Figure. Axial MRI shows an abnormal quadratus femoris muscle with edema (marked with white arrow) and narrowing of the ischiofemoral and quadratus femoris space.
A 57-year-old woman presents with an 8-month history of posterior right buttock pain. She denies a known injury or precipitating event. She has been seen at an orthopedic clinic at least 3 to 4 times for this pain and received trochanteric bursa injections with no relief. She also had a magnetic resonance imaging (MRI) of her lumbar spine, which was unremarkable for any source of buttock and radicular pain. The patient describes the pain as deep into the posterior buttock that does not radiate down the right leg. Axial MRI image shows an abnormal quadratus femoris muscle with edema (marked with white arrow) and narrowing of the ischiofemoral and quadratus femoris space (Figure). On physical examination, the pain is worse with extension, adduction, and external rotation of the right hip.
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Posterior hip pain can be a difficult problem to diagnose and treat. Common sources of radiating pain to the posterior buttock, such as the lumbar spine and hip joint, must be ruled out before further work-up is performed. Often this means radiographs, MRI of the spine, and an intra-articular hip injection to exclude these areas as source.1
An understanding of the complex anatomy of the posterior hip and a careful physical examination also helps narrow the differential. Pain to palpation laterally over the greater trochanter is typical of trochanteric bursitis; pain deep in the buttocks directly posterior to hip joint may include piriformis syndrome, ischiofemoral impingement, and obturator internus tears. Sacroiliac pain usually occurs over the entire posterior pelvis and buttock and may radiate down the leg much like sciatic nerve pain.1,2
Radiograph and computed tomography (CT) imaging are useful for diagnosing hip and spine pathology; however, they are not useful for the diagnosis of soft tissue pain. MRI is an essential modality to evaluate extra-articular soft tissue pain around the posterior hip. Guided injections offer the best diagnostic and therapeutic treatment option once a source of pain is suspected clinically and on MRI.1
For the patient in this case, ischiofemoral impingement was suspected based on her MRI findings. Ischiofemoral impingement is a condition where the quadratus femoris is compressed directly between the lesser trochanter and the ischium. Symptoms may be reproduced by a combination of extension, adduction, and external rotation of the hip.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Gómez-Hoyos J, Martin RL, Martin HD. Current concepts review: evaluation and management of posterior hip pain. J Am Acad Orthop Surg. 2018;26(17):597-609. doi:10.5435/JAAOS-D-15-00629
2. Stafford GH, Villar RN. Ischiofemoral impingement. J Bone Joint Surg Br. 2011;93(10):1300-1302. doi:10.1302/0301-620X.93B10.26714