Hip Impingement (FAI): Symptoms and Surgical Solutions

Femoroacetabular impingement — usually shortened to FAI — has gone from being a poorly understood diagnosis to one of the most important conditions in modern hip surgery. We now recognise FAI as a leading cause of groin and lateral hip pain in active adults in their 20s, 30s and 40s — patients who would previously have been told they had a “muscle strain” or a “sports hernia” and sent away without an answer. The good news is that FAI is now well-treatable, often with hip arthroscopy that returns athletes to full sport and may slow or prevent the development of hip arthritis. This article explains what FAI is, who gets it, how it is diagnosed, and the modern treatment pathway.

What is FAI?

The hip is a ball-and-socket joint. Throughout life, it should move freely through its range without the bones colliding. In FAI, repeated abnormal contact occurs at the rim of the socket during normal movement, damaging the labrum (the ring of cartilage around the socket) and the cartilage on the head of the femur. Over years, this repetitive injury can progress to arthritis.

There are two main morphologies:

• Cam impingement — the head of the femur is not perfectly spherical and has a slight bump on the front, which crushes the labrum during hip flexion.
• Pincer impingement — the socket is slightly over-coverage, with an over-prominent rim that grinds against the femoral neck.

Many patients have a mix of both morphologies. The bony shape itself is established during adolescence and often reflects high-level sports participation during the growth years.

Symptoms

The classic story is groin pain, often deep, that worsens with prolonged sitting (a long drive, a long meeting), squatting deeply, hip flexion exercises, and certain pivoting sports movements. Patients often describe a “C-sign” — they cup the hip with the index finger over the groin and the thumb on the buttock. Mechanical symptoms — catching, locking, a sense of the hip giving way — suggest associated labral tears.

Diagnosis

A focused history and examination is the foundation: an anterior impingement test (pain in flexion–adduction–internal rotation) is highly suggestive. Plain X-rays show the bony shape. MRI with arthrogram is the gold standard imaging — it shows the labrum, the cartilage, and the bone changes. Diagnostic injection of local anaesthetic into the joint can be useful when the picture is mixed.

Conservative treatment

Not every patient with imaging findings needs surgery. Many improve with:

• Activity modification — particularly avoiding deep flexion and prolonged sitting
• Targeted physiotherapy emphasising posterior chain and core stability
• Activity-specific technique work (cycling fit, squat depth modification)
• Short courses of anti-inflammatories and occasional cortisone injections

A 3–6 month structured trial is the right starting point for most patients with mild to moderate symptoms.

Hip arthroscopy

When symptoms persist despite conservative treatment, or when there is a significant labral tear, hip arthroscopy is the surgical answer. Through small portals around the hip, the surgeon trims the cam bump or rim overcoverage, repairs the labrum (rather than resecting it whenever possible), and addresses any cartilage damage.

This is technically demanding surgery best performed by a hip-arthroscopy-trained surgeon. Volume matters significantly — outcomes are clearly better in experienced hands.

Recovery

Patients use crutches for partial weight bearing in the first 2–3 weeks. Hip-mobilisation exercises start immediately to prevent stiffness. Office work resumes at 2–3 weeks; cycling at 6 weeks; running at 12–14 weeks; cutting and pivoting sport at 4–6 months. Full recovery and peak performance are typically reached around 9 months.

Outcomes

For well-selected patients with FAI and labral tears, hip arthroscopy returns 70–90% to their previous level of sport, depending on the sport and the underlying joint health. Outcomes are best when surgery is performed before significant cartilage damage has developed — early diagnosis matters. The hope, and the increasing evidence, is that addressing FAI early may slow or prevent the progression to arthritis.

When arthroscopy is not the right answer

Significant cartilage damage on imaging or at arthroscopy reduces the predictability of a good outcome. In these patients, conservative management may be preferred until the arthritis is severe enough to consider hip replacement. We discuss this openly at the consultation.