Ossicular chain reconstruction in austin-kartush type A and B defects using titanium prosthesis: Audiological and anatomical outcomes

Tarun Malhotra; Sujay Nadiger; Vaidehi Thakur; Deep Kamal

doi:10.4103/jmms.jmms_163_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 24 | Issue : 2 | Page : 142-148

Ossicular chain reconstruction in austin-kartush type A and B defects using titanium prosthesis: Audiological and anatomical outcomes

Tarun Malhotra¹, Sujay Nadiger¹, Vaidehi Thakur², Deep Kamal³
¹ Department of Otolaryngology, INHS Kalyani, Visakhapatnam, Andhra Pradesh, India
² Department of Gynaecology, NH Powai, Mumbai, Maharashtra, India
³ Department of Medicine, INS India, New Delhi, India

Date of Submission	27-Dec-2021
Date of Decision	29-Dec-2021
Date of Acceptance	01-Jan-2022
Date of Web Publication	10-Aug-2022

Correspondence Address:
Surg Cdr (Dr) Deep Kamal
Department of Medicine, INS India, New Delhi
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jmms.jmms_163_21

Abstract

Introduction: Ossicular chain reconstruction (OCR) augments the hearing mechanism in various ossicular pathologies. Titanium allograft with superior properties was evaluated in the study. Materials and Methods: To assess the audiological and anatomical outcomes following titanium OCR, a retrospective review was performed for 47 cases who underwent OCR from January 2015 to December 2018 at a tertiary care center. The ossiculoplasty was carried out in a single stage tympanoplasty. The partial ossicular replacement prostheses (PORP) and total ossicular replacement prostheses (TORP) were used in 28 and 19 patients, respectively, with a follow up for 12 months. The pre and postoperative air conduction pure tone averages and air bone gaps(ABG) were analyzed. The operative success was defined as a postoperative ABG of ≤20 dB. Fisher's test, analysis of variance (ANOVA), and t test were used depending on data compared. Results: Postoperatively, the mean ABG was 15.4 ± 2.8 dB; about 80. 85% of cases achieved operative success. ABG values showed significant improvement compared with preoperative values (P = 0.001, t test). Successful OCR was achieved 85.7% of PORP and 73.6% TORP cases. Discussion: The mean postoperative ABG was 13.75 ± 5.4 dB for the PORP group and 17.84 ± 2.5 dB for the TORP group. No variation in audiological outcomes was observed when comparing PORPs to TORPs. There was no significant difference in postoperative ABG on comparison of different etiologies (P = 0.508, ANOVA), procedures undertaken (P = 0.226, ANOVA), and primary/ revision surgery (P = 0.172, t test). The extrusion and displacement rates were 2% each. These findings highlight that Titanium OCR gives stable hearing gains with low extrusion rates.

Keywords: Cholesteatoma, ossicular chain reconstruction, ossicular prosthesis, pure-tone audiometry, tympanoplasty

How to cite this article:
Malhotra T, Nadiger S, Thakur V, Kamal D. Ossicular chain reconstruction in austin-kartush type A and B defects using titanium prosthesis: Audiological and anatomical outcomes. J Mar Med Soc 2022;24:142-8

How to cite this URL:
Malhotra T, Nadiger S, Thakur V, Kamal D. Ossicular chain reconstruction in austin-kartush type A and B defects using titanium prosthesis: Audiological and anatomical outcomes. J Mar Med Soc [serial online] 2022 [cited 2023 Mar 24];24:142-8. Available from: https://www.marinemedicalsociety.in/text.asp?2022/24/2/142/353646

Introduction

Chronic otitis media (COM), with and without cholesteatoma, is often associated with ossicular chain defects. The resultant conductive hearing loss is due to either ossicular chain discontinuity or fixation. The most common defect is variable erosion of the long process of incus followed by erosion of stapes superstructure. Trauma and congenital anomalies account for most of the remaining causes of ossicular damage.^[1]

The aims of tympanoplasty are to make the ear safe, dry and to improve hearing. The last of the three is often the most challenging. Ossicular chain reconstruction (OCR) entails the transfer of acoustic energy from a mobile tympanic membrane (TM) to the inner ear fluids. The ideal material for ossicular reconstruction should be biocompatible, of optimal mass and rigidity, and stable. The outcome of ossiculoplasty depends on prosthesis design, surgical technique and the status of the middle ear.

Various materials have been used for OCR. Options include autografts such as ossicles, cartilage, and cortical bone; homografts from human donor tissues such as cartilage, ossicles, and en bloc ossicular chain with TM attached; and alloplastic materials such as metals, plastics, and ceramics.^[2] Titanium implants have many superior properties: biocompatibility, high rigidity, low-weight designs, and open head configuration for accurate placement.

The present study was designed to evaluate the anatomical and hearing outcomes of OCR using titanium prostheses.

Materials and Methods

All patients who underwent ossiculoplasty using titanium prosthesis from Jan 2015 to December 2018 were retrospectively reviewed. The data included 47 patients (28 males, 19 females), with ages ranging from 18 to 64 years. The follow-up period ranged from 9 to 18 months (mean 15.5 months).

Inclusion criteria

COM with or without cholesteatoma
Cases with the following ossicular status:

Incus erosion, malleus and stapes intact (M+, I−, S+)
Incus and stapes erosion, malleus intact (M+, I−, S−).

Traumatic ossicular discontinuity
Primary ossiculoplasty: one stage tympanoplasty and ossiculoplasty.

Exclusion criteria

Cases with the following ossicular status:

Malleus handle absent, stapes superstructure present (M-,I-,S+)
Malleus handle and stapes superstructure absent (M-,I-,S-).

Sensorineural hearing loss/mixed hearing loss
Smokers
Congenital etiology for conductive hearing loss
Only hearing ear
Lateral chain ossicular fixation and footplate fixation.

Preoperative steps

The patients were enquired for chronicity of the hearing loss, otorrhea, associated tinnitus, vertigo, previous ear surgery, trauma, and nasal diseases. All patients underwent otoscopy and microscopic examination of both ears. The condition of the ossicles and the correlation of ossicles to associated ear diseases were noted. In cases of COM, ossicular discontinuity was assessed through a large perforation or with severe atelectasis of the TM. Besides, tympanosclerosis and the presence of cholesteatoma was noted.

Pure-tone audiogram was done as recommended by AAO-HNS. Air conduction (AC) and Bone conduction (BC) pure tone averages (PTA) results were calculated using 0.5, 1, 2, and 3 kHz thresholds. The Air-Bone Gap (ABG) was calculated as the difference between BC PTA and AC PTA. Draining middle ears were treated with aural toilet and oto-topical agents. Patients with nasal conditions were treated to optimize eustachian tubal function.

Operative steps

Post auricular approach was used in all cases. Initially, middle ear disease was corrected/resected before OCR. The ossicular chain was inspected and palpated. Ossiculoplasty was performed in a one-stage surgery in all cases.

In cases with incus erosion with malleus and stapes superstructure present (Austin-Kartush Type A defect, M + I-S+) [Figure 1]a, Titanium Partial Ossicular Replacement Prosthesis (PORP) [Figure 2]a was used between stapes head and TM. In cases with incus erosion with malleus present and stapes superstructure absent (Austin-Kartush Type B defect, M + S-) [Figure 1]b, Titanium Total Ossicular Replacement Prosthesis (TORP) was used between footplate and TM [Figure 2]b.

Figure 1: (a) Austin-Kartush Type A defect- Stapes superstructure present (Arrow); (b) Austin-Kartush Type B defect- Stapes superstructure absent (Arrow); fn: Facial nerve, sf: Stapes footplate, ct: Chorda tympani, s: Stapes superstructure, m: Malleus, rw: Round window, p: Promontory

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Figure 2: (a) Partial ossicular replacement prostheses (pre-crimping) placed in a droplet of water (Arrow) to remove any electrostatic charging of the prosthesis before implantation; (b) Titanium total ossicular replacement prosthesis

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Before the placement of the prosthesis, a template sizer system was used in the middle ear to measure the correct length required for the actual prosthesis [Figure 3]a and [Figure 3]b. During sizing, we also calculated the 0.5 mm transplant (cartilage) thickness into the final length of prosthesis. Hence, the length of the titanium prosthesis chosen was template sizer minus cartilage thickness (0.5 mm). Titanium prostheses were adjustable to a variable functional length as per requirement.

Figure 3: (a) Prosthesis sizer disk with various template sizes attached at the periphery (white arrow); (b) Sizer in the middle ear to assess the correct size of the prosthesis (black arrow)

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The finally configured PORP and TORP were implanted in the middle ear [Figure 4]a and [Figure 4]b. The site of the prosthesis head was in the posterosuperior quadrant of the TM. It was placed perpendicular to the stapes to allow for the proper vector of sound energy transduction. In the case of TORP, an omega-shaped titanium connector was also placed on the footplate to provide additional stability to TORP and compensate for TM movements in the healing phase [Figure 4]c. We avoided using a too-long prosthesis, which can stress the annular ligament of the stapes footplate and adversely influence the hearing outcome.

Figure 4: (a) Partial ossicular replacement prostheses placed over intact stapes suprastructure; (b) Total ossicular replacement prosthesis placed perpendicular to the stapes footplate and stabilized with Ω shaped connector (arrow); (c) Omega connector placed over stapes footplate

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A 0.5 mm thick cartilage graft (from tragus) was placed between the TM and head plate of the prosthesis to prevent extrusion. Temporalis fascia was placed as an underlay graft and external auditory canal packed with gel foam.

Postoperative steps

Audiometry was carried out at 03 and 12 months. Postoperative ABG was calculated, and the difference between the preoperative and postoperative ABG (ABG closure) was recorded. In this study, success was defined, wherein patient's postoperative ABG was <20 dB. Patients were evaluated for anatomical outcomes (Intact neo membrane) [Figure 5], functional results (audiometry), and complications (reperforation, retraction, prosthesis extrusion, or displacement).

Figure 5: Postoperative otoendoscopy showing intact neomembrane with cartilage cover over titanium prosthesis

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Statistical analysis

Continuous variables are expressed as mean and standard deviation (SD) are compared over time using the Wilcoxon sign-rank test. Categorical variables are expressed as the number of patients and percentage of patients. Fisher's test, analysis of variance (ANOVA) and t-test were used depending on data compared. The statistical software SPSS Version 22 (International Business Management,Armnork,New York,USA) has been used for the analysis. An alpha level of 5% has been taken, i.e., if any P < 0.05, it has been considered significant.

Results

The epidemiological data, etiology, surgical procedures, and prosthesis employed are elaborated in [Table 1]. The majority of ossicular chain defects were as a consequence of COM with or without cholesteatoma (74.4%) and retraction pocket (23.4%).

Table 1: Epidemiology, etiology, and operative features

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Audiological outcomes

Overall functional results are shown in [Table 2]. In this study, operative success, defined as a postoperative ABG ≤20 dB, was noted in 38 cases (80.85%) at 12 months after surgery. Preoperatively, the mean AC PTA was 43.9 ± 5.5 dB, and the mean ABG was 31.9 ± 5.3 dB. Postoperatively, the mean AC PTA was 27.6 ± 5.3 dB and the mean ABG was 15.4 ± 2.8 dB. On analysis of preoperative and postoperative audiological results, there was the improvement in AC PTA and ABG values. This difference was statistically significant (P = 0.001, t-test), thus corroborating the benefit of titanium ossiculoplasty in re-establishing the aberrant sound conduction of the ear.

Table 2: Comparison of preoperative and postoperative audiological results

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[Table 3] depicts the hearing outcomes depending on the type of prosthesis used. PORP was used in 28 cases (59.5%), and TORP was used in 19 cases (40.4%). Operative success was attained for 24 cases (85.7%) in the PORP group and 14 cases (73.6%) in the TORP group, although there was no significant difference between the groups (P = 0.453, Fisher). The mean preoperative ABG was 29.4 ± 6.1 dB in the PORP group and 35.6 ± 3.9 dB in the TORP group and mean postoperative ABG was 13.75 ± 5.4 and 17.84 ± 2.5 dB, respectively. In comparison of pre- and postoperative ABG, there was a significant improvement in both PORP (P < 0.001) and TORP group (P < 0.001). Besides, on the evaluation of ABG closure, the difference between PORP and TORP group was statistically insignificant (P = 0.2, t-test). These results highlight the statistically significant improvement in hearing outcomes with both PORP and TORP.

Table 3: Audiological outcomes and comparison between titanium prostheses

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[Table 4] shows the audiometric results based on the different parameters studied. On the evaluation of different etiologies, the mean postoperative ABG values for COM mucosal disease, COM with cholesteatoma, and retraction pocket were 13.13 ± 1.8, 18.05 ± 5.2 dB, and 14.8 ± 1.6 dB, respectively. The operative success for the three entities was 84.2%, 75%, and 81.82%, respectively. However, the difference was not significant among different etiologies regarding postoperative ABG (P = 0.508, ANOVA) or operative success (P = 0.482, Fisher). This indicates that OCR results using titanium prostheses were unaffected by different etiologies.

Table 4: Audiological outcomes and comparison among different etiologies, operative procedures, and primary versus revision cases

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The present study included 07 cases of revision surgery. The mean postoperative ABG was 13.28 ± 3.45 dB with operative success in five cases (71.4%). In 40 cases of primary surgery, the mean postoperative ABG was 15.77 ± 2.8 dB with operative success in 33 cases (82.5%). The difference was found to be statistically insignificant regarding postoperative ABG (P = 0.172, t-test) and operative success (P = 1.00, Fisher), indicating similar outcomes using titanium OCR in primary/revision cases.

Finally, hearing outcomes based on various operative procedures employed were compared. In 20 cases of tympanoplasty without mastoidectomy, the mean postoperative ABG was 13.85 ± 2.4 dB and operative success was noted in 17 cases (85%); In 16 cases of CWU procedure, the mean postoperative ABG was 15.75 ± 2.5 dB, and operative success was noted in 13 cases (81.25%). Moreover, in 11 cases of CWD procedures, the mean postop ABG was 21 ± 7.6 dB and operative success was seen in 08 cases (72.72%). There was statistically no significant difference on comparison of operative success (P = 0.619, Fisher) and postoperative ABG (P = 0.226, ANOVA) among various operative procedures employed, indicating hearing outcomes using titanium OCR were not dependent on operative procedure.

Anatomical results

Reperforation of the TM with extrusion of the prosthesis occurred in one case (2%). Complete closure of TM was attained in 46 cases (98%). Dislocation of prosthesis occurred in one case (2%). Both cases of extrusion and dislocation were observed in patients with COM with cholesteatoma. Consequently, a second surgery was undertaken for these 2 cases. One case of TM Retraction was seen at 12 months (1%). P value using Fisher's exact test of 0.06 was observed in extrusion rates of PORP and TORP groups, which is not statistically significant.

Discussion

The ossicular chain and TM play a vital role in acoustic coupling between the low-impedance system of air in the external auditory canal and the high impedance system of the cochlear fluids. This occurs by two mechanisms. First, mechanical advantage is afforded by manubrium of malleus, being 1.3 times longer than long process of incus; this results in 1.3 fold increase in sound energy. The second mechanism is the hydraulic lever effect, wherein the ratio of the surface area of TM to the stapes footplate allows for a sound energy gain of 20.8 : 1. Together, these mechanism allows for a gain of 27–34 dB as sound is transduced from the TM through the ossicles to the inner ear.^[3]

Ossicular disruption due to various causes results in conductive hearing loss and warrants OCR. Reconstruction of the middle ear sound-transformer mechanism has continued to progress since the initiative efforts of Wullstein and Zollner in the 1950s. The availability of plethora of materials for reconstruction signifies that the search for ideal prosthesis continues.

In the present study, titanium prostheses were used for OCR. The titanium prosthesis combines the low weight (<4 mg) and high rigidity, and it is the closest in mass to the ossicles it tries to replace. These characteristics lead to the reduction in acoustic impedance and sound damping, particularly for higher frequencies.^[4]

In Austin-Kartush Type A defects, we used titanium PORP between the TM and stapes head with good results. Advantages of this configuration were medial stabilization point and vector of force being in the line of stapes in the malleus-stapes offset situation. In Austin-Kartush type B defects, we used TORP between the TM and the stapes footplate. This type of reconstruction is innately less stable due to the lack of fixed connection point on the footplate. Several studies using multivariate analysis have identified the presence of stapes superstructure as being a key determinant of success following ossiculoplasty, with poorer outcomes to be expected when it is absent.^[5] To improve the stability of TORP, we used an omega-shaped connector placed on the footplate. This greatly enhanced steadiness of TORP and surgical success was achieved in 14 cases (73.6%). There are studies which highlight the significance of mechanical coupling between the TORP and the stapes footplate to improve stability.^[6],[7]

According to our study data, overall postoperative ABG <20 dB was observed in 80.85% of the cases at 12 months; 85.7% for PORP and 73.6% for the TORP group. The improvement in mean postoperative ABG was significant in both PORP and TORP groups (P < 0.001), but the difference between the two groups was statistically insignificant (P = 0.21, t-test). We contribute this stable hearing outcomes to the two-point stabilization in the TORP group provided by the placement of the omega connector on the stapes footplate. The results of this study are corroborated by other authors also. O'Connell et al.^[8] assessed that on long-term follow-up, mean ABG was 20 ± 15.4 dB and AC PTA was 35.3 ± 16.1 dB; 62% of patients achieved ABG ≤20 dB. ABG and AC PTA were significantly improved on comparison with preoperative values. No difference in hearing outcomes was observed when comparing PORPs to TORPs. Chen and Tao^[9] obtained postoperative ABG ≤20 dB in 83.7% of PORP cases versus 71.4%of TORP cases. There was no statistically significant difference between the TORP and PORP groups. However, there are studies, which have noted better hearing outcomes of PORP compared with TORP.^[10],[11]

Titanium is biocompatible with low extrusion rate of <5%.^[12] In our study, we interposed 0.5 mm sliced tragal cartilage between the prosthesis head and TM to reduce the risk of extrusion. The overall extrusion and displacement rates were 2.1% (01/47), and 2.1% (01/47), respectively, and the most common reason was postoperative atelectasis. In short-term studies, extrusions are reported between 1% and 5%, with displacements in 2% of cases.^[13] Long-term studies show more cases of displacements (3.5%–10.8%).^[8] This can be due to a nonoptimal prosthesis size or recurrence of etiology, especially atelectasis or cholesteatoma. While most surgeons interpose cartilage between a titanium prosthesis and the TM, Pringle has questioned whether this is necessary.^[14]

The length of the prosthesis is an important operative consideration. We used a shorter, optimally fitting prosthesis to reduce excessive pretension at the stapes footplate and TM. Tension-sensitive annular ligament of stapes footplate and the TM play a key role in the reconstruction of ossicular chain: If undesirable pre tension develops here, it can have significant impact on the middle ear transfer function.^[15] Lower tension reconstructions with a short prosthesis resulted in better sound transmission than higher-tension reconstruction with a long prosthesis.^[16]

In the present study, we performed primary ossiculoplasty as a single-stage surgery. In cases at the higher risk of residual or recurrent disease and TM retraction, OCR can be deferred until a disease-free, ventilated middle ear has been achieved. However, it is possible to offer primary OCR, particularly as diffusion-weighted MRI techniques allow the option for cholesteatoma surveillance without necessitating second-look surgery.^[17]

The hearing results were also evaluated according to the etiologies and types of surgery. In our study, there was no statistically significant effect of these variables on the mean improvement in ABG. This indicates that the titanium OCR results were unaffected by different pathologies and types of surgeries undertaken. Similar results were noted by Alaani and Raut^[18] where they found no significant difference with presence or absence of cholesteatoma (2-tailed t-test, P-0.63), and also between canal wall up and canal wall down procedures (2-tailed t-test, P-0.28). Castro Sousa et al.^[19] also observed that ABG closure between ossiculoplasty without and with mastoidectomy was found to be not significant (P = 0.115). We also observed no significant difference in titanium OCR results between primary and revision surgery cases (P = 0.172, t-test). Iniguez-Cuadra R et al.^[20] observed in their study of 94 patients, 64.7% of cases of revision surgery and 69% cases of primary had a postoperative ABG ≤20 dB. The difference between the groups was not significant (X² = 0.3, correlation = 0.058, P = 0.5). They also observed that all cases undergoing CWU had a mean ± SD postoperative ABG of 14.59 ± 11.28 dB. There were no statistically significant differences (Independent-samples t-test, P = 0.5) between these patients and those receiving CWD surgery (15.95 ± 10 dB).

Numerous implant materials can be used in OCR. Autograft offers the advantage of biocompatibility. Limitations are lack of availability in erosive disease, risk of implanting residual disease if the ossicle has been engulfed in cholesteatoma. In many studies, titanium ossiculoplasty is more successful than autologous ossicle.^[21],[22] Hydroxyapatite can achieve osseo-integration; and has low extrusion rate; however, it is brittle and difficult to sculpt. The hearing outcomes are comparable to titanium implants.^[23],[24]

The limitations of the study include variance in COM status among patients. Besides, the majority of studies are retrospective, making much of the literature difficult to decipher. There remains a need for prospective, well-controlled study, long-term trial with a large sample size to establish the result. The strength of the study is that surgical uniformity was maintained and hearing outcomes have been compared among diverse etiopathologies, procedures, and type of prosthesis. Additional maneuvers were employed to improve the stabilization and to reduce complications.

Conclusion

Titanium PORPs and TORPs offer an effective method of OCR for the rehabilitation of hearing loss. These prostheses produce superior hearing outcomes with favorable safety profiles. Majority of the patients had operative success (ABG ≤20 dB) with a low complication rate illustrating the efficacy and safety. Among the vast array of materials available, titanium implants can be considered as a material of choice due to its excellent mechanical properties, low weight, the platform with an open-top design, and biocompatibility.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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