The effect of reamed and nonreamed intramedullary nailing on fracture healing.

Intramedullary nailing has revolutionized the treatment of fractures. It is important to be aware of the biological and mechanical effects of reaming and nailing on bone. Most nails are substantially stiffer than bone, but because of their location in the medullary canal do not have nearly as adverse an effect on callus strength as plates. Reaming and nailing embolizes marrow contents into the systemic circulation and reduces blood flow to the total bone and cortex by 30% to 80%. This results in a hyperemic reaction that revascularizes the cortex depending on the type of nail used. Preservation of the soft tissue envelope around the fracture enhances this response resulting in fracture healing ratio of 98% when closed nailing techniques are used. The primary advantage of nonreamed nailing is better preservation of the blood supply to the cortex whereas the major advantage of reamed nailing is a more rigid construction, stronger implants, and earlier fracture union.