[A locked knee without previous trauma].

A 22-year-old female presented at our hospital with a spontaneous extension deficit of the left knee. Examination revealed a luxation of the semitendinosus tendon under an osteochondroma on the posteromedial side of the proximal tibia. The tendon was repositioned by flexion and endorotation of the knee. Subsequently, the osteochondroma was surgically resected to prevent recurrence of the complaints.