Comparison of cyclic loading versus constant compression in the treatment of long-bone fractures in rabbits

The strengths of healing long-bone fractures treated in two different mechanical environments were compared using a rabbit experimental model. Constant compression was applied to one healing tibial fracture, while the other was subjected to cyclic compression. At six weeks of healing, the group of tibial fractures treated with cyclic loading exhibited significantly higher torque and energy absorption to failure and lower stiffness than their pair-mates treated with constant compression. No statistically significant differences were detected at four or eight weeks of healing, although there was a suggestion that compression-treated bones may be stronger in the earlier phases of healing.

This experiment suggests that the requirements for rapid fracture-healing may vary with the stage of healing; that is, rigid immobilization applied during the initial stages of healing followed by intermittent compression during later stages.