The aim of this systematic review was to determine the rates of scalar dislocation (SD) after cochlear implant surgery with two types of electrode arrays (lateral wall, LW, and pre-formed, PF) from three manufacturers. Literature databases were systematically searched for relevant articles covering three time periods between August 2014 and December 2023. Retrieved articles were evaluated for inclusion in further analysis. We performed a quantitative synthesis to estimate the overall rates of SD with each array type and manufacturer, and to test if these differences were significant. 66 publications covering 4,729 implantations were used for the systematic review. These implantations included 1,782 LW arrays and 2,737 PF arrays. The breakdown according to manufacturer was 903 arrays from MED-EL, 2,527 from Manufacturer A, 850 from Manufacturer B, and 449 where the manufacturer was unspecified. SD occurred in 923 cases overall (19.5%). The SD rates by array type were 8.1% for LW arrays and 25.0% for PF arrays. The SD rates by manufacturer were 6.4% for MED-EL arrays, 23.2% for Manufacturer A arrays, and 21.3% for Manufacturer B arrays. The SD rate was significantly lower for MED-EL LW arrays compared to Manufacturer A LW arrays (p = 0.001). Within manufacturers, the SD rate was significantly lower for LW arrays compared to PF arrays for both Manufacturer A and Manufacturer B devices (both p < 0.001). Rates of SD vary by array type and manufacturer. LW arrays had the lowest rate. By manufacturer, MED-EL arrays had the lowest rate.
Bu et al. (Mon,) studied this question.