Drei Jahre Erfahrungen mit lonomer-Zement in der rekonstruktiven Mittelohrchirurgie*

Zusammenfassung

Seit April 1990 verwenden wir zur Behebung von knöchernen Defekten des Mittelohrraumes, des Gesichtsskelettes oder der Schädelbasisregion den ionomeren Zement in der HNO-Klinik des Allgemeinen Krankenhauses Barmbek. Bei über 170 Patienten wurde bisher das Material zur Rekonstruktion des Schalleitungsapparates, zur Verkleinerung von Radikalhöhlen und zum Verschluß von Defekten der Gehörgangswand eingesetzt. Dabei wurde das Material sowohl in vorgefertigter Form wie auch als Rohling angewendet. Bei 156 Patienten handelte es sich um die Rekonstruktion des Schalleitungsapparates mit Mittelohrprothesen, bei 14 Patienten erfolgte im Rahmen einer klinischen Studie die Verkleinerung der Radikalhöhlen mit ionomeren Mikroimplantaten. Über deren Langzeitergebnisse wird anhand von Bilddokumentationen und histologischer Nachuntersuchung berichtet.

Summary

For nearly three years we have been using implants of polymaleinate ionomer in the reconstruction of the ossicle chain (Figure 1). Implants of this material can be easily formed by a diamond drill. An implant in site 18 months later is to be seen in Figure 2. From August 1990 through April 1993 this material has been implanted into 156 middle ears. Only one implant had to be explanted again for a second-look Operation in cholesteatoma. Extrusion or any tissue reaction on the foreign substance could not be seen. The implant was examined histologically. It was covered by mucosa and not destructed anyway (Figure 3). According to the extension of a cholesteatoma we take away the dorsal wall of the ear canal for reasons of sanitation and leave a radical mastoid cavity in children. In adult patients we tend to reconstruct the earcanal to avoid the disadvantages of a radical mastoid cavity: Frequent treatments and hearing-loss by resonance-shifting (2). For reconstructing the dorsal wall of the earcanal cartilage of the concha and tragus is well qualified. In support of experimental and clinical experience of the Würzburg group (1) we take ionomer micro-implants for reducing large radical mastoid cavities (Figure 4). The radical mastoid cavity is finished by the diamond-drill before being filled up with micro-implant in the dorsal parts. The micro-implant is covered by a flap of periost and connecting tissue. Figure 5 shows a Situation operated by this technique 20 months ago, Figure 6 shows the result after Operation of a fonner secerning radical mastoid cavity. The earcanal has a nearly normal volume. We reduced the radical mastoid cavity in 15 patients after Operation of a cholesteatoma by micro-implant in this way. Only in one patient a pearl of cholesteatoma had to be removed from the rim of the implants bed without removing the implant itself. We believe that the palva flap had covered the material insufficiently in this case, so that epithelium immigrated to form the pearl of cholesteatoma. Histology showed a unaffected imbedding of the implant of the implant particles in the meshwork of the connective tissue. The advantage of the ionomer micro-implant, however, is that its particles do not form a bony connection but are surrounded by fibres of connecting tissue (1). This enables a recurring cholesteatoma to penetrate towards the lumen of the earcanal instead of destroying the bone by subsequent intracranial complications. In all patients epithelisation of the micro-implant was completed after 6 months. No granulations or infections occurred.

Schlüsselwörter

Mittelohrimplantate - lonomer-Zement

Key words

Middle ear surgery - Ionomer cement