One-staged tibial corrective osteotomy and total knee arthroplasty is a challenging but effective treatment for arthritic knees with extra-articular deformity. Although osteocutaneous thermal necrosis is accepted as a complication of intramedullary reamed nailing following long bone fractures, only 15 cases have been reported in the English literature at present. This report illustrates a rare case of thermal necrosis in a patient undergoing tibial corrective osteotomy coincident with long-stemmed total knee arthroplasty. Excessive reaming with a machine reamer is hypothesized as the cause of this serious complication. In this report, we highlight this rare but serious complication after long-stemmed total knee arthroplasty.