VASCULARIZED GROWTH-PLATE TRANSPLANTATION - A COMPARATIVE-STUDY IN THE RAT

The purpose of this study was to evaluate the influence of hormonal mi lieu on endochondral growth. This was achieved by transplanting hind l imbs of juvenile rats to syngeneic adult rats. Because there is no pot ential for rejection, the limb can be transplanted between animals of different ages, to study the influence of hormonal maturity on stimula tion and cessation of physeal growth and maturation. Tibial length and the histologic appearance of the physis were recorded. Whole vascular ized hind-limb transplantation in syngeneic Lewis rats was used. Group 1: Thirty-five transplants between animals of the same age (three wee ks old) were performed (isochronografts). Group 2: In 35 procedures, t he age of the donor was three weeks and of the recipient, 15 weeks (he terochronografts). In the first two study groups, the transplanted lim b was placed on the dorsal flank of the recipient animal without nerve reconstruction. Controls were the contralateral hind limb of the dono r animal. Because the limb was transplanted with loss of femoral and s ciatic nerve supply to the dorsal flank position, the effects of dener vation and lack of weight bearing were also evaluated. Group 3: Thirty -five limbs in three-week-old animals were transposed to the dorsal fl ank position, after severing the femoral and sciatic nerves. Analysis of variance of tibial length was used to compare study groups. Limbs t ransplanted to older animals (heterochronografts-Group 2) achieved the greatest length, 91 percent of normal, and significantly more when co mpared to Groups 1 (84 percent) and 3 (83 percent) (p < .005). Growth of the limb was adversely affected by limb position and denervation. T he growth rate of the transposed limb (Group 3), in comparison to the paired unoperated limb, significantly slowed at four weeks of age. The columnar arrangement at the growth plate was also adversely affected by limb position and denervation.