Fusion surgery with instrumentation following carbon ion radiotherapy for primary lumbar tumors: A case series.

Carbon-ion radiotherapy (CIRT) is a useful modality for treatment of primary spinal sarcoma, but osteonecrosis after CIRT may cause pseudoarthrosis that can make subsequent reconstruction surgery difficult. The patients were a 68-year-old man (case 1), a 30-year-old woman (case 2), and a 49-year-old man (case 3) with lumbar lesions. After CIRT, cases 1 and 3 were treated with instrumented spondylectomy and case 2 underwent posterior decompression and instrumentation surgery. Cases 1 and 2 required several salvage procedures because of failure of instrumentation (rod breakage) before bone union was achieved. After multiple revision surgeries, these cases did achieve bone union without tumor recurrence. In contrast, in case 3, only spondylectomy using a pedicle screw system at 20 months after CIRT was required for fusion. At follow-up 11 years postoperatively, CT showed bone union with invasion of autograft bone from the iliac crest into adjacent vertebra. Collapse or a finding of viable tumor cells after CIRT requires surgery such as spondylectomy with reconstruction. Instrumented fixation following CIRT for a lumbar primary tumor should be performed with multilevel anterior support using a sufficient amount of bone graft in posterior fusion levels.