Comparison of various interpositional materials in the prevention of transphyseal bone bridge formation.

Various interpositional materials, except muscle, have been used to prevent transphyseal bone bridge formation after resection of the damaged physeal plate. In this animal model, muscle was used as an interpositional material, and its effectiveness was compared with that of 3 known materials (fat, physeal allograft, and iliac apophyseal autograft). Five experiments were done on the distal femoral physis of 40 skeletally immature 3-month-old New Zealand white rabbits. The rabbits were divided into 5 groups, each containing 8 rabbits. A standard defect was created in the lateral distal physis of the left femur in all the rabbits. In Group A, there was no interpositional material. Vastus lateralis muscle, groin fat, physeal allograft, and iliac apophyseal autograft were inserted into the femoral defect in Groups B, C, D, and E, respectively. The right femur served as a sham control for the animals. The animals were sacrificed at 12 weeks after surgery. The results of limb length discrepancy and angular deformity of the groups with interpositional material were compared with those of Group A (experimental control). Muscle, fat, and iliac apophyseal autografts had less severe limb length discrepancy and angular deformity. These differences were statistically significant, whereas the differences between allograft and experimental control were statistically insignificant.