COMPARISON OF THE EFFECT OF REAMED AND UNREAMED LOCKED INTRAMEDULLARYNAILING ON BLOOD-FLOW IN THE CALLUS AND STRENGTH OF UNION FOLLOWING FRACTURE OF THE SHEEP TIBIA

This study was performed to compare the effects of reamed and unreamed locked intramedullary nailing on blood flow in the callus and early s trength of union in a fractured sheep tibia model. After the creation of a standardized short spiral fracture by three-point bending with to rsion, each tibia was stabilized by the insertion of a locked intramed ullary nail. Ten animals were allocated randomly into two groups: one that had reaming prior to nail insertion and one that did not. Blood f low was measured in real time with use of laser Doppler flowmetry. End osteal perfusion was determined at the fracture site before and after nail insertion. Perfusion of the callus was measured at three location s (proximal diaphysis, fracture site, and distal diaphysis) and at thr ee time intervals (2, 6, and 12 week follow-up). All animals were kill ed 12 weeks postoperatively, and the tibiae were tested to failure in four-point bending. Nailing with reaming resulted in a larger decrease in overall endosteal perfusion than nailing without reaming (p < 0.01 5). The presence or absence of reaming did not affect blood now within fracture callus. Perfusion of callus was greatest at 6 weeks of follo w-up. Bending strength and stiffness were the same in bath groups at 1 2 weeks. The study demonstrated that perfusion of callus and early str ength of union are similar following intramedullary nailing with or wi thout reaming.