bone at the junction between the ball and the neck of the thigh bone, giving the head a less spherical shape. As the hip bends and rotates, this extra bone is driven into the rim of the socket. Associated with high sporting load during adolescence while the growth plate is still open.
Symptoms
How It Tends to Feel
FAI has a fairly characteristic pattern, most obviously in what provokes it:
Deep Groin Pain
Felt in the groin and front of the hip, often indicated by cupping the hand around the side of the hip.
Worse With Deep Flexion
Squatting, deep lunging, getting in and out of low cars, and cycling with a low handlebar position.
Pain After Prolonged Sitting
Long periods with the hip bent — desk work, driving, flights — commonly build symptoms.
Clicking or Catching
A sense of catching within the joint at end range, though clicking alone is common and often meaningless.
Reduced Rotation
Turning the hip inwards is typically restricted and often reproduces the pain.
Stiffness After Activity
The hip feeling tight and restricted for hours after a heavy session or a long drive.
Causes & Risk Factors
What Drives It
FAI reflects the interaction between joint shape and the loads placed through it.
Adolescent Sporting Load
High-volume sport during growth, particularly football, ice hockey and basketball, is strongly associated with cam morphology developing.
Joint Shape
The underlying bony morphology is largely established by skeletal maturity and doesn’t change afterwards without surgery.
Deep Flexion Activities
Sports and occupations involving repeated deep hip bending load the impingement mechanism repeatedly.
Reduced Muscular Control
Weakness in the deep hip stabilisers and gluteal muscles increases the load reaching the joint rim.
Sitting Posture
Prolonged sitting in deep hip flexion, particularly in low or reclined seats, maintains the provocative position.
How We Can Help You
Treatment & Management
Conservative management works for a substantial proportion of people. The goal is to reduce time spent in the provocative range and build the strength that keeps the joint well controlled.
What the evidence says
The UK FASHIoN randomised trial compared arthroscopic hip surgery with a structured physiotherapy programme for FAI syndrome. Surgery produced a modest additional improvement at twelve months, but both groups improved meaningfully — which makes structured rehabilitation a reasonable first choice for many people.
Cam morphology is present in a large proportion of asymptomatic athletes, and labral tears are found on MRI in most asymptomatic adults over 40. This is why the diagnosis requires symptoms and clinical signs, not just a scan.
When to Seek Help
Red Flags — Don’t Ignore These
Groin pain in a younger adult is usually musculoskeletal. Seek assessment if you notice:
⚠ Seek prompt medical assessment if you notice:
- Inability to weight-bear, particularly after trauma (possible fracture)
- A hot, swollen hip with fever or feeling generally unwell (possible joint infection — seek emergency care)
- Groin pain in an adolescent with a limp (needs prompt assessment to exclude slipped capital femoral epiphysis or Perthes)
- Constant night pain unrelated to position, with unexplained weight loss or a history of cancer
- Progressive groin pain in someone on long-term steroids or with heavy alcohol use (possible avascular necrosis)
These symptoms can point to a cause that needs medical rather than physiotherapy assessment. Please don’t wait for a physiotherapy appointment — contact your GP, call 111, or attend A&E as appropriate.
Common Questions
Frequently Asked Questions
Do I need surgery?
Not necessarily. The FASHIoN trial found surgery gave a modest additional benefit over structured physiotherapy at a year, but both groups improved. A properly delivered rehabilitation programme is a reasonable first step, with surgery a considered option if it doesn’t work.
Can exercise change the bone shape?
No. The bony morphology is fixed once you’re skeletally mature. But symptoms depend on how much time the joint spends in the impinging position and how well it’s controlled — and both of those are very changeable.
Should I stop squatting?
Usually just reduce the depth. Squatting to a depth that stays out of the impinging range allows you to keep training legs hard without repeatedly provoking the joint. Complete avoidance costs you strength you actually need.
Will this lead to hip arthritis?
Cam morphology is associated with an increased risk of hip osteoarthritis in population studies, though most people with it never develop symptomatic arthritis. Whether surgery alters that long-term risk is not yet established.
Rehabilitation First Is a Reasonable Choice
A proper assessment, a programme that addresses position and strength, and an honest conversation about when surgery is worth considering.
Book Your Initial AssessmentThis page is for general information only and isn’t a substitute for individual medical advice. If you’re experiencing any of the warning signs above, contact your GP or seek emergency medical care as appropriate.