Healing pattern of reamed bone following bone harvesting by a RIA device

Abstract

Intramedullary nailing has been used for decades to treat fractures of the long bones. However, complications related to the increase in medullary pressure culminated in the development of the Reamer Irrigator Aspirator (RIA). Since its first clinical use, the RIA has moved from a reaming device to a cell and autologous bone-harvesting tool. This increase in use brings with it further clinical questions; namely, does the endosteal bone regenerate sufficiently to allow subsequent reaming procedures.In the current study, endosteal bone regeneration post reaming was assessed in an ovine model. The study included six animals that had one tibia reamed, while the contralateral tibia acted as an intact control. Animals were administered fluorochrome labels in vivo, and bone regeneration was assessed using radiographical analysis. The endpoint of the study was 12 weeks post-surgery, at which time ex vivo analysis consisted of computed tomography and histological assessments.In vivo radiographs indicated limited healing of the reamed bone. However, ex vivo computer tomographical analysis indicated no significant differences in terms of bone volume between the reamed bone and the intact bone. Histological assessment of these regions indicated new bone formation. Fluorescent labelling indicates strong bone formation from 9 weeks post-surgery and as such, the bone formed at 12 weeks was immature in nature and was actively undergoing remodelling.These results indicate that bone regeneration postreaming was continuing at three months. Therefore, given more time it may have sufficiently healed to allow a surgeon to use the intramedullary canal for a re-reaming procedure. Keywords BackgroundThe Reamer Irrigator Aspirator (RIA) was designed to allow the simultaneous suctioning and irrigation of the medullary canal while reaming for the placement of an interlocking nail. The RIA process results in the harvesting of a large amount of bone, which can be collected separately in a dedicated filter system. Consequently, the RIA has being used in clinical situations for autologous bone harvesting for the treatment of large bone defects. However, the endosteal healing pattern of the reamed bone has not been studied.