Pingling Kwok

Stapes surgery: how precisely do different prostheses attach to the long process of the incus with different instruments and different surgeons?

Hypothesis The goal of this study was to compare the attachment of stapes prostheses with differently shaped loops to the long process of the incus. Background In stapes surgery, the attachment of the prosthesis to the long process of the incus plays an important role concerning the gain in hearing and the development of late complications such as incus erosion and necrosis. Band-shaped and spiral loops have been developed to achieve a broad, firm attachment to the long process of the incus. During stapes surgery, the view at the prosthesis is restricted, making it impossible to evaluate the effects of the differently shaped loops. Methods Gold, steel/Teflon, platinum/Teflon, and two different titanium stapes prostheses were inserted in 30 specially prepared temporal bones by three experienced surgeons using the Fisch technique with the McGee and straight alligator forceps for the crimping of the loops. Photographs were taken with 0- and 70-degree rod lens telescopes at defined views. Results In all prostheses, a sufficiently firm attachment to the long process of the incus was achieved. The attachment of band-shaped loops proved to be better with the straight alligator forceps. The band-shaped loops showed a better contact with the incus than did the wire loops. However, the broad spiral-shaped loops led to a loss of the perpendicular axis of the piston to the long incus process. Conclusion The geometry of the loop affects the final length of the piston in the vestibule and its angle to the long process of the incus.

PROGNOSTIC IMPORTANCE OF ''CLEAR VERSUS REVISED MARGINS'' IN ORAL AND PHARYNGEAL CANCER

Opinions differ regarding the usefulness of accurate, but costly, frozen sections. Most physicians believe that negative margins are essential for the prognosis of patients with oral and pharyngeal cancer. We examined whether immediate repeated resections in patients with positive margins, based on findings from frozen sections, resulted in improved patient survival.

Comparative electron microscopic study of the surface structure of gold, Teflon, and titanium stapes prostheses.

Hypothesis The goal of this study was to compare stapes prostheses of different materials with respect to their surface structures and to discuss their suitability for their use in stapes surgery. Background The surface condition of a stapes prosthesis plays an important role in relation to the type of membrane that forms between the stapes piston and the bony edge of the stapedotomy opening. The quality of this membrane in thickness and mobility is one of the determinants for postoperative hearing improvement. Methods The surface conditions of gold, Teflon/steel, Teflon/platinum, and titanium stapes prostheses were examined with a scanning electron microscope. The loop, shaft, and end of each prosthesis were studied. Results The gold piston was the smoothest of the four pistons examined. When it was cut with a scalpel, a very smooth surface was achieved at the end area. The Teflon piston had the roughest surface. However, when it was cut, a smooth surface with a parallel arrangement of fibers resulted. Its steel loop was the smoothest, followed by gold and platinum. The titanium shaft had a scaly surface, which remained when the end of the shaft was shortened. Conclusion Because a certain roughness of the piston surface is necessary for the development of a stable membrane between the piston and the edge of the stapedotomy opening, the titanium prosthesis is considered to be the most suitable for stapes surgery of the three pistons examined.

Stapes surgery: the diameter of the long process of the incus.

Hypothesis: The aim of this study was to examine the long process of the incus in respect of its shape and its dimensions at the site of the attachment of a stapes prosthesis. Background: One of the complications in stapes surgery is the erosion of the long process of the incus at the site of the attachment of the prosthesis, resulting in a fluctuating conductive hearing loss. Knowing the dimensions of the attachment site of the prosthesis at the long process of the incus will make it possible to optimize the size of the prosthesis loop. Methods: The incus was obtained from 11 patients who had undergone middle ear surgery for hearing improvement or cholesteatoma removal. The ossicles were kept in 4% paraformaldehyde and were processed for histological examination after decalcification in ethylenediamine tetra-acetic acid. The 5-&mgr;m slices were stained with toluidine blue and examined in the light microscope. Using digitized video images of the histological slices, the diameters, circumference, and surface of the specimens were determined. Results: The diameter of the long process of the incus at 1.4 ± 0.28 mm from the tip, which is the average site of prosthesis attachment, showed an oval shape with a minimum diameter of 0.66 ± 0.05 mm, a maximum diameter of 0.81 ± 0.1 mm, and a circumference of 2.46 ± 0.23 mm. Conclusion: The loop of a stapes prosthesis should have the following dimensions: diameter 0.9 mm, loop length of 2.2 mm, and opening of loop 0.7 mm. However, the material of the prosthesis and its malleability are also important factors.

Morphology of the malleus handle and the comparison of different prostheses for malleostapedotomy.

Objectives: To assess malleus morphology to characterize optimal sites for prosthesis attachment in malleostapedotomy and to examine attachment, position, and depth of penetration in the vestibule of the 3 most used prostheses. Methods: Ten mallei were processed for histologic examination with the light microscope. Using digitized video images of the histologic slices, the diameters, circumference, and shape of the specimen were determined. Implantation of 3 prostheses (Gyrus Nitinol piston, Storz titanium stapes piston, and Kurz malleovestibulopexy piston), was performed in 3 temporal bones for a total of 27 implantations. Results: The cross-section of the malleus just distal to the lateral process shows an inclined oval shape with a mean minimum diameter of 0.84 ± 0.10 mm, a mean maximum diameter of 1.02 ± 0.23 mm, and a mean circumference of 3.23 ± 0.49 mm. The quality of attachment to the malleus, the position of the prosthesis piston, and the depth of penetration were reliable for the Storz titanium stapes piston, satisfactory though variable for the Gyrus Nitinol piston and poor for the Kurz malleovestibulopexy piston as judged by contact with the malleus surface and predictability of insertion depth into the vestibule. Conclusion: The oval and inferoanteriorly inclined shape of the malleus distal to the lateral process requires the use of a prosthesis capable of molding itself to its surface for reliable attachment. To achieve the correct perpendicular position of the piston as it relates to the stapedotomy opening, individualized adaptation ofthe prosthesis shaft and loop to the anterior position of the malleus should be made in situ.

The crimping problem in stapes surgery.

AIM OF THE STUDY The goal of this study was to compare the attachment of stapes prostheses with differently shaped loops to the long process of the incus. METHOD Gold, steel/Teflon, platinum/Teflon, and two different titanium stapes prostheses were inserted in 30 specially prepared temporal bones by three experienced surgeons using the Fisch technique with the McGee crimper and straight alligator forceps for the crimping of the loops. RESULTS In all prostheses, a sufficiently firm attachment of the long process of the incus was achieved. The band-shaped loops showed a better contact with the incus than did the wire loops. However, the broad spiral-shaped loops led to a loss of the perpendicular axis of the piston to the long incus process. CONCLUSION The geometry of the loop affects the final length of the piston in the vestibule and its angle to the long process of the incus.

Influence of Surface Processing on the Biocompatibility of Titanium

Surface conditioning of titanium middle ear implants results in an improved biocompatibility, which can be characterized by the properties of fibroblasts cultured on conditioned surfaces. Titanium has been established as a favorable biomaterial in ossicular chain reconstruction. The epithelization of the surface of the implants is important for their integration and stable positioning in the middle ear. Mouse fibroblast cells were cultured on platelets made from pure Grade 2 titanium. Platelets that had been etched along their production process were compared to unetched platelets. The DNA in the cell nuclei was stained with DAPI and the actin filaments of the cytoskeleton were stained with FITC-conjugated phalloidin in order to analyze the cells grown on etched and unetched platelets by fluorescence microscopy. SEM (scanning electron microscopic) images were used to compare the surface structure of etched and unetched titanium platelets. There was a statistically significant increase of the area covered by the cytoplasm and increased actin expression by fibroblasts grown on the etched titanium platelets. In addition, the area of the platelets covered by nuclei on the etched platelets exceeded on average the one on unetched platelets, although this difference was not significant. The SEM pictures comparing unetched and etched titanium platelets showed a clear difference in surface structure. Surface conditioning of titanium implants improved the epithelization by fibroblasts and consequently etched titanium should be the preferred biomaterial for reconstructive middle ear surgery.

A Micro-Computed Tomographic Study: Determination of the Angle Between the Tympanic Membrane and Stapes Footplate in a Total Ossicular Reconstruction Prosthesis Reconstruction

Objectives: To examine the anatomical relationship of the angles between tympanic membrane and stapes footplate and the variation of these angles among different temporal bones in order to characterize the optimal shape of total ossicular reconstruction prostheses (TORPs). Methods: Ten specimens of human temporal bones were prepared for examination with micro-computed tomography. Five of the 10 temporal bones were implanted with 3 types of TORPs before subjecting them to micro-computed tomography. The angles between tympanic membrane and stapes footplate were determined. The contact of the TORPs to these structures was assessed. Results: The angle between the stapes footplate and the tympanic membrane was, on average, 25.9 degrees in a plane along the transverse axis of the stapes footplate and 24.6 degrees in a plane along the longitudinal axis of the stapes footplate. Consideration of these angles in TORPs resulted in an optimal contact with the tympanic membrane and stapes footplate, especially for prostheses with a large foot. Conclusion: TORPs should be adjusted in shape before insertion into the middle ear. Further developments should consider prostheses with preadjusted angles or appliances for the exact modification of the prostheses during surgery.