Sugino Atsushi, Ohtsuki Chikara, Miyazaki Toshiki
Graduate School of Engineering Nagoya University, Furo-cho, Chikusa-ku Nagoya 464-8603, Japan.
J Biomater Appl. 2008 Nov;23(3):213-28. doi: 10.1177/0885328207081694. Epub 2008 Jul 16.
The use of polymethylmethacrylate (PMMA)-based bone cement is popular in orthopedics for the fixation of artificial joints with bone. However, it has a major problem with prostheses loosening because of coverage by fibrous tissue after long-term implantation. Recently, a bioactive bone cement has been developed that shows direct bonding to living bone through modification of PMMA resin with gamma-methacryloxypropyltrimethoxysilane (MPS) and calcium acetate. The cement is designed to exhibit bioactivity, through incorporation of silanol groups and calcium ions. Thus, it has the potential to form a layer of bone-like hydroxyapatite, which is essential for achieving direct bonding to living bone. This type of modification allows the cement to show spontaneous hydroxyapatite formation on its surface in a simulated body fluid after one day, and there is evidence of osteoconduction of the cement in rabbit tibia for periods of more than three weeks. However, the influence of the dissolved ions from the modified cement has not yet been clarified. Thus, the authors focused on the dissolution of the modified PMMA-based bone cement and its tissue response in muscle and bone by comparison with the behavior of non-modified PMMA-based bone cement. One week after implantation in the latissimus dorsi of a rabbit, the modified PMMA-based bone cement showed more inflammatory width than the commercial cement. However, four weeks after implantation, the inflammatory width of both cements was essentially the same. The osteoconductivity around the modified cement was higher than that for the conventional cement after four weeks implantation. These results indicate that the initial dissolution of calcium acetate from the modified cement to form the hydroxyapatite induced the acute inflammation around tissue, but also developed the osteoconductivity. It is suggested that the initial inflammation can be effective for inducing osteoconduction through a bone healing reaction when the material provides an environment that promotes bone formation.
基于聚甲基丙烯酸甲酯（PMMA）的骨水泥在骨科领域广泛用于人工关节与骨的固定。然而，长期植入后由于被纤维组织覆盖，它存在假体松动的重大问题。最近，一种生物活性骨水泥已被开发出来，它通过用γ-甲基丙烯酰氧基丙基三甲氧基硅烷（MPS）和醋酸钙对PMMA树脂进行改性，显示出与活骨的直接结合。这种骨水泥旨在通过引入硅醇基团和钙离子来展现生物活性。因此，它有潜力形成一层类骨羟基磷灰石，这对于实现与活骨的直接结合至关重要。这种改性使得骨水泥在模拟体液中一天后就能在其表面自发形成羟基磷灰石，并已有证据表明该骨水泥在兔胫骨中具有超过三周的骨传导性。然而,改性骨水泥中溶解离子的影响尚未阐明。因此，作者通过比较未改性PMMA基骨水泥与改性PMMA基骨水泥的行为,重点研究了改性PMMA基骨水泥在肌肉和骨骼中的溶解及其组织反应。在植入兔背阔肌一周后,改性PMMA基骨水泥比市售骨水泥表现出更宽的炎症带。然而,植入四周后,两种骨水泥的炎症带基本相同。植入四周后,改性骨水泥周围的骨传导性高于传统骨水泥。这些结果表明,改性骨水泥中醋酸钙的初始溶解以形成羟基磷灰石,不仅引发了组织周围急性炎症,还提高了骨传导性,这表明当材料提供促进骨形成的环境时,初始炎症可通过骨愈合反应有效诱导骨传导。
