Differential Diagnosis: Femoroacetabular Impingement

Hip pain is an all too common occurrence among older adults and adolescents alike. According to a survey and subsequent study conducted based on a predominantly female German population by Thiem et al. Out of the 2,221 individuals (> 40 years old) who responded, 15.2% reported hip pain and 3.5% reported bilateral hip pain. Similarly, Spahn et al found that 6.5% of German adolescents reported experiencing hip pain. Additional risk factors indicated in this study included female gender and the consumption of alcoholic beverages. There are a multitude of different pathologies and medical conditions that can result in the pain experienced by these individuals and one of the more common causes is femoroacetabular impingement (FAI). Young, active individuals who are experiencing hip pain generally have a very high incidence of FAI with Ochoa et al finding FAI in 87% of symptomatic patients. With such a high proportion of younger individuals experiencing this pain, there are some risk factors or patient characteristics that coincide with this pathology identified by current clinical research.

Clohisy et al conducted a cross-sectional study to determine specific characteristics of patients diagnosed with symptomatic FAI. After analyzing the patient presentation of 1,076 patients and 1,130 hips, they found that those included within this cohort were predominantly young, white patients with a normal BMI, and there were more female than male patients. Additionally, the majority of patients experienced symptoms for between 12 and 36 months, while less than 100 patients experienced symptoms for less than 6 months.
In terms of anatomical classification, cam impingement was the most prevalent (48%), followed by combined cam/pincer (45%), while isolated pincer impingement only occurred in 8% of cases. While these factors allow the clinician the ability to visualize the typical patient, the activities and/or sports that the patient takes part in can also factor into the equation. For example, impingement typically occurs biomechanically with the combination of hip flexion and internal rotation. There are several sports and positions within these sports that are predisposed to FAI based on the biomechanical demands placed upon them. For example, within the sport of ice hockey, goaltenders have been shown to demonstrate an increased prevalence of FAI compared to other position players (Epstein et al).

Further solidifying your diagnosis of FAI, there are some physical examination procedures that are superior to others in differentiating FAI from other pathologies of the hip. Reiman et al conducted a systematic review with meta-analysis to determine just how beneficial individual special test of the hip are for identifying pathologies of the hip. While the special tests evaluated did not have the capacity of predicting the presence of FAI versus acetabular labral tear versus arthritic/cartilaginous changes, these tests still allow the clinician to differentiate intra-articular versus extra-articular pathologies. Additionally, labral tears and chondral defects are commonly found in conjunction with FAI, thus treatment should fairly consistent amongst these intra-articular defects (Beck et al). Of the tests evaluated, below are the statistical analyses:

While none of these tests demonstrate an overwhelming ability to diagnose FAI and/or intra-articular pathologies of the hip, it does give the practicing clinician a foundation to stand on when conducting a physical examination. One test result in isolation does not give the clinician the ability to exclude or diagnose any condition (especially when the predictive values and specificities/sensitivities are so low). Clustered findings when compared to the patient’s complaints and characteristics should give the therapist the information necessary to produce and carry out a successful treatment plan. When FAI appears to be a likely diagnosis, consider the patient’s sport and/or occupation, characteristics (Clohisy et al), and clinical examination findings (Reiman et al). By taking all factors of the evaluation into consideration, the ability to accurately diagnose the injury and apply interventions found to be beneficial for that specific pathology improves immensely. All this being said, can FAI be managed conservatively?

A systematic review published by Wall et al shows preliminary evidence that conservative management with the addition of activity modification may provide improved symptoms in patients with FAI. Within the randomized controlled trials evaluated, interventions found to be beneficial included joint mobilization (Long-axis Distraction, Lateral distraction, anterior glide, and posterior glide), core strengthening, gluteal strengthening, proprioception, and hip flexor stretching. Additionally, several studies found that passive range of motion of the hip results in counter-productive exacerbation of symptoms and should be avoided in lieu of the aforementioned beneficial interventions. In addition to these interventions provided by physical therapists, many patients will also be prescribed NSAIDs and be asked to modify their activities and/or techniques in order to avoid positions that exacerbate their symptoms (Samora et al). Treatment and diagnosis of femoroacetabular impingement is in its infancy, however by utilizing current evidence and relying on all aspects of your patient’s evaluation and response to treatment, your patient outcomes will continue to improve as our knowledge of this condition continues to grow.

For further information on Femoroacetabular Impingement, visit MedBridge Education’s website for continuing education courses.

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