[Results after rebuilding the ossicular chain using the autogenous incus, ionomer-cement-and titanium implants (tympanoplasty type III)].

BACKGROUND: A defective ossicular chain can reliably be reconstructed with standardized techniques using e. g. modern alloplastic materials. The comparison of clinical and functional results have proved its worth. Prospective clinical trial as well as collecting and evaluating relevant intraoperative and postoperative findings may be helpful to find the appropriate bone substitute in each case when rebuilding middle ear structures.
METHOD: In 354 middle ears (332 patients) the defective or destroyed ossicular chain was rebuilt with the carefully trimmed autogenous incus (n = 83), with ionomer-cement implants (n = 100) and with titanium prostheses (n = 171). The follow-up of the earmicroscopic findings and middle ear function extended over a period of 1.5 years postoperatively on an average (min. 3 months, max. 6 years). The modified otologic record form named "Würzburger Ohrbogen" was used for preoperative and operative data, the "Ohrnachsorgebuch" for the postoperative follow-up.
RESULTS: Using incus the air bone gap was improved up to 15 dB in the main speech area. Thus the average remaining conduction deficit was less than 10 dB. The "taking" of ionomer based cement prostheses and titanium prostheses was equally good. The cement implants showed a tendency to protrusion (n = 3), 2 titanium implants were extruded. The air bone gap decreased about 10 to 35 dB using titanium total prosthesis and about 15 to 20 dB using ionomer-cement total prosthesis. The remaining air bone gap with titanium implants was slightly less than with the ionomer-cement PORP (10-15 dB). The air bone gap using the titanium TORP was diminished in a reach of 10 to 35 dB, with the ionomer cement prosthesis between 15 to 20 dB. The remaining gap in the main speech area was slightly favorable to titanium (less than 15 dB) compared with the ionomer-cement TORP. Comparing higher frequencies the air bone gap of titanium was recognizable due to its light weight, but less impressive than expected. Revision surgery (n = 50) has to be performed by reason of cholesteatoma (n = 9), adhesive process (n = 8), dislocation of alloplastic prostheses (n = 8) and because of proposed "second look" (n = 14).
CONCLUSIONS: Compared with other materials autogenous implants used for reconstruction of the incus have proved their value, however a deterioration of the sound transmission may develop in the long run. The middle ear compatibility of ionomer-cement implants is similar to titanium implants. The functional results of the titanium implants seem to be slightly superior.