Distraction epiphysiolysis as a method of limb lengthening. I. Experimental study.

The tibiae of 41 growing sheep were lengthened by distraction epiphysiolysis. The distraction apparatus was applied for varying periods of time to the proximal epiphysis of a tibia; the contralateral tibia was used as the control. Daily application of the distraction force initially induced a fracture within the growing cartilage, and then progressively increased the distance between epiphysis and metaphysis. In the newly created space, new bone tissue gradually formed, which in time developed into a neometaphysis with a new cortex. This neometaphysis gradually acquired radiographic characteristics resembling those of control tibia, and they were capable of supporting normal body weight. Elongation of the bone ranged between 30 and 100 mm. Except in one incident of sepsis, no significant changes were observed in the structures adjoining the elongation area, nor in the soft tissue. In general, bone growth was not affected, although premature fusion of the epiphysis occurred in a few cases.