|Year : 2011 | Volume
| Issue : 2 | Page : 75-79
Ossiculoplasty with autologous incus versus titanium prosthesis: A comparison of anatomical and functional results
Amith I Naragund, RS Mudhol, AS Harugop, PH Patil
Department of ENT and HNS, KLE University's Jawaharlal Nehru Medical College, Nehru Nagar, Belgaum, Karnataka, India
|Date of Web Publication||20-Dec-2011|
Amith I Naragund
37, Bhagya Nivas, Rukmini Nagar, Opp. KMF, Mal Maruti Extension, Belgaum - 590016, Karnataka
Source of Support: None, Conflict of Interest: None
Aims: To analyze and compare the outcomes of ossiculoplasty in terms of hearing results and graft take-up rates, using autograft incus and titanium middle ear prosthesis in patients with ossicular chain erosion. Study Design: Randomized clinical trial. Materials and Methods: Patients between 10 and 60 years of age with a history of chronic ear discharge with moderate conductive deafness (>40 dB HL) were included in the study. The patients underwent detailed ENT examination followed by audiological and radiological assessment of temporal bone and those patients with evidence of ossicular erosion were subjected to ossiculoplasty with autologous incus (group I) or titanium prosthesis (group II) randomly. The patients were followed up after 3 months to analyze the functional and anatomical results. Results: A total of 24 patients with ossicular chain defect were included in the study, of whom 12 patients underwent ossiculoplasty with autograft incus and 12 with titanium prosthesis. Postoperative hearing evaluation by pure tone audiogram was done after 3 months, which showed successful hearing improvement in 58% of cases with autologous incus as compared to 33% cases with titanium prosthesis. Complications and extrusion rate were also higher in patients with titanium prosthesis. Conclusion: Hearing results after ossiculoplasty with autologous incus were significantly better compared with those after titanium prosthesis. Also, complications and extrusion rate were higher in patients with titanium prosthesis. This indicates that ossiculoplasty with autoincus offers better hearing results with minimal complications and extrusion rates as compared to titanium prosthesis.
Keywords: Autologous incus, Ossiculoplasty, Titanium middle ear prosthesis
|How to cite this article:|
Naragund AI, Mudhol R S, Harugop A S, Patil P H. Ossiculoplasty with autologous incus versus titanium prosthesis: A comparison of anatomical and functional results. Indian J Otol 2011;17:75-9
|How to cite this URL:|
Naragund AI, Mudhol R S, Harugop A S, Patil P H. Ossiculoplasty with autologous incus versus titanium prosthesis: A comparison of anatomical and functional results. Indian J Otol [serial online] 2011 [cited 2020 Mar 29];17:75-9. Available from: http://www.indianjotol.org/text.asp?2011/17/2/75/91042
| Introduction|| |
The incidence of chronic otitis media is still high in our population, and ossicular chain destruction or erosion is a common complication of chronic suppurative otitis media. A moderate conductive deficit in excess of 40 dB indicates ossicular discontinuity, usually from erosion of the long process of the incus or stapes superstructure.  Definitive treatment in these cases includes primarily the clearance of disease from middle ear cleft followed by ossicular chain reconstruction.  Over the years, various grafts (autografts/allografts) have been used for ossicular reconstruction, like cortical bone, ossicular bones, tragal or septal cartilages, and also, ossicular prostheses like Total or Partial Ossicular Replacement Prosthesis (TORP or PORP) are used. 
Many commercial readymade prostheses have come up, but there are not many clinical trials which have proved the efficacy of these materials in terms of graft take-up rates and hearing results. The numerous techniques and middle ear prosthesis available to otologic surgeon lend credence to the idea that ossicular chain reconstruction techniques remain to be perfected.  In our study, we have subjected the patients with ossicular erosion to ossiculoplasty using autograft incus and titanium (Ti) prosthesis and compared the outcomes of surgery in terms of graft take-up rates and hearing improvement postoperatively.
| Materials and Methods|| |
Patients in the age group between 10 and 60 years attending ENT OPD at KLES Dr. Prabhakar Kore hospital between October 2008 and April 2011, were included in the study. The inclusion criteria for the patients were those with i) chronic otitis media with moderate degree of conductive hearing loss; ii) traumatic ossicular chain dislocation and iii) adhesive otitis media with moderate to severe conductive deafness. Patients with mixed hearing loss and extensive cholesteatoma cases were excluded from our study. The patients underwent detailed ENT examination followed by audiological and radiological assessment of temporal bone, and those patients with evidence of ossicular erosion were subjected to ossiculoplasty with autologous incus (group I) or titanium prosthesis (group II) randomly.
Ethical clearance was obtained from KLE University's institutional ethical committee for research on human subjects. Written informed consent was obtained from all the subjects using the standard consent form approved by the ethical committee.
All the 24 cases who fulfilled the inclusion criteria were divided into two groups randomly: Group I for which autologous incus repositioning was done and group II for which titanium gold prosthesis [Decibel's titanium-gold prosthesis: PORP (2 mm) wire and bell type with flanges and TORP (3 mm) with wire and flat bell with flanges] was used. Post-aural approach was used in all our cases. Canal wall down mastoidectomy with ossicular reconstruction was done in 5 cases in each group and canal wall up with ossiculoplasty was done in 7 cases in each group. The patients with Austin type A (erosion of incus with intact malleus and stapes) and type C (erosion of stapes superstructure with intact malleus) ossicular defects were considered for ossiculoplasty. In group I, the incus with necrosed lenticular/long process was detached from the incudomaleal joint and taken out. It was then held with Derlacki's ossicle holding forceps such that the body of incus was available for drilling and reshaping. Drilling of incus was performed using 0.6 mm diamond burr. The remnant long process was drilled to make it cylindrical in shape with a flat base. A socket was drilled in the undersurface of remodeled long process for engaging the head of stapes. Part of short process was removed and a notch was drilled on the superior surface of body to accommodate the handle of malleus. The refashioned incus was then interposed between the handle of malleus and stapes superstructure (notched incus with short process) [Figure 1]. In cases where stapes superstructure was absent, the incus graft was placed between handle of malleus and stapes footplate (notched incus with long process) [Figure 2]. In group II, titanium PORP was placed between handle of malleus and stapes superstructure [Figure 3]. In cases where stapes superstructure was absent, titanium TORP was placed between handle of malleus and stapes footplate [Figure 4]. A piece of conchal cartilage was placed over the prosthesis to prevent its extrusion, followed by temporalis fascia grafting.
|Figure 1: Notched incus with short process (M, malleus handle; I, incus autograft; S, stapes head)|
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|Figure 2: Notched incus with long process (M, malleus handle; I, incus autograft; F, stapes footplate)|
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|Figure 3: Titanium PORP placed between stapes head (S) and handle of malleus (M)|
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|Figure 4: Titanium TORP placed between stapes footplate (F) and malleus handle (M)|
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Audiometric evaluation was done after 3 months (mean 4.5 months) postoperatively, which included postoperative air-bone gap (ABG), postoperative air-conduction (AC) threshold, and postoperative bone-conduction (BC) threshold. Only AC and BC results that were obtained at the same time postoperatively were used for calculation of ABG and pure tone average (PTA) values. We used four PTA values for BC and AC (0.5, 1, 2, 4 kHz), which were obtained at the last follow-up visit. Postoperative ABG of 20 dB or less was considered a successful hearing result. Audiometry was reported according to American Academy of Otolaryngology-Head and Neck Surgery guidelines, except for thresholds at 3 kHz, which were substituted in all cases with thresholds at 4 kHz. Anatomical results, that is, closure of tympanic membrane perforation, graft take up and retraction pockets were analyzed oto-microscopically.
For different quantitative parameters, mean, median, and standard deviation (SD) were calculated. Student's t-test (unpaired) was used to calculate the statistical significance between two groups (I and II).
Paired t-test was used to analyze the pre- and postoperative hearing results in the same group. All the data were analyzed using SPSS-16 software.
| Results|| |
A total of 24 patients with ossicular chain defect were included in the study, of whom 12 patients underwent ossiculoplasty with autograft incus and 12 with titanium prosthesis. [Table 1] shows the profile of all the 24 cases analyzed. There were 13 male and 11 female subjects in the study. Fifteen cases were on the right ear and 9 cases on the left ear. Cholesteatoma was found in 18 cases at the time of ossiculoplasty, 4 cases were non-cholesteatomatous mucosal type of chronic otitis media and 2 cases had adhesive otitis media. The ossiculoplasty was performed during the primary operation in 21 cases and as the second-stage procedure in only 3 cases wherein titanium prosthesis was used. Canal wall down mastoidectomy with ossiculoplasty was performed in 5 cases in each group.
|Table 1: Basic characteristics of the two groups (n=24) - autoincus and titanium (Ti) prosthesis|
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Follow-up with postoperative audiological evaluation ranged from 3 to 12 months, with an average of 4.5 months. [Table 2] compares the hearing outcome of ossiculoplasty with autologous incus and titanium prosthesis. Average postoperative ABG closure of less than 20 dB was considered as successful hearing gain, which was seen in 7 cases (58%) with autologous incus and 4 cases (33.3%) with titanium prosthesis. The mean preoperative ABG values in autoincus, titanium TORP and PORP groups were 43.3 dB (SD 8.34), 44.2 dB (SD 10.17) and 42 dB (SD 5.7), respectively, whereas the postoperative ABG closure values were 24.5 (SD 9.15), 30.7 (SD 15.66) and 25 dB (SD 6.12), respectively. There was a statistically significant improvement in preoperative PTA ABG of 43.3 dB ± 8.34 SD to mean postoperative ABG of 24.5 dB ± 9.16 SD (P = 0.046) in autologous incus group.
|Table 2: Comparison of postoperative hearing results with autoincus and titanium prosthesis (TORP and PORP)|
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Postoperative complications with autologous incus group were 25% as compared with titanium prosthesis in which the complication rate was 41.6%. The rates of various complications in both the groups are compared in [Table 3].
| Discussion|| |
The commonest type of ossicular chain erosion encountered is necrosis of long process of incus because of its anatomical position and the course of its blood supply. , Various surgical techniques and materials have been used for ossicular chain reconstruction since 1950, but still there is no standardized technique and ideal material accepted worldwide. Three general classes of prosthesis are used today: autograft, homograft and allograft. 
Autograft prostheses include ossicles (incus, malleus), cartilages (septal, tragal), cortical bone. Advantages of autograft prostheses include a very low extrusion rate, no risk of transmitting disease, biocompatibility, and no necessity for reconstitution. Displacement, complete absorption, small remnant size, and possibility of harbouring microscopic disease have been cited as potential disadvantages to their use. 
Allograft prostheses are readily available, pre-sculpted, and made of synthetic materials like hydroxyapatite, plastipore, titanium, glass ceramics, etc., designed to be biocompatible. Ossicular necrosis, extrusion, displacement, and unsatisfactory hearing restoration have been encountered with virtually every type and design. Extrusion of the prosthesis has been reported as high as 39% but can be significantly reduced by placing cartilage or bone between the tympanic membrane and the prosthesis. 
In our study, titanium prosthesis (TORP and PORP) has been used as it is an excellent material for ossicular reconstruction because of its high biocompatibility, biostability, and low ferromagnetism. In addition, titanium is lightweight and rigid, making it a good sound conductor.  The anatomical and functional results are compared with ossiculoplasty using autologous incus. The postoperative follow-up period ranged from 3 to 12 months (average 4.5 months). Closure of ABG to less than 20 dB was regarded as successful hearing outcome. We found that hearing improvement and graft take-up rate were significantly better in ossiculoplasty with autoincus. The complication rate was also very less in this group. This is because transposition of incus is well tolerated as it is more physiological and biocompatible, thereby giving better hearing results and reducing graft extrusion rate. But this technique requires time and skill to ensure appropriate sculpting in order to minimize ankylosis of the Fallopian canal More Details, scutum and posterior canal wall.  Medium (1-5 years) and long-term (>5 years) outcomes require high patient compliance for follow-up.
In our study, 2 patients (one in each group) developed facial palsy as the complication postoperatively, which did not respond to medical treatment. On re-exploration, it was found that the prosthesis was impinging on the dehiscent tympanic segment of facial nerve near the second genu in both cases, for which the prosthesis was removed and facial nerve decompression was done. One patient who underwent placement of TORP developed severe sensory neural hearing loss (SNHL) at the end of 3 months. On re-exploration, the prosthesis had migrated into the vestibule possibly due to pressure necrosis of stapes footplate caused by the weight of prosthesis.
Martin et al. have performed ossiculoplasty using only titanium prosthesis in 68 cases with postoperative period ranging from 3 months to 2.5 years. Average ABG improvement was 13 dB with closure of the ABG to within 20 dB in 57% of cases as compared to 33% in our study. Hearing results were better for primary versus revision cases, for PORPs versus TORPs and for intact canal wall (ICW) procedures versus canal wall down (CWD) procedures, which is similar to our study. 
Iurato et al. have reported that equally good results may be achieved with autograft, homograft or alloplastic partial prostheses. With alloplastic total prostheses, 74% of patients had a postoperative ABG of 0-20 dB. 
However, there are no randomized clinical trials available in literature, which have compared anatomical and functional results of ossiculoplasty with autologous incus and titanium prosthesis as in our study. Further patient follow-up is required to assess the long-term outcomes of ossiculoplasty, but patient compliance for longer follow-up is a concern.
Multiple factors impact successful reconstruction of the middle ear's sound conduction mechanism. Prosthesis design, surgical technique, and the underlying disease process are the most obvious variables. The mass and stiffness of a prosthesis may influence sound conduction in a frequency-dependent manner. Studies by Meister et al. and Kelly et al.  have suggested that mass is the most important variable and have recommended, therefore, that a prosthesis be as light as possible to optimize transmission of frequencies above 1000 Hz. Early studies indicated that a prosthesis should weigh less than 40 mg. More recent mathematical modeling by Zenner et al.  has determined that a mass of 5 mg or less provides the maximal transfer of energy. In the same studies, the influence of an attached piece of cartilage was investigated. An inertial load of 30 mg had little or no effect on the transfer function for titanium and ceramic prostheses. High stiffness of prosthesis is important to prevent signal loss and distortion.
The coupling of a prosthesis to the tympanic membrane (or manubrium) and to the stapes superstructure or footplate also influences overall stiffness. A loose coupling can introduce unwanted resonance that can distort the primary signal. 
The ideal prosthesis design, therefore, is one that combines low mass with high stiffness and that facilitates the surgeon's ability to achieve a tight, permanent coupling between the tympanic membrane and stapes. Coffey et al.,, demonstrated significant benefit of titanium across frequencies in the normal hearing range, likely due in part to the advantages conferred by low mass and high stiffness.
| Conclusion|| |
Hearing results after ossiculoplasty with autologous incus were significantly better as compared with those obtained after titanium prosthesis. Also, complications and extrusion rate were higher in patients with titanium prosthesis. This indicates that ossiculoplasty with autoincus offers better hearing results with minimal complications and extrusion rates as compared to titanium prosthesis.
However, the results were better in both groups if canal wall was preserved or reconstructed. Complication rates were more with titanium TORP than with PORP. Further patient follow-up is required to assess the long-term outcomes of ossiculoplasty, but patient compliance for longer follow-up is a matter of concern. It is worthwhile to conclude that there is a need for many more clinical trials with a larger sample size and longer follow-up period to standardize the ossiculoplasty techniques and accept an ideal ossicular prosthesis.
| Acknowledgments|| |
I am thankful to our beloved Principal, Dr. V D Patil, and Medical Superintendent of KLE Charitable Hospital, Dr. R S Mudhol, for providing us with excellent infrastructure for conducting the study. I also thank our honourable Vice Chancellor, Dr. C K Kokate, and Registrar, Dr. P F Kotur, for encouraging us to involve in research. We thank our statistician, Prof. Mallapur, for helping us in statistical analysis of the data.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]
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