The effect of epiphysial stapling on growth in length of the rabbits tibia and femur.

In a previous communication (Hall-Craggs 1968) the results of experimental epiphysiodesis of the upper and lower ends of the rabbit tibia were reported. It was found that when growth in length at either the proximal or distal extremity of the bone was restricted by epiphysiodesis a reduction in the normal deceleration of growth rate occurred at the opposite end. As a result the undamaged epiphysis contributed a greater amount to the final length of the bone than the corresponding epiphysis of the other limb of the animal. These findings, together with the fact that no change in foot length was observed in the experimental limb, suggested that the phenomenon was limited to the experimental bone, and that it provided evidence of a local growth-controlling system. Although the additional contribution made by the uninjured epiphysis was never sufficient to compensate for the loss which followed epiphysiodesis, there was reasonable evidence to suggest that the degree of failure of the injured epiphysis to grow was directly related to the additional contribution at the other end of the bone. As each experimental bone was submitted to the same degree of trauma whatever the success of the epiphysiodesis, it was also argued that the trauma per se was not responsible for the increase in growth. However, one sequel to the epiphysiodesis was the formation of a bony bridge between the epiphysial and metaphysial bone, which established a new vascular communication between these regions and thus introduced an additional variable that was not present on the control side. Further experiments have therefore been performed to test the local nature of the response to arrested epiphysial growth which at the same time eliminated the vascular communication established between epiphysis and diaphysis after epiphysiodesis.