Spector M, Heyligers I, Roberson J R
Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Clin Orthop Relat Res. 1988 Oct(235):207-19.
Porous polymers are recommended as coatings for femoral stems on the basis of their low modulus, which allows uniform distribution of stress to surrounding bone and the fabrication of more flexible stems by reducing the metallic cross section. Application of the porous polymer coating to the metallic substrate reduces metal ion release; the polymer coating does not affect the mechanical properties of the device. Porous polytetrafluoroethylene-carbon fiber composite, (PCFC), porous polyethylene, and porous polysulfone are undergoing investigation for this application. However, the low strength of the PCFC makes its use for this application questionable. Recently reported unfavorable clinical results (i.e., a high incidence of pain) have led to the discontinuation of one trial of porous polyethylene. Clinical investigation of porous polysulfone-coated titanium alloy devices are in progress. Animal studies have shown bone ingrowth into porous polyethylene and porous polysulfone implants in cortical and cancellous bone and in canine femoral stems coated with these materials. Pull-out testing of porous polysulfone implants revealed that the strength of the porous material was higher than the strength of surrounding bone. Less cortical bone loss was found around porous polysulfone-coated canine stems than was reported for fully coated porous metallic prostheses, presumably because of the lower stiffness.
基于其低模量，多孔聚合物被推荐作为股骨柄的涂层，低模量可使应力均匀分布于周围骨骼，并通过减小金属横截面来制造更灵活的柄。将多孔聚合物涂层应用于金属基底可减少金属离子释放；聚合物涂层不会影响器械的机械性能。多孔聚四氟乙烯 - 碳纤维复合材料（PCFC）、多孔聚乙烯和多孔聚砜正在为此应用进行研究。然而，PCFC的低强度使其在此应用中的使用受到质疑。最近报道的不良临床结果（即疼痛发生率高）导致一项多孔聚乙烯试验停止。多孔聚砜涂层钛合金器械的临床研究正在进行中。动物研究表明，在皮质骨和松质骨以及涂有这些材料的犬股骨柄中，骨会长入微孔聚乙烯和多孔聚砜植入物中。多孔聚砜植入物的拔出试验表明，多孔材料的强度高于周围骨骼的强度。在多孔聚砜涂层的犬股骨柄周围发现的皮质骨丢失比全涂层多孔金属假体报道的要少，这可能是由于较低的刚度所致。
