Outcomes of primary stapedotomy using ionomeric cement at incus-prosthesis attachment versus nonuse of ionomeric cement: a prospective case–control study (2024)

Background

Stapedotomy is the main stay management of otosclerosis till the present day. Other alternatives are hearing aids and medical treatment. Many complications arise at the step of crimping of the prosthesis. Bone cement is a material that has strong adhesive and osteointegration properties. The aim of the present study is to compare hearing results between bone cement-applied and non-bone cement-applied primary stapedotomy patients at the incus prosthesis attachment.

Methods

Thirty patients diagnosed with otosclerosis were randomly selected. Classical primary stapedotomy was performed for both groups, except for using GIC over the incus–prosthesis attachment in group A patients. The duration of follow-up was 2months. Mean thresholds were measured at 0, 1, 2, and 4kHz frequency levels and used to calculate the primary outcome measurements, which were ABG closure and hearing gain.

Results

The overall 30 patients’ mean age was 37.2years. Bilateral disease occurred in 73.3%. Both groups showed significant ABG closure in relation to the preoperative values (P < 0.001). However, ABG closure in cement-used patients was significantly better (P 0.007). The mean for air conduction hearing gain was higher in group A (31.9dB) than in group B (27.3dB). However, this was statistically insignificant (P 0.313).

Conclusions

GIC can improve hearing outcomes in classical primary stapedotomy and potentially reduce postoperative complications and should be considered in routine practice.

Otosclerosis is an autosomal-dominant hereditary local disease with incomplete penetrance (25–40%), in which a new vascularized spongy bone replaces the normal compact bony labyrinth, gradually resulting in stapes fixation over the oval window (OW) leading to conductive hearing loss (CHL). It can also cause sensorineural hearing loss (SNHL) or mixed hearing loss (MHL) [1, 2].

Hearing aids and medical treatment may be offered; however, surgery remains the mainstay in most cases of otosclerosis [3]. The aim of stapes surgery is the restoration of ossicular impedance and the achievement of physiologic vibration of inner ear fluid [4].

There are 4 types of stapes surgery namely total and partial stapedectomies, anterior crurotomy, and stapedotomy [5]. Stapedotomy is simpler, conserves ear anatomy, and has lower risk of vestibule and high-frequency receptors/hair cell damage. It yields more hearing gain at 4kHz and minimizes prosthesis migration and postoperative SNHL [4]. It is, therefore, the most commonly performed technique at this present time.

Crimping of the prosthesis over the incus is one of the important steps during stapes surgery, instigating complications such as incus erosion or slipped prosthesis that can result in more than 85% of cases associated with poor hearing outcomes. Proper crimping and augmentation with bone cement can therefore potentially prevent complications and yield better hearing results [6].

Alan Wilson and Brian Kent developed Glass ionomer cement (GIC) in the 1970s. This polymer composite is derived when an alkaline inorganic ionomer is reacted with organic polyacrylic acid and glass particles. It is commercially available in separate liquid and powder containers, or in bi-component, 2-chamber capsules. The liquid and powder form a white paste through an acid–base reaction when mixed, which hardens over minutes [7,8,9,10].

Glass ionomer cement has strong adhesive and antimicrobial properties and comprehensive strength and elasticity comparable with cortical bone. It does not shrink in the healing phase and reacts with minimal thermal energy. It enhances osteo-conduction and osteointegration due to increased porosity [7, 8].

The aim of the present work was to study hearing outcomes in otosclerotic patients undergoing classical primary stapedotomy with GIC augmentation of incus–prosthesis attachment, and compare them to the control group without it, at a tertiary referral University Hospital.

This was a prospective study conducted on 30 consecutive patients who underwent classical primary stapedotomy for management of otosclerosis, at a tertiary referral University Hospital starting 1st of September 2022. Patients were randomly allocated to two groups, namely group A (GIC intervened) and group B (non-GIC intervened/ control).

All patients had to present with a minimum air–bone gap (ABG) of 30dB with normal otoscopy, tympanometry, and absent acoustic reflexes. There was neither age, nor sex, nor side limitation. Exclusion criteria denoted patients with etiologies of stapes fixation other than otosclerosis (for example, tympanosclerosis and congenital stapes fixation), and any previous major trauma or surgery in the same ear including previous stapedotomy and any ossicular anomalies other than stapes fixation.

Written informed consent for both the surgery and participation in research was obtained from all patients. Ethics approval from the allocated committee at our university was obtained for this study IRB: 00012098. In this prospective study, all participants were subjected to complete history taking, otoscopic examination, and tuning fork tests (Rinne and Weber). Basic audiological investigations in the form of pure-tone audiometry (PTA), tympanometry, acoustic reflexes, and speech audiometry were performed.

Surgical technique

Thirty patients were equally and randomly allocated with group A for odd and group B for even numbered patients. Patients were ordered chronologically. Therefore group A and group B comprised each 15 patients. All patients were performed by the same surgeon to avoid inter-subject variability. All patients in both groups were subjected to general hypotensive anesthesia. Local anesthesia was infiltrated into the skin of the external auditory canal (EAC).

The tympanomeatal flap (TMF) was elevated together with the annulus, and the middle ear (ME) was entered. All procedures were performed endomeatally microscopically.

Curettage of the postero-superior meatal wall was done to fully expose and visualize the footplate, the round window (RW), incudostapedial joint (ISJ), stapedial tendon, and the tympanic segment of the facial nerve (FN). Mobility was tested to confirm stapes fixation.

The superstructure was then fractured, and a 0.8-mm fenestra was buried in the middle third of the footplate using a Fisch perforator. A 0.6-mm diameter, 4.5-mm-long, whole Teflon, fluoroplastic piston (Medtronic, USA) was inserted between the stapes footplate and the long process of incus (LPI).

Group A patients were subjected to augmentation of the incus–prosthesis attachment, using RIVA self-cure 1.5ml GIC capsules (SDI, Australia). Manual pressing of the capsule was done to mix the liquid and powder contents within, and shaking was done for 13s using an amalgamator. The GIC paste was finally delivered using an applicator. The piston’s loop was widened in both groups. However, there was no crimping for group A, and it was left to recoil on its own. In all group B cases, the prosthesis was crimped to the LPI.

Gelfoam was placed over the footplate to prevent GIC spillage (Fig.1), and GIC was applied on the LPI–prosthesis attachment within 2min (Fig.2), allowing it to settle for 3min (Fig.3). The total working time was approximately 5min. The gelfoam was removed, and the prosthesis position and mobility were confirmed. The OW was sealed with blood clots, and TMF was repositioned.

Follow-up

Postoperative PTA was performed two months postoperatively. Preoperative and postoperative audiograms were performed using a 2-channel audiometer in a sound-treated room. Air conduction (AC) thresholds were measured via supra-aural headphones, and bone conduction (BC) thresholds via a bone vibrator. Thresholds were measured at 500, 1000, 2000, and 4000Hz, and the mean air–bone gap (ABG) was noted.

Mean thresholds for the 4 frequencies were calculated as per the guidelines by the American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS), and plotted on graphs for observation of overall outcome (Amsterdam Hearing Evaluation Plots (AHEPs)) [11]. This was done with the exception that we replaced the 3000Hz by 4000Hz because the 3000Hz is not routinely done in our center.

The success of hearing outcome was measured by 2 methods namely, AC gain and postoperative ABG closure. The mean hearing AC gain was calculated by subtracting postoperative from preoperative mean AC thresholds at 3 frequency levels (500, 1000, and 2000Hz) [11, 12].

The postoperative ABG was calculated by subtracting postoperative BC from postoperative AC thresholds at all 4 frequencies, and patients were categorized into those having closure ≤ 10dB as success, closure > 10 to 20dB as an acceptable result, and ABG above 20dB considered as failure [11, 12].

Preoperative and postoperative AC, BC, and ABG as means and at individual frequencies were compared and statistically analyzed.

Statistical analysis

Data was entered into the Statistical Package for Social Science (Rstudio) version 2.3.2. The data were presented as numbers and percentages for the qualitative data, mean, standard deviations, and ranges for the quantitative data with parametric distribution, and median with inter-quartile range (IQR) for the quantitative data with non-parametric distribution. The Shapiro test was used to verify the normality of distribution.

The chi-square test was used in the comparison between two groups with qualitative data and the Fisher exact test was when the expected count in any cell was found less than 5.

Independent t-test was used in the comparison between two groups with quantitative data and parametric distribution, and Wilcoxon Mann–Whitney test was used in the comparison between two groups with quantitative data and non-parametric distribution. The p-value was considered significant as the following: P > 0.05, non-significant; P < 0.05, significant.

Epidemiology

The overall patients’ mean age was 37.2years, ranging between 19 and 55years. The male-to-female ratio was approximately 1:1.3. As regards disease laterality, bilateral otosclerosis was most common (73.3%) in both studied groups, with 60% incidence of tinnitus and 13.3% incidence of vertigo.

Operative data

As regards the operated side, 60% were right and 40% were left. All patients were surgically confirmed with stapes fixation. Regarding complications, accidental tympanic membrane perforation (TMP) occurred in 2/15 patients (13.2%) in group B. Both were repaired intraoperatively by underlay tragal perichondrial graft. No residual perforation was seen at follow-up 2months later. Chorda tympani nerve (CTN) had to be severed in 1 patient (6.7%) from group B, resulting in dysgeusia postoperatively. Persistent ABG occurred in 26.7% (4 patients) from group B, 2months postoperatively.

Primary hearing outcome measures

The preoperative and postoperative mean AC and BC thresholds measured at 500, 1000, 2000, and 4000Hz were used to calculate primary outcome measurements for overall comparison between both studied groups. This comparison showed better primary outcomes in group A patients than those in group B, with significantly better ABG closure in group A (0.007) (Table1).

Each of the studied groups showed significantly lower postoperative mean ABG compared to their respective preoperative mean ABG (P < 0.001).

Comparison between the 2 studied groups according to each frequency showed less postoperative values (denoting better results) in group A than B across all 4 frequencies. Nonetheless, they were not statistically significant (Table2).

The mean for air conduction hearing gain was higher in group A (31.9dB) than in group B (27.3dB). However, this was statistically insignificant (P 0.313) (Table1).

Regarding significant sensorineural hearing loss (SNHL), it was defined as deterioration of more than 10dB for 3 or more frequencies. This occurred in 4 non-GIC-intervened subjects and 2 GIC-intervened patients, with no statistical significance (P 0.10).

Otosclerosis is an autosomal-dominant, hereditary disease of the otic capsule, in which compact bone is remodeled to vascularized spongy bone, causing stapes fixation and hearing loss (HL) [1, 2].

According to the literature, patients are usually present in their 2nd–4th decades of life, with female predominance and gradual onset, slowly progressive, bilateral, asymmetric HL, tinnitus, and/or vertigo [1, 6, 13]. Similarly, in the present study, the patients’ age ranged between 19 and 55years with a mean value of 37.2years. Females were slightly more affected than males (1.3:1).

When examined, our patients were all found to have a negative Rinne test, a falsely lateralized Weber’s test to the worse hearing ear and normal otoscopy, which concurs with the common presentation of the disease [1, 13]. Among our patients, there was 73.3% incidence of bilateral disease, 60% incidence of tinnitus, and 13.3% incidence of vertigo.

Authors report findings of gradual low to high frequencies CHL, ABG widening, and Carhart’s notch at 2kHz frequency on PTA, excellent speech discrimination scores (SDS), and type As tympanogram in otosclerosis [13, 14]. Similar findings were observed in this study during patients’ evaluation.

Surgical treatment remains the gold standard for the vast majority of otosclerosis patients. Malcrimping, however, accounts for 85% of revision surgery [6]. The aim of this randomized, prospective study was to compare hearing results between otosclerotic patients undergoing classical primary stapedotomy with or without stabilization of incus–prosthesis attachment using GIC. The follow-up period in the present study was 2months.

Regarding complications, accidental TMP occurred in 13.2%. Chorda tympani nerve was severed in one patient (6.7%) from group B, resulting in taste affection. Tysome et al. also reported a single case of severed chorda tympani in their series of 25 subjects, whereas 3 such incidents were encountered by Mostafa et al. from their 60 subjects [6, 15]. Ergun et al. also reported TMP occurring in 2 of their 32 subjects, in addition to 1 severed chorda tympani and 3 dislocated prostheses among non-GIC intervened subjects, while Elzayat encountered TMP and severed chorda tympani nerve in 4 and 2 subjects respectively [6, 16].

Authors consider ABG closure of up to 10dB as success, and up to 20dB as acceptable, while postoperative ABG above 20dB is deemed as failure [12]. Tysome et al. reported 77% and 92% of their GIC-intervened subjects achieved closure of up to 10dB and 20dB respectively, which were lower compared to the present study’s findings (86.7% and 100% respectively). However, more of their non-GIC-intervened subjects achieved closure of up to 10dB (65%) and 20dB (85%) compared to the present study (40% and 73.3%) respectively. They also reported a mean postoperative ABG of 5dB among GIC-intervened subjects, which was in the same range of the present study (6.2dB), but less among non-GIC-intervened subjects (9dB), compared to the present study (13.9dB) [15].

In our study, four patients had persistent ABG postoperatively. All were from non-GIC intervention group B. Unfortunately, all of them opted for amplification and declined re-exploration and postoperative computer tomography (CT). Prosthesis dislocation was highly suggested to have been the cause of the persistent gap based on the relatively high incidences reported in previous studies [6, 16, 17]. Incus erosion was unlikely to occur in the course of the 2-month follow-up period. Too short prosthesis and missed attic fixation are also valid causes. Attic fixation is less likely due to good testing of ossicles intraoperatively before and after prosthesis insertion. Too short prosthesis remains valid since, in our country, only 4.5mm prosthesis is available and measuring is not routinely done in our center.

The mean hearing gain in the present study was 31.9dB and 27.3dB among GIC- and non-GIC-intervened subjects respectively. This was, however, statistically insignificant (P = 0.313). Nonetheless, this was slightly more compared to 27dB and 25dB among GIC- and non-GIC-intervened subjects respectively reported by Tysome et al. [15]. Ergun et al. also reported less gains of 24.6dB and 23.0dB among GIC- and non-GIC-intervened subjects respectively compared to the present study [16].

Best outcomes in group A patients among the 4 frequencies were achieved at 2kHz for both groups A and B, with mean postoperative ABG of 3.3dB and 11.43dB respectively. Mostafa et al. reported significant postoperative improvement only at 2kHz in terms of postoperative mean ABG among GIC-intervened subjects. Although this parameter was not statistically significant in the present study, results concurred that 2kHz frequency had the most favorable outcomes [6].

Elzayat et al. reported mean ABG values similar to those by Tysome et al. However, hearing gain was similar to this present study. Closure of up to 10dB was reported among all (100%) GIC-intervened subjects compared to 86.7% among their counterparts in the present study, while all (100%) non-GIC-intervened subjects reported by Elzayat et al. achieved closure of up to 20dB, compared to 73.3% among their counterparts in the present study [17].

Apart from Ergun et al., all the aforementioned authors reported considerably better hearing outcomes and less complications using GIC, although not overwhelmingly significant across all parameters, crediting GIC for helping improve ABG closure to some extent. Each author has, however, acknowledged limitations to their studies, that may have otherwise had improved outcomes, as in the case of this study. The limitations shared in the present study were a small sample size and a short follow-up period.

Sensorineural hearing loss, which is defined as a negative value in the difference between BC postoperative and preoperative thresholds at three consecutive frequencies exceeding 10dB, was found in 1 non-GIC-intervened patient among patients by Mostafa et al. [6]. In the present study, however, SNHL was evident in 4 non-GIC-intervened subjects and 2 GIC-intervened patients but was statistically insignificant. Neither profound nor total hearing loss occurred in the present study.

Authors and Affiliations

1. Oto-Rhino-Laryngology, Faculty of Medicine, Alexandria University, Khartoum Square, Azarita, Alexandria, Egypt

   Ahmed Galal,Yasser Shewel,Hani F. Elgarem&Amir Mina

2. ENT department, Lamu county hospital, Lamu County, Kenya

   Mashrab Saggaf

Contributions

AG helped in the conception and design of the study, performed the surgeries, and helped in writing. MS was a major contributor in writing, literature review, and data collection. YS helped in the conception and design of the study and language proof of the final manuscript. HG helped in data analysis, interpretation, and writing. AM shared in writing and interpretation of data and had a major role in statistical analysis. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Ahmed Galal.

Ethics approval and consent to participate

Ethics institutional board at our university (Faculty of Medicine, Alexandria University, Alexandria, Egypt) was obtained. Ethics approval from the allocated committee IRB: 00012098. Written informed consent for participation in research was obtained from all patients.

Consent for publication

Informed consent for both the surgery and publication of research was obtained from all patients.

Competing interests

The authors declare no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and permissions