The obturator externus tendon is the distal tendinous portion of the obturator externus muscle, arising from the muscle belly that fills the outer surface of the obturator membrane and adjacent bone. The tendon passes posteriorly in a groove below the femoral neck and inserts into the trochanteric fossa on the medial surface of the greater trochanter. It travels inferior to the hip joint capsule and courses through the posterior obturator foramen groove.
The obturator externus tendon passes through a groove under the femoral neck immediately posterior to the hip joint capsule and is an important anatomical structure in the context of ischiofemoral impingement. Impingement between the lesser trochanter and the ischial tuberosity can compress the quadratus femoris and obturator externus tendon, producing posteromedial hip pain worsened by hip extension and external rotation. The tendon is also at risk during posterior and medial hip surgical approaches. Tears of the obturator externus are increasingly recognised on MRI in patients with posterior hip pain.
Acute or degenerative tearing of the obturator externus at its musculotendinous junction or trochanteric fossa insertion produces deep posterior hip and groin pain worsened by external rotation against resistance, increasingly identified on MRI as a cause of posterior hip pain in athletes.
Narrowing of the ischiofemoral space compresses the obturator externus tendon and quadratus femoris between the lesser trochanter and ischium, producing deep posterior and medial hip pain, diagnosed by MRI showing quadratus femoris oedema and managed with activity modification, injection, or surgical decompression.
