Figure. Anteroposterior radiograph of the pelvis.
A 14-year-old girl presents to the office for evaluation of pain in her left posterior buttock after sustaining an injury playing soccer 2 days earlier. She is having trouble walking; the pain originates in her buttock and radiates to her hamstring. Anteroposterior radiograph of the pelvis (Figure) shows an avulsion fracture of the left ischial tuberosity. The avulsion appears to be displaced 1.5 cm.
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The ischial tuberosity (sit bones) is the attachment site for the proximal hamstring muscles. The 3 muscles that make up the hamstring include the semimembranosus, the semitendinosus, and the biceps femoris. The hamstring muscles and tendons act to extend the hip and flex the knee.1
Tears can occur in the proximal, midsubstance, or distal part of the hamstring. The most common site of rupture is the proximal myotendinous junction; this occurs most often during sprinting. Avulsion injuries are less common and are generally seen in patients who are skeletally immature. Hamstring injuries are characterized by a sharp pain in the posterior buttock that can be associated with significant ecchymosis and sciatica.1
Any patient with suspected hamstring injury should undergo anteroposterior radiographic examination of the pelvis to identify an avulsion fracture of the ischial tuberosity. Most hamstring injuries are treated nonoperatively with a 4- to 6-week period of protected weight-bearing.
The hamstring muscles can tighten quickly following a tear; therefore, initiating physical therapy after 4 weeks is important to stretch the hamstring. Athletes are allowed to return to sports when the affected hamstring is 90% as strong as the contralateral side.
Operative treatment is indicated for proximal avulsion rupture, partial avulsion in which nonoperative management for 6 months has been unsuccessful, or rupture that involves at least 2 tendons with >2 cm of displacement (retraction) of an osseous avulsion. These patients generally have significant chronic weakness and pain when treated nonoperatively.1-3
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 Orthopedics for Physician Assistants.
1. Hughes M. Hamstring injuries. OrthoBullets website. https://www.orthobullets.com/knee-and-sports/3102/hamstring-injuries. Updated October 1, 2018. Accessed March 2, 2020.
2. Hofmann KJ, Paggi A, Conors D, Miller SL. Complete avulsion of the proximal hamstring insertion: functional outcomes after nonsurgical treatment. J Bone Joint Surg Am. 2014;96(12):1022-1025.
3. Alzahrani MM, Aldebeyan S, Abduljabbar F, Martineau PA. Hamstring injuries in athletes: diagnosis and treatment. JBJS Rev. 2015;3(6).