Table 3.

Experimental studies considering the effects of inter-fragmentary bending on fracture healing.

Author	Subjects (n)	Method	Outcome
Hente et al. (33)	Sheep (18)	Mid-diaphyseal femoral osteotomy was performed and fixed with a gap of 2.0 mm. Using a custom fixator bending cycles lasting 0.8 s creating a 50% inter-fragmentary strain at the endosteum was applied. The number of loading cycles was varied, the control received no loading, while the first group received 10 bending cycles per day and a second group received 1000 cycles per day	The compressive side of the osteotomy gap resulted in 25-fold greater periosteal callus formation. Greater cycle number showed again a 10-fold difference to the lower cycle number. Bridging occurred exclusively at the compressed side.
Palomares et al. (3)	Rats (85)	Mid-diaphyseal femoral osteotomy of 1.5 mm, the animal were fixed with an external frame, which allowed bending, approximately centered on the gap, the experimental group had stimulated −25/+35° bending applied at 1 Hz for 15 min per day starting 10 days post-surgery	Stimulation up regulated cartilage related genes, and down regulated several genes responsible for bone morphogenetic proteins (BMPs). Serial sectioning showed a much more prolific presence of cartilage and less mineralized callus compared to control.