Patent Publication Number: US-2021169626-A1

Title: Artificial contractile structure

Description:
TECHNICAL FIELD 
     The present invention relates to the field of artificial sphincters, in particular, but not exclusively, for the treatment of urinary incontinence. 
     BACKGROUND ART 
     WO2015/117664 describes a form of mechanical artificial contractile structure proposed as an alternative to problematic hydraulic systems such as the AUS 800 marketed by American Medical Systems, Inc. The artificial contractile structure disclosed in the above-mentioned document comprises a flat strip arranged to be closed in a loop around the urethra (or any other hollow body organ) of a patient by means of a closure. Once applied to the hollow body organ, this latter can be constricted by means of tension applied by a wire passing through the structure of the strip. A series of lateral reinforcing elements are formed on outer side of the strip, which cause it to adopt a substantially U-shaped cross-section when said tension is applied, and thus to gently apply pressure to the organ. 
     In acute testing, this artificial contractile structure has shown promise in treating male incontinence, however it has certain drawbacks in treating the same condition in females, since its shape is insufficiently adapted to the female urethra. Indeed, the contractile structure disclosed in WO2015/117664 is designed to extend on both sides of the locking system when it is wound around the male urethra. When applying strength on the cable, the portion extending beyond the locking system present a lower resistance to contraction and would contract first, decreasing the efficiency of the cuff so designed. Whereas ways to strengthen this portion -so-called “dead zone” so that the contractile portion surrounding the urethra contracts in priority exist, they require additional devices and complicate the surgery. The present invention intent to remedy the situation. 
     Due to the female urethras being bigger than male urethras and their anatomical condition very different, the pulling distance needed to contract the structure may exceed the actual length of the structure disclosed in WO2015/117664 and, as such, may not achieve the intended pull distance required to make the patient continent again on the long term. 
     In addition, the sphincter muscle responsible for closing, respectively opening, the female urethra has a substantially U-shape (viewed in anatomical median plan), which only partially surrounds it. It is therefore contra-indicated to provide contraction forces about the full circumference of the female urethra as in the case of male patients, in particular under the urethra where the vagina wall is as this may possibly induce friction and erosion. 
     At the present time, the standard treatment of incontinence in female patients is by means of so-called slings, which are passive devices attached so as to apply pressure to the urethra, and thus to replace a certain amount of muscle function and thereby to restore continence. However, in long-term use, slings often fail as constant pressure of the slings on soft tissues leads to erosion or migration of slings through the urethra., thereby reducing the pressure applied to the urethra, and require placement of yet another sling. Indeed, some patients can undergo placement of several slings over time. 
     Due to the inadequacies of slings and limitations of hydraulic systems, there is a long-felt need for an improved system to better treat female incontinence. 
     DISCLOSURE OF THE INVENTION 
     An aim of the present invention is to overcome the above-mentioned drawbacks of the prior art, and thus to provide an artificial contractile structure particularly suitable for treatment of female incontinence. Although the artificial contractile structure of the invention is primarily intended for treatment of female incontinence, it can also be used in males, and may be used to constrict other hollow body organs such as blood vessels, ducts (such as the bile duct), the intestine, and so on. 
     This aim is attained by an artificial contractile structure for a medical device, as defined in claim  1 . This artificial contractile structure, also known as a “cuff”, comprises an elongated member, i.e. a long, relatively thin member which may be a strip of flat cross-section, or may have a more elaborate cross section such as a V or U shape or a corrugated shape, said elongated member comprising an elongated body extending a longitudinal direction between a first and a second end. Said elongated member is adapted to contact a hollow body organ such as a urethra around at least part of its circumference. 
     A tension system arranged to be connected to a control unit is also provided, said tension system being adapted to bring said first and second ends of the elongated body closer together in response to a force applied by said control unit so as to constrict the hollow body organ and thus form an artificial sphincter. 
     According to the invention, the elongated member comprises a resilient core and a biocompatible outer sheath, and the tension system comprises a first tensile element (such as a wire, cord, thread, tape or similar) attached to said first end of said elongated member, and a second tensile element (again such as a wire, cord, thread, tape or similar) attached to a second point of said elongated member. Each of said tensile elements passes through an adaptor situated on the elongated member between said first point and said second point. 
     This construction permits applying even, selective pressure to the hollow body organ, and is simple to position and adjust around a hollow body organ by laparoscopic surgery. 
     Advantageously, said resilient core comprises a lattice structure. This structure allows optimising the elasticity and the dimensions of the resilient core. 
     Advantageously, the resilient core comprises a shape memory alloy. These alloys typically have excellent elastic properties, and permit a particularly advantageous method of fabrication, disclosed below. 
     Advantageously, said first tensile element is attached at a said first end of said body of the elongated member, and said second tensile element is attached at a said second end of said of said body of the elongated member. The cuff thereby does not show any so-called “dead zone”, or inactive portion. 
     Alternatively, said first tensile element may be attached at a first anchoring member arranged within the elongated member at said first end thereof, and said second tensile element may attached at a second anchoring member arranged within the elongated member at said second end of the body of the elongated member. 
     In an embodiment, said first and second anchoring members comprise a pivot means about which said first and second tensile element may slide in response to a force applied by said control unit so as to constrict the hollow body organ and thus form an artificial sphincter. 
     In embodiments, the first and second anchoring members may be integrally formed in said resilient core of the artificial contractile structure. 
     In embodiments, the artificial contractile structure may further comprise a closure adapted to form the artificial structure into a closed loop around said hollow organ. Preferably said closure then forms a link between said first and second ends of said elongated member. 
     In an embodiment, the artificial contractile structure may further comprise an arcuate self-supporting structure wherein said elongated member is installed, said self-supporting structure being configured for insertion on top of the circular striated muscle, thereby preventing dissection of the vaginal wall of a patient. Such configuration may be much favourable for implantation of female patients. 
     Advantageously, said closure may be integral with said elongated member, i.e. monobloc therewith, thereby resulting in a simple construction with a minimum number of pieces. 
     Advantageously, said tension system further comprises a flexible transmission attached pivotably to said elongated member, said first tensile element and said second tensile element passing through said flexible transmission. The flexible transmission can thus pivot with respect to the elongated member without kinking, which is useful not only in use, but also when being inserted into the patient by means of a trocar, since it can be easily folded up alongside the cuff. The cuff and the flexible transmission together constitute a medical device. 
     Advantageously, said flexible transmission is attached to an adaptor, said adaptor comprising at least one pulley around which said first tensile element and said second tensile element pass so as to enter into said flexible transmission. The one or more pulleys may be rotary or fixed, and serve to minimise friction with the tensile elements when they make the transition from the cuff into the flexible transmission. 
     Advantageously, a control system comprising an actuator is provided, said first tensile element and said second tensile element being attached to said actuator by means of an connector, said connector being attached to said actuator by means of a push-fit connection. Connection of the tensile elements and the flexible transmission to the actuator is thus simple, and does not require any rotation. 
     Advantageously, said push-fit connection comprises one or more coil springs and one or more O-ring linking a first annular groove provided in one of said actuator and said connector and providing a kinematic link with a further annular groove provided in another of said actuator and said connector. A particularly simple form of push-fit is thus proposed. 
     Advantageously, the connector comprises a connecting rod longitudinally movable within a coaxial plug, said connecting rod being attached to said tensile elements. Preferably, connecting rod comprises a crenelated part cooperating with releasable hooking members of said plug to allow locking of the connecting rod in said plug, whereas the connector is designed to disconnect automatically when a given force is reached, preventing harms to the patient, the crenelated portion also allows to disconnect the tensile element in any position of the rod without applying effort to the tensile element (this to protect the urethra from uncontrolled pull forces). 
     The aim of the invention is also attained by a method of manufacturing an artificial contractile structure as defined above, comprising steps of:
         forming said resilient core, thanks to the memory alloy that can be manufactured flat to ease the operations to follow (bending the guides for the tensile elements, overmolding, sheating, sleeving, etc.);   applying said biocompatible sheath to said resilient core, for instance by overmoulding or sleeving on a pre-prepared sheath;   assembling said closure and said tension system to said elongated member, either before or after applying said biocompatible sheath.       

     This method results in an artificial contractile structure presenting the advantages mentioned above. 
     Advantageously, the resilient core is formed from a shape memory alloy capable of adopting a first state and a second state, and hence exhibiting at least a one-way memory effect, the method comprising steps of:
         conforming said resilient core to be substantially flat in said first state, and to be curved in said second state, e.g. following an arc of a circle or oval, or following a horseshoe shape;   causing said resilient core to adopt said first state, such as by bending it from its second state into said first state;   applying said biocompatible sheath to said resilient core when said resilient core is in said first state;   causing said resilient core to adopt said second state after application of said biocompatible sheath so as to impose a curvature on said elongated member, e.g. by heating it above the transition temperature of the material of the resilient core.       

     As a result, the artificial contractile structure can be assembled and its outer sheath can be applied in a flat state, which simplifies processing, and can then be caused to adopt the curved state beneficial for implantation in the patient without applying an external force which might damage the flexible elongated member. 
     Advantageously, the tension system is at least partially applied to said elongated member before said step of applying said biocompatible sheath to said resilient core. The tension elements can then pass through or under the outer sheath, 
     Advantageously, the outer sheath applied by overmoulding onto said resilient core, resulting in a unitary construction without joints. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described below in connection with the appended drawings, which illustrate:
           FIG. 1 : a schematic, perspective transparent view of an artificial contractile structure according to the invention in a first embodiment;       

         FIG. 2A : a schematic, perspective transparent view of the detail of a first embodiment of an adaptor forming part of the artificial contractile structure of  FIG. 1 ; 
         FIG. 2B : a schematic, perspective transparent view of the detail of a second embodiment of an adaptor forming part of the artificial contractile structure of  FIG. 1 ; 
         FIG. 3A : a schematic, perspective transparent view of an artificial contractile structure according to the invention in a first embodiment 
         FIG. 3B : a schematic, cross-sectional view of an artificial contractile structure according to the invention in a second embodiment; 
         FIG. 4A to 4C : schematic cross-sectional views of the artificial contractile structure of  FIG. 3  in different contracting positions about a female urethra; 
         FIG. 5 : a schematic cross-sectional view of a connector to a control system for an artificial contractile structure according to the invention; 
         FIG. 6 : a schematic cross-sectional view of the connector of  FIG. 5  connected to a control system for an artificial contractile structure according to the invention; and 
         FIG. 7 : a schematic flow diagram of a particularly advantageous method of manufacturing an artificial contractile structure according to the invention. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
       FIG. 1  illustrates an artificial contractile structure  1  according to the invention. Such artificial contractile structures are often referred to as “cuffs”, and this term will be used interchangeably with “artificial contractile structure” in the following description for ease of readability. 
     The cuff  1  comprises an elongated member  3 , i.e. a long, relatively thin member which may be a strip of substantially flat cross-section or may have a V-shaped, U-shaped or corrugated cross-section (or similar), comprising a resilient core  5  and a biocompatible outer sheath  7 . The elongated member  3  would typically be considered as being substantially flat, even if it comprises longitudinal corrugations or other similar structures; in other words, “flat” is not to be construed as being synonymous with “planar”. 
     In the illustrated embodiment, the resilient core  5  is formed as a lattice of a resilient, elastic material such as a metal, however certain polymers such as SMPs (Shape Memory Polymers) are also suitable so as to give the elongated member  3  sufficient rigidity and flexibility. A shape memory alloy such as Nitinol is particularly suitable, for reasons which will be made clear below, although other metals are possible, such as titanium or stainless steel for instance. Although an oval lattice shape is shown in the figures, any other convenient shape of lattice (such as square, triangular, hexagonal or similar) is also possible, as is a solid ribbon of the resilient material. A typical thickness of the resilient core is 0.25 to 0.5 mm, and its width would typically be between 5 and 20 mm. However such dimensions shall be construed as limitative of the scope of the present invention. 
     The biocompatible outer sheath 7 may be formed as a hollow sleeve containing the resilient core  5 , or may be overmoulded or laminated or dipped into a liquid silicone mixture to impregnate the stent onto the resilient core  5 , and hence pass through the openings in the lattice structure of the resilient core  5  so as to form a unitary structure. The resilient core  5  may also be accommodated between two discrete sheets (halves) forming the outer sheath  7  when assembled together, Many suitable materials for the outer sheath are known in the field of implantable devices, such as biocompatible silicone, PTFE, and similar. The thickness of the outer sheath  7  should be sufficiently thin to be flexible, but sufficiently thick to act as a cushion and prevent the lattice structure, if present, from applying excessive pressure to the hollow body organ or hurting adjacent tissues. The skilled person is capable of carrying out the experimentation needed to determine the required thickness for a given structure of resilient core  5 . In its resting, i.e. unstressed, position, the elongated member may follow a curve, e.g. an arc of a circle or oval, or a horseshoe shape, corresponding to the maximum diameter of hollow body organ intended for the cuff  1 . This facilitates placing the cuff  1  around a hollow body organ, however, it is possible to supply such a cuff  1  with a flat resting shape. 
     Optionally, as represented in  FIGS. 1 and 2 , the artificial contractile structure  1  may comprise a closure band or strap  9 . Such closure strap  9  may in some cases help forming the cuff  1  into a loop around a hollow body organ such as a urethra, blood vessel, intestine or similar. In the illustrated embodiment, the closure strap  9  is formed as a substantially loose ribbon or tape permanently attached at one end  9   a  to a first extremity  3   a  of the elongated member  3 , its loose end  9   b  being arranged to pass through a suitable opening  3   c  in the elongated member  3 , and to be retained therein. This opening  3   c  may be formed by a bar or loop of material integral with the resilient core  5 , and/or integral with the outer sheath  7 . Alternatively, a buckle arrangement may be provided as an additional piece fixed on, or integrated with, the second extremity  3   b  of the elongated member  3 . Further alternately, the ribbon or tape may be a completely separate piece to the elongated member  3 , and attached to each end thereof. 
     In order to secure the loose end  9   b  of the closure  9  at the desired point, a plurality of corrugations  9   c  are provided at intervals of e.g. 2.5 to 4 mm, so as to arrest the closure  9  at the desired point such that the cuff  1  has the desired circumference to conform to the hollow body organ of the patient around which it has been secured. Other forms of closure are also suitable. To help passing the end  9   b  of the closure strap  9  into the opening  3   c  arranged at the second end  3   b  of the elongated member  3  a holding tab  3   d  is advantageously provided as a free loose end of the outer sheath  7  of the elongated member, which advantageously help a surgeon firmly holding the end  3   b  of the elongated member while passing the closure strap end  9   b  in the opening  3   c  to set the closure  9  in place laparoscopically or otherwise. The closure  9  being devoid of any lattice structure may easily be cut after the proper adjustment has been found. 
     In order to cause the cuff  1  to constrict the hollow body organ, a tension system  11  is provided. This tension system  11 , also represented in  FIG. 2 , comprises a first tensile element  13  secured at a first point at or proximate to the first extremity  3   a  of the elongated member  3 , for instance by being tied, welded, glued or otherwise secured to a point at the end of the resilient core  5 . The tension system  11  also comprises a second tensile element  15 , again similarly secured at or proximate to the second extremity  3   b  and opening  3   c  of the elongated member  3 . Ideally, the first and second tensile element  13 ,  15  are secured at the very ends  3   a ,  3   b  of the elongated member where the closure strap  9  attaches thereto, so as to minimise the so-called “dead zone” of the cuff, and to provide pressure on the hollow body organ over the greatest possible length of cuff  1 . 
     The tensile elements  13 ,  15 , may be wires, cords, threads, ribbons or similar. In practice, threads of braided Dyneema® (ultra-high-molecular-weight polyethylene), Aramid, or similar work well. They may pass through one or more tubes and/or longitudinal passages provided in the structure of the resilient core  5 , or may pass around the outer side thereof either inside or outside of the outer sheath  7 , for instance through one or more tubes. Also, first and second tensile elements  13 ,  15  may be two extremities of a single, unitary wire, cord, thread, ribbon or similar, or may be two distinct pieces. Since such tensile elements typically only work in tension, the inherent elasticity of the resilient core  5  and that of the underlying tissue causes the cuff  1  to relax once tension is removed from the tensile elements  13 ,  15  by the control unit  28  (see below). This is particularly advantageous as the failsafe state of the system is for the cuff is to reopen automatically to return the constricted hollow body organ to its naturally open position. 
     At a third point  3   d  intermediate between said ends  3   a ,  3   b  of the elongated member, an adaptor  17  is provided. This adaptor  17  serves to direct the tensile elements  13 ,  15  into a flexible transmission  19 , which leads to a control system  28  (see  FIGS. 4 and 5 ) arranged to apply tension to the tensile elements  13 ,  15 , and to form a complete medical device. The flexible transmission  19  may be of any convenient type, such as a wire coil provided in an outer sheath, the tensile elements  13 ,  15  passing through an opening at the centre of this coil, and need not be described further. WO2015/117664 contains a discussion of various embodiments of such a flexible transmission, and is hereby incorporated in by reference in its entirety. 
       FIG. 2  illustrates in detail the adaptor  17 , with its cover  17   a  removed. 
     The adaptor  17  serves to help the tensile elements  13 ,  15  make the transition from the elongated member  3  into the flexible transmission  19 . In the illustrated embodiment, this is achieved by a pair of pulleys  21   a ,  21   b , associated with the first tensile element  13  and the second tensile element  15  respectively, and around which the respective tensile element  13 ,  15  passes. The pulleys  21   a ,  21   b  are mounted rotatably or fixedly on an axle  23 , itself mounted onto the resilient core  5  by means of a support element  25  fixed thereupon. Advantageously, the end of flexible transmission  19  is attached to the same axle  23 , to allow it to pivot around the axis of the axle  23 . As illustrated, the end of the flexible transmission  19  is provided with two parallel arms  19   a  (of which only one is visible) extending towards the axle  23  and terminating in “C”-shaped clips so as to clip onto the axle  23 . These arms  19   a  bear a support platform  24  for transmission  19 . Other arrangements, such as circular bearings, are also possible, but the illustrated variant is particularly simple and easy to assemble. This articulation of the flexible transmission  19  onto the cuff  1  is also particularly advantageous to permit folding the assembly formed of the cuff  1  and the transmission  19  into a trocar to permit insertion by laparoscopic surgery. This design is particularly suited for pulling perpendicular to the cuff  1 . However, it may be in some instances convenient to pull transmission  19  substantially horizontally or more generally following a tangent to the cuff  1 . In such case, the “pulleys” may advantageously be turned to 90° compared to  FIG. 2 . 
     Support element  25  may be rigidly fixed or integral with the resilient core, e.g. by laser soldering, or may be fixed so as to allow movement about at least one another axis so as to create a gimbal-type joint. For instance, the support element may be arranged to pivot according to an axis parallel to the longitudinal axis of the elongated member  3 , and/or according to the axis perpendicular to the plane of the tangent of the elongated member  3  where it meets the adaptor  17 . Such an arrangement helps to prevent kinking of the flexible transmission  19 , and to permit it to be folded in a trocar. 
     In more simple embodiments, the tensile elements  13 ,  15  may simply pass through appropriately-placed passageways or around appropriately-placed surfaces, which may be provided with a low-friction surface such as highly-polished biocompatible metal, PTFE or similar. However, the use of pulleys  21   a ,  21   b  ensures that friction is kept to a minimum and a maximum of the force applied by the control unit (not illustrated) is applied to the cuff  1 . 
     A second embodiment of a cuff  100  specifically designed for female incontinence prevention is represented in  FIGS. 3 to 5 . 
     In that embodiment the cuff  100  shows an overall horseshoe shape, wherein an arcuate self-supporting structure  27  is adjusted over the elongated member  3 , tension system  11  and adaptor  17 . This horseshoe shape is specifically chosen for easing implantation of the cuff  1  about the circular striated muscle in order to compensate for weaknesses of said muscle, which is a main cause of female incontinence. As dissection of the vaginal wall is a risky procedure when trying to wrap a closing strap of the cuff  1  of  FIG. 1 , the horseshoe-shape cuff  1  of  FIG. 3  is very appropriate for implantation of female patients. 
     The self-supporting structure  27  comprises an envelope  271  of a same material as the outer sheath  7  of the elongated member of the cuff of  FIG. 1 , which is tensioned or overmoulded on an arch  272  made of a substantially flexible polymeric rib  273 , conforming two resting feet  274  for the arch to steadily rest against the vaginal wall V without hurting it. 
     The inner wall of the arch of the self-supporting structure  27 , which is arranged for contacting a urethra U of a patient to provide contracting effort thereon is advantageously made of an elongated member  3 , visible in shadow lining in  FIG. 3A , similar in structure to the elongated member of the cuff  1  of  FIG. 1 , to the exception of an absence of closure strap  9 , passing hole  3   c  and holding tab  3   d . Depending on the materials used, the elongated member  3  may be glued or welded using heat, ultrasonic or high frequencies to the supporting structure  27 . 
     The adaptor  17  and flexible transmission  19  remain identical to those described in relation to  FIG. 1  and serve to transmit contractile force from an actuator to the tensile elements  13 ,  15  in order to constrict the elongated member  3  about the urethra of a patient as represent in  FIGS. 4A to 4C , representing the shape evolution for the cuff  10  from a fully released position of the elongated member  3  to a contracted position thereof. 
       FIG. 3B  represents an alternative embodiment of the cuff  100 , wherein the self-supporting structure  27  comprises an arch  275  with two arms  275   a ,  275   b  supporting pulleys  276  about which the tensile elements  13 ,  15  are tensioned, the end of tensile elements  13 ,  15  joining on top of the elongated member  3 . Thanks to that structure, the tensile efforts of the tensile elements  13 ,  15  are spread over the arms  275   a ,  275   b  supporting pulleys  276 , for even constricting pressure on the urethra U. 
       FIGS. 5 and 6  illustrate a push-fit connector system  29  for attaching the flexible transmission  19  comprising the tensile elements  13 ,  15  to a control system  28 , such as a remotely operated actuator. It should be noted that the cuffs  1 ,  100  of the invention is however usable with any convenient control system. 
     The illustrated control system  28  comprises a housing  28   a  inside which a screw-type actuator  28   b  is mounted. Naturally, other types of actuator  28   b  are possible. 
     In order to simplify assembly of the entire system in situ, i.e. inside a body cavity of the patient, the attachment of the connector  29  to the control system  28  is carried out by means of push-fit joints, as will be explained in more detail below. 
     As illustrated in  FIGS. 5 and 6 , the tensile elements  13 ,  15  are formed from a single thread, an end  13   e ,  15   e  of which is secured to a plug  30 . In  FIG. 5 , plug  30  comprises a substantially cylindrical body  30   a , extending longitudinally within a cavity of a protective shell  31  made of biocompatible flexible material, in particular a silicon-based material for example, which can be overmoulded on the plug  30  and retained thereon by material insertion into recesses (not shown) arranged on the outer surface of the body. A plug head  30   b  extends outwardly from said body  30   a  outside the protective shell  31 . The plug  30  has an open inner channel or tube  30   c  extending over the full length thereof, wherein a connecting rod  32  is fitted, said connecting rod comprising a crenelated part  32   a  housed in the plug&#39;s body  30   a  and a connecting head  32   b  extending through the plug&#39;s head  30   b . Each tensile element  13 ,  15  is passed in a lumen or capillary in the connecting rod  32  and its end  13   e ,  15   e , is preferably knotted to form a retention point received in an end recess  32   c  in the connecting head  32   b . Tensile elements  13 ,  15  are thus fastened to the connecting rod  32 , which will mechanically link the transmission  19  to the control system  28  as will be described herein after, 
     Advantageously, the connecting rod  32  can translate within the plug  30  but that displacement is limited by the toothed configuration of the crenelated part, which engages with inner hooking members radially extending internally from the plug&#39;s body  30   a . These hooking members can be actuated to engage the crenelated part by applying pressure as shown by arrows F in  FIG. 5 , thereby locking the connecting rod in place and allowing safe disconnection of the connector from the actuator without undue tension on the tensile elements 
     The head  30   bc  of the plug  30  is cylindrical and is a sliding fit within a tube socket  28   c  extending from the housing of the control system. Upon insertion of the plug head  30   b  into the socket  28   c  the connecting head  32   b  attaches to a distal extremity  28   d  of the screw-type actuator  28   b  by any convenient attachment. In the illustrated embodiment, a first coil spring  33  held within a corresponding first annular groove  33   g  in the distal extremity  28   d  of the screw-type actuator  28   b  cooperates in a corresponding groove  32   d  arranged on the outer surface of the connecting head  32   b . As an alternative, an O-ring may be used instead of a coil spring. Upon insertion of the connecting head  32   b  in the distal extremity  28   d  of the screw-type actuator  28   b , the coil spring  35  clips into the annular groove  32   d  so as to retain the connecting head  32   b  and plug  30  upon the distal extremity of the screw-type actuator and to transmit force and movement thereto. In this sense, the coil spring provides a kinematic link between the connecting rod  32  and the distal extremity of the actuator. As a variation, the position of the two annular grooves  33   g ,  32   d  can be inverted if desired, the coil spring  33  thereby being supported in the connecting head  32   b  and clipping into the groove in the distal extremity  28   d  of the actuator. 
     In order to support the outer sheath  19   a  of the flexible transmission  19 , a distal end of the protective shell  31  of the connector forms a hollow end cap fixed upon the outside of sheath  19   a  by means of a further coil spring  34  provided in between the tensile element  13 ,  15  and the sheath  19   a  on the one end and a seat  35  arranged between a distal end of the crenelated part  32   a  of the connecting rod  32  and the distal end of the cavity  30   c . The tensile elements  13 ,  15  (see  FIG. 4 ) pass through an axial passage in the seat  35 . 
     In order to minimise ingress of fluid between connector  29  and the socket tube  28   c , one or more coil spring(s)  35  and sealing rings  36  are provided in corresponding grooves in an inner wall of the socket tube  28   c , in contact with the outer part of the plug head  30   b.    
     The artificial contractile structure  1  of the invention can be manufactured by any convenient conventional manufacturing method, with the outer sheath  7  being either overmoulded or sleeved onto the resilient core  5 , and the tension system assembled thereto at a convenient moment in the process. However, a particularly advantageous method of manufacture will be described below. 
     This method of manufacture applies when the resilient core  5  is constructed of a shape memory alloy such as Nitinol. In this method, the shape memory properties are not exploited to apply force to a hollow body organ when the cuff  1  is installed in a patient, but are exploited during its manufacture. 
     A summary of the main steps of this method is illustrated in  FIG. 6 . 
     In step  101 , the resilient core  5  is formed of a shape memory alloy (SMA), such as nitinol, however other SMA&#39;s are also available and are suitable. 
     In this step, the resilient core  5  is formed in a substantially flat, planar configuration, e.g. by machining, deposition, extrusion (in the case of a solid strip) or similar. Since it is easier to work on a planar piece, this is significantly easier than forming the resilient core  5  with its final curvature already at this stage. 
     Since SMA&#39;s can present a one-way and/or a two-way memory effect, as is generally known, it is possible to define two shapes for the resilient core  5 , and changing temperature above or below a transition temperature will cause the material to transition from one shape to another. Exploitation of a one-way memory effect is sufficient for this method, as will appear clearly below. 
     A simple way to exploit this effect is to bend the resilient core  5  to its desired final, curved, shape around a mandrel, while heating it above the material&#39;s transition temperature, thereby defining its “second state” (“second” being chosen here since it is the final shape adopted during manufacture, as will become clear below). This second state can have a form correspond to the maximum diameter of the hollow body organ around which the cuff  1  is intended to be placed, but may also be a different diameter, and may be formed into an arc of a circle or oval, or a horseshoe shape. The resilient core  5  can then be cooled to below the transition temperature, and bent back into a substantially flat configuration, defined as its “first state” (step  103 ). 
     Once the resilient core  5  has been placed in its first state by bending it out of its second state, assembly and application of the outer sheath  7  can occur (step  104 ). The adaptor  17 , or at least part thereof such as support element  25 , can be assembled thereto, and if the tensile elements  13 ,  15  are to pass through the structure of the resilient core  5  and/or under the outer sheath  7 , these are then placed, and if desired attached at ends  3   a ,  3   b  of the elongated member  3 . Otherwise, these can be attached later at an opportune moment. The outer sheath  7  is then applied to the resilient core  5 , e.g. by overmoulding, or by sleeving a tube-shaped sheath thereupon. Overmoulding is the most advantageous process, since it results in a hermetically-sealed and encapsulated elongated member  3 , in a single process step, and without seams or joints. Furthermore, the closure  9  can be formed integrally with the outer sheath  7  during such an overmoulding step, although it may be formed in a separate step and fixed to the elongated member  3  in any appropriate fashion. 
     If the tensile elements  13 ,  15  are not to pass underneath the outer sheath  7 , they can be fixed after application of the outer sheath  7 , i.e. in such a variant the assembly occurs after application of the outer sheath  7 . 
     Once the cuff  1  is thus assembled, in step  105  the resilient core  5  is placed into (i.e. is caused to adopt) its second state, by heating it back up over the transition temperature of the SMA. The desired shape and curvature of the cuff  1  is hence obtained, and remains once the resilient core  5  cools back down below the transition temperature. 
     The cuff  1  is then ready for sterilisation, packaging and use. 
     Since the cuff  1  is provided with an appropriate curvature already, it is easier for the surgeon to place around the hollow body organ. A flat cuff is harder for the surgeon to handle laparoscopically, since it requires the surgeon to impose the desired curvature before he is able to close the closure  9 . 
     One particular advantage of this method is that the curvature of the elongated member  3  does not need to be formed before applying the outer sheath  7 , which would make assembly and application of the outer sheath  7  difficult. It also avoids having to bend the assembled cuff  1  into shape after assembly and after application of the outer sheath  7 . Since the materials used for the resilient core  5  are elastic, in order to stress them sufficiently to obtain the required final shape by plastic deformation and yet retain sufficient elastic properties, high curvatures have to imposed thereon and heat may need to be applied. These curvatures (and heat, if applied), are likely to damage the outer sheath  7 , reducing its integrity, and possibly delaminating it from the resilient core. This is not to say that such processes cannot be used to manufacture the cuff  1  of the invention, however they are not as adapted to its manufacture as the above-described method. Furthermore, if the cuff  1  is to be bent to fit into a trocar for insertion by laparoscopic surgery, the material of the resilient core  5  needs in any case to be capable of withstanding significant curvatures without undergoing plastic deformation, so any manufacturing method requiring plastically bending of the cuff  1  into its final shape after assembly is likely to be suboptimal. 
     In use, the cuff  1  is inserted into the patient by means of a trocar, an incision is made if necessary (depending on the hollow body organ around which the cuff  1  is being applied) so as to enable the elongated member  3  to be passed around the hollow body organ, and the closure  9  is closed and tightened to give the cuff  1  the desired diameter. Subsequently, the flexible transmission  19  and the first and second tensile elements  13 ,  15  are attached to the control module  28 , e.g. as shown in  FIG. 4 or 5 . 
     Although the invention has been described in terms of specific embodiments, variations thereto are possible without departing from the scope of the invention as defined in the appended claims.