Schneider Manuel, Buschbaum Jan, Joeris Alexander, Röhrle Oliver, Dwyer Jonathan, Hunter James B, Reynolds Richard A K, Slongo Theodor F, Gueorguiev Boyko, Varga Peter
AO Research Institute Davos, Davos, Switzerland.
AO Clinical Investigation and Documentation, Davos, Switzerland.
J Orthop Res. 2018 May;36(5):1398-1405. doi: 10.1002/jor.23762. Epub 2017 Nov 2.
Implants used to correct pathological varus-valgus deformities (VVD) and leg length discrepancies (LLD) may not be optimized for the specific treatment, as suggested by their off-label use. Detailed analysis of this issue has been limited by the poorly understood mechanical behavior of the growing physis and ignorance of the loads acting on the implants. The aim of this study was to predict and compare the loading conditions of a growth modulation implant in VVD and LLD treatments. Idealized finite element (FE) models of the juvenile distal femur treated with the Eight-Plate implant were developed for VVD and LLD. Bone growth was simulated using thermal strains. The axial force in the plate was compared between the two treatments. Case-specific plate forces were predicted by virtually reproducing the screw deformation visible on radiographs of LLD (N = 4) and VVD (N = 4) clinical cases. The simple FE models reproduced the clinical implant deformations well. The resulting forces ranged from 129 to 580 N for the VVD patients. For LLD, this range was from 295 to 1002 N per plate, that is, 590-2004 N for the entire physis. The higher forces in LLD could be explained by restricted screw divergence in the double-sided implant application. For the first time, the loading conditions of a growth modulation implant were investigated and compared between two treatments by FE analyses, and the range of case-specific loads was predicted. These simulation tools may be utilized for guiding appropriate usage and for efficient development of implants. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1398-1405, 2018.
用于矫正病理性内翻-外翻畸形（VVD）和腿长差异（LLD）的植入物可能未针对特定治疗进行优化，这从其标签外使用情况可见一斑。对这一问题的详细分析一直受到生长中的骺板力学行为了解不足以及对作用于植入物的载荷认识不足的限制。本研究的目的是预测和比较生长调节植入物在VVD和LLD治疗中的加载条件。针对VVD和LLD，开发了用八钢板植入物治疗的青少年股骨远端理想化有限元（FE）模型。使用热应变模拟骨生长。比较了两种治疗中钢板的轴向力。通过虚拟再现LLD（N = 4）和VVD（N = 4）临床病例X线片上可见的螺钉变形，预测了特定病例的钢板力。简单的有限元模型很好地再现了临床植入物变形。VVD患者产生的力范围为129至580 N。对于LLD，每块钢板的力范围为295至1002 N，即整个骺板为590 - 2004 N。LLD中较高的力可以通过双侧植入物应用中螺钉发散受限来解释。首次通过有限元分析研究并比较了生长调节植入物在两种治疗中的加载条件，并预测了特定病例载荷的范围。这些模拟工具可用于指导适当使用和植入物的高效开发。© 2017骨科研究协会。由Wiley Periodicals, Inc.出版。《矫形外科学研究》36:1398 - 1405, 2018。
