A 12-year-old boy presented with pain and a mass on the medial aspect of the right proximal leg. He first noticed symptoms at around 10 years of age. The pain appeared on knee flexion, and was absent when he walked or ran. His height and body weight were 162 cm and 59 kg, respectively. He had no past medical history related to the lesion. There was no history of trauma or injury at the knee. On examination, a non-mobile hard mass was palpable with tenderness at the medical side of the proximal tibia. Swelling was not obvious. Plain radiographs showed a lesion protruding from the bone with continuity to the underlying bone. The size of the lesion was 0.8 cm on a plain radiograph (Fig. ). CT depicted a protuberant bone lesion with continuity to normal bone (Fig. ), but an overlying cartilaginous cap was not obvious. The MRI showed the lesion had continuity to the host bone marrow. There was no obvious inflammation characterized by high signal intensity on a T2 weighted fat-suppression image around the tip of the osteochondroma (Fig. ). For surgical resection, the lesions were approached posterior to the conjoint tendon (Fig. ). While retracting the attachment of the pes anserinus, the lesion was resected using a curved chisel. Histologically, the specimen showed partially sclerotic lamellar bone trabeculae covered by an attenuated hyaline cartilaginous cap undergoing endochondral ossification with fatty marrow, compatible with osteochondroma. There was no evidence of malignancy. Six months after surgery, the symptoms disappeared.
Another 13-year-old male child presented to the outpatient department with similar complaints of knee pain on the left side for the last two months. The onset was insidious and there was no history of trauma. There was no history of swelling or pain in any other part of the body. On examination, it was found that tenderness was present at the medial aspect of left proximal tibia. No swelling was palpable. Rest of the local examination and systemic examination were unremarkable. Plain radiographs of the left knee revealed a sharp bony spur arising from proximal tibial metaphysis, similar to the first case (Figure ). But the radiograph of the contra-lateral knee was unremarkable. The patient was again advised rest and analgesic medications for three weeks. No other subsequent intervention was required, and at the last follow-up of two years, there was no recurrence of pain.