Contents>Expert Panel
This editorial was written for the 2007 National Knowledge Week on Osteoarthritis. The following member of the Expert Panel contributed to this section: Professor Damian Griffin
What is femoroacetabular impingement?
Femoroacetabular impingement or FAI is a relatively recently recognised condition that usually affects young adults. They describe intermittent aching groin or hip pain, sometimes spreading into the thigh, buttock or lower back. Sometimes this pain has come on suddenly, as a result of a specific injury, but more often it gradually gets worse over several months. The pain is usually brought on by exercise or sport, or by sitting for a long time. Sometimes the symptoms include pain with specific movements, or sharp, catching or locking pain, or even giving way of the hip.
What causes FAI?
Impingement occurs between the ball (femur) and socket (acetabulum) of the hip joint. Two types have been recognised: in cam impingement, a bulge at the junction of the femoral head and neck rubs against the cartilage lining the acetabulum; in pincer impingement a prominent anterior rim of the acetabulum blocks normal movement of the femur. Cam impingement is more common in young men, and pincer in athletic middle-aged women, but they often co-exist. Both may lead to inflammation, labral tears (the cartilage rim of the acetabulum), or damage to the smooth articular cartilage that lines the acetabulum. In most cases it is not known why people have the bone shapes that lead to FAI, but FAI patients are probably symptomatic because they have a particular combination of shape variants along with a high level of activity.
How can FAI be identified?
FAI is one of many possible diagnoses in young people with hip and groin pain. The history is often very suggestive, and examination findings of restricted movement and postive impingement testing are helpful. Conventional X-rays of the hip may be normal. Magnetic resonance arthrography (MRA) is much more sensitive for cartilage damage and labral tears than plain MRI, and can be used to identify impingement shapes. 3D surface reconstructed CT provides the best impression of all aspects of hip shape contributing to FAI.
How is FAI related to osteoarthritis?
Damage to the labrum and articular cartilage leads to significant pain and instability and is strongly implicated in the subsequent development of arthritis. Continued impingement seems to damage and delaminate acetabular cartilage, often starting at the antero-superior rim and then spreading throughout the hip and across to the femoral head. It seems likely that FAI is an important factor in the development of hip osteoarthritis in a large proportion of those people who eventually need hip replacement.
How can FAI be treated?
Activity modification or physiotherapy to strengthen hip muscles cannot cure FAI, but they may relieve symptoms temporarily. Surgical treatment aims to correct the shape variations that cause impingement, either by open surgery or by arthroscopic techniques. Open surgery involves an extensive approach with trochanteric osteotomy and dislocation of the hip, while the more recently developed arthroscopic technique is performed through several 1cm incisions. There is increasing observational evidence that both techniques can reliably relieve symptoms in the short and medium term. Open and arthroscopic surgery have both been reviewed by NICE, who concluded that they are still under evaluation and should only be used in expert centres where results are carefully audited.
Is arthroscopic or open surgery better for FAI?
Open surgery allows circumferential assessment for the hip and is relatively straightforward for many specialist hip surgeons, whilst arthroscopic surgery is technically difficult, requires specific training and may not be suitable for the most extensive disease. Open surgery is a major operation involving trochanteric osteotomy and hip dislocation - most patients stay in hospital for several days and use crutches for three months. Arthroscopic surgery is often done as a day case, and patients can begin a rehabilitation programme immediately.
What are the key research questions?
- What is the natural history of FAI?
- Does surgery slow down, stop or even reverse degenerative changes in the impinging hip?
- Are there long-term differences in the outcome of open and arthroscopic surgery for FAI?
Bibliography
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 2003-417:112-20. ( Link to PubMed abstract )
Jager M, Wild A, Westhoff B, Krauspe R. Femoroacetabular impingement caused by a femoral osseous head-neck bump deformity: clinical, radiological, and experimental results. J Orthop Sci 2004;9-3:256-63. ( Link to PubMed abstract )
Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res 2004-418:67-73. ( Link to PubMed abstract )
Beaule PE, Le Duff MJ, Zaragoza E. Quality of life following femoral head-neck osteochondroplasty for femoroacetabular impingement. J Bone Joint Surg Am 2007;89-4:773-9. ( Link to PubMed abstract )
Guanche CA, Bare AA. Arthroscopic treatment of femoroacetabular impingement. Arthroscopy 2006;22-1:95-106. ( Link to PubMed abstract )
Philippon MJ, Schenker ML. Arthroscopy for the treatment of femoroacetabular impingement in the athlete. Clin Sports Med 2006;25-2:299-308, ix. ( Link to PubMed abstract )
Griffin D R. Arthroscopic femoral osteochondroplasty for femoro-acetabular impingement. American Association of Orthopaedic Surgeons Annual Meeting 2007 ( Link to presentation text )
Parvizi J, Leunig M, Ganz R. Femoroacetabular impingement. J Am Acad Orthop Surg. 2007 Sep;15(9):561-70. ( Link to PubMed abstract )
Kim KC, Hwang DS, Lee CH, Kwon ST. Influence of femoroacetabular impingement on results of hip arthroscopy in patients with early osteoarthritis. Clin Orthop Relat Res. 2007 Mar;456:128-32. ( Link to PubMed abstract )
Additional Information
Guidelines:
Arthroscopic femoro-acetabular surgery for hip impingement syndrome: NICE Guidance 2007 ( Library Link )
Open femoro-acetabular surgery for hip impingement syndrome: NICE Guidance 2007 ( Library Link )
Patient information:
Treating hip impingement syndrome with arthroscopic femoro–acetabular surgery - NICE 2007 ( Link - format PDF )
Treating hip impingement syndrome with open femoro–acetubular surgery - Patient Information - NICE 2007 ( Link - format PDF )
Please also see: How effectively can we prevent injuries to the athlete with arthritis and should the athlete with arthritis be advised to give up?
