For better adherence to tympanic membrane
Siddharth R. Sandip S. Anand M., Manish D.
Both Hydroxyapatite (HAP) and Titanium (Ti) are well-accepted alloplastic materials for ossicular prostheses. Many different designs of HAP and Ti prostheses are presently available1. Prostheses using both types of biomaterial gave good functional results and stability with low extrusion rates, with no statistically significant differences between the two. Nevertheless, extrusions could be seen during long -term follow-up in both materials2.
Hydroxyapatite is a calcium phosphate ceramic whose elemental constituents closely resemble those of the mineral matrix of human bone3. Hydroxyapatite prostheses are widely used for ossicular reconstruction because of their excellent biocompatibility2 and favorable properties. Even though having favorable properties with HAP ossicular implants, the extrusion rate with HAP prosthesis is >7%3.
Titanium implants provide comparable hearing improvement compared with other materials. The extrusion rate seems quite low if cartilage interposition graft is inserted. Its ease of handling, biocompatible properties, and sound conducting properties improve its efficacy as an ossicular prosthesis. Overall extrusion rate with Titanium Ossicular implants was <4%4. However, Low extrusion can be accomplished using with the placement of cartilage graft interposed between the prosthesis and the tympanic membrane.
Both materials are having their own advantage with ossicular prosthesis. The addition of different amount of inclusions in presently available titanium ossicular prosthesis gives combine advantage of both materials. The development focuses on combining HAP and Ti for better results.
HAP coating technology on Titanium
The HAP material has been coated (Figure-1, Osseous Tita-HAP ossicular prosthesis, EON Meditech Pvt. Ltd.) with strength >15MPa on Titanium disk having Ca/P ratio 1.67/1.76. This development provides excellent Tympanic Membrane fixation with prosthesis.
A true union between hydroxyapatite and middle ear ossicular bone may occur, but it is much more common for the prosthesis to become stable because of a fibrous capsule that forms around the prosthesis and surrounding tissue.
(Figure-1; HAP coated Titanium Ossicular Implant, Osseous Tita-HAP Ossicular Prosthesis, EON Meditech Pvt. Ltd.)
HAP coated Titanium ossicular prosthesis (Osseous Tita-HAP, EON Meditech Pvt. Ltd.) can be used directly against the tympanic membrane without the need for cartilage interposition. Cartilage, of course, may be used if this is the surgeon’s preference.
M. W. Yung and C. Brewis; A comparison of the user-friendliness of hydroxyapatite and titanium ossicular prostheses, Journal of Laryngology & Otology (2002), 116:2:97-102.
Taisuke Kobayashi, Kiyofumi Gyo, Takayuki Shinohara, and Naoaki Yanagihara; Ossicular Reconstruction Using Hydroxyapatite Prostheses with Interposed Cartilage, Am J Otolaryngol 2002; 23:222-227. Copyright 2002, Elsevier Science (USA).
ROBERT A. GOLDENBERG, MD, and MARK DRIVER; Long-term results with hydroxyapatite middle ear implants, the American Academy of Otolaryngology– Head and Neck Surgery.
HO Steven Y., BATTISTA Robert A., WIET Richard; Early results with titanium ossicular implants, Department of Otolaryngology, Northwestern University School of Medicine, Chicago, Illinois, ETATS-UNIS.