Context
Pelvic static (or prolapse) is a frequent female functional pathology. Its impact on the women quality of life can be significant and constitutes a real public health issue [1-3]. This disorder is a hernia, permanent or on effort, protruding into the vaginal lumen and in which one or more elements of the pelvic contents engage. The occurrence of female genital prolapse comes from a deficiency in the natural supports of the pelvic organs.

Epidemiological data report an 11 to 19% risk of developing this pathology during the lifetime for a woman [2.4]. Pelvic static and urethral hypermobility disorders affect one in three women of all ages and more than 60% of women over 60 years old [5,6]. About 11% of women will resort to surgery for the treatment of a prolapse [2].

The sacrospino fixation is a reference surgical technique for the treatment of this disorder, which requires fixation on the sacrospinous ligament of the pelvis. However, this technique proceeds via the vaginal route, leading to a lack of vision for the surgeon on the suture target zones which are then localized by palpation. The difficulty of the exercise sometimes leads to suturing in the wrong place, which involves postoperative complications in 5% to 10% of cases. In addition, apprentice surgeons find it very difficult to master this technique, which considerably lengthens the duration of the operation. Surgeons are therefore looking for a guidance system that would allow them to be more precise and faster in their surgical gestures.

Initial work in the laboratory led to the encouraging validation of a proof of concept of the system from a mock-up [7]. For this project, a software was created to allow virtual visualization of the position of the suture device in relation to the target area (Figure 1). The next step will be to transpose this concept so that it can be applied to patients in real conditions.

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Objectif
The objective of this thesis project will be to develop a computer-assisted surgery system allowing surgeons to guide them to the target area when suturing surgical threads.

Approach
The principle of this guidance system should allow surgeons to know the position of the suture device in relation to the target suture area: the sacrospinous ligament. For this, the identification of the target area must be carried out beforehand via the preoperative MRI performed for each patient. However, conventional MRI sequences do not identify the ligament, so it will be necessary to propose a new sequencing from the literature.

Then, it will be necessary to localize the spatial coordinates of the target zone of the ligament in the pelvis of the patient ready for the operation. The identification of the position of the pelvis in the operating room will be carried out using a technique developed in the laboratory from ultrasound images. However, this technique will have to be perfected and automated, to adapt it to the problem of this project.
As the suture device will be equipped with markers allowing it to be located in space, it will be possible to show live on a screen the position at any time of all the elements important to the operation as it is the case in the proof of concept already developed (Figure 2).

Once the system is functional, an experimental study will be carried out on cadaveric specimens to validate the method and evaluate it compared to the current method by palpation.

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Advantages: Modern and very promising subject, real clinical interest, involves collaborating with surgeons, imagers, researchers, technicians, etc.

Key-words: Biomechanics, Surgical guidance, Image processing, movement analysis

Laboratory: The Laboratory of biomechanics an impact mechanics (Laboratoire de Biomécanique et Mécanique des Chocs: LBMC UMR_T9406, https://lbmc.univ-gustave-eiffel.fr/), in Lyon, France, is a joint unit between the University Gustave Eiffel and the University Claude Bernard Lyon 1. Based on societal challenges, the LBMC leads researches, on two themes: Facilitating travel (automated vehicles, autonomous travel) and Maintaining good health (functional capacities, the repaired body: the implant in its environment).

Thesis supervisors: Pr Laurence CHEZE*, Pr Géry LAMBLIN*α, Laura DUBUIS*, Laure-Lise GRAS*
* LBMC, University Claude Bernard Lyon 1
α Hôpital Femme Mère Enfant, Service de Chirurgie Urogynécologique, Hospices Civils de Lyon

Application: Send your CV, your cover letter, your grades from the last three years, as well as a reference letter (if possible) to: laura.dubuis at univ-lyon1.fr.

Références
[1] Onwude JL. Genital prolapse in women. 2012.
[2] Olsen AL et al. Epidemiology of surgically managed pelvic organ prolapse and urinary incontinence. 1997.
[3] De Tayrac R, Marès P. Symptômes et qualité de vie dans le prolapsus génital. 2009.
[4] Smith FJ et al. Lifetime risk of undergoing surgery for pelvic organ prolapse. 2010.
[5] Luber KM et al. The demographics of pelvic floor disorders: current observations and future projections. 2001.
[6] Samuelsson EC, et al. Signs of genital prolapse in a Swedish population of women 20 to 59 years of age and possible related factors. 1999.
[7] Rozaire J et al. Development of an Innovative Surgical Navigation System for Sacrospinous Fixation in Pelvic Surgery. 2022