Histopathologic analysis of human vertebral bodies after vertebral augmentation with polymethylmethacrylate with use of an inflatable bone tamp. A case report.

V ertebroplasty, first described by Galibert et al.1 for the treatment of vertebral angiomas, is now often used to treat painful osteoporotic compression fractures of vertebral bodies and the pain associated with malignant tumor osteolysis2,3. Vertebral augmentation with percutaneous injection of polymethylmethacrylate cement after the use of an inflatable bone tamp is a variant of vertebroplasty that is commonly called kyphoplasty, a term that we will use hereafter. Inflation of the balloon tamp elevates the vertebral body end plates to reduce kyphosis4-6. Although infrequent, the complications of these procedures include leakage of cement into perispinal areas or the epidural space, embolization of cement, and spinal infection. Cement leakage is responsible for neurologic complications, including transient radiculopathies and spinal cord compression2,7,8. Thermal necrosis is a well-established consequence of cement-curing in conjunction with arthroplasty9-11, but the role of the exothermic polymerization of polymethylmethacrylate in vertebroplasty is unknown. Temperatures measured in an ex vivo study were sufficiently high for thermal necrosis to be considered a possibility12,13. The authors of a histopathologic study14 attributed a zone of necrosis around polymethylmethacrylate cement that had been injected into a metastatic vertebral tumor to thermal necrosis, but there may be other causes. We are aware of only two previous postmortem human studies in which augmented vertebral bodies were analyzed histologically14,15. The aim of our study was to investigate histopathologically the response of vertebral bodies to augmentation with polymethylmethacrylate cement introduced in a kyphoplasty. Fig. 1 Lateral radiograph of a spine specimen, showing four vertebrae (T11, L2, L4, and L5) containing polymethylmethacrylate. Compression fractures can be seen in several other vertebrae. Aseventy-five-year-old man presented with multiple, extremely painful compression fractures of the …