Knee locking caused by osteochondroma of the proximal tibia adjacent to the pes anserinus: A case report

Figure 1 Preoperative plain radiographs of the left knee. A and B: Plain anteroposterior (A) and lateral (B) radiographs revealed a bony protuberance on the medial side of the patient’s proximal tibia; C and D: Plain anteroposterior (C) and lateral (D) radiographs revealed that osteochondroma was sufficiently resected at immediately after surgery; E and F: Plain anteroposterior (E) and lateral (F) radiographs revealed no recurrence of osteochondroma at one year after surgery.

Figure 2 Preoperative computed tomography scans of the patient’s left knee. A-C: Axial (A) and 3D (B and C) computed tomography scans showed a bony protuberance with bone marrow continuity on the medial side of the proximal tibia.

Figure 3 Preoperative T2-weighted magnetic resonance imaging of the left knee. A-C: Coronal (A), sagittal (B), and axial (C) T2-weighted magnetic resonance imaging of the left knee indicating bone marrow continuity within the lesion and the pes anserinus directly covered the bony protuberance. A high signal change was observed in the semitendinosus tendon.

Figure 4 Pathological findings of surgical specimens. Pathologically, a coating of vitreous cartilage which was thought to be a cartilage cap was observed on the surface of the lesion. A: Hematoxylin-eosin (H-E) staining, × 2; B: H-E staining, × 20.