The malleus-absent situation represents one of the most useful indications for cartilage tympanoplasty but one of the more challenging situations for ossicular reconstruction because there is no malleus enabling an exact fit between two essentially stable, bony platforms and allowing the surgeon to build the ossicular reconstruction to the TM. The cartilage tympanoplasty technique described below has proven useful to alleviate this problem.
The perichondrium/cartilage island flap from tragal cartilage is utilized. Even though the malleus is absent, a similar circular cartilage flap is constructed, again removing the 1- to 2-mm strip of cartilage from the center section to facilitate accurate placement of the ossicular replacement prosthesis. The cartilage is inserted in an underlay technique medial to the anterior TM remnant, with the perichondrium again toward the ear canal. Several pieces of Gelfoam are inserted to support the graft securely to the anterior annulus and the bony ledge just lateral to the supratubal recess. With the anterior portion of the cartilage graft held securely in place, the posterior half is folded out to expose the trailing edge of the anterior piece of cartilage, which acts, in effect, as a neo-malleus (Fig. 6-11). The distance between the stapes footplate or superstructure and this trailing edge of the anterior cartilage is measured, and the prosthesis is cut to the appropriate length.
For ossicular reconstruction, a prosthesis specifically designed for use with cartilage tympanoplasty techniques is used. For example, the Dornhoffer HAPEX TORP or PORP has a head that notches the malleus, or the edge of the cartilage if the malleus is absent, and broadens posteriorly to shift the center of gravity over the shaft, acting as a scaffold for the cartilage reconstruction.45 The notched portion of the prosthesis is hooked under the trailing edge of the anterior piece of cartilage, much in the same way that the malleus would be used in conventional ossiculoplasty, with the shaft placed on the stapes (Fig. 6-12).46 The posterior half of the cartilage is folded back and is supported by the broader posterior head of the prosthesis. This technique allows accurate length measurement and placement of the prosthesis, with direct visualization to the stapes superstructure or footplate. Once the freestanding prosthesis is accurately positioned, supporting Gel-foam is placed to provide extra security during the postsurgical healing phase.
Our results for cartilage reconstruction of the TM after ossiculoplasty have been encouraging. We have performed this type of reconstruction with the stapes superstructure present (PORP) in 499 cases, of which 43% were revisions. The average preoperative PTA-ABG was 26.7 + 12.5 dB, and the postoperative PTA-ABG was 14.50 8.7 dB. This
difference was statistically significant (p < 0.05). Ossicular reconstruction was performed with no stapes superstructure (TORP) in 282 cases, of which 72% were revision cases. The average preoperative PTA-ABG was 34.4+111.9 dB, and the postoperative PTA-ABG was 16.6H 10.5 dB, which was statistically significant (p </ 0.05). The average follow-up was 2.7 years, and the overall prosthesis extrusion rate was 1%. We have found no statistical difference in results due to age (average patient age of 30 years; range, 4 to 88 years). Overall, there was a 3% incidence of recurrent conductive hearing loss due to displaced prostheses, requiring revision surgery. Most of the displaced prostheses occurred in the malleus-absent group, however, which had an 8% incidence of prosthesis displacement. At revision surgery, the most common cause of prosthesis displacement was thought to be lateralization of the cartilage graft during healing, causing the prosthesis to be slightly too short. Typically, minimal graft elevation and a prosthesis cut 1 mm longer at the time of revision surgery rectified this problem and gave good results.
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