Wissenschaftliche Grundlagen der aufgebohrten und unaufgebohrten Marknagelung

Abstract

A comparative investigation of differences in new bone formation and cortical remodelling after reamed and unreamed nailing was carried out in a standardized animal model. An oblique osteotomy of the tibia was created in 19 sheep, followed by intramedullary nailing. The medullary cavity was reamed ¶in 10 of the animals, while in 9 sheep unreamed nailing was performed. After an observation period of 10 weeks, microradiographical assessment indicated more intensive bone regeneration and better bridging of the osteotomy in the animals with unreamed nailing. In addition, fewer aseptic bone sequestra were identified in the “unreamed” group. Morphometric measurements of the specimens by fluorescence ¶microscopy showed a significantly earlier and more pronounced interfragmentary and periosteal regeneration of bone, and significantly smaller central cortical zones without any remodelling. The results are of particular clinical relevance to the stabilization of fractures with severe open or closed soft tissue injury. Unreamed nailing procedures do less damage to the bone than reamed procedures. The former are less invasive and lead to earlier and more intensive bone regeneration. Not only these biological advantages, but also the lower mechanical stability and strength associated with unreamed nailing should be taken into account when assessing whether reamed or unreamed nailing is indicated.