Clarification of the Structure and Bone Mineral Content of Heterotopic Ossification

INTRODUCTION Heterotopic ossification (HO) is a pathological process characterized by ectopic osseous growth in muscle and periarticular regions. Although HO may develop from rare genetic disorders, abnormal bone growth has been most frequently reported following trauma, arthroplasty, burns, spinal cord injury and traumatic brain injury. The amount of HO that forms following soft tissue injury has ranged from small osteophytes to widespread osseous attachment to the skeleton, and thus heterogeneity has existed in the orthopaedic literature regarding HO bone morphology. Previous reports have speculated that HO manifested as cancellous bone, cortical bone or woven bone. Confusion regarding HO bone type has resulted from radiographic assessment and light microscopy which lack the resolution required for accurately determining advanced bone architecture. Therefore, a more complete histological assessment was necessary for characterizing HO using scanning electron microscopy (SEM) in the backscatter electron (BSE) imaging mode. The focus of this study was to examine resected trauma induced HO samples with BSE and histology to determine ectopic bone morphology. Advanced imaging techniques with BSE would improve clarification of the structure and bone mineral content of HO. Advanced understanding of HO may also provide insight into HO bone pathology and improve surgical planning.