Tripod allograft in reconstruction of incudal lesions

Long-term results of allograft ossiculoplasty with erosion of the long process of the incus in 44 patients are described. The pyramidal-shaped allograft leans on the stapes, the remaining part of the incus and the side of the malleus--forming a 'tripod' shape or construction. The study includes two groups of patients: group A (34 patients) in whom the pre-operative three-frequency average air-bone gap was 20 dB or more and group B (10 patients), in whom the pre-operative air-bone gap was less than 20 dB. In the latter group the indication for surgery was not their hearing loss, but a different pathological condition (infected retraction pocket, a cholesteatoma, etc.) which necessitated surgical disconnection of the chain during the operation. The average period of follow-up 46 months for group A and 24.9 months for group B. In group A, the preoperative average air-bone gap was 33 dB. Following surgery, the air-bone gap was 20 dB or less in 27 ears (79 per cent), and 10 dB or less in 18 of them (53 per cent). In group B, pre-operatively, the average air-bone gap was 11 dB. Following surgery, the air-bone gap was either better than before the operation or did not increase by more than 5 dB in eight patients (80 per cent). Comparison of the audiometric results of 20 patients after mean follow-up times of 23.8 months and 64.9 months shows that no deterioration of hearing occurred in the intervening period. Graft extrusion was not observed in any of the operated ears.