Grynpas M D, Pilliar R M, Kandel R A, Renlund R, Filiaggi M, Dumitriu M
Institute for Biomaterials and Biomedical Engineering, University of Toronto, Ontario, Canada.
Biomaterials. 2002 May;23(9):2063-70. doi: 10.1016/s0142-9612(01)00336-2.
Porous rods (6 mm in length and 4 mm in diameter) of calcium polyphosphate (CPP) made by gravity sintering of particles in the size ranges of 45-105, 105-150. and 150-250 microm and with initial volume percent porosity in the range of 35-45% were implanted in the distal femur of New Zealand white rabbits. In an initial experiment, four rabbits implanted with rods made from coarse particles (150-250 microm) were sacrificed at each of the following time points: 2 days, 2 weeks, 6 weeks and 12 weeks. In a subsequent experiment, 10 rabbits were implanted with rods made by sintering 45-105 microm particles and another 10 were made by using particles of 105-150 microm. These rabbits were sacrificed at 6 weeks (five rabbits) and 1 year (five rabbits). No adverse reaction was found histologically at any time point in either experiment. These experiments show that CPP macroporous rods can support bone ingrowth and that between 12 weeks and 1 year, the amount of bones formed is equivalent to the natural bone volume found at similar sites. The degradation of the CPP material is inversely proportional to the original particle size and is rapid initially (within the first 6 weeks) and slows down thereafter. In conclusion, this material seems to promote rapid bone ingrowth and can be tailored to degrade at a given rate in vivo to some degree through appropriate selection of the starting particle size.
通过对粒径范围为45 - 105微米、105 - 150微米和150 - 250微米的颗粒进行重力烧结制成的聚磷酸钙（CPP）多孔棒（长度6毫米，直径4毫米），其初始孔隙率体积百分比在35 - 45%范围内，被植入新西兰白兔的股骨远端。在最初的实验中，对每组4只植入由粗颗粒（150 - 250微米）制成的棒的兔子，在以下每个时间点进行处死：2天、2周、6周和12周。在随后的实验中，10只兔子植入由烧结45 - 105微米颗粒制成的棒，另外10只植入由105 - 150微米颗粒制成的棒。这些兔子在6周（5只兔子）和1年（5只兔子）时被处死。在任何一个实验的任何时间点，组织学检查均未发现不良反应。这些实验表明，CPP大孔棒能够支持骨长入，并且在12周和1年之间，形成的骨量与在相似部位发现的天然骨体积相当。CPP材料的降解与原始颗粒大小成反比，最初降解迅速（在前6周内），此后减缓。总之，这种材料似乎能促进快速骨长入，并且通过适当选择起始颗粒大小，在一定程度上可以使其在体内以给定速率降解。
