Experimental Study of Distraction Epiphysiolysis: Rabbit Model

Ahn, Jae In; Park, Heui Jeon; Cho, Yong Moon

Abstract

Shortening and angular deformities in children are one of important orthopedic management problem. Conceptually, lengthening of the short side in treatment of limb length inequality is, in most instance, the most attractive approach to this problem. Throughout the evolution of lengthening procedures, the method that has remained most consistently acceptable is osteotomy followed by gradual distraction. However, the idea of increasing the length of or modifying the axis of s bone during growth by means of distraction of the grwoth plate is relatively new. Recently, Monticelli and Spinelli have had experience with a new and novel method of lower limb lengthening by physeal distraction. We have studied the results of effect of distraction epiphysiolysis and the use of nonsteroidal anti-inflammatory agents to impede bone bridge as well as premature epiphyseal closure. There are some reports in which indomethacin could prevent reformation of a bone bridge between the epiphysis and metaphysis without inhibiting normal growth and bone remodeling. For this study, a total of 30 rabbits with an initial weight of about 600 gram was used. At operation two K-wires(l.lmm in diameter) were drilled percutaneously on parallel trscks through the epipaysis and diaphysis of proximal tibia. Epiphyseal distraction of Turnbuckle type designed at our school was applied on each side of K-wire insertion at the tibia. The correct position of pin was confirmed by radiography and the rate of distraction is 0.5-1mm per day. Distrsction was continued for 3-6 weeks and radiographs was taken every 2 weeks. Some rabbits was sacrified sfter removal of distractor. Through these examination, following results were obtained. 1. Seperation of the epiphysis from the metaphysis occurred after average 3 days, and it always occurred in the zone of provisional calcification. 2. Short term results of growth plate distraction looked promising and longer limbs were seen, but long term results were unsstisfactory with premature epiphyseal closure and bone bridge formation occuring in many cases. 3. The role of indomethacine to impede bone bridge formation across the seperated growth plate could be observed, and was found that shortening could be possibly decreased. 4. Distraction epiphysiolysis would be one of valuable leg lengthening procedure at an age when the subjects bone growth is nearly complete, and also the administration of indomethacin with growth plate distraction might be effective to diminish the significant Change of shortening or angulation in high-risk juvenile fractures.