Quan-Chang Tan1, Zi-Xuan Liu2, Yan Zhao3, Xin-Yi Huang3, Hao Bai3, Zhao Yang3, Xiong Zhao3, Cheng-Fei Du2, Wei Lei4, Zi-Xiang Wu5. 1. Department of Orthopedics, Xijing Hospital, The Air Force Medical University, Changlexi Road No. 127, Xi'an, Shaanxi Province, 710032, PR China; Department of Orthopedics, Air Force Hospital of Eastern Theater Command, Malujie Road No. 1, Nanjing, Jiangsu Province, 220001, PR China. 2. Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, 300384, PR China; National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, 300384, China. 3. Department of Orthopedics, Xijing Hospital, The Air Force Medical University, Changlexi Road No. 127, Xi'an, Shaanxi Province, 710032, PR China. 4. Department of Orthopedics, Xijing Hospital, The Air Force Medical University, Changlexi Road No. 127, Xi'an, Shaanxi Province, 710032, PR China. Electronic address: leiwei@fmmu.edu.cn. 5. Department of Orthopedics, Xijing Hospital, The Air Force Medical University, Changlexi Road No. 127, Xi'an, Shaanxi Province, 710032, PR China. Electronic address: wuzixiang@fmmu.edu.cn.
Abstract
BACKGROUND: Different constructs are applied in revision surgery (RS) for adjacent segment disease (ASD) aiming to further decompress and fixate the affected segment(s) in two ways: replacing or preserving the primary implants. This study aimed to compare the biomechanical properties of four constructs with different configurations. METHODS: An T12-L5 finite element (FE) model was constructed and validated. Primary surgery was performed at L4-L5 and instrumented from L3 to L5. Thereafter, RS was undertook by decompressing L2-L3 and fixated with implant-replacing construct A, or implant-preserving construct B, C or D. Range of motion (ROM) and intervertebral disc pressure (IDP) were compared. Maximum von Mises stress on the rods between Construct A and B was evaluated. RESULTS: An obvious reduction of ROM was observed when the FE model was instrumented with four constructs respectively. The overall changing characteristics of ROM were approximately identical among four constructs. The changing characteristic of IDP among four constructs was similar. The degree of IDP reduction of Construct B was comparable to Construct A, while that of Construct C was comparable to Construct D. Maximum von Mises stress on the rods between Construct A and B indicated that no stress concentration was recorded at the locking part of the connector rod. CONCLUSIONS: The biomechanics of implant-preserving constructs were comparable to the traditional implant-replacing construct. The location of side-by-side connector could not affect the stability of Construct C and D. Construct B might be an optimal choice in RS for less dissection, less complication and more convenience in manipulation.
BACKGROUND: Different constructs are applied in revision surgery (RS) for adjacent segment disease (ASD) aiming to further decompress and fixate the affected segment(s) in two ways: replacing or preserving the primary implants. This study aimed to compare the biomechanical properties of four constructs with different configurations. METHODS: An T12-L5 finite element (FE) model was constructed and validated. Primary surgery was performed at L4-L5 and instrumented from L3 to L5. Thereafter, RS was undertook by decompressing L2-L3 and fixated with implant-replacing construct A, or implant-preserving construct B, C or D. Range of motion (ROM) and intervertebral disc pressure (IDP) were compared. Maximum von Mises stress on the rods between Construct A and B was evaluated. RESULTS: An obvious reduction of ROM was observed when the FE model was instrumented with four constructs respectively. The overall changing characteristics of ROM were approximately identical among four constructs. The changing characteristic of IDP among four constructs was similar. The degree of IDP reduction of Construct B was comparable to Construct A, while that of Construct C was comparable to Construct D. Maximum von Mises stress on the rods between Construct A and B indicated that no stress concentration was recorded at the locking part of the connector rod. CONCLUSIONS: The biomechanics of implant-preserving constructs were comparable to the traditional implant-replacing construct. The location of side-by-side connector could not affect the stability of Construct C and D. Construct B might be an optimal choice in RS for less dissection, less complication and more convenience in manipulation.