To investigate the growth modulation effect of plate-rod system for scoliosis（PRSS）in the management of progressive scoliosis in children.
Thirty-one early-onset scoliosis （EOS） patients who had been treated by PRSS were followed up for more than 2 years. The anteroposterior and lateral standing spinal radiographs were taken in all patients pre-，post-operatively and at each time point of follow up. The Cobb angle and apical vertebral wedge angle（AVWA）were measured for assessment of the height difference between two sides of the vertebrae. Afterwards，the relationship between the change of AVWA and modulation in growth period after operation was analyzed.
The mean Cobb angle was corrected from （63.74±20.99）° preoperatively to （25.38±14.76）° after surgery，and（31.68±19.53）° at the last follow-up，without obvious loss of correction（P>0.05）. The average AVWA improved from（13.74±5.88）° immediately after operation to（8.74±5.08）° at the last follow-up，with an average decline of（5.00±4.46）° showing a statistically significant difference（P<0.05）. Additionally，the AVWAs in the congenital scoliosis group were larger than those in the idiopathic scoliosis group immediately after surgery，however，gradually decreased in both 2 groups，which indicated that growth rate at the concavity side was superior to that at the convexity side. In the patients who underwent PRSS surgery at age less than 5 years，the apical vertebrae were less wedging，and the change of AVWA in later growth period after PRSS was more stable than those more than 5 years.
Measurement of AVWA reveals that the growth rate at the concavity side exceeded the convexity side after PRSS instrumentation，which indicates that PRSS has an ability of reversing asymmetrical growth in the scoliotic spine. Therefore，this is a reliable method to evaluate the modulation of growing rod.