The applicability of porous polyethylene for tympanoplasty; an animal experimental study.

The problem of a replacement material for the reconstruction of the posterior wall of the auditory canal, as well as for the obliteration of the radical cavity has not been solved satisfactor;ly so far. In order to examine the possible applicability of porous plastics, the posterior wall of the auditory canal of guinea pigs was first removed and then reconstructed using porous polyethylene and filling the bulla tympanica with fine polyethylene chips. One third of the animals had an infected middle ear at the time of implantation. Histologic assessments were made until 24 weeks after implantation. In 80% of the animals the implant settled well, even in cases where the middle ears had been originally infected. By proliferation of vessels and connective tissue, the polyethylene had almost been completely integrated into the surrounding tissue after one week. Extent and frequency of metaplastic osseous growth was greater inthe chip-filled bulla than in the reconstructedposterior wall(Fig. 9). After four weeks, the new osteoid substance was firmly connected with the regional bone (Fig. 4). According to these results, it would seem possible to use porous polyethylene even for the nonaseptic implant bed as it is found in the chronically infected middle ear.