Presentation
Posterior thigh pain. Sports injury.
Patient Data
Prior left ACL reconstruction. Absent distal semitendinosus tendon, presumably ACL graft donor site without regeneration.
Semitendinosus has a slightly wavy, redundant appearance. Reduced bulk of the distal semitendinosus muscle belly around the distal myotendinous junction with moderate fatty atrophy on T1WI. Superimposed STIR hyperintensity for a length of 9.5 cm and >50% cross-sectional diameter. No discrete fiber disruption. No myofascial fluid.
Case Discussion
The distal semitendinosus tendon, usually in conjunction with the distal gracilis tendon, can be used as a donor site for an ACL graft repair. The semitendinosus tendon has been shown to regrow in most (~95%) but not all patients. This case demonstrates long-standing changes of atrophy.