Proximal Hamstring Strains of Stretching Type in Different Sports: Injury Situations, Clinical and Magnetic Resonance Imaging Characteristics, and Return to Sport

¹ Swedish School of Sport and Health Sciences and the Karolinska Institutet, Stockholm, Sweden
² Department of Radiology, Sophiahemmet Hospital, Stockholm, Sweden
³ Karolinska Institutet, Stockholm, Sweden
⁴ Swedish School of Sport and Health Sciences, Stockholm, Sweden

^* To whom correspondence should be addressed. E-mail: carl.askling{at}ihs.se.

	Abstract

Background: Hamstring strains can be of at least 2 types, 1 occurring during high-speed running and the other during motions in which the hamstring muscles reach extreme lengths, as documented for sprinters and dancers.

Hypothesis: Hamstring strains in different sports, with similar injury situations to dancers, also show similarities in symptoms, injury location, and recovery time.

Study Design: Case series (prognosis); Level of evidence, 4.

Methods: Thirty subjects from 21 different sports were prospectively included. All subjects were examined clinically and with magnetic resonance imaging (MRI). The follow-up period lasted until the subjects returned to or finished their sport activity.

Results: All injuries occurred during movements reaching a position with combined extensive hip flexion and knee extension. They were located proximally in the posterior thigh, close to the ischial tuberosity. The injuries were often complex, but 83% involved the semimembranosus and its proximal free tendon. Fourteen subjects (47%) decided to end their sports activity. For the remaining 16 subjects, the median time for return to sport was 31 weeks (range, 9-104). There were no significant correlations between specific clinical or MRI parameters and time to return to sport.

Conclusions: In different sports, an injury situation in which the hamstring muscles reach extensive length causes a specific injury to the proximal posterior thigh, earlier described in dancers. Because of the prolonged recovery time associated with this type of injury, correct diagnosis, based on history and palpation, and adequate information to the subject are essential.