Hip impingement, formally called femoroacetabular impingement (FAI), is a condition where the bones of the hip joint don’t fit together smoothly. Extra bone along the femur (thighbone), the hip socket, or both creates abnormal contact during movement, pinching the soft tissue between them. This causes pain, limits range of motion, and over time can damage the cartilage that lines the joint. It’s one of the most common causes of hip and groin pain in active adults, particularly those under 50.
One important thing to know upfront: having the bone shape associated with impingement doesn’t automatically mean you’ll have problems. Imaging studies of people with no hip pain at all show cam-type bone changes in up to 38% of the general population, and up to 66% in Western countries. The condition only becomes a clinical “syndrome” when three things are present together: symptoms, abnormal findings on a physical exam, and matching changes on imaging.
The Three Types of Hip Impingement
Hip impingement comes in three forms, depending on where the extra bone sits.
- Cam type: The femoral head isn’t perfectly round. Instead, there’s a bump where the ball meets the neck of the thighbone. When the hip bends or rotates, this bump jams into the socket rim, grinding against the cartilage and the labrum (the ring of fibrous tissue that seals the joint). Cam impingement is more common in young men and athletes.
- Pincer type: The hip socket itself extends too far over the femoral head, covering more of the ball than it should. This over-coverage can come from the socket being tilted backward (called retroversion) or from general deepening of the socket. The extra rim of bone catches on the femur neck during movement, crushing the labrum between them.
- Mixed type: Both cam and pincer changes are present in the same hip. This is the most common pattern seen in clinical practice.
On imaging, cam morphology is identified by measuring the “alpha angle,” which describes the roundness of the femoral head. An angle of 60 degrees or higher is the widely accepted threshold for cam-type bone shape.
What Hip Impingement Feels Like
The hallmark symptom is a deep ache in the groin or front of the hip that develops gradually. Many people instinctively cup their hand in a “C” shape around the front and side of the hip when asked to point to where it hurts. The pain can radiate into the thigh.
Certain positions and activities predictably make it worse: deep squatting, sitting for long stretches, getting in and out of a car, and sports that involve cutting, pivoting, or kicking. Anything that combines hip flexion with inward rotation of the leg tends to provoke the sharpest discomfort. Some people first notice it after increasing their training volume or starting a new sport, then find it lingers even during everyday tasks.
Early on, the pain may only show up during or after intense activity. As the condition progresses and cartilage damage accumulates, it can become more constant, with stiffness after rest and a noticeable loss of hip rotation.
How It’s Diagnosed
Diagnosis starts with a physical exam. The most commonly used clinical test is the FADIR, where a clinician bends your hip, moves it inward, and rotates it. This test is extremely sensitive for labral tears (essentially 100%), meaning it rarely misses the problem. The FABER test, which moves the hip into a figure-four position, is highly specific, meaning a positive result strongly confirms something is wrong. Neither test alone is definitive for impingement specifically, so imaging follows.
Standard X-rays reveal the bone shape, including the alpha angle and signs of socket over-coverage. An MRI, sometimes with contrast dye injected into the joint (called an MR arthrogram), shows the labrum and cartilage in detail. The formal diagnosis requires all three pieces of the puzzle: your symptoms, abnormal exam findings, and imaging that matches. This framework, established by an international consensus known as the Warwick Agreement, prevents people with painless bone variations from being unnecessarily labeled or treated.
The Link to Osteoarthritis
Untreated hip impingement syndrome carries a real risk of accelerating joint wear. A prospective study published in the British Journal of Sports Medicine tracked middle-aged individuals over 10 years and found striking numbers. People with symptomatic cam-type impingement were nearly 7 times more likely to develop radiographic hip osteoarthritis compared to those without impingement. For end-stage osteoarthritis (the kind that often leads to hip replacement), the risk jumped to almost 48 times higher.
Among those with FAI syndrome in the study, 81% showed signs of osteoarthritis by the 10-year mark, and 33% had reached the end-stage. These numbers don’t mean every person with impingement will need a new hip, but they underscore why the condition is worth managing rather than ignoring.
Physical Therapy and Conservative Treatment
Physical therapy is the first line of treatment, and it works for a significant number of people. One study of 76 young athletes with hip impingement found that 70% were successfully managed with structured exercise, activity modification, and rest, avoiding surgery entirely. A meta-analysis of five randomized controlled trials confirmed that non-surgical treatment is an effective initial approach.
Rehabilitation targets several areas at once. Core stability work, including exercises like bird-dogs, planks, and dead-bug variations, trains the deep trunk muscles that stabilize the pelvis during movement. Hip strengthening focuses heavily on the gluteal muscles, which are often weak in people with impingement. Side-lying leg raises, clamshells, bridges, and resisted side-stepping with a band are staples. Flexibility and mobility drills round out the program: foam rolling, hip self-mobilization, and dynamic movements like leg swings and gate openers help restore range of motion without aggravating the joint.
Posture correction also plays a role. Many people with impingement have poor awareness of their pelvic position, and learning to find and maintain a neutral pelvis during daily activities can reduce how often the bones collide. The overall goal isn’t to reshape the bone (that requires surgery) but to optimize how the hip moves, distribute forces more evenly, and reduce the situations that trigger impingement.
A large randomized trial from the UK (the FASHIoN trial) found that both surgery and physical therapy groups improved their hip function scores at 12 months. Surgery had a modest edge, but the surgical group also experienced more side effects.
When Surgery Is Considered
Hip arthroscopy is the standard surgical approach when conservative treatment hasn’t provided enough relief, typically after three to six months of dedicated physical therapy. The procedure uses small incisions and a camera to reshape the bone (shaving down the cam bump or trimming excess socket rim) and address any labral damage.
How the labrum is handled during surgery matters for long-term outcomes. When the labral tissue is healthy enough, surgeons repair it with sutures. When it’s too degenerated or thin, they trim away the damaged portion (debridement). The difference is significant: labral repair has a 10-year survival rate of about 95% (meaning only 5% of patients go on to need a total hip replacement), compared to 75% for debridement. The roughly four-fold lower risk of needing a hip replacement makes labral preservation a priority whenever the tissue allows it. For patients who don’t ultimately need a hip replacement, both approaches produce similar scores for pain, daily function, and satisfaction.
Recovery After Surgery
Recovery from hip arthroscopy follows a gradual progression, though no single universal protocol exists. Most rehabilitation programs move through four phases, advancing from protected weight-bearing and gentle range-of-motion work to full strength training and sport-specific drills.
The average return to sport is about 7 months after surgery, with a wide range depending on the sport and the individual. Lower-impact activities come back sooner: swimming averages 3.4 months, cycling about 4.5 months, and golf around 4.7 months. Sports with higher hip demands take longer. Soccer players average 9.2 months, runners about 8.5 months, and those doing high-intensity interval training close to 10 months. Basketball players return around 7 months, and football players around 6 months.
These timelines reflect averages across studies, and your actual recovery will depend on the extent of the bone work and labral repair, your fitness level going in, and how consistently you follow the rehabilitation program. Rushing the process increases the risk of re-injury and a poorer outcome.