What is Femoral Acetabular Impingement?

Femoral Acetabular Impingement (FAI) is a common source of anterior hip pain. True Femoral Acetabular Impingement is due to a bony abutment of the femoral neck and the acetabulum

Femoral Acetabular Impingement (FAI) is a common source of anterior hip pain. True Femoral Acetabular Impingement is due to a bony abutment of the femoral neck and the acetabulum(1). This abutment occurs primarily with end range flexion and adduction. When treating conservatively without imaging, a functional impingement must be ruled out before facilitating compensation around a possible Femoral Acetabular Impingement. A functional impingement will also reproduce the CC of anterior hip pain at end range flexion and adduction. Pericapsular structures such as iliocapsularis, psoas, gluteus minimus, and rectus femoris must be addressed before ruling out a functional femoroacetabular impingement (2) (3).

Case Report and Diagnosis

A 17 year old male track athlete presented with right anterior hip pain. This pain is made worse when he squats or walks up stairs. This pain came on gradually over the past 2 months without a mechanism of injury. His track season started 3 months ago in which he runs the 200, 400, and hurdle. His hip pain increases with activity, especially after and during hurdling. The patient did not have a significant health history contributing to his CC nor were any other systems involved. Physical findings include pain with right hip flexion and pain with hip flexion plus adduction with a harder than normal end feel.

Muscle testing bilaterally of psoas, rectus femoris, vastus medialis, and gluteus medius/minimus was graded 4 out of 5. Palpation revealed hypertonicity and trigger points in psoas (and most likely subsequent iliocapsularis (4)) and rectus femoris bilaterally, worse on the right. Pertinent negative findings of the right hip included FABER test, anvil test, and scour test. Differential diagnosis included FAI and functional FAI. Functional FAI must be ruled out first by trial of care before continuing with imaging of the hip to confirm pathology. 

Treatment for Femoral Acetabular Impingement

Treatment consisted of re-establishing correct motor control of the core and lower extremity through dynamic neuromuscular stabilization (DNS) exercises. The focus of the exercises was to synergise muscular influence around the hip by activating gluteus medius/minimus and vastus medialis as well as maintaining intra-abdominal pressure through hip flexion. In this way, the antagonistic muscular activity will normalize tone in the hypertonic musculature (5) as well as teach a synergistic relationship and motor control of the muscles surrounding the joint. After 3 weeks of treatment the patient was pain free in hip flexion and adduction.

Femoral Acetabular Impingement (FAI)

Contact The Rehab Docs for Femoral Acetabular Impingement Relief

This case is important to recognize functional vs. structural Femoral Acetabular Impingement. A trial of care is the best way to conservatively determine if the Femoral Acetabular Impingement is extracapsular or boney. This condition should be treated from an antagonistic and synergistic view point to best treat the patient’s poor motor control that lead to hypertonicity and impingement. If you are experiencing pain in any area of your body contact The Rehab Docs today. 


  1. Loudon, Janice K., and Michael P. Reiman. “Conservative management of femoroacetabular impingement (FAI) in the long distance runner.” Physical Therapy in Sport 15.2 (2014): 82-90.
  2. Alradwan, Hussain, et al. “Extra-articular hip impingement: a systematic review examining operative treatment of psoas, subspine, ischiofemoral, and greater trochanteric/pelvic impingement.” Arthroscopy: The Journal of Arthroscopic & Related Surgery 30.8 (2014): 1026-1041.
  3. Walters, Brian L., John H. Cooper, and José A. Rodriguez. “New findings in hip capsular anatomy: dimensions of capsular thickness and pericapsular contributions.” Arthroscopy: The Journal of Arthroscopic & Related Surgery 30.10 (2014): 1235-1245.
  4. Sato T, Sato N, Sato K (2016) Review of the Iliocapsularis Muscle and its Clinical Relevance. Anat Physiol 6:237. doi: 10.4172/2161-0940.1000237
  5. Paz, Gabriel Andrade, et al. “Maximal Exercise Performance and Electromyography Responses after Antagonist Neuromuscular Proprioceptive Facilitation: A Pilot Study.” Journal of Exercise Physiology Online 15.6 (2012).