CLOSED VERSUS OPEN MEDULLARY NAILING OF FEMORAL FRACTURES - BLOOD-FLOW AND HEALING STUDIED IN RATS

In rats, bilateral closed femoral fractures were produced. On the left side, closed intramedullary nailing was done, and on the right side, the nail was inserted by an open procedure. The healing process of the fractures was evaluated at 4, 8, and 12 weeks, bone and muscle blood flows were also determined. Reaming had no acute impact on bone blood flow, while reaming and fracture halved total bone flow (P < 0.04), and reduced cortical diaphyseal flow to approximately one quarter (P < 0.01). No differences were found between the open and closed methods. At 4 weeks, the bending moment, rigidity, and fracture energy of the fractures treated by closed medullary nailing were greater than those treated by open nailing. The fracture energy was still greater at 8 weeks, while no differences were seen in bending moment and rigidity. At 12 weeks, however, there were no differences in the mechanical parameters. Bone blood flows in both the cortical diaphysis and callus area were increased at 4 and in the callus area at 8 weeks in bones treated by the open method. No differences were found at the end of the experiment. Muscle blood flow was not different in the two limbs, and was constant during the experimental period. We conclude that femoral fractures treated by closed nailing heal better in the initial phase compared with those that have been openly nailed. This difference cannot be explained by an impaired muscle or bone blood flow due to open surgery.