Bone fractures at weight-bearing sites are challenging to treat due to the difficulty in maintaining articular congruency. An ideal biomaterial for fracture repair near articulating joints sets rapidly after implantation, stabilizes the fracture with minimal rigid implants, stimulates new bone formation, and remodels at a rate that maintains osseous integrity. Consequently, the design of biomaterials that mechanically stabilize fractures while remodeling to form new bone is an unmet challenge in bone tissue engineering. In this study, we investigated remodeling of resorbable bone cements in a stringent model of mechanically loaded tibial plateau defects in sheep. Nanocrystalline hydroxyapatite-poly(ester urethane) (nHA-PEUR) hybrid polymers were augmented with either ceramic granules (85% β-tricalcium phosphate/15% hydroxyapatite, CG) or a blend of CG and bioactive glass (BG) particles to form a settable bone cement. The initial compressive strength and fatigue properties of the cements were comparable to those of non-resorbable poly(methyl methacrylate) bone cement. In animals that tolerated the initial few weeks of early weight-bearing, CG/nHA-PEUR cements mechanically stabilized the tibial plateau defects and remodeled to form new bone at 16 weeks. In contrast, cements incorporating BG particles resorbed with fibrous tissue filling the defect. Furthermore, CG/nHA-PEUR cements remodeled significantly faster at the full weight-bearing tibial plateau site compared to the mechanically protected femoral condyle site in the same animal. These findings are the first to report a settable bone cement that remodels to form new bone while providing mechanical stability in a stringent large animal model of weight-bearing bone defects near an articulating joint.

中文翻译：

---

可固化的聚合物/陶瓷复合骨移植物可稳定负重的胫骨平台槽缝缺损，并与绵羊模型中的宿主骨整合。

由于难以保持关节全合，因此负重部位的骨骨折很难治疗。一种理想的生物材料，用于在关节附近进行骨折修复，在植入后迅速凝固，用最少的刚性植入物稳定骨折，刺激新的骨形成，并以保持骨完整的速率进行重塑。因此，在组织重建过程中机械稳定骨折同时重塑以形成新骨的生物材料的设计是尚未解决的挑战。在这项研究中，我们调查了羊的机械负载胫骨平台缺损的严格模型中可吸收骨水泥的重塑。纳米晶羟基磷灰石-聚（酯氨基甲酸酯）（nHA-PEUR）杂化聚合物均用两种陶瓷颗粒（85％β-磷酸三钙/ 15％羟基磷灰石，CG）或CG与生物活性玻璃（BG）颗粒的混合物，以形成可固化的骨水泥。水泥的初始抗压强度和疲劳性能与不可吸收的聚（甲基丙烯酸甲酯）骨水泥相当。在能忍受早期负重的最初几周的动物中，CG / nHA-PEUR水泥可机械稳定胫骨平台缺损，并在16周时重塑形成新的骨骼。相比之下，掺有BG颗粒的水泥则被纤维组织吸收，从而填补了缺损。此外，与同一只动物的机械保护股骨con部位相比，CG / nHA-PEUR水泥在整个负重胫骨平台部位的重塑速度明显更快。