Comparison of two types of fixation for proximal tibial epiphysiodesis: An experimental study in a rabbit model

In this study, we describe a novel hemiepiphysiodesis technique to prevent implant-related perichondrial ring injury in a rabbit model.

Proximal tibial epiphyseal plates of a total of 16 white New Zealand rabbits were used for this animal model. The subjects were divided into three equal groups as follows: Group 1 (Kirschner wire [K-wire]/cerclage), Group 2 (8-plate) right-hind legs, Group 3 (Control) left hind legs. Using anteroposterior radiography, the medial slope angle (MSA), articular line-diaphyseal angle (ALDA), and the angle between screws of 8-plate in lateral X-ray tibial slope angle (TSA) were measured. The radiographs were taken early postoperative (Day 1) and on sacrification day (Week 8). The histological evaluation of the perichondrial ring was made on a 7-mm axial section that stained with Safranin O/fast green at X10 magnification.

In both K-wire and 8-plate groups, the early postoperative ALDA and TSA were greater than the sacrification ALDA and TSA (p=0.028 and p<0.001, respectively). The early postoperative MSA was lower than the sacrification MSA in groups, (p<0.001). The MSA in the control group was lower than the K-wire and 8-plate groups (p<0.001 and p=0.009; respectively). The perichondrial ring thickness of the K-wire group was greater than the 8-plate group in histological evaluation (p<0.001).

Both of the K-wire and 8-plate groups showed similar angulation effects in the proximal tibia, although histologically less damage to the perichondrial ring was observed in the K-wire group, compared to the 8-plate group.