Literature review of alloplastic materials in ossiculoplasty.

The use of alloplastic materials in ossicular reconstruction has a long history. However, many new materials have been described and become commercially available without any evidence that they are superior to the existing ones. The aim of the present literature review is to understand why changes in materials used for ossicular reconstruction have occurred. The literature review was conducted using a Medline search. In addition, the references of each captured publication were examined to identify earlier publications that had escaped the Medline search. In general, there has been a paucity of longterm follow-up studies. Only one randomized study comparing one alloplastic material to another was identiŽed (Plastipore vs Ceravital). Virtually all the reports were either a series on one particular type of ossicular prosthesis or compared results of different prostheses based on historical data. It has been difŽcult to compare the results from different reports because of many other variables affecting the outcome of ossiculoplasty such as the state of the middle ear and the stage of the ossiculoplasty. The criteria used by different authors to report success varied between reports e.g. different ways of calculating the frequency average from the audiogram and different levels of post-operative air-bone gap being used to describe ‘success’. Some authors only reported extrusion but not exposure of the prosthesis. Furthermore, some surgeons modiŽed their surgical techniques during the study period e.g. placing cartilage over the head plate of the prosthesis. In order to make the comparison between different reports meaningful, the author considered both extrusion and exposure of the prosthesis as ‘prosthesis-related complications’. A post-operative air-bone gap of 20.dB or less was used as the criterion for success following ossiculoplasty since this was described by the majority of the authors in their reports. Particular attention was given to the length of the follow-up period, the average frequency for reporting of hearing results and the difference in the surgical techniques, in particular the use of cartilage over the head plate of the prosthesis. Of many alloplastic materials that have been described, not many have stood the test of time. In Figure 1, a time line with the speciŽc year when each alloplastic material was Žrst reported in clinical use is shown. Some materials were more popular than others, at least for a period. Some are still being used at the present time. These speciŽc alloplastic materials are highlighted on the time line and are given a more detailed review. The Žrst report of using alloplastic material in ossiculoplasty was made in 1952, when Wullstein used an oval strut of vinyl-acrylic ‘palavit’ as an acoustic transmitter between the mobile footplate and the tympanic membrane graft. Poor results with this material quickly caused him to abandon its use. Following the success of using polyethylene rods in stapes surgery, Shea and Austin used a length of polyethylene 90 tubing to reconstruct the ossicles in tympanoplasty. Some surgeons, including House and Hayden reported initial success with this material. Others, such as Shambaugh, reported a high rate of post-operative labyrinthine damage of up to 15 per cent of cases. Inammatory tissue reactions have also been histologically conŽrmed following the use of polyethylene grafts in the oval windows of cats. In 1962, Austin reported the use of polytetrauoroethylene (PTFE) tubing as a hollow ‘umbrella like’ columella in ossiculoplasty. The greater compatibility of PTFE, which is ensheathed by mucosa in the middle ear, has been demonstrated in experimental animals. In 1969, Palva et al. Žrst reported using metallic implants in chronic otitis media. Whereas both PTFE and metals give favourable results in stapes surgery, these solid plastic and metallic materials have not been so successful in tympanoplasty procedures. Manifestations of absorption at the ossicular interfaces and spontaneous rejection from the tympanic membrane have been observed. The results of these materials were so disappointing, that by the time of the