Limb lengthening promotes muscle growth.

Studies of limb lengthening have demonstrated successful bone formation in the distraction gap. Failure of the muscle units to lengthen leads to many complications that significantly limit the success of this approach; it is, therefore, of paramount importance to characterize the behavior of the muscle during limb lengthening. In this study, tibiae of adult rabbits were lengthened for 10 days at a rate of 1 mm/day. The proliferative ability of the lengthened muscle was characterized using bromodeoxyuridine, a thymidine analogue that is incorporated during cell division, and desmin, a muscle-specific marker. We observed a large number of proliferating cells, specifically in the lengthened muscle, that were co-localized with many desmin-positive cells. The presence of bromodeoxyuridine nuclei inside desmin-positive muscle fibers suggests that limb lengthening promotes muscle growth by triggering myoblast proliferation and fusion into the lengthened muscle. Our findings are consistent with those of other studies in the reviewed literature that also suggest that limb lengthening promotes muscle growth.