Allograft Tympanoplasty: A Historical Perspective

Titanium Biohybrid Middle Ear Prostheses: A Preliminary In Vitro Study

Ossiculoplasty is a surgical operation performed to restore auditory transmission through the reconstruction of the ossicular chain using prosthetics. Tissue bioengineering has assumed a pivotal role in implementing alternatives to conventional ossicular middle ear replacement prostheses, to overcome extrusion while preserving acoustic properties. This in vitro study aims to explore, for the first time in current literature, the feasibility of a biohybrid middle ear prosthesis, composed of titanium surrounded by a bone extracellular matrix as bio-coating. We have hereby studied the adhesion and proliferation of human adipose-derived mesenchymal stem cells (hASC) on titanium scaffolds in vitro. Moreover, we identified the osteogenic differentiation of hASC using an immunofluorescence assay to analyze osteoblasts' gene expression profiles (Alp, Runx2, Col1a1, Osx, and Bglap), and we counted the presence of collagen as a marker of hASC's ability to secrete an extracellular matrix. We utilized scanning electron microscopy to evaluate the presence of an extracellular matrix on the scaffolds. Our preliminary data demonstrated the titanium's ability to support human adipose-derived mesenchymal stem cell colonization, proliferation, and osteoblastic differentiation, in order to obtain a biohybrid device. Our experience seems encouraging; thus, we advocate for further in vivo research to corroborate our results regarding bone transplantation.

"Mushroom" Autologous Partial Ossicular Replacement Prosthesis: Long-term Results

OBJECTIVE

Evaluate a new autologous mushroom-shaped cortical bone partial ossicular replacement prosthesis (MPORP) for cost-effective and sustainable hearing results.

STUDY DESIGN

Prospective study.

SETTING

Tertiary care center.

PATIENTS

Forty-two patients suffering from chronic otitis media with intact superstructure of the stapes and partially or completely eroded incus.

INTERVENTIONS

Group-1 (n = 24) underwent only tympanoplasty with MPORP; group-2 (n = 18) underwent intact canal wall mastoidectomy (ICW) with MPORP.

MAIN OUTCOME MEASURES

Hearing results were evaluated using a four frequency average (measured at 0.5, 1, 2, 3 kHz) pure tone air conduction (PTA), air-bone gap (ABG), and word recognition scores (WRS) after 3, 6, and 12 months and compared with preoperative results.

RESULTS

Overall, successful rehabilitation of ABG to 20 dB or less was achieved in 92% of patients. Mean postoperative ABG was 15.35 ± 4.18 dB showing mean improvement of 23.89 ± 5.95 dB. In group-1, mean postoperative ABG was 18.47 ± 3.65 dB, showing an improvement of 25.92 ± 5.3 dB. In group-2, mean postoperative ABG was 18.47 ± 3.65 dB showing an improvement of 20.14 ± 4.96 dB. Hearing improvement in all the cases together and both the groups checked separately was statistically significant (paired t test, p < 0.001). Group 1 had, on average, 5 dB better hearing than group 2 (unpaired t test, p > 0.05).

CONCLUSION

The MPORP is obtainable from the local site, easily constructed, bio-compatible, cost-effective, less bulky, adequately rigid for sound transmission, magnetic resonance imaging (MRI) compatible, and provides sustainable hearing gain because it has better chances of integration with the head of stapes.

Repair of subtotal tympanic membrane perforations: A temporal bone study of several tympanoplasty materials

The aim of this project was to investigate the effects of different types of graft material, and different remaining segments of the native TM on its motion. In twelve human temporal bones, controlled TM perforations were made to simulate three different conditions. (1) Central perforation leaving both annular and umbo rims of native TM. (2) Central perforation leaving only a malleal rim of native TM. (3) Central perforation leaving only an annular rim of native TM. Five different graft materials (1) perichondrium (2) silastic (3) thin cartilage (4) thick cartilage (5) Lotriderm^® cream were used to reconstruct each perforation condition. Umbo and stapes vibrations to acoustic stimuli from 250 to 6349 Hz were measured using a scanning laser Doppler vibrometer. Results showed that at low frequencies: in the Two Rims condition, all grafting materials except thick cartilage and Lotriderm cream showed no significant difference in umbo velocity from the Normal TM, while only Lotriderm cream showed a significant decrease in stapes velocity; in the Malleal Rim condition, all materials showed a significant decrease in both umbo and stapes velocities; in the Annular Rim condition, all grafting materials except Lotriderm and perichondrium showed no significant difference from the Normal TM in stapes velocity. Umbo data might not be reliable in some conditions because of coverage by the graft. At middle and high frequencies: all materials showed a significant difference from the Normal TM in both umbo and stapes velocities for all perforation conditions except in the Annular Rim condition, in which silastic and perichondrium showed no significant difference from the Normal TM at umbo velocity in the middle frequencies. In the low frequencies, the choice of repair material does not seem to have a large effect on sound transfer. Our data also suggests that the annular rim could be important for low frequency sound transfer.

Ossicular replacement prostheses from banked bone with ergonomic and functional geometry

This study shows the fabrication of innovative ossicular replacement prostheses (ORPs) based on banked cortical bone using computer numerically controlled ultraprecision micromilling, as a substantial improvement of "second generation" ORPs. Our aim is to combine optimal middle ear compatibility and surgical manageability in a single device, by releasing off-the-shelf homograft ORPs provided with the appealing features of synthetic ORPs, such as lightness, safety, measurement accuracy, surface decoration, and geometric plasticity. The new total ORP prototype was 13.1 ± 0.1 mg, leading to 81% weight reduction with respect to the previous model. Surface motifs of the head plate were applied to prevent slipping and migration after surgery, as shown by finite element modeling analysis. In addition, bone ORPs were provided with holed head plates to facilitate their surgical positioning while reducing their mass. A comparative measurement of acoustic responses of bone against synthetic partial ORPs in the 250-8000 Hz frequency range demonstrated their superior behavior. This study showed that banked compact bone can be optimally manufactured, eventually enabling the fabrication of light, standardized, and highly performant ORPs. The new bone ORPs may represent the ideal combination of biocompatibility and technology which can ultimately accomplish unmet otosurgical needs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2495-2506, 2017.

Endoscopic procurement of allograft tympano-ossicular systems: valuable to replace the Schuknecht bone plug technique?

Recently, our group demonstrated the technical feasibility of allograft tympano-ossicular systems (ATOS) procurement directly through the external auditory canal by using a rigid endoscope. This novel technique has several advantages compared to the traditional transcranial Schuknecht bone plug technique: it avoids contact with the dura mater, it is less time-consuming and it doesn't require a thorough reconstruction of the donor. In our tissue bank, we are currently transitioning from the transcranial procurement technique to the endoscopic procurement technique. The learning curve to master the endoscopic technique is steep but our preliminary results suggest that the percentage of good quality endoscopically procured ATOS is at least similar to the percentage of good quality transcranially procured ATOS dissected from the temporal bone plug. Additionally, the number of donations has increased significantly. By avoiding contact with the dura mater and therefore eliminating the risk of potential prion disease transmission, this technical evolution in procurement technique might allow dedicated tissue banks to (re-)introduce ATOS procurement and implantation.