Yang Li1,2, Guy R Fogel3, Zhenhua Liao4, Weiqiang Liu5,6. 1. State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China. 2. Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China. 3. Spine Pain Begone Clinic, San Antonio, TX, USA. 4. Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen, 518057, People's Republic of China. 5. State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China. weiqliu@hotmail.com. 6. Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen, 518057, People's Republic of China. weiqliu@hotmail.com.
Abstract
PURPOSE: Few finite element studies have investigated changes in cervical biomechanics with various prosthesis design parameters using hybrid surgery (HS), and none have investigated those combined different HS strategies. The aim of our study was to investigate the effect of ball-and-socket prosthesis geometry on the biomechanical performance of the cervical spine combined with two HS constructs. METHODS: Two HS strategies were conducted: (1) ACDF at C4-C5 and anterior cervical disc replacement (ACDR) at C5-C6 (ACDF/ACDR), and (2) ACDR/ACDF. Three different prostheses were used for each HS strategy: prosthesis with the core located at the center of the inferior endplate with a radius of 5 mm (BS-5) or 6 mm (BS-6), or with a 5 mm radius core located 1 mm posterior to the center of the inferior endplate (PBS-5). Flexion and extension motions were simulated under displacement control. RESULTS: The flexion motions in supra- and infra-adjacent levels increased in all cases. The corresponding extension motions increased with all prostheses in ACDR/ACDF group. The stiffness in flexion and extension increased with all HS models, except for the extension stiffness with ACDF/ACDR. The facet stresses between the index and infra-adjacent level in ACDR/ACDF were significantly greater than those in the intact model . The stresses on the BS-5 UHMWPE core were greater than the yield stress. CONCLUSION: The core radii and position did not significantly affect the moments, ROM, and facet stress in extension. However, the moments and ROM in flexion were easily affected by the position. The results implied that the large core radii and posterior core position in ACDR designs may reduce the risk of subsidence and wear in the long term as they showed relative low stress . The ACDF/ACDR surgery at C4-C6 level may be an optimal treatment for avoiding accelerating the degeneration of adjacent segments.
PURPOSE: Few finite element studies have investigated changes in cervical biomechanics with various prosthesis design parameters using hybrid surgery (HS), and none have investigated those combined different HS strategies. The aim of our study was to investigate the effect of ball-and-socket prosthesis geometry on the biomechanical performance of the cervical spine combined with two HS constructs. METHODS: Two HS strategies were conducted: (1) ACDF at C4-C5 and anterior cervical disc replacement (ACDR) at C5-C6 (ACDF/ACDR), and (2) ACDR/ACDF. Three different prostheses were used for each HS strategy: prosthesis with the core located at the center of the inferior endplate with a radius of 5 mm (BS-5) or 6 mm (BS-6), or with a 5 mm radius core located 1 mm posterior to the center of the inferior endplate (PBS-5). Flexion and extension motions were simulated under displacement control. RESULTS: The flexion motions in supra- and infra-adjacent levels increased in all cases. The corresponding extension motions increased with all prostheses in ACDR/ACDF group. The stiffness in flexion and extension increased with all HS models, except for the extension stiffness with ACDF/ACDR. The facet stresses between the index and infra-adjacent level in ACDR/ACDF were significantly greater than those in the intact model . The stresses on the BS-5 UHMWPE core were greater than the yield stress. CONCLUSION: The core radii and position did not significantly affect the moments, ROM, and facet stress in extension. However, the moments and ROM in flexion were easily affected by the position. The results implied that the large core radii and posterior core position in ACDR designs may reduce the risk of subsidence and wear in the long term as they showed relative low stress . The ACDF/ACDR surgery at C4-C6 level may be an optimal treatment for avoiding accelerating the degeneration of adjacent segments.
Entities:
Keywords:
Ball-and-socket; Cervical biomechanic; Design parameter; Finite element; Hybrid surgery
Authors: Michael J Lee; Mark Dumonski; Frank M Phillips; Leonard I Voronov; Susan M Renner; Gerard Carandang; Robert M Havey; Avinash G Patwardhan Journal: Spine (Phila Pa 1976) Date: 2011-11-01 Impact factor: 3.468
Authors: Yang Li; Guy R Fogel; Zhenhua Liao; Rajnesh Tyagi; Gaolong Zhang; Weiqiang Liu Journal: Spine (Phila Pa 1976) Date: 2017-10-15 Impact factor: 3.468
Authors: Anup A Gandhi; Swathi Kode; Nicole A DeVries; Nicole M Grosland; Joseph D Smucker; Douglas C Fredericks Journal: Spine (Phila Pa 1976) Date: 2015-10-15 Impact factor: 3.468