Soft-tissue response to synthetic biomaterials

The soft-tissue response to an implanted synthetic material is an inflammatory reaction to foreign body; factors that minimize this inflammation will maximize biocompatibility. The ideal implant is selected from a material that is nontoxic, nonantigenic and in chemical proximity to calcium or carbon on the periodic table. If it is porous, the pores should be large enough to admit immune and phagocytic cells and ideally, to allow native tissue ingrowth. The implant should be of appropriate size and shape and should be implanted in the correct location. The material should be nonparticulate, should resist fragmentation, and should be secured in the selected location after gentle insertion. All these factors help decrease the body's natural response to an implanted foreign body, but inflammation and foreign body reaction are the common threads in all responses to all implanted synthetic materials. Optimum soft-tissue biocompatibility, characterized either by thin fibrous encapsulation or by mesenchymal ingrowth into pores and interstices, is achieved by avoiding or containing this response.