1838 COPYRIGHT © 2005 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED HISTOPATHOLOGIC ANALYSIS OF HUMAN VERTEBRAL BODIES AFTER VERTEBRAL AUGMENTATION WITH POLYMETHYLMETHACRYLATE WITH USE OF AN INFLATABLE BONE TAMP A CASE REPORT BY UMASUTHAN SRIKUMARAN, BA, WADE WONG, DO, STEPHEN M . BELKOFF, PHD, AND EDWARD F. MCCARTHY, MD Investigation performed at the Departments of Pathology and Orthopaedic Surgery, Johns Hopkins University, Baltimore, Maryland, ami the Department of Radiology, University of California-San Diego, San Diego, California V ertebroplasty, first described by Galibert et al.' for the trfiitment of vertebral angiomas, is now often used to treat painful osteoporotic compression fractures of vertebral bodies and the pain associated with malignant tu- mor osteolysis'. Vertebral augnienlation 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 hereaf- ter. Inflation ofthe balloon tamp elevates the vertebral body end plates to reduce kyphosis^'. Although infrequent, the complications of these procedures include leakage of cement into perispinal areas or the epidural space, embolization of ce- ment, and spinal infection. Cement leakage is responsible for neurologic complications, including transient radiculopathies and spinal cord compression' ". Thermal necrosis is a well- established consequence of cement-curing in conjunction with arthroplasty'*", but the role ofthe exothermic polymer- ization of polymethylmethacrylate in vertebroplasty is unknown. Temperatures measured in an ex vivo study were sufficiently high for thermal necrosis to be considered a possibility'^". The authors ofa histopathologic study" attributed a zone of ne- crosis 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 histologically'" . The aim of our study was to investigate his- topathologically the response of vertebral bodies to augmenta- tion with polymethylmethacrylate cement introduced in a kyphoplasty. Case Report A seventy-five-year-old man presented with multiple, ex- tremely painful compression fractures of the spine sec- Fig, i Laterai radiograph of a spine specimen, showing four vertebrae (Til, L2. L4, and L5) containing poiymethyimethacryiate. Compres- sion fractures can be seen in several other vertebrae.