Laboratory for Laser Aided Additive and Subtractive Manufacturing, Department of Materials Science and Engineering, University of North Texas, 1155 Union Circle-305310, Denton, TX, 76203-5017, USA.
Walker Department of Mechanical Engineering, The University of Texas at Austin, 204 E. Dean Keeton Street, ETC II 5.160, Austin, TX, 78712-1591, USA.
Lasers Med Sci. 2024 Jun 15;39(1):157. doi: 10.1007/s10103-024-04106-y.
Frequently orthopedic surgeries require mechanical drilling processes especially for inserted biodegradable screws or removing small bone lesions. However mechanical drilling techniques induce large number of forces as well as have substantially lower material removal rates resulting in prolong healing times. This study focuses on analyzing the impact of quasi-continuous laser drilling on the bone's surface as well as optimizing the drilling conditions to achieve high material removal rates. An ex-vivo study was conducted on the cortical region of desiccated bovine bone. The laser-based drilling on the bovine bine specimens was conducted in an argon atmosphere using a number of laser pulses ranging from 100 to 15,000. The morphology of the resulting laser drilled cavities was characterized using Energy dispersive Spectroscopy (EDS) and the width and depth of the drills were measured using a laser based Profilometer. Data from the profilometer was then used to calculate material removal rates. At last, the material removal rates and laser processing parameters were used to develop a statistical model based on Design of Experiments (DOE) approach to predict the optimal laser drilling parameters. The main outcome of the study based on the laser drilled cavities was that as the number of laser pulses increases, the depth and diameter of the cavities progressively increase. However, the material removal rates revealed a decrease in value at a point between 4000 and 6000 laser pulses. Therefore, based on the sequential sum of square method, a polynomial curve to the 6th power was fit to the experimental data. The predicted equation of the curve had a p-value of 0.0010 indicating statistical significance and predicted the maximum material removal rate to be 32.10 mm/s with 95%CI [28.3,35.9] which was associated with the optimum number of laser pulses of 4820. Whereas the experimental verification of bone drilling with 4820 laser pulses yielded a material removal rate of 33.37 mm/s. Therefore, this study found that the carbonized layer formed due to laser processing had a decreased carbon content and helped in increasing the material removal rate. Then using the experimental data, a polymetric equation to the sixth power was developed which predicted the optimized material removal rate to occur at 4820 pulses.
经常需要骨科手术进行机械钻孔过程，特别是对于插入的可生物降解螺钉或去除小骨病变。然而，机械钻孔技术会产生大量的力，并且材料去除率大大降低，导致愈合时间延长。本研究专注于分析准连续激光钻孔对骨表面的影响，并优化钻孔条件以实现高材料去除率。对干燥牛骨的皮质区进行了离体研究。在氩气气氛中使用 100 到 15000 个激光脉冲对牛骨标本进行了基于激光的钻孔。使用能量色散光谱法 (EDS) 对产生的激光钻孔腔的形态进行了表征，并使用基于激光的轮廓仪测量了钻孔的宽度和深度。然后使用轮廓仪的数据来计算材料去除率。最后，使用材料去除率和激光加工参数基于实验设计 (DOE) 方法开发了一个统计模型，以预测最佳的激光钻孔参数。基于激光钻孔腔的研究的主要结果是，随着激光脉冲数的增加，腔的深度和直径逐渐增加。然而，在 4000 到 6000 个激光脉冲之间的某个点，材料去除率的值下降。因此，根据顺序和平方和方法，将六次多项式曲线拟合到实验数据。该曲线的预测方程的 p 值为 0.0010，表明具有统计学意义，并预测最大材料去除率为 32.10mm/s，95%CI [28.3,35.9]，与最佳激光脉冲数 4820 相关。而使用 4820 个激光脉冲进行骨钻孔的实验验证产生了 33.37mm/s 的材料去除率。因此，本研究发现，由于激光加工而形成的碳化层的碳含量降低，有助于提高材料去除率。然后使用实验数据，开发了一个六次多项式方程，预测最佳材料去除率出现在 4820 个脉冲时。
