[Show abstract][Hide abstract] ABSTRACT: Objective: To present our mid-term results of our multicenter study using the Nitinol self-crimping stapes piston, focusing on the interindividual variations of postoperative air-bone gap closures (ABGC), postoperative hearing results, and postoperative recurrences of conductive hearing loss and to compare these findings with our pilot group of patients.Study Design: Prospective, multicenter cohort study involving three academic tertiary care referral centers from Australia, Switzerland, and the United States.Methods: Ninety patients with otosclerosis undergoing laser-stapedotomy with the Nitinol stapes piston were matched to reference patients from our titanium piston database. The effects of the self-crimping Nitinol piston on the postoperative ABGC, the postoperative interindividual air-bone gap (ABG) variations, and the postoperative hearing results were investigated 3, 6, 12, 18, and 24 months postoperatively. These data were statistically compared with the results of the control patients in our titanium stapes piston database and the results of our previously published pilot study.Results: The mean postoperative ABG and the interindividual variations of the postoperative ABG continue to be significantly smaller in the Nitinol group; the extent of ABGC now is significantly larger in the Nitinol piston group. The postoperative mid-term stability of ABGC was similar in both groups. No adverse reactions occurred during follow-up.Conclusion: Our mid-term results continue to show that the self-crimping shape memory alloy Nitinol stapes piston overcomes the limitations of manual malcrimping in stapedotomy, thus simplifying and optimizing the surgical procedure. This so far has allowed reliable, safe, and consistent ABGC in patients with otosclerosis.