Michel Cosson

Biomechanical properties of prolapsed or non-prolapsed vaginal tissue: impact on genital prolapse surgery

Introduction and hypothesisOur aim is to characterize prolapsed and non-prolapsed vaginal tissue, and thus offer a better understanding of the genital prolapse physiopathology and an improvement of surgical treatments.MethodsVaginal tissue was collected in 30 patients with prolapse (POP) and ten fresh cadavers without prolapse (nPOP) with a favorable advice of Ethics Committee. Uniaxial tension tests were performed. Statistical comparisons of rigidity under moderate deformation and under large deformation have been performedResultsPOP is significantly stiffer than nPOP tissue, both on anterior and posterior walls. A significant difference between POP and nPOP tissues was highlighted when anterior or posterior vaginal walls were respectively compared.ConclusionsThese results might explain the higher rate of relapse when repair is autologous, using already defective and more rigid vaginal tissue. This study suggests that it might be interesting to adapt the characteristics of prosthetic implants to the vaginal face concerned by the prolapsus.

Prosthetic reinforcements: how to manage bladder injuries?

The aim of this study was to describe our experience in the management of bladder injuries occurring at intervesicovaginal dissection during the tension-free vaginal mesh (TVM) procedure. Seven hundred four patients were treated for prolapse by vaginal route using the TVM procedure. Bladder injury was diagnosed during the procedure in five patients. Polypropylene mesh was placed in the intervesicovaginal space after a careful repair of the bladder injury. Major postoperative complications were not diagnosed during the short-term follow up. We describe the occurrence and treatment of bladder injuries during the dissection phase in the TVM procedure. Such injuries can occur during the dissection. Placing an intervesicovaginal mesh is acceptable if cautious bladder repair is performed.

Tissue resistance of the tension-free procedure: What about healing?

The aim of our work was to objectify and quantify the mechanical benefits of healing with regards to tearing meshes off of tissues and maximal resistance after cicatrization. In vivo, we tested the mechanical gain in resistance by healing after implantation of a Prolene® mesh. We measured the value of forces when traction was exerted until mobilization at different stages of cicatrization. Resistance increased progressively at the beginning of tissue inclusion. A maximal plateau was reached around the 25th day. It is important to understand the role of sustaining and reinforcement we hope tissue integration of the mesh will play. We can thus adapt procedures to have the best kinetics and maximal resistance of montages. Study of the kinetics and maximal plateau allows us to make the best clinical recommendations.

Experimental study of the mechanical behavior of an explanted mesh: The influence of healing

To better understand the in vivo mechanical behavior of synthetic mesh implants, we designed a specific experimental protocol for the mechanical characterization of explanted mesh under uniaxial tension. The implantation of a mesh leads to the development of scar tissue and the formation of a new composite made of native tissue, a mesh implant and scar tissues. This study focused on three points: determining the minimum representative size of mesh implants required for mechanical test samples, highlighting the influence of healing, and defining the healing time required to ensure stabilized mechanical properties. First, we determined the minimum representative size of mesh implants for the mechanical characterization with a study on a synthetic composite made of mesh and an elastomeric matrix mimicking the biological tissues. The size of the samples tested was gradually decreased. The downsizing process was stopped, when the mechanical properties of the composite were not preserved under uniaxial tension. It led to a sample representative size 3cm long and 2cm wide between the grips. Then an animal study was conducted on Wistar rats divided into eight groups. One group was set as control, consisting of the healthy abdominal wall. The other seven groups underwent surgery as follows: one placebo (i.e., without mesh placement), and six with a mesh installation on the abdominal wall and healing time. The rats were sacrificed after different healing times ranging from 1 to 5 months. We observed the influence of healing and healing time on the mechanical response under uniaxial tension of the new composite formed by scar, native tissue, and textile. It seems that 2 months are required to ensure the stabilization of the mechanical properties of the implanted mesh. We were not able to tell the control group (native abdominal wall) from the placebo group (native and scar tissue). This protocol was tested on two different prostheses after 3 months of healing. With this protocol, we were able to differentiate one mesh from another after host integration.

Feasibility and benefits of the ewe as a model for vaginal surgery training

Introduction and hypothesisThe objective was to evaluate the ewe as an animal model for teaching and training in vaginal surgery.MethodsTwenty-nine postgraduate surgeons attended a training course on vaginal prolapse surgery. After a review of human and sheep anatomy, the participants performed transvaginal meshes, vaginal hysterectomy, SSLF (Richter), and OAS repair in ewes and human cadavers. Participants completed questionnaires on the whole course.ResultsQuestionnaires showed the significant superiority of ewes over human cadavers for all items evaluated regarding surgical dissections. Only identification of the sacrospinous ligament and the spine were judged to be similar in ewes and human cadavers. Participants noticed that ewe model is appropriate for vaginal prolapse surgery training for resident and for postgraduate surgeons. Two vaginal hysterectomies were also performed. Operating time, surgery, and anatomy were nearly identical to that of humans. The same conclusions were made while performing sacrospinous ligament fixation (Richter) and obstetric anal sphincter injury repair.ConclusionThis series indicates that the ewe is a useful animal model for teaching vaginal surgery.

Le Prolapsus genital : Etat Des Lieux de la Chirurgie Par Vole Vaginale

Treatment of genital prolapse is mainly surgical. The vaginal approach is a shorter procedure than the abdominal approach with a quicker resumption of activity for the patients. We describe different techniques which are most often performed in our daily practice. For the complete prolapse affecting the three components of the pelvic floor, we most often associate a colpohysterectomy, a native tissue reinforcement for the treatment of cystocele, sub-symphyseal crossing of the uterosacral ligaments using the technique of Campbell and finally a suspension of the vaginal vault according to Richter with a levator myorraphy. Currently, native tissues used in these techniques tend to be superseded in our service by reinforcement prosthetic implants, which according to the latest French Health Higher Authority guidelines (November 14, 2007) could be of interest in relapse surgery, if a clinical element raises fears of high risk of recurrence. In any case, patients seeking a surgical treatment of their genital prolapse must be fully informed of the specific risk related to each technique. They must also be informed of the long-term results or of the lack of available data, regarding techniques using native tissue or prostheses.