Xuyang Zhang1,2, Hao Wu3, Yilei Chen1,2, Junhui Liu1,2, Jian Chen1,2, Teng Zhang3, ZhaoFeng Zhou4, Shunwu Fan1,2, Patricia Dolan5, Michael Anthony Adams6, Fengdong Zhao7,8. 1. Department of Orthopaedics, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, No. 3, Qingchun Road East, Hangzhou, 310016, People's Republic of China. 2. Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, People's Republic of China. 3. Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong, SAR, People's Republic of China. 4. Department of Mechanical Engineering, College of Engineering, Zhejiang University City College, Hangzhou, People's Republic of China. 5. Department of Anatomy, University of Bristol, Southwell Street, Bristol, BS2 8EJ, UK. 6. Department of Anatomy, University of Bristol, Southwell Street, Bristol, BS2 8EJ, UK. M.A.Adams@bristol.ac.uk. 7. Department of Orthopaedics, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, No. 3, Qingchun Road East, Hangzhou, 310016, People's Republic of China. zhaofengdong@zju.edu.cn. 8. Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, People's Republic of China. zhaofengdong@zju.edu.cn.
Abstract
PURPOSES: To explore the function of endplate epiphyseal ring in OLIF stand-alone surgery using a biomechanical model to reduce the complications of endplate collapse and cage subsidence. METHODS: In total, 24 human cadaveric lumbar function units (L1-2 and L3-4 segments) were randomly assigned to two groups. The first group was implanted with long fusion cages which engaged with both inner and outer regions of epiphyseal ring (Complete Span-Epiphyseal Ring, CSER). Those engaged with only the inner half of epiphyseal ring were the second group (Half Span-Epiphyseal Ring, HSER). Each group was divided into two subgroups [higher cage-height (HH) and normal cage-height (NH)]. Specimens were fixed in testing cups and compressed at approximately 2.5 mm/s, until the first sign of structural failure. Trabecular structural damage was analyzed by Micro-CT, as well as the difference of bone volume fraction (BV/TV), trabecular thickness (Tb.Th) et al. in different regions. RESULTS:Endplate collapse was mainly evident in the inner region of epiphyseal ring, where trabecular injury of sub-endplate bone was most concentrated. Endplate collapse incidence was significantly higher in HSER than CSER specimens (P = 0.017). A structural failure occurred at a lower force in HSER (1.41 ± 0.34 KN) compared with CSER (2.44 ± 0.59 KN). HH subgroups failed at a lower average force than NH subgroups. Micro-CT results showed a more extensive trabecular fracture in HSER specimens compared to CSER specimens, especially in HH subgroup. CONCLUSIONS:Endplate collapse is more likely to occur with short half span cages than complete span cages, and taller cages compared with normal height cages. During OLIF surgery, we should choose cages matching intervertebral disc space height and place the cages spanning over the whole epiphyseal ring to improve support strength.
RCT Entities:
PURPOSES: To explore the function of endplate epiphyseal ring in OLIF stand-alone surgery using a biomechanical model to reduce the complications of endplate collapse and cage subsidence. METHODS: In total, 24 human cadaveric lumbar function units (L1-2 and L3-4 segments) were randomly assigned to two groups. The first group was implanted with long fusion cages which engaged with both inner and outer regions of epiphyseal ring (Complete Span-Epiphyseal Ring, CSER). Those engaged with only the inner half of epiphyseal ring were the second group (Half Span-Epiphyseal Ring, HSER). Each group was divided into two subgroups [higher cage-height (HH) and normal cage-height (NH)]. Specimens were fixed in testing cups and compressed at approximately 2.5 mm/s, until the first sign of structural failure. Trabecular structural damage was analyzed by Micro-CT, as well as the difference of bone volume fraction (BV/TV), trabecular thickness (Tb.Th) et al. in different regions. RESULTS: Endplate collapse was mainly evident in the inner region of epiphyseal ring, where trabecular injury of sub-endplate bone was most concentrated. Endplate collapse incidence was significantly higher in HSER than CSER specimens (P = 0.017). A structural failure occurred at a lower force in HSER (1.41 ± 0.34 KN) compared with CSER (2.44 ± 0.59 KN). HH subgroups failed at a lower average force than NH subgroups. Micro-CT results showed a more extensive trabecular fracture in HSER specimens compared to CSER specimens, especially in HH subgroup. CONCLUSIONS: Endplate collapse is more likely to occur with short half span cages than complete span cages, and taller cages compared with normal height cages. During OLIF surgery, we should choose cages matching intervertebral disc space height and place the cages spanning over the whole epiphyseal ring to improve support strength.
Entities:
Keywords:
Biomechanical model; Endplate collapse; Epiphyseal ring; OLIF; Stand-alone surgery
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