Xiao-Jiang Yang1, Hong-Xun Sang2, Chen-Xin Liu1, Zhen-Sheng Ma1, Bing Meng1, Tian-Qing Li1, Ming-Chun Jiang1, Xiao-Zhong Liu1, Wei Lei1, Yang Zhang3. 1. Department of Orthopaedic Surgery, Xijing Hospital, The Air Force Medical University, No. 127 Changlexi Road, Xincheng District, Xi'an, 710032, Shaanxi, China. 2. Department of Orthopaedics, Shenzhen Hospital, Southern Medical University, No. 1333, Xinhu Road, Bao'an District, Shenzhen City, 518100, China. 3. Department of Orthopaedic Surgery, Xijing Hospital, The Air Force Medical University, No. 127 Changlexi Road, Xincheng District, Xi'an, 710032, Shaanxi, China. zhangyang@fmmu.edu.cn.
Abstract
PURPOSE: To build a mathematical model which could calculate the desired laminoplasty opening size (LOS) based on the target sagittal canal diameter (SCD) before single-door cervical laminoplasty (SDCL) when taking the effects of surgery drill into consideration. METHODS: The model was based on geometric analysis on deformation of spinal canal; the formula was derived and characterized as: y (mm) = 2 [Formula: see text] × sin(β/2) = c - d (y is the size of LOS, [Formula: see text] the size of transverse canal diameter, β the size of laminoplasty opening size, c the size of mini-plate and d the diameter of the drill bit used during the surgery operation). The parameters of pre- and postoperative computed tomography scans of 20 patients who had undergone SDCL were measured by the picture archiving and communication system (PACS) software and a new instrument named as Lei's ruler, respectively. RESULTS: The effects of surgery SDCL were very significant; for each patient, the SCD was enlarged dramatically after the surgery (P < 0.01). The differences between the data obtained by PACS and Lei's ruler were no statistically significant (P > 0.05). According to the derived formula, the 95% confidence intervals of SCD after the surgery were within the range of 14 mm and 14.5 mm. CONCLUSION: Applying the mathematical model and derived formula, the desired LOS could be calculated according to the target SCD which could help the surgeon select an optimum mini-plate before SDCL. At the same time, a new measuring device named Lei's ruler is designed for the convenience of the derived formula. These slides can be retrieved under Electronic Supplementary Material.
PURPOSE: To build a mathematical model which could calculate the desired laminoplasty opening size (LOS) based on the target sagittal canal diameter (SCD) before single-door cervical laminoplasty (SDCL) when taking the effects of surgery drill into consideration. METHODS: The model was based on geometric analysis on deformation of spinal canal; the formula was derived and characterized as: y (mm) = 2 [Formula: see text] × sin(β/2) = c - d (y is the size of LOS, [Formula: see text] the size of transverse canal diameter, β the size of laminoplasty opening size, c the size of mini-plate and d the diameter of the drill bit used during the surgery operation). The parameters of pre- and postoperative computed tomography scans of 20 patients who had undergone SDCL were measured by the picture archiving and communication system (PACS) software and a new instrument named as Lei's ruler, respectively. RESULTS: The effects of surgery SDCL were very significant; for each patient, the SCD was enlarged dramatically after the surgery (P < 0.01). The differences between the data obtained by PACS and Lei's ruler were no statistically significant (P > 0.05). According to the derived formula, the 95% confidence intervals of SCD after the surgery were within the range of 14 mm and 14.5 mm. CONCLUSION: Applying the mathematical model and derived formula, the desired LOS could be calculated according to the target SCD which could help the surgeon select an optimum mini-plate before SDCL. At the same time, a new measuring device named Lei's ruler is designed for the convenience of the derived formula. These slides can be retrieved under Electronic Supplementary Material.