[First experiences with a new nickel-titanium piston with a shape memory feature]

A Partial Ossicular Replacement Prosthesis With a Concentric Ball Joint in the Headplate

OBJECTIVE

In passive middle ear prosthetics, rigid implants have proven successful in reconstructing the ossicular chain. However, these cannot fully replicate the physiology of the ossicular chain. Pressure fluctuations cause high stresses in rigid passive prostheses, which can result in dislocation, protrusion, and pre-tension in the annular ligament resulting in unsatisfactory hearing results.

METHODS

In collaboration with MED-EL, we developed a new passive middle ear prosthesis that features a balanced, centered ball joint between the headplate and shaft of the prosthesis. We compared the sound transmission properties of this new prosthesis with those of a standard rigid prosthesis. Using Laser-Doppler-Vibrometry, we measured the sound-induced velocity of the stapes footplate relative to a given acoustic stimulus.

RESULTS

The new prosthesis showed equivalent sound transmission characteristics compared to the rigid prosthesis, whereas retaining the ability to compensate for pressure fluctuations due to its ball joint. This ensures good transmission properties even during displacements of the tympanic membrane.

CONCLUSION

This development is a further step toward a physiological reconstruction of the ossicular chain.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2022.

Review of a single surgeon's stapedotomy cases performed with a nickel titanium prosthesis over a 14-year period

CONCLUSION

Stapes surgery with a nickel titanium prosthesis is a safe and well-tolerated procedure that leads to a significant improvement in hearing outcomes.

OBJECTIVE

To identify the efficacy and safety of stapedotomy procedures performed with a nickel titanium prosthesis for patients with otosclerosis.

METHODS

A review of 431 unique stapedotomies performed over 14 years by a single surgeon at an academic tertiary care center yielded 312 cases with nickel titanium prosthesis that met inclusion criteria of otosclerosis diagnosis, initial surgery in operative ear, and presence of pre-operative and post-operative audiograms. Pure-tone averages (PTA) at baseline and 8 weeks after surgery were calculated over four frequencies; 0.5, 1, 2, and 4 kHz. Average air-bone gaps (ABG) were calculated from pre-operative and post-operative audiograms.

RESULTS

Average pre-operative baseline PTA was 56.7 dB in the affected ear. Post-operative PTA was 30.1 dB, a 26.6 dB improvement. Initial average ABG was 29.7 dB, while post-operative ABG averaged 5.4 dB, a 24.2 dB improvement. Surgical success (closure of ABG within 10 dB) was achieved in 263 (84%) patients. Rate of surgical success was not correlated with age, gender, race, or affected ear. Complications included recurrent conductive hearing loss (14), progressive SNHL (4), and post-operative BPPV (3).

[Stapes surgery for otosclerosis using a new titanium prosthesis with a superelastic nitinol clip: First experiences]

BACKGROUND

Coupling of the prosthesis to the long process of the incus is a critical step in stapes surgery. We report first experiences with the NiTiFLEX® stapes prosthesis, a further development of the Soft CliP® stapes prosthesis (Kurz, Dusslingen, Germany). Instead of pure titanium, the CliP® now consists of nitinol, a superelastic nickel-titanium alloy. This further reduces the pressure exerted on the long process of the incus, aiming to improve coupling and minimize the risk of incus luxation.

METHODS

In a monocentric, retrospective cohort study, we evaluated air-bone gap reduction (4PTA0.5-4 kHz), understanding of monosyllables at 65 and 80 dB SPL stimulation levels, and adverse effects, such as changes in bone conduction (4PTA0.5-4 kHz). During a 12-month period (May 2014 to April 2015), stapes surgery was performed in 21 otosclerosis patients using the NiTiFLEX® prosthesis. The footplate was perforated using a CO2 laser (scanning mode; 0.7 mm; 20-21 W) in almost all cases. The diameter of the titan piston was 0.4 mm. Immersion at an angle of almost 90° thus results in a gap between the footplate perforation and the piston of 0.15 mm. Positioning onto the long incus process was performed with a 90°microhook (0.6 mm).

RESULTS

In all cases the NiTiFLEX® stapes prosthesis was inserted without complications. The mean bone conduction threshold did not change significantly postoperatively and the mean air-bone gap (4PTA0.5-4 kHz) improved on average from 29.0 to 9.5 dB HL. Handling of the prosthesis was rated as very good.

CONCLUSION

The limited experience of this study suggests that the NiTiFLEX® stapes prosthesis is a successful further development of the Soft CliP® technique with very good intraoperative handling qualities. While long-term results from larger studies are needed, this case series demonstrates that the hearing outcome is comparable to other prostheses.

Treatment of otosclerosis with a superelastic nitinol piston: first results

Stapedotomy with implantation of an alloplastic prosthesis is a well-established therapy for the treatment of otosclerosis. Since the middle of 2008, a new Nitinol prosthesis with memory function and superelastic properties has been available which is expected to make fixation on the long process of the incus much easier. The advantage of this prosthesis is that heat-induced wire crimping is no longer necessary and damage to the incus caused by heat is avoided. Since May 2008, laser-assisted stapedotomy with implantation of a Nitinol prosthesis was performed in 21 patients suffering from otosclerosis. The prostheses used for all patients had a size of 4.5 mm × 0.4 mm. The patient collective consisted of 14 women and 7 men with a mean age of 53.4 years. Pre- and postoperatively, an ENT examination was carried out followed by an audiological evaluation of the hearing result. In addition, the properties of the prosthesis ("proper fitt", "handling", and "overall rating") were evaluated intraoperatively by means of a test protocol. The Nitinol prosthesis was implanted successfully in all 21 patients. The mean air-bone gap for the frequencies from 0.5 to 4 kHz was 9.83 dB postoperatively. Intraoperatively, the fit of the prosthesis was rated as "good to very good", the handling as "good" and the overall rating of the system was "good to very good". Our patient collective showed good postoperative hearing results. Due to simple intraoperative handling, especially placing the Nitinol prosthesis in position, the critical work step of crimping is no longer necessary.

Passive and active middle ear implants

Besides eradication of chronic middle ear disease, the reconstruction of the sound conduction apparatus is a major goal of modern ear microsurgery. The material of choice in cases of partial ossicular replacement prosthesis is the autogenous ossicle. In the event of more extensive destruction of the ossicular chain diverse alloplastic materials, e.g. metals, ceramics, plastics or composits are used for total reconstruction. Their specialised role in conducting sound energy within a half-open implant bed sets high demands on the biocompatibility as well as the acoustic-mechanic properties of the prosthesis. Recently, sophisticated titanium middle ear implants allowing individual adaptation to anatomical variations are widely used for this procedure. However, despite modern developments, hearing restoration with passive implants often faces its limitations due to tubal-middle-ear dysfunction. Here, implantable hearing aids, successfully used in cases of sensorineural hearing loss, offer a promising alternative. This article reviews the actual state of affairs of passive and active middle ear implants.

Superiority of nitinol piston over conventional prostheses in stapes surgery: first comparative results in the Chinese population in Taiwan

BACKGROUND

A growing number of studies conducted on stapes surgery have suggested that firm and adequate attachment of the prosthesis onto the long process of the incus plays a key role in surgical success. For this reason, a new prosthesis made of Nitinol characterized by "self-crimping" has been developed. Although better postoperative outcomes achieved with a Nitinol piston have been previously confirmed, the superiority of the Nitinol piston over the conventional manual-crimping prostheses remains controversial. The aim of this study was to determine the advantages of the Nitinol piston with regard to hearing improvement.

METHODS

We retrospectively compared postoperative hearing in otosclerosis surgeries with the Nitinol piston versus the manual-crimping prostheses. Sixteen surgeries with Nitinol pistons (carried out between April 2007 and August 2009) and 21 surgeries with conventional prostheses (carried out between January 2004 and January 2009) were evaluated. All patients received pure-tone audiograms preoperatively and postoperatively.

RESULTS

In the Nitinol piston group, the air-bone gap (ABG) average (7.92 + or - 6.75 dBHL) was significantly smaller postoperatively than preoperatively (26.79 + or - 8.33 dBHL, p < 0.001). Similarly, the ABG average for the conventional piston group (13.09 + or - 6.99 dBHL) was significantly smaller postoperatively than preoperatively (26.19 + or - 6.76 dBHL, p < 0.001). Although both groups demonstrated an improvement in average ABG postoperatively, the Nitinol piston group showed a greater improvement than the conventional piston group (p = 0.018). Additionally, ABG closure within 10 dB was attained in significantly more patients (75%) in the Nitinol piston group compared with the conventional piston group (33.3%, p = 0.012).

CONCLUSION

The Nitinol piston has a distinct advantage over conventional prostheses, providing an easier, safer and more effective treatment option in otosclerosis surgery. To our knowledge, this is the first comparative analysis of hearing results of the Nitinol piston with conventional prostheses in the Chinese population in Taiwan. In this population, there is a much lower prevalence of otosclerosis, leading to a lack of surgical experience in otosclerosis surgery, even at large medical centers. This may explain, in part, the relative lack of studies conducted on stapes prostheses in Asian patients. Therefore, our preliminary research may provide a reference for future investigations on stapes surgery in Asian patients with otosclerosis based on ethnic differences.

[Significance of computed tomography evaluation before revision stapes surgery]

BACKGROUND

Stapedectomy and, more recently, stapedotomy have been widely accepted as the primary surgical techniques to improve conductive hearing in patients suffering from otosclerosis. Unsuccessful outcomes are infrequent, but revision surgery may become necessary. We have analyzed the value of computed tomography (CT) scanning following unsuccessful stapes surgery.

PATIENTS AND METHODS

In a total of 37 CT scans, the depth of insertion, angle between prosthesis and footplate, location of prosthesis within the oval niche, visibility of the prosthesis, dehiscence of the superior semicircular canal, and extent of otospongiotic foci were evaluated and compared with the audiometric results.

RESULTS

There was no significant correlation between CT parameters and audiologic results, except for patients with cochlear otosclerosis or lateral dislocation of the piston. One previously unknown dehiscence of the superior semicircular canal was diagnosed. Otospongiotic foci were seen in 13 ears (35%).

CONCLUSION

Displacements of the stapes piston and rare causes for an insufficient result, such as a dehiscence of the superior semicircular canal, can be diagnosed accurately by CT. However, correlation between the audiologic results and the findings on CT scans was possible in only a few cases. Nevertheless, CT scans provide additional information for surgical planning in revision stapes surgery and may become increasingly important to reduce unanticipated intraoperative risks; they may even guide the surgeon not to perform unnecessary revision surgeries.

Laser-assisted stapedotomy with a Nitinol heat-crimping prosthesis: Outcomes compared with a platinum fluoroplastic prosthesis

Objective

To assess the hearing outcomes achieved with a Nitinol heat-crimping prosthesis when used with a laser-assisted stapedotomy for otosclerosis.

Study Design

Prospective assessment of 50 stapedotomies performed in 48 patients. Data collected included audiological results and duration of hospital admission. Outcomes were compared with a previously reported series of 66 stapedotomies performed in 59 patients.

Setting

Tertiary referral center and private practice.

Results

In the Nitinol group, hearing was improved in all cases (100%). The air-bone gap (ABG) was closed to within 10 dB in 48 (96%). This group's results are significantly better ( P ≥ 0.01) than those of the platinum fluoroplastic group, in whom ABG was within 10 dB in 74 percent.

Conclusion

Laser-assisted stapedotomy, under local anesthesia with sedation, using a Nitinol heat-crimping prosthesis is a safe, well-tolerated technique with which excellent audiological results can be achieved.