Results:
Fig1.
The average postoperative AC-PTA was 46.4dB, which is significantly
better compared to the61.5dB preoperative value. ABG-PTA also
significantly improved after the surgical intervention:15.9dB vs 31.1dB.
No significant difference could be seen between pre- and postoperative
BC-PTAs, 30.4dB vs 30.5dB.The minimum of 30dB AC-PTA was achieved in
44% of the cases. In 56%, at least 10 dB ABG gain was achieved, while
the 10dB or better ABG closure was 44%, ABG closure between 10-20dB
prevailedin 20%.
Fig2
Intratympanicfibrosis wasthe most common finding during revision; with a
prevalence of 64%, in 32% it was the main reason behind compromised
ossicular chain mobility. In the remaining 36%,the main problem was due
to surgical failures. The most common prosthesis-related complication
was the disconnection between the piston loop and the LPI. Both fibrosis
and surgical failure was noticed in 32% (fig2). According tofig2, the
highest hearing gains were accomplished in cases where the cause of
failure was LPI-prothesis disconnection, while in the cases with
adhesions as the primary cause of failure, the hearing gains were the
lowest.
Fig3
Althought in the presence of intratympanic fibrosis mean ABGgain and
hearing gain was lower compared to other cases (fig3a), no statistically
significant difference could be found (p=0,087;p=0.095). On this
basis,TOST test was performed to determine equivalence. Concerning
hearing gain and ABGgain,equivalence was rejected, and the
non-inferiority of the intratympanic fibrosis associated negative effect
was shown compared to the other group(p=0.94 upper tailed; p=0.037 lower
tailed and p=0.94; p=0.03 respectively).
There was no statistically significant difference between preoperative
(after primarystapes surgery) ABG and AC PTA levelsacross ’fibrosis’ and
’no fibrosis’ groups (fig3b) (p=0.44 and p=0.96 respectively).