Objective: To study on the therapeutic mechanism of an innovated instrumentation--Plate-Rod System for scoliosis (PRSS) and its effectiveness for the surgical management of early on-set scoliosis (EOS).

Method: Between June 2000 and July 2008, 23 patients with progressive EOS who underwent one stage PRSS procedure without bony fusion.and had been followed-up for more than 2 years were evaluated prospectively. The mean age at the time of surgery was 7.98 years The experimental studies including: X-ray analysis; photo-elastic test and type ~ collagen were studied to express the therapeutic mechanism.

Results: The mean follow up period was 2.8 ±1.4 years, more than 5 years in 5 cases.

The mean scoliosis improved from 80.7° to 30.5° after surgery with a corrective rate of 62.2% and in latest follow.-up was 34.7° The length of the growth of the instrumented spine was average 13.3mm. No severe complications in our series. When PRSS is placed in place, compressive stress was found to exert on the convex side, while tensile stress on the concave side of the curvature which were reflected by the changes on the color band in the photo-elastic test and by the changes in width of the disc spaces, and more type X collagen expressed on convex side than concave side, it suggest that compressive stress leads to increase earlier cartilage degeneration of end plate in convex side correlating with the decreased growth of the end plate of this side, and resulting in maximum spinal realignment.

Conclusion: The PRSS which dispenses with spinal fusion and allows extension along with the children’s growth, is able to provide and maintain desirable correction of scoliosis in the later growing year due to its modulating efficiency in normalizing the spinal growth, This new device is an effective instrumentation for correcting scoliosis, especially for EOS.