Meischel M, Eichler J, Martinelli E, Karr U, Weigel J, Schmöller G, Tschegg E K, Fischerauer S, Weinberg A M, Stanzl-Tschegg S E
University of Natural Resources and Life Sciences, Institute of Physics and Materials Science, Peter-Jordan-Straße 82, 1190 Vienna, Austria.
Medical University of Graz, Department of Orthopedic Surgery, Auenbruggerplatz 5, 8036 Graz, Austria.
J Mech Behav Biomed Mater. 2016 Jan;53:104-118. doi: 10.1016/j.jmbbm.2015.08.004. Epub 2015 Aug 12.
Aim of this study was to evaluate the response of bone to novel biodegradable polymeric composite implants in the femora of growing rats. Longitudinal observation of bone reaction at the implant site (BV/TV) as well as resorption of the implanted pins were monitored using in vivo micro-focus computed tomography (µCT). After 12, 24 and 36 weeks femora containing the implants were explanted, scanned with high resolution ex vivo µCT, and the surface roughness of the implants was measured to conclude on the ingrowth capability for bone tissue. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to observe changes on the surface of Polyhydroxybutyrate (PHB) during degradation and cell ingrowth. Four different composites with zirconium dioxide (ZrO2) and Herafill(®) were compared. After 36 weeks in vivo, none of the implants did show significant degradation. The PHB composite with ZrO2 and a high percentage (30%) of Herafill® as well as the Mg-alloy WZ21 showed the highest values of bone accumulation (increased BV/TV) around the implant. The lowest value was measured in PHB with 3% ZrO2 containing no Herafill®. Roughness measurements as well as EDX and SEM imaging could not reveal any changes on the PHB composites׳ surfaces. Biomechanical parameters, such as the adhesion strength between bone and implant were determined by measuring the shear strength as well as push-out energy of the bone-implant interface. The results showed that improvement of these mechanical properties of the studied PHBs P3Z, P3Z10H and P3Z30H is necessary in order to obtain appropriate load-bearing material. The moduli of elasticity, tensile strength and strain properties of the PHB composites are close to that of bone and thus promising. Compared to clinically used PLGA, PGA and PLA materials, their additional benefit is an unchanged local pH value during degradation, which makes them well tolerated by cells and immune system. They might be used successfully for personalized 3D printed implants or as coatings of rapidly dissolving implants.
本研究的目的是评估生长中大鼠股骨对新型可生物降解聚合物复合植入物的骨反应。使用体内微焦点计算机断层扫描（µCT）监测植入部位骨反应（骨体积分数）的纵向变化以及植入针的吸收情况。在12、24和36周后，取出含有植入物的股骨，用高分辨率离体µCT扫描，并测量植入物的表面粗糙度，以推断骨组织的向内生长能力。使用扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDX）观察聚羟基丁酸酯（PHB）在降解和细胞向内生长过程中表面的变化。比较了四种含有二氧化锆（ZrO2）和Herafill®的不同复合材料。体内植入36周后，所有植入物均未显示出明显降解。含有ZrO2和高比例（30%）Herafill®的PHB复合材料以及镁合金WZ21在植入物周围显示出最高的骨积累值（骨体积分数增加）。在不含Herafill®的3%ZrO2的PHB中测量到最低值。粗糙度测量以及EDX和SEM成像未发现PHB复合材料表面有任何变化。通过测量骨-植入物界面的剪切强度和推出能量来确定骨与植入物之间的粘附强度等生物力学参数。结果表明，为了获得合适的承重材料，有必要改善所研究的PHBs P3Z、P3Z10H和P3Z30H的这些机械性能。PHB复合材料的弹性模量、拉伸强度和应变性能与骨接近，因此很有前景。与临床使用的聚乳酸-羟基乙酸共聚物（PLGA）、聚乙醇酸（PGA）和聚乳酸（PLA）材料相比，它们的额外优势是降解过程中局部pH值不变，这使得它们能被细胞和免疫系统良好耐受。它们可能成功用于个性化3D打印植入物或作为快速溶解植入物的涂层。
