Hip Impingement (FAI): When the Hip Pinches

Some hip pain aches on the outside of the joint or refers down from the back. But a particular kind of hip pain sits deep in the front of the hip or the groin, and it bites when you squat low, sit for a long time, or twist through a loaded hip. Athletes sometimes cup the front of the hip with a "C" of the hand to show where it hurts, a gesture so common it has a name: the C-sign. That deep, pinching, flexion-and-rotation pain is the hallmark of femoroacetabular impingement, or FAI.

What FAI Actually Is

The hip is a ball-and-socket joint: the ball is the head of the femur, and the socket is the acetabulum of the pelvis. In FAI, the shapes of the ball and socket lead to abnormal contact at the edge of the joint during certain movements, particularly deep hip flexion combined with rotation. Over time, that repeated contact can irritate the joint and its rim of cartilage, the labrum.¹

There are two classic shapes involved, and many people have a mix of both:

• Cam morphology: The head of the femur is not perfectly round; extra bone at the head-neck junction causes it to jam into the socket during flexion.
• Pincer morphology: The socket covers the ball a little too much, so the rim makes contact sooner in the range.

Importantly, current understanding treats FAI as a syndrome, meaning the diagnosis requires the combination of symptoms, clinical signs, and imaging findings, not any one of them alone.² The shape on an x-ray is not the whole story, which brings us to an important caveat.

The Imaging Caveat

Here is something that surprises many patients: cam and pincer shapes are extremely common in people who have no hip pain at all. Studies imaging pain-free athletes and members of the general public routinely find these morphologies, and even labral changes, in people whose hips work perfectly well.³ In other words, seeing a cam bump on an image does not automatically explain someone's pain, and it certainly does not, on its own, mean surgery is required.

This matters because imaging findings can frighten people into avoiding activity or believing their hip is damaged beyond repair. The more accurate framing is that FAI is diagnosed clinically, when the shape, the symptoms, and the movement limitations line up, and that the presence of a bony shape is a risk factor, not a verdict. It is a similar lesson to the one we discuss in our article on hurt versus harm: what you see on a scan does not always match what you feel, or what you can do.

Why Loading and Strengthening Come First

For most people with FAI-related hip pain, the first line of management is not surgery, it is a course of well-structured, progressive exercise-based rehabilitation.⁴ Research comparing physiotherapist-led programs to surgery for FAI syndrome shows that many patients do well with conservative care, and rehab is a reasonable and often effective starting point.

A good program tends to focus on a few things: building strength and control around the hip and pelvis, particularly the glutes and deep hip stabilizers; improving how the hip, pelvis, and trunk move together; and modifying the specific positions and loads that provoke symptoms while capacity is being built. The goal is not to avoid movement, but to change the demand and raise the tissue's tolerance for it. This is the principle we return to again and again: there are no bad exercises, only too much too soon.⁵

Activity modification deserves a note of its own. Temporarily reducing the volume of end-range, deeply flexed, or heavily rotated positions, deep squatting, prolonged low sitting, aggressive stretching into the pinch, can settle an irritated hip enough for strengthening to progress. This is a short-term adjustment to buy room for loading, not a permanent list of forbidden movements.

Thinking Beyond the Hip

The hip does not work in isolation. A stiff mid-back, a poorly controlled pelvis, or limited ankle mobility can all change how load funnels into the hip during a squat or a cut. That is why we assess the whole chain rather than just the joint that hurts, an approach that reflects the regional interdependence at the core of how we work at Boreal Spine & Sport. Sometimes the most effective way to reduce a hip's pinch is to improve how the segments above and below it share the work. Our overview of the rehab-first approach explains that thinking in more detail.

When to Consider More

Surgery, typically arthroscopic, has a role for a subset of people with FAI syndrome who do not respond to a genuine trial of well-structured rehabilitation, or who have specific structural problems. But it is best considered after conservative care has been given a fair chance, not as a reflex to an imaging finding. A sensible plan starts with an accurate diagnosis, a real loading program, and time, and reserves more invasive options for hips that clearly need them.

Deep hip and groin pain that pinches with flexion and rotation is worth taking seriously, but it is rarely cause for alarm. Understood correctly, and loaded progressively, most of these hips can be built back toward the activities that matter.

References

1. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003;417:112-120.
2. 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.
3. Frank JM, Harris JD, Erickson BJ, et al. Prevalence of femoroacetabular impingement imaging findings in asymptomatic volunteers: a systematic review. Arthroscopy. 2015;31(6):1199-1204.
4. 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.
5. Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280.