Numerical study of Hough technique in surgery of otosclerosis, using the finite element method.

PURPOSE: Otosclerosis is a metabolic bone disease of the otic capsule that can cause the stapes fixation, resulting in conductive hearing loss or, in a profound sensorineural deafness threshold. Surgery is one of the possible treatments for the otosclerosis. To repair small focus of otosclerosis in the anterior crus of the stapes, in 1960, Hough suggested the implementation of a technique in which part of the anterior crus is fractured and the stapes turned. As a result, the posterior crus of the stapes is the only connection with the inner ear. In this work, the outcome of Hough's surgical technique was simulated. METHODS: Based on computerized images, a finite element model of middle ear ossicles and tympanic membrane was created, as well as a model where the stapes has changed. The discretization of the tridimensional solid model was made using the ABAQUS software. The mechanical properties used were taken from the literature and adequate boundary conditions were applied. RESULTS: The results obtained with the Hough technique simulation were compared with a representative model of the normal ear, taking into account the displacements obtained on the central part of the stapes footplate and the maximum principal stress in the stapes crus. CONCLUSIONS: The results obtained are closer to the normal ear model, therefore Hough technique stands out as a good option to correct small focus of otosclerosis.

[Long term results stape surgery]. / Wyniki odlegle w otosklerozie.

For many years otosclerosis has been an interesting otologic problem in regard to pathological and clinical aspects. Many various conceptions of otosclerosis development which finally lead to the stapes immobility in the oval window were discussed. Resent genetic studies indicate that genetic factors as a cause of otosclerosis possibly in combination with other factors localize 3 genes responsible for otosclerosis to chromosom 15q25q-q26, 7q34-36, 6p21-22. The aim of the study was audiometric evaluation of 1380 patients out of 1716 stapes operations performed in years 1973-2004. Audiometric assessment for air and bone conduction was performed according to the European Academy of Otology and Neuro-Otology (EAO-NO) criteria. Postoperative air-bone gap 11-20 dB for speech frequencies (500, 1000, 2000, 4000 Hz) was obtained in 64.8% and in 28.9% was less than 10 dB. Postoperative air-bone gap (11-20 dB) recognized as a good result is determined by factors such as preoperative hearing loss, onset and duration of the disease, advanced and multiple otosclerotic foci, patient's age etc. Actually postoperative air-bone gap shows the improvement of air and bone thresholds obtained post stapedotomy versus preoperative air bone gap. In previous years an "over-closure" effect was taken into consideration. Hearing improvement post stapes surgery which included the "over closure" effect was obviously better. The authors indicate the necessity of standardization of audiometric results post ear surgery.

Clinical consequences of feedback on ear surgery: the continuous recording of adverse events and complications with regard to reducing the number of surgeons who perform otosclerosis surgery.

Electronically stored data may be used to generate feedback overviews. This paper describes a method for establishing a picture of ear surgery complications. In this prospective study, the working definition of adverse events and complications is "incidents that are not intrinsic to the surgical procedure and that have a potential or actual negative effect on surgical outcome or postoperative morbidity". A simple method is used to categorise otologic adverse events and complications. This scale varies from adverse events (grade A) to death (grade D). All adverse events and complications in ear surgery that met this definition were documented electronically as part of continuous follow-up between 1 July 1992 and 30 June 1999. In the first 3 years, 1,009 ear operations were performed, and in 51 (5%) of them, adverse events or complications were noted during or after surgery. There were 30 (3%) grade A (adverse events), 18 (2%) grade B (minor complications), 3 (0.3%) grade C (major complications) and no grade D complications. Otosclerosis surgery was evaluated additionally, because halfway through a 7-year period, the number of surgeons was changed. Only three experienced, senior members of staff were involved, and inexperienced residents no longer were allowed to perform this kind of surgery. The reduction of surgeon numbers did indeed improve the outcome of the stapes surgery. Our results were comparable to the literature. This monitoring of outcome-results in relation to changes in care can be seen as a study of care quality. A review of this kind links daily clinical practice to the literature and induces an improvement in quality.

Stapedectomy trends for the resident.

The diminishing number of cases of otosclerosis limits the training experience in stapes surgery during residency. Results are suboptimal. Closure of the preoperative air conduction to within 10 dB of bone conduction was obtained in only 64% of resident cases. Efforts to maximize experience and improve results include closer faculty supervision, use of one stapedectomy technique, and a prospective study of individual residents' performance.