den Dunnen S, Dankelman J, Kerkhoffs G M, Tuijthof G
Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands.
Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands.
J Mech Behav Biomed Mater. 2017 Aug;72:219-228. doi: 10.1016/j.jmbbm.2017.05.009. Epub 2017 May 6.
In orthopaedic surgery, water jet drilling provides several advantages over classic drilling with rigid drilling bits, such as the always sharp cut, absence of thermal damage and increased manoeuvrability. Previous research showed that the heterogeneity of bone tissue can cause variation in drilling depth whilst water jet drilling. To improve control over the drilling depth, a new method is tested consisting of two water jets that collide directly below the bone surface. The expected working principle is that after collision the jets will disintegrate, with the result of eliminating the destructive power of the coherent jets and leaving the bone tissue underneath the focal point intact. To assess the working principle of colliding water jets (CWJ), the influence of inhomogeneity of the bone tissue on the variation of the drilling depth and the impact of jet time (t) on the drilling depth were compared to a single water jet (SWJ) with a similar power. 98 holes were drilled in 14 submerged porcine tali with two conditions CWJ (impact angle of 30° and 90°) and SWJ. The water pressure was 70MPa for all conditions. The water jet diameter was 0.3 mm for CWJ and 0.4 mm for SWJ. t was set at 1, 3, 5 and 8s. Drilling depth and hole diameter were measured using microCT scans. A non-parametric Levene's test was performed to assess a significant difference in variance between conditions SWJ and CWJ. A regression analysis was used to determine differences in influence of t on the drilling depth. Hole diameter differences were assessed using a one way Anova. A significance level of p<0.05 was set. Condition CWJ significantly decreases the drilling depth variance caused by the heterogeneity of the bone when compared to SWJ. The mean depth for CWJ was 0.9 mm (SD 0.3 mm) versus 4.8 mm (SD 2.0) for SWJ. t affects the drilling depth less for condition CWJ (p<0.01, R=0.30) than for SWJ (p<0.01, R=0.46). The impact angle (30° or 90°) of the CWJ does not influence the drilling depth nor the variation in depth. The diameters of the resulting holes in the direction of the jets is significantly larger for CWJ at 90° than for 30° or a single jet. This study shows that CWJ provides accurate depth control when water jet drilling in an inhomogeneous material such as bone. The maximum variance measured by using the 95% confidence interval is 0.6 mm opposed to 5.4 mm for SWJ. This variance is smaller than the accuracy required for bone debridement treatments (2-4 mm deep) or drilling pilot holes. This confirms that the use of CWJ is an inherently safe method that can be used to accurately drill in bones.
在骨科手术中，水刀钻孔相较于使用刚性钻头的传统钻孔具有诸多优势，比如切割始终锋利、无热损伤且可操作性增强。先前的研究表明，骨组织的异质性会导致水刀钻孔时钻孔深度出现变化。为了更好地控制钻孔深度，人们测试了一种新方法，该方法由两个在骨表面正下方直接碰撞的水刀组成。预期的工作原理是，碰撞后水刀会分散，从而消除连贯水刀的破坏力，使焦点下方的骨组织保持完整。为了评估碰撞水刀（CWJ）的工作原理，将骨组织不均匀性对钻孔深度变化的影响以及水刀作用时间（t）对钻孔深度的影响，与具有相似功率的单个水刀（SWJ）进行了比较。在14个浸没在水中的猪距骨上钻了98个孔，设置了两种条件，即CWJ（冲击角度为30°和90°）和SWJ。所有条件下的水压均为70MPa。CWJ的水刀直径为0.3mm，SWJ的水刀直径为0.4mm。t设置为1、3、5和8秒。使用微型计算机断层扫描（microCT）测量钻孔深度和孔径。进行非参数Levene检验以评估SWJ和CWJ条件之间方差的显著差异。使用回归分析来确定t对钻孔深度影响的差异。使用单向方差分析评估孔径差异。设定显著性水平为p<0.05。与SWJ相比，CWJ条件显著降低了由骨组织异质性引起的钻孔深度方差。CWJ的平均深度为0.9mm（标准差0.3mm），而SWJ为4.8mm（标准差2.0）。与SWJ（p<0.01，R = 0.46）相比，t对CWJ条件下钻孔深度的影响较小（p<0.01，R = 0.30）。CWJ的冲击角度（30°或90°）不影响钻孔深度或深度变化。在90°时，CWJ产生的孔在水刀方向上的直径明显大于30°或单个水刀的情况。这项研究表明，在诸如骨这样的不均匀材料中进行水刀钻孔时，CWJ能提供精确的深度控制。使用95%置信区间测量的最大方差为0.6mm，而SWJ为5.4mm。这个方差小于骨清创治疗（2 - 4mm深）或钻引导孔所需的精度。这证实了使用CWJ是一种本质安全的方法，可用于在骨中精确钻孔。
