Purpose: To detect for irritation of the sciatic nerve by the piriformis.
Test position: Sidelying.
Performing the Test: Have the patient lay in the side-lying position with the tested hip on top. Passively move the patient's lower extremity into flexion (90 degrees), adduction, and internal rotation. A positive test occurs when pain is produced in the sciatic/gluteal area. Due to the position of the test, pain may produced in the anterior thigh as well as a result of femoral acetabular impingement, so be sure to ask where the patient is feeling pain!
Diagnostic Accuracy Sensitivity: .88; Specificity: .83; +LR: 5.2; -LR: .14 ("Piriformis syndrome: Diagnosis, treatment and outcome- a 10-year study," "Unilateral limitation of abduction of the hip: A valuable clinical sign for DDH?").
Importance of the Test: Sciatic nerve pain can originate from several factors including a disc herniation, sacroiliac joint dysfunction, degenerative joint disease, a tight piriformis, and more. If you are suspecting a patient's neural symptoms to be originating from a tight piriformis, the FAIR test can help strengthen your hypothesis. According to Neumann, the piriformis originates at the ventral surface of the sacrum and runs through the greater sciatic foramen to insert on the superior part of the greater trochanter, leading to the actions of hip external rotation, abduction, potentially slight extension (due to the posterior to anterior line of pull). The position of flexion, adduction, and internal rotation places a stretch on the piriformis muscle and, theoritically, compressing the sciatic nerve. Additionally, a ROM assessment, palpation skills, and movement analysis would be very beneficial in your physical examination.
Note: these tests should only be performed by properly trained health care practitioners.