Objective: To present the preliminary results of new malleus replacement prosthesis combined with a total ossicular prosthesis in middle ear reconstruction in patients missing the malleus and stapes.
Study design: Prospective experimental and nonrandomized clinical study.
Setting: Tertiary referral center.
Methods: An original titanium malleus replacement prosthesis (MRP) was designed to be inserted into the external auditory canal and to replace a missing malleus for various middle ear pathologies. The MRP was tested experimentally and clinically. The vibratory properties of the new prosthesis were measured using laser Doppler vibrometry. Ninety patients with missing malleus and stapes, undergoing 92 ossicular reconstructions were enrolled in this study from September 1994 to March 2012. Comparative analyses were made between a group of 34 cases of ossicular reconstructions with total prosthesis (TORP) positioned from the tympanic membrane to the stapes footplate (TM-to-footplate assembly) and a group of 58 cases of ossicular reconstructions with TORP positioned from a newly designed malleus replacement prosthesis (MRP) to the stapes footplate (MRP-to-footplate assembly). Preoperative and postoperative audiometric evaluation using conventional audiometry, that is, air-bone gap (ABG), bone-conduction thresholds (BC), and air-conduction thresholds (AC) were assessed.
Results: Experimentally, the vibratory properties of the MRP are promising and remain very good even when the MRP is cemented into the bony canal wall mimicking its complete osseous-integration, if this were to occur. This finding supports the short-term clinical results as in the TM-to-footplate group; the 3-month postoperative mean ABG was 23.3 dB compared with 12.5 dB in the MRP-to-footplate group (difference, 10.8; 95% confidence interval, 4.0-17.6); 37.0% of patients from the TM-to-footplate group had a postoperative ABG of 10 dB or less, and 48.1% of patients had a postoperative ABG of 20 dB or less, as compared with 58.1% and 79.1%, respectively, in the MRP-to-footplate group. The average gain in AC was 11.0 dB in the TM-to-footplate group as compared with 21.3 dB in the MRP-to-footplate group (difference, -10.3; 95% confidence interval, -18.2 to -2.4).
Conclusion: The results of this study indicate that superior postoperative hearing thresholds could be achieved using a MRP-to-footplate assembly, compared with a TM-to-footplate assembly in patients with an absent malleus undergoing ossiculoplasty. The postoperative AC thresholds, after 3 months and 1 year, are significantly lower in patients treated with the MRP-to-footplate assembly.