German Armed Forces Hospital Ulm, Oberer Eselsberg 40, 89081, Ulm, Germany.
Schwarzach Orthopedic Clinic·Spine Surgery & Traumatology, Dekan-Graf-Straße 2 - 6, 94374, Schwarzach, Germany.
Eur Spine J. 2021 Aug;30(8):2283-2291. doi: 10.1007/s00586-020-06676-1. Epub 2020 Dec 23.
In an osteoporotic vertebral body, cement-augmented pedicle screw fixation could possibly be optimized by the creation of an initial cavity. The aim of this study is to compare three test groups with regard to their loosening characteristics under cyclic loading.
Eighteen human, osteoporotic spine segments were divided in three groups. Flexibility tests and cyclic loading tests were performed with an internal fixator. The screws were fixed after creation a cavity and with cement (cavity-augmented group), without cavity and with cement (augmented group), and without cavity and without cement (control group). Cyclic loading up to 100,000 cycles was applied with a complex loading protocol. Screw loosening was measured with flexibility tests after implantation and after cyclic loading. Cement distribution was visualized from CT scans.
In all groups, range of motion increased during cyclic loading, representing significant screw loosening after 100,000 cycles. In both augmented groups, screw loosening was less pronounced than in the control group. The cavity-augmented group showed only a slight tendency of screw loosening, but with smaller variations compared to both other groups. This may be explained with a trend for a more equal and homogeneous cement volume around each tip for the cavity-augmented group.
This study demonstrated that creating a cavity may allow a more equal fixation of all pedicle screws with slight reduction of loosening. However, augmentation only through a cannulated screw is almost equivalent, if care is taken that enough cement volume can be pushed out around the tip of the screw.
在骨质疏松的椎体中，通过创建初始空腔，可优化骨水泥增强椎弓根螺钉固定。本研究旨在比较三组在循环加载下的松动特性。
将 18 个人体骨质疏松脊柱节段分为三组。使用内置固定器进行柔韧性测试和循环加载测试。在创建空腔和使用骨水泥（空腔增强组）、无空腔和使用骨水泥（增强组）以及无空腔和无骨水泥（对照组）的情况下固定螺钉。用复杂的加载方案进行高达 100,000 次循环的循环加载。在植入后和循环加载后用柔韧性测试测量螺钉松动。从 CT 扫描中可视化水泥分布。
在所有组中，在循环加载过程中活动范围增加，表明在 100,000 次循环后螺钉明显松动。在两个增强组中，螺钉松动程度低于对照组。空腔增强组仅显示出轻微的螺钉松动趋势，但与其他两组相比变化较小。这可能是由于空腔增强组每个尖端周围的水泥体积更均匀和均匀所致。
本研究表明，创建空腔可使所有椎弓根螺钉的固定更加均匀，松动程度略有降低。然而，如果注意到可以在螺钉尖端周围推出足够的水泥体积，则通过套管螺钉进行增强几乎是等效的。
