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.
Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, People's Republic of China.
Eur Spine J. 2021 Jan;30(1):79-87. doi: 10.1007/s00586-020-06667-2. Epub 2020 Nov 23.
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.
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.
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.
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.
通过生物力学模型探索终板骺环在 OLIF 独立手术中的作用，以减少终板塌陷和 cage 下沉的并发症。
共 24 个人体腰椎功能单位（L1-2 和 L3-4 节段）被随机分配到两组。第一组植入长融合 cage，与骺环的内、外区域接触（完全 Span-骺环，CSER）。与骺环内半接触的第二组为（半 Span-骺环，HSER）。每组分为两个亚组[高 cage 高度（HH）和正常 cage 高度（NH）]。标本固定在测试杯中，以 2.5mm/s 的速度压缩，直到出现结构失效的第一个迹象。通过 Micro-CT 分析小梁结构损伤，以及不同区域的骨体积分数（BV/TV）、小梁厚度（Tb.Th）等差异。
终板塌陷主要发生在骺环的内区，那里的 sub-endplate 骨小梁损伤最集中。HSER 标本的终板塌陷发生率明显高于 CSER 标本（P=0.017）。HSER 的结构失效力较低（1.41±0.34 KN），低于 CSER（2.44±0.59 KN）。HH 亚组的平均失效力低于 NH 亚组。Micro-CT 结果显示，HSER 标本的小梁骨折比 CSER 标本更广泛，尤其是在 HH 亚组。
短半 Span cage 比完整 Span cage 更容易发生终板塌陷，高 cage 比正常高度 cage 更容易发生终板塌陷。在 OLIF 手术中，我们应选择与椎间盘间隙高度匹配的 cage，并将 cage 放置在整个骺环上，以提高支撑强度。
