An 11-year-old boy presented in 2012 with pain in his right knee during running. He was referred to our orthopedic department after a radiograph showed an abnormal shadow. This patient's past medical history and family history included nothing of note. Physical examination revealed right knee edema and warmth. Serum phosphorus was 1.92 mmol/L (normal: 0.9-1.9 mmol/L), and serum alkaline phosphatase was 186 IU/L (normal: 45-125 mmol/L). Radiography revealed sclerotic changes and a periosteal reaction in the lateral part of the proximal tibia.On magnetic resonance imaging (mri), the lesion had homogeneous low signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images, which demonstrated full contact between tumour and epiphysis. Angiography showed a tumour stain, and 99m Tc scintigraphy demonstrated increased uptake in the proximal tibia.A puncture biopsy was performed, and the tumour was histologically diagnosed as an osteosarcoma (Figure 1).We administered 2 cycles of preoperative chemotherapy consisting of cisplatin 120 mg/m 2 (day 1), doxorubicin 30 mg/m 2 (days 1-3), and ifosfamide 2 g/m 2 (days 1-5) 4 . Consequently, the chief complaint of pain was relieved, and by angiography and 99m Tc uptake, the tumour stain disappeared. Serum phosphorus and alkaline phosphatase concentrations declined to 1.06 mmol/L and 113 IU/L respectively. The tumour response was judged to be complete.The surgical procedure consisted of two phases:• In phase 1, two pins were inserted into the epiphysis and another two into the diaphysis 10 cm from the tumour. An external monolateral fixator with a 5-cm T-shaped piece for the epiphyseal pins, strong enough for achieving epiphysiolysis, was attached 5 . Distraction began in the operating room and was continued at a rate of 1-1.5 mm
ABSTRACTIn an 11-year-old boy with osteosarcoma in the proximal tibia (type iii), 2 cycles of dia chemotherapy (cisplatin, ifosfamide, doxorubicin) were administered preoperatively while epiphysiolysis was performed. Clinical response was determined to be complete by radiography and histopathology. Marginal excision was then performed with preservation of the proximal tibial epiphysis. Metaphyseal reconstruction was performed using distraction osteogenesis. Six cycles of dia chemotherapy were administered postoperatively. Twenty months later, the patient had developed no complications and experienced full bone healing, with no limb discrepancy. In selected adolescent patients with osteosarcoma, in whom the tumour is in full contact with the epiphysis, epiphyseal preservation by epiphysiolysis and reconstruction by distraction osteogenesis can provide an excellent outcome, resulting in a stable reconstruction that functionally restores the native limb.