Bone healing stimulated by plasma factor XIII. Osteotomy experiments in sheep.

Sheep had their right metatarsals osteotomized midshaft and stabilized by plate and screws. One group was injected with 1250 units of Factor Thirteen for 9 days postoperatively, and a control group received placebo injections. After 8 weeks, the bones were evaluated biomechanically, histomorphologically and by densitometry. The bones of the treated group had a significantly higher tensile strength than the bones of the control animals. The correlation of biomechanical and morphological results demonstrated that the tensile strength increased with an increasing number of osteons crossing the osteotomy gap. The hydroxyapatite content of the bone healing zone was 7.3 per cent higher for the treated bones than for the control bones.