The effectiveness of the use of superelastic nitinol stapedial prostheses in comparison with titanium ones in the surgical treatment of patients with otosclerosis

This article presents the results of a comparative evaluation of surgical treatment of patients suffering from conductive and mixed hearing loss in various clinical forms of otosclerosis using titanium and nitinol stapedial prostheses. 
Materials and methods. In the department of surgical treatment of diseases of the ear and the base of the skull of the NMICO from 2017 to 2020, the functional results of stapedoplasty using titanium and nitinol prostheses were compared in the near (up to 3 months) and long-term (more than 6 months) postoperative period. The comparison groups included 50 patients who were divided into two equal in all major indicators groups that differ only in the type of prosthesis used (SE NiTiNOL/PTFE and Ti/PTFE). In the postoperative period (the average follow-up period was 3 years), the values of the bone-air interval in operated patients were evaluated; clinical and experimental comparison of computed tomography data obtained during the installation of titanium and nitinol prostheses was also carried out. 
Results. Functional results were assessed in the immediate (13 months) and long-term (6 months3 years) periods after surgery. The average postoperative CVI was 12.29 dB (SD 5 dB) in patients in the group with nitinol prostheses and 11.93 dB (SD 5 dB) in titanium. 88% and 80% of patients in both groups had an "excellent" or "good" result in hearing improvement. 
The cadaveric material was used to compare the CT data obtained during the installation of stapedial prostheses: in 4 cases, when installing a nitinol prosthesis, there were no artifacts, which made it possible to visualize the prosthesis attachment ring; in the other 4 cases with a titanium prosthesis, this was not possible to detect. 
Conclusions. The installation of a nitinol prosthesis has a number of advantages: it does not require additional fixation of its head on the long stem of the anvil in the form of a compression, which minimizes the risks of traumatizing the structures of the inner ear and, accordingly, the development of sensorineural hearing loss in the postoperative period, as well as the use of SENiTiNOL prostheses reduces the likelihood of developing aseptic necrosis of the long leg of the anvil due to the properties of the metal and a decrease in its thickness. Analyzing the data of computed tomograms of patients after stapedoplasty, only in the group with installed nitinol prostheses, it was possible to visualize the position of the prosthesis on the long stem of the incus, in the area of the vestibule, its length, the integrity of the long stem of the incus.