Hip impingement (FAI): symptoms, causes and treatment

Whittington Health NHS Trust lists the usual symptoms as hip or groin pain during certain movements, discomfort extending to the thigh, lower back or buttocks, joint stiffness and limited range of motion, clicking, catching or locking sensations, and difficulty walking or taking part in physical activities.

The NHS hip pain guidance stresses not trying to diagnose the cause of hip pain yourself. It lists several possible causes of hip pain, so persistent groin or hip pain is worth having assessed.

The trust says most cases can be managed with non-surgical treatments and that severe cases may need surgery. Conservative options it lists are activity modification (avoiding positions that aggravate symptoms), anti-inflammatory pain relief as advised by a medical professional, physiotherapy to strengthen the hip muscles, particularly the gluteals, plus stretching, balance and proprioception exercises, manual therapy, and orthotics and postural adjustments. Ultrasound-guided corticosteroid injections can temporarily reduce inflammation and pain, aiding rehabilitation.

If conservative treatment is ineffective, surgery may be considered. The trust describes hip arthroscopy as a minimally invasive procedure in which the surgeon removes excess bone and repairs damaged cartilage or labral tears, with open surgery in severe cases where a larger incision reshapes the hip.

The FAIT trial, a multicentre randomised controlled trial across seven NHS England sites published in the BMJ in 2019, randomised 222 adults aged 18 to 60 with symptomatic FAI to arthroscopic surgery or to a programme of up to eight physiotherapy sessions over five months with activity modification. At eight months the mean hip outcome score (activities of daily living) was 78.4 after surgery and 69.2 after physiotherapy, a difference of 10.0 points, and no serious adverse events were reported. The authors concluded patients referred to secondary or tertiary care achieve superior outcomes with arthroscopy.

These results come from people already referred to hospital with confirmed FAI, excluding those with established osteoarthritis or hip dysplasia, and from a single eight-month time point, so they do not mean that everyone needs surgery. A specialist will discuss whether physiotherapy first or surgery is right for you.

The hip is a ball-and-socket joint. The trust describes the socket (acetabulum) as part of the pelvis housing the ball-shaped top of the thigh bone (femoral head), with smooth articular cartilage covering the bone surfaces and a ring of fibrocartilage called the labrum surrounding the socket to stabilise the joint.

In FAI, abnormal bone shape means the ball and socket do not fit smoothly, so movement causes friction. The trust lists three types: cam impingement, where the femoral head is misshapen and grinds against the socket; pincer impingement, where the socket extends excessively over the ball; and combined impingement, a mix of both.

The trust says FAI occurs due to abnormal bone development in the hip joint. Contributing factors it lists include structural variation in hip shape, either congenital or developmental, repetitive high-impact movements or sports involving excessive hip flexion, previous hip injuries, and underlying conditions such as Perthes disease or slipped capital femoral epiphysis (SCFE).

Risk factors it adds include hip muscle imbalance or weakness, abnormal joint mobility (too stiff or too flexible), tight muscles around the hip, previous hip fractures and sport that stresses the hip, particularly in adolescence.

A healthcare professional will assess hip pain and movement limits and perform an impingement test during a physical examination. The trust says X-rays can identify bone irregularities and joint wear, and MRI scans evaluate soft tissue damage such as labral tears.

The FAIT trial required symptoms to be confirmed clinically and with imaging (radiography or MRI), reflecting that imaging alone is not enough: bone shape differences can be found in people without symptoms, so the story, examination and imaging need to fit together.

The trust says that with early intervention most individuals recover well and can return to normal activities, and that treatment aims to relieve pain, improve function and prevent long-term complications such as arthritis. It suggests keeping hip muscles strong and flexible, using proper technique in sport and avoiding repetitive stress.

In the FAIT trial, the physiotherapy programme ran over five months and the main outcome was measured at eight months. Recovery after arthroscopy follows a rehabilitation programme directed by your surgical team, and timescales vary between people.

The NHS says to see a GP if hip pain is stopping you doing normal activities or affecting sleep, is getting worse or keeps coming back, has not improved after 2 weeks of home treatment, or comes with stiffness lasting more than 30 minutes after waking. In many areas you can refer yourself to NHS community musculoskeletal services for help such as physiotherapy.

Ask for an urgent GP appointment or NHS 111 for severe hip pain that started suddenly without a fall, a hot swollen hip, skin colour change, or hip pain with feeling unwell and a high temperature. Call 999 or go to A&E for severe hip pain after a fall or injury, being unable to walk or put weight on the leg, or tingling or loss of feeling in the hip or leg after an injury.

On the NHS the route is usually a GP or MSK physiotherapy service, with referral to an orthopaedic hip service for imaging and a surgical opinion if conservative care does not help. Hip arthroscopy is performed in hospital by orthopaedic surgeons.

Private physiotherapy, MRI and orthopaedic consultations are also available. The same evidence applies: the FAIT trial supports surgery for selected people who do not improve, and it is reasonable to ask how often a surgeon performs hip arthroscopy and what rehabilitation follows.