Calcaneal insufficiency fracture in a child with osteosarcoma after chemotherapy and limb-sparing surgery

We report a rare case of a calcaneal insufficiency fracture in an 11-year-old boy with an osteosarcoma of the right proximal tibia. After one course of neoadjuvant chemotherapy for 4 months, we performed limb-sparing surgery. The knee joint was replaced with a custom-made endoprosthesis and the knee extensor mechanism was reconstructed with a medial gastrocnemius muscle flap. Seven months postoperatively, he complained of pain in the right foot and a plain radiograph revealed a calcaneal insufficiency fracture. Osteoporosis induced by chemotherapy and change of forces transmitted to the calcaneus after reconstruction with a gastrocnemius muscle flap might contribute to this fracture. It is important to be aware of the rare clinical entity of insufficiency fracture for making an early diagnosis and for differentiating them from pathological fractures associated with malignancy.