Department of Oral and Maxillofacial Surgery, Charité Universitätsmedizin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany; Berlin Institute of Health (BIH), Anna-Louisa-Karsch-Straße 2, 10178 Berlin, Germany.
Department of Oral and Maxillofacial Surgery, Charité Universitätsmedizin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany; Department of Veterinary Medicine, Institute of Veterinary Anatomy, Freie Universität Berlin, Koserstraße 20, 14195 Berlin, Germany.
Biomater Adv. 2022 May;136:212788. doi: 10.1016/j.bioadv.2022.212788. Epub 2022 Apr 4.
Bone defects of the craniofacial skeleton are often associated with aesthetic and functional impairment as well as loss of protection to intra- and extracranial structures. Solid titanium plates and individually adapted bone cements have been the materials of choice, but may lead to foreign-body reactions and insufficient osseointegration. In contrast, porous scaffolds are thought to exhibit osteoconductive properties to support bone ingrowth. Here, we analyse in critical size defects of the calvaria in sheep whether different bone replacement materials may overcome those remaining challenges. In a critical size defect model, bilateral 20 × 20 × 5-mm craniectomies were performed on either side of the sagittal sinus in 24 adult female blackheaded sheep. Bony defects were randomised to one of five different bone replacement materials (BRMs): titanium scaffold, biodegradable poly(d,l-lactic acid) calcium carbonate scaffold (PDLLA/CC), polyethylene 1 (0.71 mm mean pore size) or 2 (0.515 mm mean pore size) scaffolds and polymethyl methacrylate (PMMA)-based bone cement block. Empty controls (n = 3) served as references. To evaluate bone growth over time, three different fluorochromes were administered at different time points. At 3, 6 and 12 months after surgery, animals were sacrificed and the BRMs and surrounding bone analysed by micro-CT and histomorphometry. The empty control group verified that the calvaria defect in this study was a reliable critical size defect model. Bone formation in vivo was detectable in all BRMs after 12 months by micro-CT and histomorphometric analysis, except for the non-porous PMMA group. A maximum of bone formation was detected in the 12-months group for titanium and PDLLA/CC. Bone formation in PDLLA/CC starts to increase rapidly between 6 and 12 months, as the BRM resorbs over time. Contact between bone and BRM influenced bone formation inside the BRM. Empty controls exhibited bone formation solely at the periphery. Overall, porous BRMs offered bone integration to different extent over 12 months in the tested calvaria defect model. Titanium and PDLLA/CC scaffolds showed remarkable osseointegration properties by micro-CT and histomorphometric analysis. PDLLA/CC scaffolds degraded over time without major residues. Pore size influenced bone ingrowth in polyethylene, emphasising the importance of porous scaffold structure.
颅面骨骼的骨缺损常与美观和功能障碍以及颅内和颅外结构的丧失有关。固体钛板和个体化适应的骨水泥一直是首选材料，但可能导致异物反应和骨整合不足。相比之下，多孔支架被认为具有促进骨生长的特性，以支持骨向内生长。在这里，我们在绵羊的颅骨临界尺寸缺陷中分析了不同的骨替代材料是否可以克服这些遗留的挑战。在临界尺寸缺陷模型中，在矢状窦两侧的每一侧进行 20×20×5mm 的颅骨切除术，共 24 只成年雌性黑头羊。将骨缺损随机分为五种不同的骨替代材料（BRM）之一：钛支架、可生物降解的聚（D，L-乳酸）碳酸钙支架（PDLLA/CC）、聚乙烯 1（0.71mm 平均孔径）或 2（0.515mm 平均孔径）支架和聚甲基丙烯酸甲酯（PMMA）基骨水泥块。空对照组（n=3）作为参考。为了评估随时间的骨生长，在不同时间点给予三种不同的荧光染料。手术后 3、6 和 12 个月，处死动物，通过 micro-CT 和组织形态计量学分析 BRM 和周围骨。空对照组证实，本研究中的颅骨缺损是一种可靠的临界尺寸缺陷模型。通过 micro-CT 和组织形态计量学分析，在所有 BRM 中均在 12 个月后检测到体内骨形成，除了非多孔 PMMA 组。在钛和 PDLLA/CC 组的 12 个月组中检测到最大的骨形成。PDLLA/CC 的骨形成在 6 至 12 个月之间开始迅速增加，因为 BRM 随时间而降解。骨与 BRM 的接触影响 BRM 内的骨形成。空对照组仅在外周显示骨形成。总体而言，在测试的颅骨缺损模型中，多孔 BRM 在 12 个月内提供了不同程度的骨整合。钛和 PDLLA/CC 支架通过 micro-CT 和组织形态计量学分析显示出显著的骨整合特性。PDLLA/CC 支架随时间降解而无主要残留物。孔径大小影响聚乙烯中的骨向内生长，强调了多孔支架结构的重要性。
