Survival and evolution of vein grafts in otosclerosis surgery: structural and ultrastructural evidence.

The annular ligament of the stapes footplate measures 0.2 mm2 and contains elastic fibers that restrict perilymphatic movement to a molecular level. This resistance of the annular ligament prevents excessive movement of labyrinthine fluids that are potentially hazardous to the membranous and cellular structures of the inner ear. However, if the resistance of the annular ligament is overcome, then inner ear damage can occur. The vein graft, as used in our technique for otosclerosis surgery, occupies a space of 0.2 mm2 between the edge of the stapedotomy hole and the piston and has nearly the same compliance and resistance as the annular ligament of the stapes footplate. The vein graft becomes integrated with the middle-ear mucosa. It develops a rich and active blood supply and the smooth muscle cells and elastic fibers remain, although the latter show some modification of ultrastructural pattern. The graft becomes overlaid by the middle-ear epithelium. Even samples of vein graft that have been present for many years retain surviving elastic fibers, including those that have become fibrotic. In time, the number of elastic fibers increases as a result of the activity of fibroblasts, which build a poorly colored collagen.