The Influence of Prosthesis Diameter in Stapes Surgery

OBJECTIVE: To analyze the influence of stapes prosthesis diameter on postoperative hearing results after stapedotomy without interposition in otosclerotic patients. DATA SOURCES: PubMed search from 1970 to 2009 using the key words stapedotomy or stapedectomy or otosclerosis or stapesplasty. STUDY SELECTION: Inclusion criteria to select articles and patient groups for meta-analysis and statistical analyses were as follows: otosclerosis as diagnosis, clear description of technique and prosthesis size, calibrated stapedotomy, and complete report of functional results. DATA EXTRACTION: Five controlled studies were found analyzing the influence of prosthesis diameter and reporting the results in a comparable way for meta-analysis (n = 590). Sixty-two studies not analyzing the influence of prosthesis diameter contained comparable subgroups with a total of 9,536 cases. These cases were pooled according to their diameter (0.3, 0.4, 0.5, 0.6,and 0.8 mm). The results of air conduction, bone conduction, air-bone gap (ABG), and success rate (closure of the ABG within 10 dB as percentage of the total cases) for all groups and frequency-specific ABG results were gathered. Furthermore, 12 clinical and experimental studies were reviewed that did not contribute to the statistical analysis. DATA SYNTHESIS: A meta-analysis performed for success rate of the 5 controlled studies showed favorable results for 0.6-mm over 0.4-mm prostheses (success rate, 67% versus 58%, p = 0.05). In the statistical analysis of the pooled data, the 0.6-mm prosthesis showed better results compared with 0.4 mm (p < 0.001) in the postoperative air conduction threshold (29 dB versus 35 dB), postoperative ABG (7 dB versus 11 dB), ABG improvement (25 dB versus 21 dB), and success rate (81.1% versus 75.1%). The frequency-specific analysis of the postoperative ABG showed no advantage for the small prosthesis in the high frequencies. There was no difference in postoperative change of bone conduction in the 0.6- and 0.4-mm groups. Statistically significant results could not be assessed for other prosthesis diameters because of the small number of cases reported. CONCLUSION: A 0.6-mm diameter piston prosthesis is associated with significantly better results than a 0.4-mm prosthesis and should be used if the surgical conditions allow it.