Candidate's thesis: Revision tympanoplasty utilizing fossa triangularis cartilage.

OBJECTIVES/HYPOTHESIS: A small percentage of fascia graft tympanoplasties fail. Cartilage tympanoplasty has a reputation for excellent graft healing but potentially sacrifices maximum hearing improvement and creates difficulty in postoperative follow-up resulting from opacity and immobility. We sought to use a tissue thicker than fascia but thinner than tragal cartilage to repair tympanic membranes that had failed previous fascia grafting. Our hypothesis was that use of the thinner cartilage would maintain the excellent healing rate and resistance to chronic negative pressure while improving hearing and mobility.

STUDY DESIGN

The study is a retrospective review of all patients who received a total cartilage graft tympanoplasty after experiencing a failed standard fascia graft tympanoplasty. No previous operative series on impedance testing following cartilage grafting was identified in the literature. Standard audiologic and tympanometric parameters were obtained in all patients.

METHODS

Tragal and fossa triangularis cartilage were statistically analyzed for thickness and weight. Surgical indications included patients who had chronic otologic disease that resulted in recurrent tympanic membrane perforation, atelectasis, or cholesteatoma. The tympanic membrane and any posterior canal wall defect were completely replaced with cartilage. Preoperative and postoperative audiometric and impedence tympanometry measurements were compared.

RESULTS

Triangularis fossa cartilage is thinner and has less mass than tragal cartilage. Complete data were obtained on 83 of 159 patients to make up this study. The success rate for tympanic membrane integrity measured by tympanometry was 100% at a minimum 2-year follow-up in all ears included in the study. Hearing results are reported collectively and include all types of ossiculoplasty. The largest closure of air-bone gap was at 1000 Hz, followed by 2000, 500, and 4000 Hz. The patient's best hearing level was most frequently at 2000 Hz. Impedence testing showed a large shift in tympanogram configuration from B to C, indicating that cartilage grafts heal with integrity and measurable mobility although stiffened compared with normal.

CONCLUSIONS

Fossa triangularis cartilage is thinner and has less mass than tragal cartilage. This creates a relatively mobile neotympanic membrane that can be monitored postoperatively by standard tympanometry, and allows for excellent hearing results. Recurrent tympanic membrane perforation or atelectasis with or without bony canal erosion that has failed standard fascia graft tympanoplasty can be successfully repaired with fossa triangularis cartilage graft tympanoplasty. Primary surgical use of cartilage graft tympanoplasty should be considered in patients with high-risk otologic disease, since fossa triangularis cartilage is thick enough to resist prolonged negative middle ear pressure and the hearing results with fossa triangularis cartilage shield graft tympanoplasty are comparable to those reported with fascia grafting. In patients with type A or C tympanogram results following successful fossa triangularis cartilage grafts, standard impedance testing can be used to clinically evaluate tympanic membrane mobility and help identify the presence of middle ear disease. However primary placement of a tympanostomy tube should be performed in patients with granulation tissue in the middle ear at time of tympanoplasty. Further study is needed to determine the ideal thickness of cartilage for tympanic membrane reconstruction.