The effect of the presence of muscle tissue in a bone healing site.

Purpose: The recovery of a bone fracture is a process that is not yet fully understood. The literature conflicts on the results obtained by the interposition of foreign tissue inside a damaged bone. The objective of the present study was to ascertain the effect of placing muscle tissue between the stumps of a fractured bone.

Method: The study was carried out on 10 rabbits divided into 2 groups (n = 5): Group 1--partial fracture of the humerus and interposition of muscle tissue; Group 2--complete fracture of the humerus and interposition of muscle tissue. The fractured limb of all animals was immobilized for 8 weeks. At the end of this time, the rabbits were killed and their operated humeri were carefully removed for roentgenological and histological assessment.

Results: All humeri of Group 1 recovered their integrity and normal aspect. However, the healing of the humeri of Group 2 was not perfect. Gross angulation of the bone diaphysis occurred in all animals, and immature trabecular bone, osteochondral tissue, and persistence of muscle tissue substituted normal bone.

Conclusions: Interposed muscle does not affect partial bone fracture healing but causes instability in a complete fracture.