Femoroacetabular Impingement - A Morphology of One in Five People?

.1 The morphology, being found in one in five people in the general population, is common.2 However, less than 25% of people with FAI develop osteoarthritis or pain.3 FAI with anterior hip pain is referred to as femoroacetabular impingement syndrome (FAIS). The fact that 75% of the general population with this morphology does not develop symptoms may suggest that other risk factors are in play. Supervised exercise therapy is a traditional first-line treatment, and arthroscopic surgery is growing in popularity.4

Traditional physiotherapy focuses on range of motion (ROM), strength, core stability, muscle balance, and educating patients to avoid extremes of ROM that exacerbate the problem.5 Arthroscopic surgery works to reshape the hip and deal with the damage to the labrum and cartilage.6 The surgery is known to be quite effective. In a recent study, 48% of patients receiving surgery plus physiotherapy achieved a patientacceptable symptomatic state.6 Physiotherapy is also effective in FAIS as first-line treatment. Mansell et al found supervised exercise therapy not inferior to surgery, even with a twoyear follow-up.7 Griffin et al. gave their patients much less access to physiotherapists and found outcomes that favoured surgery.8 However, Griffin et al. found that the differences between surgery and physiotherapy were not cost-effective, leading to a continued recommendation ophysiotherapy as first-line treatment for hip pain, with arthroscopic surgery being recommended as a second-line treatment for FAIS.

A more recent study may, on the surface, seem to contradict previous research comparing physiotherapy to surgery as first-line treatment. Last year, the British Medical Journal published a study by Anthony Palmer and colleagues, in which surgery followed by physiotherapy produced consistently superior results to physiotherapy alone.6 The study has already been cited 20 times, including compilation into an American meta-analysis.9 Unfortunately, the physiotherapy in Palmer’s study is not generalizable outside of England’s National Health System (NHS).

According to Palmer et al. the NHS severely rations access to physiotherapy. Their patients received one to eight visits over five months, with a median of four visits. This is not comparable to the level of access available in Australia and other modern countries. As access to physiotherapy increases, the outcomes of first-line physiotherapy approach the outcomes of surgery.6-8 Palmer et al. make the additional argument that surgery should also be considered for the potential of its long-term benefits.

Modifying contact between the femoral neck and acetabular rim may subsequently reduce cartilage and joint damage, as well as lower the risk of osteoarthritis and the need for hip arthroplasty. However, this same argument could be made for exercise therapy alone. Various muscle balance and arthrokinematic scenarios could result in a functional FAI. For instance, if the tensor fascia latae overpowers the iliopsoas in hip flexion, an adverse internal rotation bias can narrow the joint clearance between the femoral head-neck junction and the acetabular rim.10 Correction of these mechanical sources of hip misalignment also has theoretical potential to mitigate or eliminate excessive joint damage.

Furthermore, Janice Loudon and Michael Reiman of Duke University in North Carolina offer a more agnostic definition of femoroacetabular impingement, that may be more helpful clinically.11 Rather than limiting the definition to a structural morphology, they simply define FAI as the limited joint clearance between the femoral head-neck junction and the acetabular rim, regardless of aetiology. This definition recognizes the possible role of both mechanical and structural contributors to this impingement and explains why supervised exercise therapy can be non-inferior to surgery in these cases.. er Limb, Shoulder & Spine ©BMA 2020

References

1. Agricola R, Waarsing JH, Arden NK, Carr AJ, Bierma-Zeinstra SM, Thomas GE, Weinans H, Glyn -Jones S. Cam impingement of the hip—a risk factor for hip osteoarthritis. Nature Reviews Rheumatology. 2013 Oct;9(10):630. 2. Frank JM, Harris JD, Erickson BJ, Slikker III W, Bush-Joseph CA, Salata MJ, Nho SJ. Prevalence of femoroacetabular impingement imaging findings in asymptomatic volunteers: a systematic review. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2015 Jun 1;31(6):1199-204. 3. Khanna V, Caragianis A, DiPrimio G, Rakhra K, Beaulé PE. Incidence of hip pain in a prospective cohort of asymptomatic volunteers: is the cam deformity a risk factor for hip pain?. The American Journal of Sports Medicine. 2014 Apr;42(4):793-7. 4. Palmer AJ, Malak TT, Broomfield J, Holton J, Majkowski L, Thomas GE, Taylor A, Andrade AJ, Collins G, Watson K, Carr AJ. Past and projected temporal trends in arthroscopic hip surgery in England between 2002 and 2013. BMJ Open Sport & Exercise Medicine. 2016 Mar 1;2 (1):e000082. 5. Griffin DR, Dickenson EJ, Wall PD, Achana F, Donovan JL, Griffin J, Hobson R, Hutchinson CE, Jepson M, Parsons NR, Petrou S. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. The Lancet. 2018 Jun 2;391(10136):2225-35. 6. Palmer AJ, Gupta VA, Fernquest S, Rombach I, Dutton SJ, Mansour R, Wood S, Khanduja V, Pollard TC, McCaskie AW, Barker KL. Arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of symptomatic femoroacetabular impingement: multicentre randomised controlled trial. BMJ. 2019 Feb 7;364:l185. 7. Mansell NS, Rhon DI, Meyer J, Slevin JM, Marchant BG. Arthroscopic surgery or physical therapy for patients with femoroacetabular impingement syndrome: a randomized controlled trial with 2- year follow-up. The American Journal of Sports Medicine. 2018 May;46(6):1306-14. 8. Griffin DR, Dickenson EJ, Wall PD, Achana F, Donovan JL, Griffin J, Hobson R, Hutchinson CE, Jepson M, Parsons NR, Petrou S. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. The Lancet. 2018 Jun 2;391(10136):2225-35. 9. Dwyer T, Whelan D, Shah PS, Ajrawat P, Hoit G, Chahal J. Operative versus nonoperative treatment of femoroacetabular impingement syndrome: A meta-analysis of short-term outcomes. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2020 Jan 1;36(1):263-73. 10. Austin AB, Souza RB, Meyer JL, Powers CM. Identification of abnormal hip motion associated with acetabular labral pathology. Journal of Orthopaedic & Sports Physical Therapy. 2008 Sep;38 (9):558-65. 11.Loudon JK, Reiman MP. Conservative management of femoroacetabular impingement (FAI) in the long distance runner. Physical Therapy in Sport. 2014 May 1;15(2):82-90.