WO2025149842A1

WO2025149842A1 - Prosthesis for the treatment of the excessive perineal descent associated to obstructed defecation syndrome

Info

Publication number: WO2025149842A1
Application number: PCT/IB2024/063336
Authority: WO
Inventors: Adolfo RENZI; Antonia DI SARNO; Corradino Maria Rosario RENZI; Clelia Francesco Vega RENZI; Antonio BRILLANTINO
Original assignee: Assut Europe SpA
Current assignee: Assut Europe SpA
Priority date: 2024-01-12
Filing date: 2024-12-31
Publication date: 2025-07-17
Anticipated expiration: 2026-07-12

Abstract

The present invention relates to a new NOT biodegradable synthetic innovative prosthesis, typically made of polypropylene, devised to correct surgically the excessive perineal descent associated to obstructed defecation syndrome. The proposed structure provides wide lateral portions with ends directed so as to ease a suitable anchoring of the same on the periosteal membrane of the two ascending branches of the pubis. Such combination of material and shape allows the prosthesis to be able to be positioned easily during the intervention and once fixed it will strengthen the resistance of the transverse muscle, by mitigating the side effects, better than any prosthesis currently on the market.

Description

PROSTHESIS FOR THE TREATMENT OF THE EXCESSIVE PERINEAL DESCENT ASSOCIATED TO OBSTRUCTED DEFECATION SYNDROME

DESCRIPTION

Technical field of the invention

The present invention relates to a new pre-shaped prosthesis made of polypropylene, devised to support the perineum and to prevent the excessive descent thereof during the evacuative straining (strain), consisting of a combination of material and shape so as to be positioned above the superficial fascia of the perineum, alone or in association with other interventions for the treatment of the obstructed defecation syndrome, in a simpler, more effective and safer way than any other prosthesis currently on the market.

Background

The perineal descent (DP), if contained, may constitute a physiological phenomenon which happens during the evacuative straining. However, an excessive perineal descent indicates an abnormal relaxation of the pelvic floor and it is associated to the Obstructed Defecation Syndrome (ODS), being considered a consequence of chronic and repeated strains for defecation. The Syndrome of the Descending Perineum is most frequent in women and it is characterized by chronic obstinate constipation due to neuropathy of the pudendal nerves, which can be secondary to trauma, childbirth and chronic defecation strain. As described by Parks et al. ["The syndrome of the descending perineum" Parks et al. Proc R Soc Med. 1966;59:477-482], the chronicity of ODS can lead, over time, to the weakening of the pelvic floor muscles and to the perineum sagging which, in turn, can lead to a further worsening of ODS, by establishing a vicious circle.

Recent studies have demonstrated that, in patients with severe ODS, the excessive perineal descent represents a very common phenomenon, being found in approximately 85% of all patients with SOD and, in particular, in approximately 96% of all patients with SOD not associated to signs of dyssynergic defecation ["The Relevance of the Excessive Perineal Descent in the Obstructed Defecation Syndrome: A Prospective Study of 141 Patients" Brillantino et al. Dis Colon Rectum. 2023 Nov 1 ;66(11 ): 1508-1515. doi: 10.1097/ DCR.0000000000002526], Moreover, in the latter group of patients, differently from the rectal anatomical anomalies commonly found within CDS (rectocele and intussusception), the perineal descent showed a good correlation with the seventy of symptoms, evaluated through the use of a dedicated score.

The interaction between obstructed defecation and perineal descent is strictly linked to the defecation pathophysiology. As it is known, a satisfactory rectal emptying is obtained if the relaxation of the puborectalis/external sphincter muscles and the increase in intra-abdominal pressure, induced by abdominal strain, occur simultaneously. In particular, during this manoeuvre, the flattening of the diaphragm downwards into the abdominal cavity and the contraction of the abdominal wall muscles, in the healthy subjects without excessive perineal descent, induce a volume decrease in the abdominal cavity which, considering the Laplace law, contributes in determining the increase in intra-abdominal pressure necessary for defecation [“Patients With Obstructed Defecation Syndrome" Renzi et al. Dis Colon Rectum. 2016 June;59(6):557-64. doi: 10.1097/ DCR.0000000000000573], In the subjects with pathological perineal descent, instead, the downward herniation of the perineum during the evacuative straining induces a change in the shape of the abdominal cavity which does not allow the reduction in volume required for effective defecation to occur. Therefore, under this condition, since it is not possible to obtain the expected increase in intra-abdominal and intra-rectal pressure required for an adequate rectal emptying during defecation, a real propulsive defect in defecation is established which contributes to the onset of the CDS symptoms.

The weakened pelvic anatomical structures involved in the perineal descent are various and include the levator ani muscles (which tend to diastase at the level of the urogenital hiatus and assume a bowl-like configuration), the complex network of suspensive ligaments of the pelvic organs (which tend to lengthen excessively and to weaken) and the muscle fibres of the perineal membrane. In particular, in the normal subjects an important role in limiting the excessive perineal descent is performed by the functional activity of the superficial and deep transverse perineal muscles. As demonstrated by electrophysiological studies, in fact, these muscles, unlike the levator ani, contract during defecation, by supporting the perineum and by protecting it from the high pressure generated during the evacuative strains which, if excessive and repeated, can determine weakening, subluxation and sagging of the perineal muscles, causing the so-called “perineocele”, that is the caudal herniation of the perineum.

Moreover, as demonstrated by anatomical studies, these muscles, in presence of a caudally directed pressure, tense, by opposing to an excessive downward displacement of the perineum. At the same way, the section of these muscle fibres in the cadaver exposes the rectum, by allowing it to prolapse downwards and anteriorly, by forming the rectocele.

Recently, the “Transverse Perineal Support’ (TPS) surgical procedure has been described and proposed for the treatment of the excessive perineal descent. The surgery provides the positioning of a prosthesis implant made of biological material just above the superficial fascia of the perineum, anchored with fixing systems to the periosteal membrane of the two ascending branches of the pubis, with the purpose of miming the function of the superficial transverse muscle and creating an element for supporting the pelvic floor during defecation, by limiting the excursion thereof downwards.

An undoubted advantage of this procedure is represented by the position of the prosthesis implant which, being located above the superficial perineal fascia, does not result to be in contact with viscera, nor it causes traction or suspension on the same.

However, in front of a documented good effectiveness of the surgery in the short-term improvement of the symptoms caused by SOD and of the perineal descent, a deterioration of the results of this procedure has been observed in the long term and this is compatible, in accordance with the description of the technique, with the use of biological prostheses.

The biological prostheses proposed on the market up to now, do not solve, in a significant percentage way, the gaps in terms of improving the functional effectiveness of the reconstruction. In other terms, the biological prostheses on the market cannot guarantee an adequate effectiveness in reducing the high rate of anatomical recurrence of corrective surgery nor pelvic organ prolapse, nor the excessive perineal descent.

This is due, in part, to the absence of an appropriate shape which does not offer correctly guided positioning in fixing the material on the most suitable anchoring points and amplifies the erosive and infective potential of the prosthesis itself and, partially, of the material of which the biological prosthesis is made. As far as the prostheses made of biological material are concerned , it is to be observed that, whereas the features of biocompatibility of a biological prosthesis do not vary considerably depending upon the function of the type of source material (pericardium, dermis, intestinal submucosa or fetal dermis) and/or the technology used to obtain the prosthesis (commonly defined mesh or patch) in case of cross-linked matrixes as well as in case of remodelling matrixes, they influence massively the mechanical behaviour of the patch.

The mechanical properties 4 play a crucial role in terms of functional guarantee of the implanted device since the TPS surgical procedure aims at implementing a “support” to the transverse muscle of the perineum functional to containing the excessive perineal descent during defecation. Apart from the capability of supporting, the “ideal” material should have, as much as possible, the same consistence, resistance, elasticity of the natural tissues. The collagen-based biological materials, obtained starting from animal tissues, have features influenced first of all by the type of origin of the used biological material, and secondly, by the treatment that the material undergoes. None of the existing biological prostheses is suitable to the type of described application. When the prosthesis is anchored to the pubic bone through suture or other fixing systems, it is locally subjected to very intense pressures to which the biological material is not compatible. The clinical practice showed that the crosslinked (permanent) ones have a slightly higher resistance, however they have a greater risk of seroma formation which makes the use more complicated.

The prosthesis, the present invention relates to, allows to obviate the above-described problems.

The prosthesis, the present invention relates to, is implanted with a surgical technique described hereinafter. The patient, after having been subjected to general anaesthesia, or sub-arachnoid anaesthesia, is placed on the operating bed in the lithotomy position (gynaecological position). The perineal skin is carefully disinfected and the ischial tuberosities are tactilely identified. At the latter the skin incision is made bilaterally for approximately 2 cm (Figure 4). Then, one proceeds with dissecting the subcutaneous tissue until exposing on each side the periosteum of the ascending breeches of the pubis. The dissection is completed by creating a subcutaneous tunnel between the two incisions. The mesh, with the described features, is housed in the subcutaneous tunnel and fixed by continuous suture made of non-absorbable material to the periosteum of the ascending branches of pubis, bilaterally (Figure 5). The skin incisions are sutured.

Summary of the invention

The technical problem placed and solved by the present invention is to provide an improved prosthesis, for the treatment of excessive perineal descent associated to the obstructed defecation syndrome allowing to obviate the above-mentioned needs, that is not only it allows to minimize the adverse events deriving from its application, but it also allows to improve the effectiveness of the functional reconstruction by means of a better anchoring by reducing consistently the risk of recurrence.

Such problem is solved by synthetic prostheses according to claim 1 .

Preferred features of the present invention are set forth in the depending claims.

The present invention relates to a new NOT biodegradable synthetic “mesh” prosthesis characterized in that it has wide lateral portions with ends having transversal directions with respect to the axis of symmetry of the prosthesis which allow a suitable anchorage of the same on the periosteal membrane of the two ascending branches of the pubis.

Clinical tests showed that the use of polypropylene for implementing the mesh is particularly suitable to this type of surgical application.

The central portion of the prosthesis, instead, has more limited sizes to allow the implantation in the anatomical portion between the anal and vaginal orifices.

The prosthesis, the present invention relates to, has been devised to ease and guide the positioning of the prosthesis during surgery.

The above-described technical effect is generated by the combination of the used material and of the selected shape, which make the proposed prosthesis capable of correcting the excessive perineal descent.

The subject prosthesis has been devised to be sutured on the periosteum of the two ascending branches of the pubis by means of different types of suture or other fixing systems. Typically the use of suture material is preferable and the suture can be made either with separate stitches or as a continuous suture also by using “barbed’ (autolocking) stitches. Clinical tests showed that the use of a barbed suture made of polypropylene 3/0 is particularly suitable to this type of surgical application.

The prosthesis, once implanted, will strengthen the resistance of the transverse muscle. Thanks to its optimized shape and to the material type, the prosthesis, the present invention relates to, is inserted easily by small cuts therethrough the surgeon succeeds in preparing the implantation site and inserting the prosthesis.

A first advantage of the proposed invention can be identified by the fact that the prosthesis is shaped to be anchored firmly and stably over time, through the wide right and left lateral portions, on the periosteum of the two ascending branches of the pubis, by defining the place most suitable to act as support.

A second advantage lies in the fact that the physical features of the prosthesis favour the correct positioning since it is guided by the anatomy of the implantation site. The correct positioning reduces the risk of sagging and then of recurrences.

An additional advantage is linked to the type of the material which is a NOT absorbable synthetic material, typically made of polypropylene (obtained with woven or “knitted” polypropylene filaments to obtain a mesh with density between 80 and 100 gr/m2) since such material does not modify the mechanical features over time, in this way by reducing the risk of recurrence.

Other advantages, features and use modes of the present invention will result evident from the following detailed description of some embodiments, shown by way of example and not for limitative purposes. The figures of the enclosed drawings will be referred to, wherein:

■ FIGURE 1 shows the prosthesis according to an embodiment of the present invention;

■ FIGURE 2 shows the prosthesis according to an embodiment of the present invention reinforced on the lateral ends by casting;

■ FIGURE 3 shows the prosthesis according to an embodiment of the present invention reinforced on the lateral ends by adding suture threads;

■ FIGURE 4 shows the initial phase of the surgery in which the anal and vaginal sphincters and at the ischial tuberosities the two incisions of the skin of about 2 cm are visible;

■ FIGURE 5 shows a phase of the surgery in which the prosthesis (mesh) housed in the sub-skin and fixed bilaterally to the periosteum of the ascending branches of the pubis is visible. The prosthesis consists of a flat surgical mesh made of a non-absorbable synthetic material having a proximal end with greater sizes and a second distal end with smaller sizes. The prosthesis is provided with axis of symmetry A. Perpendicularly to the direction A, it is possible to define a left portion and a right portion symmetrical with respect to the central portion which is normally smaller, therefore the prosthesis has an approximately “bow-tie” shape.

In a preferred configuration of the present invention the proximal and distal ends have laterally a rectilinear course and centrally a circular arc shape facing the centre of the prosthesis. Preferentially the circular arc which describes the proximal end has a lower radius of curvature (this makes the prosthesis better adaptable to the female anatomy). Still more preferentially the radius of curvature of the circular arc which describes the proximal end is 68 cm whereas the one which describes the distal end is 91 cm. Preferentially the prosthesis has a maximum size along the direction A of 3 cm and of 12 cm along the direction perpendicular to A. Still more preferentially the central portion has a maximum size along the direction A of 2 cm.

In a preferred configuration it has a maximum size of the proximal end of 12 cm and of 10 cm of the distal end. In a still more preferred configuration of the proximal end it has laterally rectilinear sections of 4 cm, whereas at the distal end it has laterally rectilinear sections of 1.5 cm.

In a preferred configuration the prosthesis has the lateral ends with converging transverse direction in the direction from proximal to distal. Preferentially the lateral ends can be reinforced (with the purpose of better resist to the tractions exerted by the suture thread) by adding reinforcement threads or by casting and accumulating material at the end. The process of casting and accumulating material at the end can be implemented through direct heating or application of ultrasounds or through the use of laser systems. Still more preferentially the prosthesis has chamfered external edges. Preferentially the prosthesis can have thickness near 0.50 mm, porosity around 80% and a linear resistance on two perpendicular directions greater than 24 N/cm.

In a preferred configuration the prosthesis along the direction perpendicular to A has an elongation at break lower than 140%, still more preferably around 100%.

Claims

1. A prosthesis for the treatment of excessive perineal descent (1 ) comprising a flat surgical mesh made of a non-absorbable synthetic material having a proximal end (2) and a second distal end (3) along a direction (A) and perpendicularly to the direction A, a left portion (4) with end (5), a right portion 6 with end (7) symmetrical with respect to the central portion (8) characterized in that with respect to the direction A, the left end (5) and the right end (7) have transverse directions and that the left (4) and right (6) portions are larger than the central portion (8).

2. The prosthesis for the treatment of excessive perineal descent (1 ) according to claim 1 , wherein the central portion is closer to the proximal end than the distal end.

3. The prosthesis for the treatment of excessive perineal descent (1 ) according to claim 1 , wherein the projection of the distal end (3) on the perpendicular to A measures 10 cm and the projection of the proximal end (2) on the perpendicular to A measures 12 cm.

4. The prosthesis for the treatment of excessive perineal descent (1 ) according to claim 1 , wherein the projections of the lateral ends (5, 7) on the direction A measure 3 cm.

5. The prosthesis for the treatment of excessive perineal descent (1 ) according to claim 1 , wherein the lateral ends (5, 7) form an acute angle of about 18-19 degrees with the direction A.

6. The prosthesis for the treatment of excessive perineal descent (1 ) according to claim 1 , wherein the central portion (8) has a width along the direction A of 2 cm.

7. The prosthesis for the treatment of excessive perineal descent (1 ) according to any one of the preceding claims having the distal end (3) formed laterally by two straight sections and centrally by a circumferential arc section having a radius of curvature of 91 cm and whose projection on the perpendicular to A measures 7 cm and having the proximal end (2) formed laterally by two straight sections and centrally by a circumferential arc section having a radius of curvature of 68 cm and whose projection on the perpendicular to A measures 4 cm.

8. The prosthesis for the treatment of excessive perineal descent (1) according to any one of the preceding claims made of polypropylene filaments.

9. The prosthesis for the treatment of excessive perineal descent (1) according to any one of the preceding claims made of synthetic textile fibre filaments and having a density between 80 and 100 grams/m²

10. The prosthesis for the treatment of excessive perineal descent (1) according to any one of the preceding claims having the left portion (4) with end (5) and the right portion (6) with end (7) reinforced by the addition of strengthening wires or by casting and accumulation of material at the end.