# Comparison Between Titanium and Thermally Activated Prostheses in Stages Surgery
## 2 Materials and Methods  
This study was conducted in accordance with the Declaration of Helsinki and with the approval of the Ethics Committee (approval number UKC-MB-KME-69/24). It included 155 patients with a confirmed diagnosis of otosclerosis who underwent stapedotomy between January 2018 and October 2023. Patients were divided into 2 groups according to the type of prosthesis inserted; 65 of them had PatriX prosthesis and 90 had NitiBond prosthesis. All patients were operated on by the same surgeon. Figure 3: NiTiBOND prosthesis fixed on the long process of the incus. Chorda typnani is located superiorly and therefore with low chance of injury by the thermic effect of the laser. Figure 2: Thermo-Dummy NiTiBOND prosthesis with dummy prosthesis already tested with the laser on the upper right corner and real prosthesis on the lower left corner prepared to be inserted into the stapedotomy. The procedures were performed under general anaesthesia with endotracheal intubation. In all cases, a transcanal approach was used after elevation of the tympanoneatal flap, which was elevated between 12 and 6 h. The bone over the chorda was drilled away to expose the oval niche. The instrument was used to check the fixation of the stapes. In case of fixation of the stapes, the stapedial muscle, the posterior crus of the stapes, the incudostapedial joint, and the anterior crus of the stapes (if possible) were disconnected with an argon laser with a tip. The stapes plate was also carbonised at a lower intensity and then a stapedotomy was drilled with a perforator at this site. We then decided on the choice of prosthesis, depending on the position of the chorda typnani, which had been mobilised beforehand. In case the chorda was very close to the long incus and the prosthesis fixation site (Figure 1), the surgeon decided to insert a titanium prosthesis because the thermal activation of the prosthesis could damage the chorda. The length of the prosthesis was measured with a measuring instrument and the diameter of the prosthesis was 0.4 mm in all cases. In the case of the thermally activated prosthesis, it was first placed in the stapedotomy area and then thermally activated with an argon laser. The thermally activated prosthesis (NiTiBOND, Heinz Kurz company, Dusslingen, Germany) (Figure 2) has an attachment site designed to contact the long incus only at certain points, thereby improving vascularisation of the distal part of the long incus. Laser settings for thermal activation of the prosthesis are determined outside the middle ear using a test prosthesis. We used 800 mW and pulse duration for the removal of stapes structure and 600 mW for the stapedotomy and prosthesis fixation on the stapes. The titanium prosthesis (MatriX, Heinz Kurz company, Dusslingen, Germany) also has a titanium fixation site, which is partially interrupted. Longitudinal perforations ensure that the loop is extremely flexible and easy to crimp around the long inlay process. From the mechanical point of view, there should be as little air as possible between the prosthesis and the incus. All MatriX prostheses were crimped with the same Fisch-McGee wire closure forceps (Storz, Tuttlingen, Germany). Audiological results were calculated according to the guidelines of American Academy of Otolaryngology, Head and Neck Surgery [13]. Each patient had their preoperative bone conduction (BC) and air conduction (AC) measured at 0.5 KHz, 1 KHz, 2 KHz, 3 KHz, and 4 KHz in accordance with the preoperative evaluation. As part of the postoperative follow-up of the patients, hearing was checked again (BC and AC at the same frequencies as preoperatively). The first postoperative hearing measurement was performed 1 day after surgery, testing bone conduction. A control hearing measurement was performed 6 weeks after surgery. All hearing measurements were performed on the same audiometer. All measured hearing values are given in decibels (dB).