Changes of incudostapedial joint angle in stapedotomy: does it impact hearing outcomes?



The aims of this article are: (1) is there an ideal incudostapedial joint (ISJ) angle after stapedotomy? (2) is there any difference between pre- and postoperative ISJ angle? and (3) what is the significance of the ISJ angle in postoperative hearing outcomes?


Forty six ears from 39 different adult patients (28 women and 11 men; 21 left and 25 right ears) with a mean age of 39 years with clinical otosclerosis who underwent stapedotomy between May 2017 and May 2019 were retrospectively registered, including seven bilateral surgery cases. ISJ angle and intravestibular depth of the stapes prosthesis were measured from multiple planar reconstruction-computed tomography images and the length of the prosthesis was measured during surgery. Relationships between the ISJ angle parameters and postoperative hearing outcomes and parameters of the prosthesis were analyzed.


The mean ISJ angle was 93.3° ± 8.8° preoperatively and 101.9° ± 6.3° postoperatively, increasing by 8.6° during stapedotomy (p < 0.01). There were weak and negative correlations between ISJ angle changes and postoperative air conduction gains at frequencies ≤1 kHz and bone conduction gains at 0.5 kHz. When the postoperative ISJ angle changed more than 20°, the success rate of the procedure decreased to 0%.


The stapedotomy operation increased the ISJ angle. The success of postoperative auditory outcomes had more to do with the ISJ angle change than the value of the angle itself, indicating there is no universal ideal ISJ angle that surgeons should aim for during stapedotomy.

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This work was supported by National Natural Science Foundation of China (No. 81822011, 81771013, 81700925, 81870726). No funding was received for this work from any of the following organizations: National Institutes of Health (NIH), Wellcome Trust, Howard Hughes Medical Institute (HHMI), and other(s).

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Yanqing Fang designed, analyzed data and wrote the paper; Kun Zhang collected and analyzed data from EENT hospital affiliated to Fudan University; and Liu-Jie redesigned, analyzed and reviewed the paper; JJ Lamb polished the paper and gave important suggestions; Rujian Hong guided how to collect MPR-CT data; Bing Chen designed the experiment, did all surgery in this study and reviewed the paper; Yilai Shu designed the experiment, reviewed and guided to write the paper. Yanqing Fang, Kun Zhang, and Liu-Jie Ren contributed equally to this work. All authors discussed the results and implications and commented on the manuscript at all stages.

Corresponding authors

Correspondence to Yilai Shu or Bing Chen.

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The authors of this manuscript declare no relationship with any company whose products or services may be related to the subject matter of the article.

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This article does not contain any studies with human participants or animals performed by any of the authors. This research was conducted in accordance with the ethical standards of the Internal Review Board of EENT Hospital affiliated with Fudan University. I, Bing Chen, as the corresponding author, ensure that there is no author identifying information anywhere in the blinded manuscript (i.e., author details, ethical statements, acknowledgements, author contribution, grant information, funding number, etc.).

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Fang, Y., Zhang, K., Ren, LJ. et al. Changes of incudostapedial joint angle in stapedotomy: does it impact hearing outcomes?. Eur Arch Otorhinolaryngol 278, 645–652 (2021).

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  • Otosclerosis
  • Prosthesis
  • Stapedotomy
  • Incudostapedial joint (ISJ)
  • MPR-CT (multiple planar reconstruction-computed tomography)