Endoscopic procurement of tympano-ossicular allografts

Subtitle:impact on donation and transplantation

Since the technique of tympano-ossicular allograft tympanoplasty was founded in the 1960s by Marquet, en bloc allografts have been procured using the Schuknecht bone plug technique. The technique was used in many centers around the world but the rise of infectious diseases that can potentially be transmitted from donor to recipient, like HIV and Creutzfeldt-Jakob disease, led to the downfall of the use of tympano-ossicular allografts in many countries. In many centers in the Antwerp region, the technique withstood these challenges. Technological progression and the shift towards the use of a tympanomeatal allograft with separate incus, enabled the introduction of an endoscopic procurement technique. We have shown that it is feasible to procure tympano-ossicular allografts of good quality via transmeatal approach using a 30° nasal endoscope. When comparing this new procurement technique to the traditional transcranial technique, the endoscopic technique is much more time efficient (the end product is retrieved immediately rather than being dissected in a separate step), it is safer (contact with the dura mater during procurement is avoided, eliminating the already low risk of transmission of Creutzfeldt-Jakob disease) and it is less invasive, which has significantly increased the donor volume and has made the procurement more acceptable for donor relatives and cooperating hospitals. On the other side it is more difficult to learn and the long term percentage of good quality allografts is lower. However, the increase in donor volume outweighs the decrease in percentage of good quality allografts. This aspect together with the other mentioned advantages have argumented our decision to fully replace the transcranial bone plug technique by the endoscopic procurement technique. After switching to the new technique, the clinical outcome of the tympano-ossicular allografts was reported. In a first step we compared in a prospective, randomized audit the results of transcranially versus endoscopically procured allografts. No statistically relevant difference was observed in a small group of patients with regards to the graft take rate three months after surgery. In a second step, the graft take rate was analyzed retrospectively on a bigger group of patients. The graft take rate at three months was shown to be similar to the graft take rate as reported in literature. Finally, literature showed that the formaldehyde solution used for tympano-ossicular allograft preservation is efficient in inactivating viruses like HIV, HBV, HCV and coronaviruses. These results, combined with other safety measures, make tympano-ossicular allografts a very safe reconstruction material.

Publication year:2022

Keywords:Doctoral thesis

Accessibility:Open