Effect Of Penetrating Injury At Different Regions Of Physis On The Development Of Epiphyseal Plate: An Experimental Study

objective To explore the effect of penetrating injuries of different regions on the development of epiphyseal plate of immature rabbits. Methods 96 New Zealand white rabbits were used in the experiment, the percentage of areas of epiphyseal plates of both femora were estimated before operations. All the 96 rabbits were allocated into two groups randomly, Kirschner wires with different diameters were used to penetrate the central or lateral marginal regions of right distal femoral epiphyseal plate of rabbits, and the left side as own control. All animals were observed at the designed time points to detect the effect of the development of epiphyseal plate with the change on the whole and histopathology. Results pencentage of injuried epiphyseal plates in three groups were 3.33±0.92%,6.77±0.23%,9.05±0.30%. In the observation for 12 weeks, the growth retardation were appeared in the groups (3.0mm and 3.5mm) of central epiphyseal plate injuries and in 3.5mm group of lateral marginal epiphyseal plate injuries. The transverse diameter of condyles of femur was diminished in the groups (3.0mm and 3.5mm) of lateral marginal epiphyseal plate injuries and it showed growth retardation in corresponding condyles of femur. The valgus angulation deformities were showed in the groups (3.0mm and 3.5mm) of lateral marginal epiphyseal plate injuries. Bone bridges were found in all injury regions of epiphyseal plates through the analysis of pathohistology and immunohistochemistry, the chondrocytes of epiphyseal plate adjacent to injury regions were scattered as"island of cartilage", but the chondrocytes aligned irregularly and were surrounded by bony tissue bridges. Conclusion①The epiphyseal plate retardation secondary to a penetrating injury from Kirschner wire is related to the percentage of the injured area. The injuries in central regions of epiphyseal plates mainly induced discrepancies of limb shortening and injuries in lateral marginal regions mainly cause deformities of valgus angulation and transversal developmental arrest of epiphyseal plate.②the fibro-vasa bridges or bone bridges were seen in all the injury regions of epiphyseal plates.③The chondrocytes of epiphyseal plate had the ability of reparation after injury, but the ability was limited.