Department for Health, University of Bath, Bath, UK; AO Research Institute Davos, Davos, Switzerland.
AO Research Institute Davos, Davos, Switzerland.
Clin Biomech (Bristol). 2020 Dec;80:105201. doi: 10.1016/j.clinbiomech.2020.105201. Epub 2020 Oct 23.
Screws are the most commonly inserted orthopaedic implants. However, several variables related to screw insertion and tightening have not been evaluated. This study aimed firstly to assess the effect of insertion variables on screw tightness, secondly to improve methodologies used by researchers when testing screw insertion techniques and thirdly to assess for any learning or fatigue effects when inserting screws.
Two surgeons tightened a total of 2280 non-locking, 3.5 mm cortical screws, with 120 screws inserted to what they felt to be optimum tightness whilst varying each of the following factors: different screwdrivers for measuring torque, screwdriver orientation, gloves usage, dominant/non-dominant hand usage, awareness to the applied torque (blinded, unblinded and re-blinded), four bone densities and seven cortical thicknesses. Screws were tightened to failure to determine stripping torque, which was used to calculate screw tightness - ratio between stopping and stripping torque.
Screw tightness increased with glove usage, being blinded to the applied torque and with denser artificial bone and with thinner cortices. Considering all the insertions performed, the two surgeons stopped tightening screws at difference values of tightness ((77% versus 66% (p < 0.001)). A learning effect was observed with some parameters including sterile gloves usage and non-dominant hand application.
Different insertion conditions frequently changed screw tightness for both surgeons. Given the influence of screw tightness on fixation stability, the variables investigated within this study should be carefully reported and controlled when performing biomechanical testing alongside practicing screw insertion under different conditions during surgical training.
螺钉是最常植入的骨科植入物。然而，螺钉插入和紧固的几个相关变量尚未得到评估。本研究旨在首先评估插入变量对螺钉紧固的影响，其次改进研究人员在测试螺钉插入技术时使用的方法，第三评估插入螺钉时是否存在学习或疲劳效应。
两名外科医生总共拧紧了 2280 个非锁定的 3.5 毫米皮质螺钉，其中 120 个螺钉插入到他们感觉最佳紧固程度的位置，同时改变了以下每个因素：用于测量扭矩的不同螺丝刀、螺丝刀方向、手套使用、惯用手/非惯用手使用、对施加扭矩的意识（盲、不盲和重新盲）、四种骨密度和七种皮质厚度。螺钉被拧紧到失效，以确定剥离扭矩，这用于计算螺钉紧固程度 - 停止扭矩和剥离扭矩之间的比率。
螺钉紧固度随着手套使用、对施加扭矩的盲目性以及人造骨密度更高和皮质更薄而增加。考虑到所有进行的插入，两名外科医生在不同的紧固程度下停止拧紧螺钉（(77% 对 66%（p<0.001)）。在某些参数中观察到学习效应，包括无菌手套使用和非惯用手应用。
不同的插入条件经常改变两名外科医生的螺钉紧固度。鉴于螺钉紧固度对固定稳定性的影响，在进行生物力学测试时，应仔细报告和控制本研究中调查的变量，并在手术培训期间在不同条件下练习螺钉插入。
