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Abstract

During the past decade the trend in surgery on the mastoid segment of the temporal bone has been toward restoration of function and normal anatomical configuration. The primary preservation of the posterior bony canal wall with aeration of the mastoidectomy cavity has eliminated many of the problems associated with an open cavity. The likelihood of good hearing increases when the support for the posterior and superior portions of the tympanic membrane are preserved; however, there are many patients whose surgery included removal of this bony barrier and exposure of the mastoid segment to the outside. It is for these patients that a means has been sought to eliminate the cavity and reconstruct the hearing mechanism.

Previous techniques have sought to eliminate the mastoidectomy cavity by obliteration with muscle pedicles, fascia, cartilage and bone. All these techniques tend to modify rather than to reconstruct nature's plan of the middle ear and mastoid. It would seem more physiologic to rebuild these structures as nearly as possible in their normal anatomical relationship and function. It was with this goal in mind that the herein described technique of knee cartilage reconstructive mastoidectomy was developed.

A review of the literature revealed that in 1940 cartilage homografts were being used in rhinoplasty by Brown. This author preserved the cartilage in alcohol because it was “simple and safe.” Homograft nasal septum cartilage had been utilized in tympanoplasty by Smyth and Jansen and in otosclerotic surgery by Pfaltz. No previous article referring to the use of knee cartilage for transplantation could be found.

Homograft knee cartilage was discovered to possess the gentle curve and thin lower border characteristic of the posterior bony canal wall. With this support the homograft tympanic membrane may be used to reconstruct the drumhead in normal anatomical position. The homograft incus then becomes a prosthesis to rebuild the conduction mechanism in this one stage operation. Silastic sheeting from the eustachian tube to the mastoid antrum prevents adhesions and assures aeration of these structures. Likewise, mucoid discharge from the remaining mastoid cells finds its way to the eustachian tube and nasopharynx.

Fifteen ears have been reconstructed by this technique. All cases have healed completely and uneventfully with no infection or extrusion of the knee cartilage transplant. Postoperatively the ear canal and drumhead have an almost normal appearance, and epithelial migration keeps these structures clean and functioning. Hearing improvement has been gratifying with a return to normal in some instances. Three case presentations are included as examples of the procedure.