Femoroacetabular Impingement (FAI) | Diagnosis & Treatment

Introduction

Femoroacetabular Impingement (FAI), also known as hip impingement, refers to morphological changes of the acetabulum and/or femoral neck that lead to impinging of the hip labrum during movement. We can distinguish between two main types: When the femoral head is too large, we are talking about a CAM morphology (which is more common in men) and an overextending acetabular rim is called a Pincer morphology and it’s more common in women. In a mixed type, both a CAM and a Pincer morphology are present.

Pathomechanism

It is suggested that this morphology develops as specific adaptions imposed to demands during adolescence. It might be that the growth plate shifts which renders the head less round, but larger. Once the growth plates close, the morphology does not change anymore. FAI morphology is common in asymptomatic people and even 50-70% of athletes. So lots of people have abnormalities, but only a small fraction develops pain.

A review by Mascarenhas et al. (2016) lists the percentages of patients with either Cam, Pincer, or mixed morphology FAI in athletic, asymptomatic, and symptomatic populations. The findings:

Clinical Picture & Examination

Patients who suffer from FAI are typically patients between 20 – 40 years of age and present with deep-seated pinching groin pain, which might present with clicking and mechanical symptoms if labral pathology is present as well. A study from St. Louis however shows that some of these people also have lateral hip, buttock, SI, and low back pain, which makes a diagnosis challenging. According to the Warwick agreement (Griffin et al. 2006) there need to be 3 components: patients need to have symptoms, clinical signs, and imaging findings to diagnose FAI.
Byrd (2005) reports a common characteristic sign of patients presenting with hip disorders, called the C-Sign:

There are no specific orthopedic tests to confirm FAI. The only useful test is the FADIR test due to its high sensitivity (99%). Be aware that this test has a low specificity (7%). (Reiman et al. 2012)

The McCarthy Test might present with consistent clicking when the leg is lowered in case a labral tear is present.

Treatment

Generally, conservative treatment should be tried first before considering surgical options. Hoit et al. (2020) conducted a meta-analysis of 5 randomized controlled trials evaluating the effectiveness of conservative management of FAI. They found that supervised physiotherapy programs focusing on active strengthening and core strengthening are more effective than unsupervised, passive, and non-core-focused programs. A comprehensive rehab program should focus on the muscles of the hip which are commonly reported to be impaired in patients with FAI.

In case patients present with a reduced range of motion, the following mobilization exercises can be considered:

Several meta-analyses have been conducted comparing conservative management to arthroscopic surgery for FAI (Gatz et al. 2020, Zhu et al. 2022, Dwyer et al. 2020, Mok et al. 2021, Bastos et al. 2021). With the exception of Bastos et al. (2021), the results show that surgery seems to be more effective than conservative treatment after 1 year, but there is no clinical difference from 2 years on. While 74% of athletes return to the same competition level after surgery (Reiman et al. 2018), but Ishoi et al. (2018) report that only, 17% reported their performance to be optimal.

References

Thomas Byrd, J. W. (2005). Physical examination. In Operative hip arthroscopy (pp. 36-50). Springer, New York, NY.

Dwyer, T., Whelan, D., Shah, P. S., Ajrawat, P., Hoit, G., & Chahal, J. (2020). Operative versus nonoperative treatment of femoroacetabular impingement syndrome: a meta-analysis of short-term outcomes. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 36(1), 263-273.

Gatz, M., Driessen, A., Eschweiler, J., Tingart, M., & Migliorini, F. (2020). Arthroscopic surgery versus physiotherapy for femoroacetabular impingement: a meta-analysis study. European Journal of Orthopaedic Surgery & Traumatology, 30, 1151-1162.

Griffin, D. R., Dickenson, E. J., O’donnell, J., Awan, T., Beck, M., Clohisy, J. C., … & Bennell, K. L. (2016). The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. British journal of sports medicine, 50(19), 1169-1176.

Ishøi, L., Thorborg, K., Kraemer, O., & Hölmich, P. (2018). Return to sport and performance after hip arthroscopy for femoroacetabular impingement in 18-to 30-year-old athletes: a cross-sectional cohort study of 189 athletes. The American journal of sports medicine, 46(11), 2578-2587.

Mascarenhas, V. V., Rego, P., Dantas, P., Morais, F., McWilliams, J., Collado, D., … & Consciência, J. G. (2016). Imaging prevalence of femoroacetabular impingement in symptomatic patients, athletes, and asymptomatic individuals: a systematic review. European journal of radiology, 85(1), 73-95.

Mok, T. N., He, Q. Y., Teng, Q., Sin, T. H., Wang, H. J., Zha, Z. G., … & Li, J. R. (2021). Arthroscopic Hip Surgery versus Conservative Therapy on Femoroacetabular Impingement Syndrome: A Meta‐Analysis of RCTs. Orthopaedic surgery, 13(6), 1755-1764.

Reiman, M. P., Goode, A. P., Hegedus, E. J., Cook, C. E., & Wright, A. A. (2013). Diagnostic accuracy of clinical tests of the hip: a systematic review with meta-analysis. British journal of sports medicine, 47(14), 893-902.

Reiman, M. P., Peters, S., Sylvain, J., Hagymasi, S., Mather, R. C., & Goode, A. P. (2018). Femoroacetabular impingement surgery allows 74% of athletes to return to the same competitive level of sports participation but their level of performance remains unreported: a systematic review with meta-analysis. British journal of sports medicine, 52(15), 972-981.

Zhu, Y., Su, P., Xu, T., Zhang, L., & Fu, W. (2022). Conservative therapy versus arthroscopic surgery of femoroacetabular impingement syndrome (FAI): a systematic review and meta-analysis. Journal of Orthopaedic Surgery and Research, 17(1), 296.