Physiologic effects of intramedullary reaming.

Reaming has a significant biologic and mechanical impact on the physiology of fracture healing. A review of the thermal, pulmonary, and osteogenic effects of reaming can provide evidence-based guidelines to assist the clinician in improving patient outcomes. Thermal necrosis is a rare but commonly referenced complication of reaming. The risks of heat-induced cortical damage can be minimized by sequential reaming with sharp instruments and by reaming with instruments that are sized appropriately to fit the intramedullary canal. The use of a tourniquet while reaming does not increase the risk of thermal necrosis. Reaming results in increased intramedullary pressure and secondary embolization of marrow elements to the pulmonary system. The clinical significance of these embolic events remains controversial. Potential complications can be reduced by using reamer designs and techniques that minimize the increases in intramedullary pressure. Outcome studies consistently show that reaming potentiates the healing response with intramedullary fixation of long-bone fractures. Recent laboratory studies implicate alterations in cortical blood flow patterns and the osteogenic potential of reaming debris as critical components of this process.