Sonography is as useful as MRI in depicting acute hamstring injuries and because of lower costs may be the preferred imaging technique. However, MRI is more sensitive for follow-up imaging of healing injuries. The longitudinal length of the strain as measured on MRI is a strong predictor for the amount of time needed until an athlete can return to competition.

Increasing activity in the general population and the high demands placed on athletes have resulted in injuries to the hamstring muscle complex (HMC) being commonplace in sports. Imaging of HMC injuries can form a considerable part of a sports medicine practice, with a wide spectrum of such injuries being reflected in their varied imaging appearances. Magnetic resonance (MR) imaging and ultrasonography (US) are the imaging modalities of choice in this setting. Both MR imaging and US provide exquisitely detailed information about the HMC with respect to localization and characterization of injury. Optimization of MR imaging involves the use of a surface coil and high-resolution techniques, allowing the musculoskeletal radiologist not only to diagnose injury and assess severity but also to provide the clinician with useful clues with respect to prognosis. The portability and availability of US make it an attractive modality for the diagnosis of acute hamstring injuries, although its effectiveness is dependent on operator experience. A thorough knowledge of the HMC anatomy and of the spectrum of imaging findings in HMC injury is crucial for providing optimal patient care and will enable the musculoskeletal radiologist to make an accurate and useful contribution to the treatment of athletes at all levels of participation.

Twenty-one patients had proximal tendon injury, with sixteen avulsions and five partial tears. Sixteen of these patients had surgical confirmation of hamstring avulsion from the ischial tuberosity (14 conjoint, 2 biceps femoris alone) and all were reliably diagnosed with MR imaging (16/16), but less so with sonography (7/12). Four distal tendon avulsions were also observed (three semitendinosus, one biceps femoris). With respect to muscle injury, the biceps femoris was most commonly injured (124/154). Semimembranosus was an uncommon muscle injury (21/154) and semitendinosus rare (9/154). Imaging can discriminate a hamstring tendon avulsion from musculotendinous strain and helps identify which patients necessitate surgical management as opposed to conservative treatment.

Groin injuries are common in athletes who participate in sports that require twisting at the waist, sudden and sharp changes in direction, and side-to-side ambulation. Such injuries frequently lead to debilitating pain and lost playing time, and they may be difficult to diagnose. Diagnostic confusion often arises from the complex anatomy and biomechanics of the pubic symphysis region, the large number of potential sources of groin pain, and the similarity of symptoms in athletes with different types or sites of injury. Many athletes with a diagnosis of "sports hernia" or "athletic pubalgia" have a spectrum of related pathologic conditions resulting from musculotendinous injuries and subsequent instability of the pubic symphysis without any finding of inguinal hernia at physical examination. The actual causal mechanisms of athletic pubalgia are poorly understood, and imaging studies have been deemed inadequate or unhelpful for clarification. However, a large-field-of-view magnetic resonance (MR) imaging survey of the pelvis, combined with high-resolution MR imaging of the pubic symphysis, is an excellent means of assessing various causes of athletic pubalgia, providing information about the location of injury, and delineating the severity of disease. Familiarity with the pubic anatomy and with MR imaging findings in athletic pubalgia and in other confounding causes of groin pain allows accurate imaging-based diagnoses and helps in planning treatment that targets specific pathologic conditions.

A history of anterior cruciate ligament injury was the only statistically significant risk factor for a recurrent hamstring strain in our study. Of the imaging parameters, the MR length of a strain had the strongest correlation association with a repeat hamstring strain and therefore may assist in identifying which athletes are more likely to suffer further reinjury.