WO2010094082A1

WO2010094082A1 - An implant for a medical application

Info

Publication number: WO2010094082A1
Application number: PCT/AU2010/000199
Authority: WO
Inventors: Linda Elizabeth Laidlaw; Anthony Clyde Neason Stephens; Brian Bernard Mckeon
Original assignee: Continence Control Systems International Pty Ltd
Priority date: 2009-02-20
Filing date: 2010-02-22
Publication date: 2010-08-26

Abstract

The present invention relates to an implant for a medical application and, particularly, to a method of preparing an implant of contractile tissue for a medical application. Contractile tissue implants are proposed for various medical applications. For urinary incontinence, for example, a smooth muscle sphincter is prepared, wrapped around the urethra and stimulated electrically to contract to cause the urethra to close. In the present invention, a pre-tension value is applied to the smooth muscle, so that an appropriate amount of Total Tension is applied for the medical application (eg urinary incontinence) when the contractile tissue is electrically stimulated. Applying a pre-tension value (eg a positive resting tension) has been found to increase the Total Tension applied when the contractile tissue is electrically stimulated. In an embodiment, the tension is applied to a predetermined tension value, utilizing a tension setting tool.

Description

AN IMPLANT FOR A MEDICAL APPLICATION

The disclosure of the following international patent applications are incorporated herein by reference:

PCT Application No. PCT/AU2006/000258 , entitled "IMPROVED METHOD AND APPARATUS FOR TREATING INCONTINENCE" , filed on 2 March 2006

PCT Application No. PCT/AU2006/001301, entitled "SMOOTH

MUSCLE IMPLANT FOR MANAGING A MEDICAL CONDITION" , filed on 4 September 2006

PCT Application No. PCT/AU2006/001158 , entitled "METHOD AND APPARATUS FOR CONTROLLING A BODILY FUNCTION, filed on 8 November 2006

PCT Application No. PCT/AU2006/001504 , entitled "A METHOD AND APPARATUS FOR TREATING FECAL INCONTINENCE" , filed on 13 October 2006

PCT Application No. PCT/AU2006/001514 , entitled "A METHOD AND APPARATUS FOR TREATING A HEART CONDITION" filed on 16 October 2006

PCT Application No. PCT/AU00/00925 , entitled "METHOD AND APPARATUS FOR TREATING INCONTINENCE", filed on 4 August 2000.

PCT Application No. PCT/AU2005/001698 , entitled "AN

IMPLANTABLE ELECTRODE ARRANGEMENT" , filed on 8 November 2005.

PCT Application No. PCT/AU2007/000525, entitled "A METHOD AND APPARATUS FOR MANAGING ERECTILE DYSFUNCTION" filed on 24 April 2007. PCT Application No. PCT/AU2007/000027 , entitled "A STIMULATOR FOR CONTROL OF A BODILY FUNCTION", filed on 16 January 2007.

PCT Application No. PCT/AU2007/001356 , entitled "A METHOD AND APPARATUS FOR TREATING A PROLAPSED RELATED CONDITION" , filed on 12 September 2007.

PCT Application No. PCT/AU2008/001405 , entitled "METHOD AND APPARATUS FOR CONTROL OF ENTEROSTOMIES", filed on 22 September 2008.

Field of the Invention

The present invention relates to an implant for managing a medical condition, a method of preparing an implant for managing a medical condition and a tool for preparing an implant for managing a medical condition. Particularly, but not exclusively, the invention relates to a contractile tissue implant, a method for preparing a contractile tissue implant, and a tool for preparing a contractile tissue implant.

Background of the Invention

It is known to use tissue implants to treat some medical conditions. For example, it is known to use innervated smooth muscle implants. International patent application number PCT/AU/00/00925 discloses a method and apparatus for managing urinary incontinence in humans. A "neo- sphincter" is formed from smooth muscle tissue taken from elsewhere in the patients body, and wrapping the smooth muscle tissue around the urethra. An implantable stimulator provides electrical signals to the neo- sphincter by way of an electrode that delivers the electrical signals. The electrical signals stimulate the neo-sphincter to maintain tension in the muscle around the urethra to prevent emptying of the bladder until the user wishes to urinate. The stimulator may provide a further electrical signal (or stop providing signals) to allow the neo-sphincter to relax and so enable the individual to urinate .

It is also envisaged that smooth muscle and other contractile tissue implants may be useful in the management of other conditions, including, but not restricted to fecal incontinence (per anus or stoma) , heart conditions, vaginal prolapse and others. The above referenced patent applications describe various applications, techniques and devices for controlling contractile tissue (particularly, but not exclusively, smooth muscle tissue) for treating medical conditions.

One of the issues with using smooth muscle implants is that the medical operative (e.g. surgeon) must select the correct size of implant and position the implant correctly so it can perform the required medical application capably. This is very difficult to do and with current applications is generally done by trial and error. Where the medical condition is urinary incontinence, for example, and a smooth muscle sphincter is to be implanted in accordance with the disclosure of PCT/AUOO/00925, the surgeon obtains a strip of smooth muscle from an appropriate site (e.g. the detrusor) . The strip is sized so that it will wrap around the patient's urethra. The surgeon then wraps the strip of smooth muscle around the urethra so that the urethra is slightly indented From experience, this should give sufficient "snugness" of the sphincter about the urethra so that when it is electrically stimulated it will provide sufficient contraction for coaptation of the urethra to prevent leakage of urine.

With this empirical implantation approach, results vary and cannot be standardised across patients, across operators and across tissue type and tissue condition. Lack of standardization of the length, position and stretching of the tissue may impact the outcomes and biomechanical properties of the tissue implant in the medical application. Similar problems may also apply to implants utilizing other contractile tissue types, including skeletal muscle and artificial muscle.

Summary of the Invention

In accordance with a first aspect, the present invention provides a method of preparing an implant for a medical application, the implant comprising a portion of contractile tissue, the method comprising the steps of pre-tensioning the contractile tissue so that it will achieve a desired tension post implantation.

In an embodiment, the pre-tensioning is achieved by tensioning the portion of contractile tissue against a applied tensioning force. The tensioning force may be applied, in an embodiment, by a tensioning tool. The tensioning tool may be specifically devised for the purpose of tensioning contractile tissue implants.

In an embodiment, the step of pre-tensioning the contractile tissue comprises the step of pre-tensioning to a predetermined tension value. The pre-determined tension value may depend on the particular medical application. In an embodiment, the predetermined tension value is a measured tension value. The predetermined tension value may be within a range of tension values. The Applicants have appreciated that one of the problems with muscle tissue implants, such as smooth muscle tissue implants for applications such as urinary incontinence as discussed above, is that after the muscle has been harvested from the original site, it tends to contract . Surgeons when implanting the smooth muscle tissue generally stretch to a particular length (e.g. to go around the urethra and leaving enough muscle wrapped around the urethra to secure the sphincter, for example) . The stretching to length is generally done, as discussed above empirically (by "look and feel") and may take no account of any contraction of the tissue, and it does not provide any control or standardization of the operation to optimize the mechanical configuration of the tissue implant .

In an embodiment of the present invention, the contractile tissue is stretched to a predetermined value of tension and observed for a period of time. If the muscle relaxes during that predetermined period of time it is stretched further until the same amount of tension is achieved. The contractile tissue may then be implanted.

In an embodiment, the desired tension post- implantation is a tension which is implemented when the contractile tissue is electrically stimulated. In an embodiment, the desired tension post-implantation is a tension that is present in the contractile tissue when it is unstimulated. The Applicants have appreciated that pre-tensioning of some contractile tissues (e.g. smooth muscle and skeletal muscle) results in changes to tension post- implementation. For example, pre-tensioning to a particular pre-determined tension will lead to a high tension post-implementation (for example, it may lead to a peak stimulated tension) . Pre-tensioning can therefore influence what the tension will be when the tissue is stimulated.

In an embodiment, the contractile tissue is pre- tensioned to a tension value which will give an optimum tension post-implantation for the particular medical application that is being managed.

In an embodiment, there can be considered to be two contributors to tension of the contractile tissue. These are the Resting Tension, being the tension of the contractile tissue at rest. In an embodiment of the present invention, a pre-tension value is applied to the contractile tissue so that the Resting Tension is above zero . Another contributor is, in an embodiment of the invention, is the tension value which is applied as a result of electrical stimulation, being the Active Tension value. The sum of the Active Tension value and Resting Tension value gives Total Tension. As discussed above, in an embodiment of the present invention the contractile tissue is pretensioned to a pre-tension value of Resting Tension which will give a required Total Tension post- implantation on stimulation appropriate for the particular medical application that is being managed.

We can define AP_max as the maximum active tension. The Total Tension developed by the smooth muscle implant will be greater than AP_max due to the addition of the underlying Resting Tension (for example Total Tension may be 120% of AP_max) . This Total Tension developed on stimulation will depend upon the properties of the contractile tissue and will vary depending on these properties. In an embodiment, a pre-tension value in the range of 2 to 40 percent of AP_max is applied to the non- stimulated contractile tissue. In an embodiment, the pretension value is in the range of 3 to 30 percent of AP_max. In an embodiment, the pre-tension value is in the range of 4 to 25% of APmax. In an embodiment, pre-tension value is in the range of 5 to 20 percent of AP_max. In an embodiment, the pre-tension value is in the range of 6 to 18 percent of AP_max. In an embodiment the pre-tension value is in the range of 7 to 16 percent of AP_max. In an embodiment the pre-tension value is in the range of 8 to 14 percent of AP_max. In an embodiment the pre-tension value is within the range of 9 to 12 percent of AP_max. In an embodiment the pre-tension value is 10 percent of AP_max.

The applicants have found that, at least in this embodiment, AP_max is only developed if a Resting Tension value is applied. If there is no Resting Tension value, then AP_max does not occur. For some types of contractile tissue (including smooth muscle) as the resting tension increases, the Active Tension may decline. Total Tension may increase or plateau, however.

AP_max depends upon the characteristics of the particular contractile tissue, and for a particular contractile tissue such as smooth muscle, for example, depends upon the cross section of the muscle. In an embodiment, the method comprises the further step of determining AP_max for the contractile tissue. In an embodiment, the method comprises the further step of selecting a portion of contractile tissue of appropriate cross-section for the medical application (eg appropriate cross section to provide the appropriate AP_max for the medical application) . In an embodiment, the medical application is treatment of urinary incontinence, and the contractile tissue may be formed into a sphincter about the urethra. In an embodiment, the medical application may be a treatment for fecal incontinence, oesophageal reflux disease, control of a stoma associated with an enterostomy or like application, treatment of a heart condition, a prolapse condition or any other application. The contractile tissue may be formed into a sphincter, may be formed as a sling (e.g. for vaginal or other prolapse) or may be formed in any other way as required for the medical application.

The contractile tissue may be smooth muscle tissue, innervated smooth muscle tissue, skeletal muscle tissue, innervated skeletal muscle tissue, artificial contractile tissue (e.g. artificial muscle tissue), augmented muscle tissue (e.g. smooth muscle or skeletal muscle augmented with different cells, and/or grown or cultured in an artificial medium - see PCT application number PCT/AU2006/001301) , electro-active polymer or any other contractile tissue.

In embodiments of the invention it may be an advantage that a desired control on the standardization of the mechanical configuration of the contractile tissue implant may be achieved across patients, surgeons, tissue types and tissue conditions and across different medical applications .

In accordance with a second aspect, the present invention provides a device for a medical application, the device comprising implanted contractile tissue, or contractile tissue intended for implant, the contractile tissue having been prepared in accordance with the method of the first aspect of the invention.

In accordance with a third aspect, the present invention provides a stimulator arranged to provide electrical stimulation to a device in accordance with the second aspect of the invention. In an embodiment, the stimulator is implantable in a patient .

In accordance with a fourth aspect, the present invention provides a stimulator controller, the stimulator controller being arranged to control stimulation signals provided by the stimulator of the third aspect of the invention.

In accordance with a fifth aspect, the present invention provides a stimulator programmer, the stimulator programmer being arranged to program control parameters of the stimulator of the third aspect of the invention.

In accordance with a sixth aspect, the present invention provides a computer program, comprising instructions for the controlling a stimulator in accordance with the third aspect of the invention. In accordance with a seventh aspect, the present invention provides a computer readable medium providing a computer program in accordance with the sixth aspect of the invention.

In accordance with an eight aspect, the present invention provides a data signal, comprising a computer program in accordance with the sixth aspect of the invention.

In accordance with a ninth aspect, the present invention provides a system for a medical application, comprising a stimulator in accordance with the third aspect of the invention, and a device in accordance with the second aspect of the invention. In an embodiment, the system further comprises a programmer in accordance with the fifth aspect of the invention.

In an embodiment, the system further comprises a controller in accordance with the fourth aspect of the invention.

In accordance with a tenth aspect, the present invention provides a device for a medical application, the device comprising contractile tissue implanted in a patient, or intended for implant in a patient, the contractile tissue having been pre-tensioned to a tension which has a value of one of :

2 to 40 percent of AP_max;

3 to 30 percent of AP_max; 4 to 25 percent of AP_max;

5 to 20 percent of AP_max;

6 to 18 percent of AP_max;

7 to 16 percent of AP_max;

8 to 14 percent of AP_max; 9 to 12 percent of AP_max;

10 percent of AP_max;

In accordance with an eleventh aspect, the present invention provides a stimulator arranged to provide electrical stimulation to a device in accordance with the tenth aspect of the invention.

In accordance with a twelfth aspect, the present invention provides a stimulator controller, the stimulator controller being arranged to control stimulation signals provided by the stimulator of the eleventh aspect of the invention.

In accordance with a thirteenth aspect, the present invention provides a stimulator programmer, the stimulator programmer being arranged to program control parameters of the stimulator of the eleventh aspect of the invention. In accordance with a fourteenth aspect, the present invention provides a computer program, comprising instructions for controlling a stimulator in accordance with the eleventh aspect of the invention.

In accordance with a fifteenth aspect, the present invention provides a computer readable medium providing a computer program in accordance with the fourteenth aspect of the invention.

In accordance with a sixteenth aspect, the present invention provides a data signal, providing a computer program in accordance with the fourteenth aspect of the invention. In accordance with a seventeenth aspect, the present invention provides a system for a medical application, comprising a stimulator in accordance with the eleventh aspect of the invention, and a device in accordance with a tenth aspect of the invention. In an embodiment, the system further comprises a programmer in accordance with the thirteenth aspect of the invention.

In an embodiment, the system further comprises a controller in accordance with the twelfth aspect of the invention.

In accordance with an eighteenth aspect, the present invention provides an apparatus for facilitating a medical application, the apparatus comprising a tool arranged to pre-tension contractile tissue intended as an implant for the medical application, so that the contractile tissue will achieve a desired tension post-implantation.

In an embodiment, the tool comprises a mount for mounting the contractile tissue and a tensioning body connected to the mount and arranged to apply a tensioning force. In an embodiment, the tensioning body comprises a resilient arm. In an embodiment, the tensioning body comprises a carriage arranged to be connected to a portion of the contractile tissue and moveable relative to the mount in order to apply tension to the contractile tissue. In an embodiment, the apparatus further comprises a measuring device for measuring the length of the pre- tensioned contractile tissue. In an embodiment, the tool comprises a strain sensor arranged to measure tension in the contractile tissue. In an embodiment, the tool is arranged to apply a pre-tension to the contractile tissue having a value of; 2 to 40 percent of AP_m1x;

3 to 30 percent of AP_max;

4 to 25 percent of AP_maχ;

5 to 20 percent of AP_max;

6 to 18 percent of AP_max; 7 to 16 percent of AP_max;

8 to 14 percent of AP_max;

9 to 12 percent of AP_max;

10 percent of AP_max

Brief Description of the Drawings

Features and advantages of the present invention will become apparent from the following description of embodiments thereof, by way of example only, with reference to the accompanying drawings, in which; Figure 1 is a graph of tension against length for a sample of contractile tissue, illustrating how values of pre-tension to apply to the contractile tissue are determined in accordance with an embodiment of the present invention; Figure 2 is a perspective view of an apparatus for pre-tensioning contractile tissue, in accordance with an embodiment of the present invention;

Figures 3 to 5, are drawings illustrating a process of pre-tensioning contractile tissue in accordance with an embodiment of the present invention, utilizing the apparatus of Figure 2 ;

Figure 6 is a perspective view of an apparatus for pre-tensioning contractile tissue, in accordance with a further embodiment of the present invention; Figure 6A is a block diagram of circuitry associated with the apparatus of Figure 6;

Figure 7 is a diagram of a female bladder anatomy illustrating implanted contractile tissue in accordance with an embodiment of the invention and a stimulator, for controlling urinary incontinence;

Figure 8 is a block diagram of a stimulator for stimulating contractile tissue, in accordance with an embodiment of the present invention;

Figure 9 is a block diagram showing the stimulator and electrodes of an embodiment of the present invention, together with a controller in accordance with an embodiment of the present invention;

Figure 10 is a block diagram showing a stimulator and electrodes in accordance with an embodiment of the present invention, together with a programmer in accordance with an embodiment of the present invention; Figure 11 is a diagram of the female bladder anatomy illustrating contractile tissue in accordance with an embodiment of the present invention implanted about the urethra, together with an electrode for stimulating the implanted contractile tissue; Figure 12 is a cross-sectional diagram of the colorectal anatomy showing an implanted stimulator and contractile tissue device in accordance with an embodiment of the present invention;

Figures 13 through 16 are further views of an apparatus in accordance with the embodiment of Figure 2, and

Figures 17 and 18 are schematic diagrams showing operation of an apparatus for pre-tensioning contractile tissue, in accordance with a further embodiment of the present invention.

Detailed Description of Embodiments

A method in accordance with the present invention comprises pre-tensioning contractile tissue to achieve a desired tension post-implantation for a medical application, such as, in one embodiment, a sphincter for controlling urinary continence. In an embodiment, for each particular medical application, an amount of pre- tensioning to be applied to the contractile tissue is determined and then applied.

In one embodiment, referring to Figure 1, a graph is shown of tension against length of contractile tissue, where the contractile tissue is innervated smooth muscle intended as an implant to control urinary incontinence. The smooth muscle is formed into a sphincter (after pre- tensioning in accordance with this embodiment) about the urethra and then stimulated to control urinary- incontinence. Refer to PCT/AU004/00925, referenced above.

The present Applicants have appreciated that pre- tensioning the smooth muscle tissue by a measured tension value leads to a standardised and predetermined mechanical configuration for stimulated tension for controlling urinary incontinence and, in an embodiment, can lead to an optimal mechanical configuration for the tension generated during electrical stimulation.

Referring to Figure 1, the plots have been prepared for a series smooth muscle tissue samples weighing 0.015 ± 0.002 grams (mean +_ standard deviation) . The value of AP_max for tissue of this type (innervated smooth muscle from the Dartos) is 1.10 kg/cm². The Applicants have appreciated that stimulated smooth muscle develops different tension when stimulated from different degrees of muscle stretch, and that stimulated tension may reach a maximum from a certain predetermined initial stretch.

Figure 1 shows three length/tension plots for the smooth muscle intended for implant. There are two experimental plots: one for passive (no stimulation) tension versus length, "Resting Tension" ; and one for stimulated tension, "Total Tension" , which is based on stimulated muscle and which will include a component of passive mechanical behaviour. The third plot, "Active Tension", is a derived plot and shows active-only tension component. This was derived by subtracting the passive tension results from the active + passive results. The Applicants observed that as the peak in active tension occurs when there is some passive tension in the smooth muscle implant, the smooth muscle implant could be stretched at the time of transplant to a length that would, subsequently to implant, develop optimum tension when stimulated. As can be seen from the plot of Total Tension, Total Tension can in fact be higher than the peak of stimulated tension (AP_max) depending upon what initial tension is applied to the "resting" muscle. For some medical applications, however, it may be important not to have a significant amount of tension on the muscle when it is in an unstimulated state. For example, where the application is a neo-sphincter for controlling urinary- incontinence, as in this embodiment, too much tension on the neo-sphincter at rest may restrict urinary flow. The Applicants consider that some resting tension is required, so that a desired total tension will be developed in the neo-sphincter when it is electrically stimulated, but not so much resting tension that urinary flow would be restricted when the neo-sphincter is not being stimulated.

A simple view of the system illustrated by Figure 1 would indicate that the muscle would need to be stretched to L_max. This would give a peak of Active Tension and good Total Tension. In practice, however, it is very difficult to determine the L_max based on length alone, as the surgically removed muscle is in an unknown state when measured prior to harvest and typically contracts after being harvested. The resting length of the muscle in this pre-harvest or post-harvest state is therefore unknown and the degree of stretch to achieve L_max length is also unknown. The applicants believe, therefore, that it is difficult, if not impossible, to use a measure of length to apply an appropriate pre-tension to the muscle.

In this embodiment we address this problem by not attempting to stretch based on a measured length but using tension instead. In the figure we would use a control tension, for example corresponding to 10% of AP_max. If this tension were applied to passive muscle this would result in a nominal stretch length of approximately 110% of L_max.

This form of setup will ensure that the muscle is stretched to a length that provides close to maximal active tension yet has a low passive tension.

In reality, although the muscle sample is measured, and width typically controlled, the muscle thickness will vary from sample to sample. The control tension could be adjusted based on measured muscle thickness however this is not necessary in most cases as the resting length will

Still be Close tO Lmax-

If the same control tension is used for different samples the effective stress will increase if the sample is thinner or will decrease if the sample is thicker. If the muscle sample had half the thickness then the control tension would result in a stress of 20% of AP_max. If the muscle sample had twice the expected thickness the stress would be 5% of AP_max. This 5-20% range of stress of AP_max gives us a resulting stretch range of 105-120% of L_max. The total muscle tension when activated is relatively insensitive to this range of stretch. The Total Tension achieved can therefore still be in the desired range. While this description of variations in length is relevant, the Applicants have also noted that implant tissue from different sources will have different elastic characteristics (for example, depending on the amount of connective tissue within the smooth muscle) . Using tension to achieve the required function in the medical application helps to take account of such variation in tissue for a particular medical application.

A further advantage of the use of tension as the setup parameter is that smooth muscle can exhibit a response to quick stretch where stretch receptors in the muscle cell wall cause the muscle cell to contract and then relax after a period of time. In the process of pre-tensioning, the muscle is therefore stretched slowly so that the passive tension dominates. The tension set up method allows this to be performed in a controlled manner and accommodates variations in tissue properties across different patients and tissue types. If the muscle is stretched to the control tension and maintained at that tension, for example for 60 seconds, there will be some initial "quick stretch" tension component and this will attenuate over time and be replaced by only the desired passive component. As the stretch-based tension subsides, the surgeon would stretch the muscle to keep the tension at the target value and eventually the applied tension will be dominated by the target passive muscle tension.

In this embodiment, a measured value of pretension is applied to the smooth muscle tissue intended for the implant, over a period of time.

In an embodiment, the value of tension applied is:

3 to 30 percent of AP_max;

4 to 25 percent of AP_max;

5 to 20 percent of AP_max; 6 to 18 percent of AP_max;

7 to 16 percent of AP_max;

8 to 14 percent of AP_max;

9 to 12 percent of AP_max;

10 percent of AP_max Where muscle, for example, smooth muscle, is to be used in any medical application, the first step in the process of getting the muscle ready for the medical application is to determine, for the implant site, a required tension of muscle to achieve the desired outcome. The implant site might be a urethra (as discussed above in the embodiment for urinary incontinence control) , a colon (e.g. an anal neo-sphincter) , or the muscle might be attached in a linear or sling fashion.

The required muscle tension is related via known muscle properties to determine the amount of muscle cross - section that would be necessary to develop the required tension when the muscle is stimulated. This calculation will also indicate if the source muscle (site from which the muscle is to be harvested e.g. Dartos in the case of the urinary continence application discussed above) could provide sufficient muscle mass to support the target medical application. The outcome will be a requirement to harvest a certain width of muscle. The required length of the muscle implant will be determined by a measurement of a parameter of this target site. For instance, the circumference of the colon or the urethra for a neo- sphincter, or distances between certain anatomical landmarks for a sling. If the target site has significant elastic deformable properties, then this will need to be accounted for in the calculation In clinical application, urethral or colon pressure measurement could be performed while measuring the required neosphincter length about the urethra or colon. Any shortening of the neosphincter to achieve the desired internal pressure would be incorporated in this measurement technique. The resulting measured length would be the required active length. The active tension that can be developed by a muscle proposed for implant is a function of the degree of stretch of the muscle and has a maximum when the active elements, actin, myosin etc, within the muscle have optimum overlap. Pre-stretching the muscle to this optimal overlap length at the implant target site in accordance with an embodiment of the invention, may be desirable, as discussed above. This will also mean that a minimum amount of muscle is required to be harvested for the implant . When a stretched muscle is not activated, as discussed above, it will still exhibit some tension due to the passive elastic properties of the stretched muscle. Typically a target application such as a neo-sphincter or sling will require this passive tension to be determined so that it does not inhibit urinary flow when the neosphincter or sling is unstimulated. Ideally, the implanted muscle is pre-stretched by an amount such that it delivers maximum tension and therefore maximum biomechanical properties when activated and when it is not activated, passive tension does not exceed a predetermined threshold. An apparatus in accordance with an embodiment of the present invention for pre-tensioning a contractile tissue implant will now be described with reference to Figure 2 and Figures 13 to 16.

Reference numeral 1 indicates an apparatus for pre- tensioning contractile tissue (in this case a smooth muscle implant) so that the tissue will achieve a desired tension post -implantation. In this example, the apparatus comprises a tool 1 having a resilient arm 3 which is arranged to apply a measured amount of tension to the smooth muscle implant 9.

In more detail, the tool of this embodiment is constructed from two folded pieces of titanium. The first piece is item 1 which includes the arm 3, a handle 2 which is intended to be held by pinching the thumb and fore- finger along the cross part of the handle 2, and a folded projecting portion 11 which extends in front of a free end 5 of the arm 3. The other end 13 of the arm 3 is integral with the body 14 of the tool 1. A slot 15 extends through a widened portion 16 of the free end 5 of the arm. Mounted within the slot 15 is one end 17 of a mounting member 7 for mounting the smooth muscle implant. The end 17 is bent so that the mounting member 7 is retained by the arm 3 and walls of the slot 15. This is most clearly seen in Figure 14, which is a section on line XX of Figure 13. The other end 19 of the mounting member 7 extends through a slot 20 in the projecting portion 11. The mounting member 7 at the mounting end forms a pair of hooks 21, 22 for holding sutures 8 connected to the smooth muscle implant 9. Sutures 10 at the other end of the smooth muscle implant 9 are mounted to one end of a measuring device . An embodiment of measuring devices as shown in Figure 15. It comprises a ruler 800 having gredations for measuring length, and a handle 801 for gripping by the surgeon.

In operation, the free end sutures 10 are pulled so that the implant 9 is stretched against the tension applied by the arm 3. When the muscle has been tensioned to the appropriate measured tension, the free end 5 of the arm is aligned with a notch 6 in the body 14 of the tool 1. At rest, the arm aligns with notch 4.

A procedure for preparing an implant for use as a neo-sphincter for controlling urinary continence will now be described with reference to Figures 3 through 5.

In this embodiment, smooth muscle tissue for use as a neo-sphincter implant about the urethra is first harvested as dartos tissue from the scrotum. It will be appreciated that the smooth muscle implant is not limited to being dartos, but could be other smooth muscle tissue from any suitable site or even any contractile tissue, natural or manufactured .

During harvesting, sutures 8 and 10 are placed at corners of the dartos muscle implant 9.

A predetermined amount of stretch should be placed on the neosphincter 9 as it is wrapped around the urethra to ensure that, when activated, the smooth muscle will generate sufficient force to cause urethral coaptation. Therefore, the total length of dartos tissue required to create the neosphincter will generally be less than the circumference of the urethra.

The tensioning tool of Figure 2 is utilized to pretension the dartos implant 9 as illustrated in Figures 4A, 4B and 4C. As well as the tensioning tool 1 the apparatus for pre-tensioning the dartos implant 9 also includes a measuring instrument 30. The measuring instrument 30 is in the form of a ruler having length graduations 31 marked on it and having a upstanding tab 32 at one end of the ruler 30 about which the stay sutures 10 may be wrapped to mount one end of the dartos implant 9.

A clinical procedure for pre-tensioning the smooth muscle implant 9 is carried out as follows:

(1) . Join the stay sutures 8,10, placed in the corners of each end of the dartos implant 9, to form two temporary loops (Figure 3) . (2.) Attach the dartos implant 9 to the mounting arm 7 of the tensioning tool 1 (and ruler 30) using the two suture loops as shown in Figure 4A; hook one suture loop onto the hook attachment points on the mounting arm 7 of the tensioning tool 1, and hook the other end around projecting portion 32 of the ruler 30 so that the suture loop lies in the two suture slots 33, 34.

Without placing tension on the implant 9, place the ruler 30 and tensioning tool 1 in the bottom of an instrument bath filled with warmed Hartmann's solution (-30 to 37°c) or other suitable media to temporarily maintain tissue viability. Ensure that the implant 9 is completely covered by the Hartmann's solution. While there is no tension placed on the implant 9, the tip of the tensioning arm should align with notch A located on the main body of the tensioning tool 1 (Figure 4A) .

(3) . Hold the projecting portion 32 of the ruler 30 with one hand, and use the other hand to grip the tensioning tool 2 to move the tool 4 and the ruler 30 slowly apart until the end of the tensioning arm 13 aligns with notch B (Figure 4B) .

(4) . Once the tensioning arm 13 is aligned with notch B, maintain this position for one minute (Figure 4C) . The muscle may relax over this time period resulting in movement of the tensioning arm 13 away from notch B. If this occurs, readjust the position of the tensioning tool 1 to maintain the tensioning arm 13 at notch B.

After one minute, without moving the tensioning tool 1 or ruler 30, place marker sutures 35 through the edges of the implant 9 at a length corresponding to the urethral circumference measured earlier. Use the graduations on the ruler 30 to measure this length. Ensure that the starting point for the measurement is at the end of the implant 9 attached to the ruler 30 (Figure 4C) .

(5) . Once both marker sutures have been inserted, remove the dartos implant 9 from the ruler 30 and tensioning tools 1, cut the suture loops attaching the implant 9 to the ruler and detach the loop at the other end to the tensioning tool 1 as this loop will aid with orientation of the neosphincter as it is placed around the urethra (Figure 5) .

In the above embodiment, the tool 1 has been calibrated during manufacture to apply a predetermined tension (in one embodiment preferably in the region of 10% of AP_max) to a smooth muscle section intended for implant as a neosphincter about the urethra. The approximate size and requirements for the smooth muscle neosphincter are known, so that the tension to be applied by the tensioning arm 13 of the tool 1 can be calibrated appropriately and the tool manufactured correctly. For other medical applications, the same type of tool may be used, but it is likely that different tensions will need to be applied so that the tool will be devised separately for each medical application it is to be used with. In another embodiment, the one tool could be set to different target tensions, depending on the intended medical application.

As discussed above, even if the thickness of the smooth muscle or contractile tissue varies either side of the desired cross sectional area of the contractile tissue, the affect on Total Tension will not be that great relatively, and desired Total Tension may still be achieved. If muscle thickness varies from sample to sample, therefore, the same tool can still apply a tension to result in a satisfactory Total Tension. As discussed above, if the muscle has half the thickness, then the control tension would result in a stress of 20% of AP_max. Twice the expected thickness would result in a tension of 5% of AP_max, which still will give satisfactory Total

Tension. The tool therefore has capacity to apply tension across an effective range for variations in contractile tissue thickness and other characteristics.

An alternative embodiment of an apparatus for pre- tensioning of a contractile tissue implant is illustrated in Figure 6. In this embodiment, the apparatus is sized such that it could be utilized within a patient by, for example, laparoscopy. The width of the device may be 8 millimeters, for example, so that it may be inserted via a 10 millimeter cannula. In this embodiment, the tool is designed to facilitate characterization, harvest and placement of the implant within the a bodily cavity using conventional laparoscopic tools. The apparatus 50 comprises a ruler portion 51 having graduations 52 so that the surgeon may measure the length of a smooth muscle implant. An upstanding tab 53 at one end of the ruler has notches 54 and 55 in its sides. The loop stay sutures of the implant (see previous figures) are placed over the tab 53 and into the slots 54 and 55 to secure one end of the implant 9.

A carriage body 56, comprising a housing 57 mounting circuitry (Figure 6A) and a further upstanding tab 58 is mounted such that it can slide on rails 59, to slide on and relative to the ruler portion 51. The carriage body tab 58 has notches 60, 61 for receiving the suture loop at the other end of the implant 9, so that the implant is retained between the upstanding tabs 58 and 53.

The carriage body 56 and upstanding tab 58 include a strain sensor to measure tissue tension. A tension signal is fed via cable 62 to an interface device (Figure 6A) outside the patient. The interface device measures the tension and provides 3 audible tones. One tone is a high whistle that indicates tension is too high. Another tone is a low whistle that indicates tension is too low. The third tone is a slow clicking tone that indicates that tension is within the desired target zone. The surgeon applies tension keeping the tabs 58 and 53 spaced such that the clicking tone is maintained for the required time period to allow the tissue implant to stabilize. The external interface device is arranged to provide an audible alert when the necessary stabilization period has elapsed. The surgeon then marks the desired tissue length with sutures, similarly as discussed above.

Figure 6A shows a block diagram of circuitry, including sensor circuitry 65 which may be mounted in operation in housing 57. Block 66 shows the interface device, which comprises circuitry for determining the sensor output and a sound producing arrangement for producing the tones discussed above.

An alternative implementation of this embodiment may include a motor drive within the carriage body 56 such that, once the implant has been attached and the system activated via cable 3, the motor drive adjusts the position of tab 58 with respect to tab 53, so as to maintain the target tension (measured via the strain sensor) . The surgeon then marks the tissue after the usual stabilization period.

A further alternative implementation may have the motor drive external to the patient and a drive mechanism driving cable 62 to adjust the position of the tab 58 relative to the tab 53. Again, the apparatus of Figure 6 will be calibrated with regard to the medical application that the implant is to implement .

A further alternative implementation uses a strain sensor without a carriage body or ruler. Referring to Figures 17 and 18, this embodiment of an apparatus for pre-tensioning of a contractile tissue implant comprises a tension sensor 500 which is arranged to be inserted within a bodily cavity using conventional laparoscopic tools. The tension sensor 500 includes circuitry for measuring tension and for providing audible signals (similar to the embodiment of Figure 6 described above) . The tension sensor 500 is connected to a laparoscopic handle and shaft arrangement 501 Hooks 502, 503 are also provided connected to the tension sensor 500, for securing to the contractile tissue (reference number 504 in Figures 17 and 18) .

This apparatus is able to be operated laparoscopically, on a contractile tissue implant 504 that is already sutured in place at one end 505 (see Figure 18) . In operation, the implant is laparoscopically sutured 505 and then the tension sensor 500 is laparoscopically connected to the other end 506 of the contractile tissue 504 either by hooking the hooks 502, 503 directly into the tissue (Figures 17B and Figure 17C) or via a loop suture 507 (Figure 17A) . Note that the end 505 that is secured in place may be secured either to the native location of the contractile tissue 504 (where the contractile tissue 504 is a transplant and is harvested from within the patients body) or at the host location (where it has been implanted) .

The tension sensor 500 is manipulated to apply tension to the contractile tissue implant 504 via manipulation of the laparoscopic handle and shaft 501. Figures 17A and 17B illustrate an arrangement where the laparoscopic handle and shaft 501 are pulled, and Figure 17C and 18 an arrangement where the laparoscopic handle and shaft 501 are pushed to operate. When the predetermined tension is achieved as indicated by audible signals from the tension sensor 500, then the free end 506 of the contractile tissue 504 is secured in place in the desired location and configuration at the pre-determined tension. Some of the circuitry of the tension sensor 500 may be connected by cable and reside outside the body, in a similar manner to the embodiment of Figure 6 described above .

The apparatus of Figures 17 and 18 will be calibrated with regard to the medical application that the implant is to implement, similarly to the other embodiments.

The invention is not limited to the three embodiments of apparatus which are discussed above. These are only three examples of tensioning apparatus that could apply tension to the contractile tissue implant, as required by the present invention. AP_max will vary for particular tissue samples (tissues having different properties, sizes, types etc.) and for different medical applications. Generally, the AP_max will be determined for a particular tissue sample for a particular application. AP_max may be tested for each tissue sample to be applied, but more generally is likely to be determined using a control tissue sample of similar tissue for a similar prospective medical application. Once the AP_max is determined for the tissue/application, then the tool can be calibrated appropriately. Example

For a target dartos smooth muscle transplant acting as a neosphincter for urinary incontinence, it is determined that the muscle would need to develop 50gm of tension when stimulated (note that this may vary from implant to implant) . The source dartos muscle is found to be lmm thick. Active tension depends linearly on cross section of the smooth muscle. From previous experiments it has been determined that the dartos muscle sample can generate a max active tension (AP_m3x) of lkg/cm². To achieve an active 50gm tension with lmm thick donor tissue the tissue would need to be approximately 5mm wide.

Tension setting tool ,is set to a 10% of the target 5gm ie 0.5gm. This is applied while the muscle is passive and we would expect the muscle to end up at a passively stretched length that would be close to the length where APmax will be generated when stimulated.

In an embodiment, the present invention also includes a stimulator for stimulating a device in the form of implanted contractile tissue which has been pre-tensioned in accordance with the above embodiment. One embodiment of a system comprising an implanted tissue device and a stimulator will now be described with reference to Figures 7 through 11. The medical application in this embodiment is a stimulated neo- sphincter for controlling urinary- continence .

Referring to Figure 7, which shows the female anatomy only (but it will be appreciated a similar arrangement can be transposed to the male anatomy) , in accordance with an embodiment of the present invention a stimulator device

100 has been implanted in the patient, as well as a smooth muscle sphincter 101, which has been pre-tensioned in accordance with an embodiment of the present invention, utilizing the process discussed above. The stimulator 100 may be implanted in any surgically convenient position, but is preferably implanted between the abdominal muscles and the skin (represented by the line designated by reference numeral 102) . The stimulator 100 includes a signal generator arranged to provide an electrical stimulation signal for stimulating the smooth muscle sphincter 101.

In Figure 7, conductor 103 is arranged to conduct electrical stimulation signals to implanted electrodes providing stimulation to the neo-sphincter 101.

In this embodiment, an electrical signal is responsible for stimulation of the smooth muscle sphincter

101 to maintain pressure on the urethra 104. In this embodiment, parameters of the stimulating signal (s) being produced by the stimulator 100 are variable, to enable adjustment of the stimulus, as will be discussed in more detail later.

In accordance with the system disclosed in the above- referenced PCT application, the stimulator 100 may also be arranged to produce a further electrical signal to stimulate the sphincter 101 to relax, to allow urine to flow through the urethra and enable the patient to evacuate their bladder. Instead of a further electrical signal, the stimulator 100 may be arranged to stop producing any electrical signal and it is the absence of a signal that causes the sphincter to relax. The stimulator 100 is shown in more detail in Figure 8. In this embodiment, a signal generator arranged to provide the electrical signal for stimulation of the sphincter is in the form of a control unit 90 and stimulus driver 91. The control unit 90 encodes the stimulus and provides a signal to the stimulus driver 91 which provides the stimulation signal at output 92. The control unit 90 may be arranged to control the stimulus driver 91 to provide a plurality of stimulation signals e.g. one or more stimulation signals to contract the sphincter 101.

In this embodiment, the control unit 90 and stimulus driver 91 form together with a demodulator 80, a processing unit 95 for generating the stimulation signal (s) at output 92. The demodulator 80 is arranged to demodulate a signal received by a transceiver 93. An external control unit and external programmer unit (both to be described later) are able to communicate via the transceiver 93 with the processing unit 95 in order to control application of stimuli and/or λra.xγ the stimuli. In addition, as described in more detail later, the processing unit 95 may transmit, via control unit 90, demodulator 80 and transceiver 93, signals to the control unit or programmer unit. The transmitted signals may deliver telemetry information indicative of parameters of the stimulator, for the purposes of calibration and control.

The entire stimulator 100 (including components 95 and 93), is enclosed in a housing which includes a casing made from a bio-compatible material, such as titanium, silicone rubber or other known inert materials. The frequency of the RF signal for transmission and reception by the transceiver 93 may depend on the material of the casing of the stimulator 100.

Figure 9 shows an apparatus in accordance with an embodiment of the present invention. The apparatus incorporates the implanted stimulator 100, including transceiver 93. The electrode (s) 110 is shown schematically together with cable 103.

The apparatus also comprises an external controller 120 which includes a transmitter 121. The controller 120 is intended for operation by a patient with the stimulator 100 implanted, for control of the stimulator 100.

The controller 120 includes means (such as a button, not shown) operable by the patient to selectively send signals to the implanted stimulator 100, for control of the stimulation signals being sent to the electrode 110. In this embodiment, the stimulator is "fail safe". Unless a signal is received from the controller 120, the stimulator 100 produces a signal which maintains tone in the smooth muscle implant 101, maintaining pressure on the urethra. When the patient wishes to urinate, they actuate the controller 120 to send, via the transmitter 121, a signal to the stimulator 100. In response to receiving the signal, the control unit 90 operates to turn the stimulating signal off causing the sphincter 101 to relax and allow the patient to urinate.

The controller 120 may also be arranged to provide a further signal under patient control, once the patient has finished urinating, the further signal causing stimulator 100 to resume providing the stimulation signals to the electrode (s) 110.

In "auto-on" mode, if the further signal is not produced, the stimulator 100 will resume providing the stimulation signal to the electrode 110 after a predetermined period of time. The stimulation signal 92 provided to contract the smooth muscle sphincter 101 is selected so as to provide a substantially continuous tone in the sphincter. A generally rectangular and symmetrically biphasic pulse may be suitable for this. The signal has a substantially constant current less than or equal to 3OmA, and may be in the order of 15mA. Stimulation pulse frequency provided to sphincter 1 is in the range of 0.25 Hz to 2.5 Hz and is preferably 2 Hz. Stimulation pulse width is in the range of 0.05 m/s to 0.02 m/s and is preferably 0.15 m/s. The stimulator is current regulated and accordingly the stimulation voltage will vary with the resistance of the muscle tissue between the electrodes. Typical values for the voltage are between 0.2 and 12 Volts. Either a current source (voltage limited) or a voltage source (current limited) stimulator may be used.

Note that it is also possible to use an asymmetric biphasic pulse, in which, for example, the first phase is shorter in duration than the second phase.

Figure 10 shows an apparatus in accordance with an embodiment of the present invention, including a programmer unit 130 which may be utilized by a physician to set and adjust parameters of the implanted stimulator 100. The programmer unit 130 may include an appropriate means for communicating with the stimulator via transceiver 131 and may include a computing device. The control unit 90 is also arranged to transmit stimulator telemetry information indicative of one or more of the parameters of the stimulator 100, for detection by the programmer 130 via transceiver 131. The programmer unit 130 can therefore determine parameters of the stimulator 100 from telemetry information and can adjust the parameters by transmitting control signals to the stimulator 100. The signal from the programmer 130 may be able to selectively vary the output current, shape, frequency and/or pulse width or stimulation mode of the stimulation signal (s) . In operation, a physician adjusts parameters of the stimulation signal (s) . The physician will note feedback from the patient as to the affect of the stimulus on bladder control, and may subsequently re-adjust the parameters until the stimulation is optimum. For example, patient perceived feedback may be used to set the maximum stimulation threshold of the smooth muscle sphincter 101. In the above-described embodiments, signals between the controller or programmer and the stimulator are RF signals. Other types of transmission media other than RF may be used. For example, microwave signals may be used, and in another embodiment magnetic transmission may be used.

Magnetic transmission may be used for the controller unit 120 to cause the stimulator to stop producing stimulation signals and therefore allow the patient to urinate. In this embodiment, the control unit 120 may be a simple magnet which, when passed over a magnetic receiver of the stimulator 100, results in the stimulator ceasing to provide stimulation signals for contracting the sphincter.

In the above embodiment, the stimulator is shown implanted within a patient. The stimulator need not be implanted, and could be external to the patient, in other embodiments .

Referring to Figure 11, a detail on Figure 7 is shown which illustrates an electrode 150, in the form of a "peg" electrode used for stimulating the smooth muscle neosphincter 101. The electrode comprises a pair of electrode arms 151, 152, which seat either side of the smooth muscle sphincter 101, in the manner of a clothes peg. This type of electrode is described in the applicants earlier international patent application referred above.

In other embodiments, any types of electrode may be used, and the invention is not limited to use with the "peg" type electrode. Button electrodes, and other electrodes may be used in other embodiments.

In the above embodiments, the use of a smooth muscle sphincter for a medical application for controlling urinary incontinence has been described. The invention is not limited to control of urinary incontinence. Tissue implants for use in all types of other medical applications fall within the ambit of the present invention. These include, but are not limited to, a contractile tissue sphincter for controlling anal continence, a sphincter for implementing heart counter pulsation in order to treat heart problems, slings and sphincters for various conditions including prolapse (e.g. vaginal and/or anal prolapse) , tissue implants and sphincters for the correction of colon and other digestive disorders, the correction of oesophageal reflux, and other applications .

Figure 12 illustrates a system for controlling fecal incontinence to which an embodiment of the present invention may be applied to pre-tension a contractile tissue implant 600 which forms, in use, a fecal sphincter.

Referring to a Figure 12, a system and apparatus in accordance with an embodiment of the present invention, for treating fecal incontinence, are illustrated in schematic form. The system includes an apparatus comprising an implantable stimulator 601 and a device comprising contractile tissue 600 which is arranged to be stimulated by a signal that is generated by a stimulator 601 and, in this embodiment, applied to the contractile tissue 600 via an electrode conductively connected between the stimulator 601 and contractile tissue 600.

In this embodiment, the stimulator 601 includes a signal generator for producing a pulsatile signal which is housed in a bio-compatible housing 603.

The contractile tissue 600 in this embodiment is formed into a sphincter which is implanted about the fecal sphincter region, in this embodiment proximate to the anus. In Figure 12, the external fecal sphincter is designated by reference numeral 605 and the internal fecal sphincter by reference numeral 6. Failure of operation of the external and/or internal fecal sphincters (perhaps because of nerve damage, or other reason) have led to fecal incontinence in this patient. Stimulation of the contractile tissue sphincter 600 in operation, causes the contractile tissue 600 to contract and maintain closure of the fecal canal 607, maintaining fecal continence. In this embodiment, the contractile tissue is smooth muscle tissue. The smooth muscle tissue may be obtained from elsewhere in the body, formed into a sphincter and surgically implanted. Alternatively, the smooth muscle tissue may be grown from smooth muscle stem cells and/or proliferate smooth muscle cells. Alternatively, the smooth muscle tissue may be transplanted smooth muscle tissue augmented by smooth muscle stem cells and/or proliferative smooth muscle cells. Alternatively, the smooth muscle tissue may be the tissue of the internal fecal sphincter.

Any other contractile tissue may be used for the sphincter.

In this embodiment, the contractile tissue 600 is pre-tensioned in accordance with an embodiment of the present invention.

In the above embodiments, a smooth muscle tissue implant has been described. The invention is not limited to smooth muscle tissue and may be applied to any contractile tissue implant, including skeletal muscle, artificial muscle or any other type of contractile tissue.

Parts of processes relating to embodiments of the present invention, for example processes implemented by the stimulator, controller and programming units, may be implemented by software. The software may be provided in any form, including in the form of data signals, encoded on disc or other media, in memory or any other form. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. Present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A method of preparing an implant for a medical application, the implant comprising a portion of contractile tissue, the method comprising the steps of pre-tensioning the contractile tissue so that it will achieve a desired tension post implantation.

2. A method in accordance with claim 1, wherein the step of pre-tensioning the contractile tissue comprises the step of tensioning the portion of contractile tissue against an applied tensioning force.

3. A method in accordance with claim 1 or claim 2 , wherein the step of pre-tensioning the contractile tissue comprises the step of measuring the pre-tension value applied.

4. A method in accordance with claim 1, 2 or 3, wherein the step of pre-tensioning the contractile tissue comprises the step of pre-tensioning to a predetermined tension value.

5. A method in accordance with claim 4, wherein the step of pre-tensioning the contractile tissue comprises the step of tensioning to a pre-tension value comprising one of the following:

2 to 40 percent of AP_max; 3 to 30 percent of AP_max;

4 to 25 percent of AP_max;

5 to 20 percent of AP_max;

6 to 18 percent of AP_max;

7 to 16 percent of AP_max; 8 to 14 percent of AP_max;

9 to 12 percent of AP_max;

10 percent of AP_max

6. A method in accordance with any one of the preceding claims, wherein the step of pre-tensioning the contractile tissue comprises the steps of pre-tensioning the contractile tissue, observing the contractile tissue to detect relaxation of the contractile tissue and, if the contractile tissue relaxes, applying further pre- tensioning.

7. A method in accordance with claim 6, wherein the contractile tissue is observed for a predetermined period of time.

8. A method in accordance with any one of the preceding claims, wherein the desired tension post-implantation is a tension which is implemented when the contractile tissue is electrically stimulated.

9. A method in accordance with any one of the preceding claims, wherein the medical application is one or more of the following: urinary incontinence, fecal incontinence, oesophageal reflux disease, control of stoma associated with colonoscopy, treatment of a heart condition, and a prolapse related condition.

10 A method in accordance with any one of the preceding claims, wherein the contractile tissue is one or more of the following: smooth muscle tissue; innervated smooth muscle; skeletal muscle tissue; innervated skeletal muscle tissue; artificial muscle tissue; augmented muscle tissue, and electro-active polymer.

11. A device for a medical application, the device comprising implanted contractile tissue, or contractile tissue intended for implant, the contractile tissue having being prepared in accordance with the method of any one of claims 1 to 10.

12. A stimulator arranged to provide electrical stimulation to a device in accordance with claim 11.

13. A stimulator in accordance with claim 12, being implantable in a patient.

14. A stimulator controller, being arranged to control a stimulation signal as provided by the stimulator of claims 12 or 13.

15. A stimulator programmer, being arranged to program control parameters of the stimulator of claim 12 or 13.

16. A computer program, comprising instructions for controlling a stimulator in accordance with claim 12 or claim 13.

17. A computer readable medium, providing a computer program in accordance with claim 16.

18. A data signal, comprising a computer program in accordance with claim 16.

19. A system for a medical application, comprising a stimulator in accordance with claim 12 or claim 13 and a device in accordance with claim 11.

20. A system in accordance with claim 19, further comprising a programmer in accordance with claim 15.

21. A system in accordance with claim 19 or claim 20, further comprising a controller in accordance with claim 14.

22_r A device for a medical application, the device comprising contractile tissue implanted in a patient, or intended for implant in a patient, the contractile tissue having being pre-tensioned to a tension which has a value of one of : 2 to 40 percent of AP_max;

3 to 30 percent of AP_max;

4 to 25 percent of AP_max;

5 to 20 percent of AP_max;

6 to 18 percent of AP_max; 7 to 16 percent of AP_max;

8 to 14 percent of AP_max;

9 to 12 percent of AP_max;

10 percent of AP_max

23. A stimulator arranged to provide electrical stimulation to a device in accordance with the claim 22.

24. A stimulator controller, the stimulator controller being arranged to control a stimulation signal provided by the stimulator of claim 23.

25. A stimulator programmer, the stimulator programmer being arranged to program control parameters of the stimulator of claim 23.

26. A computer program, comprising instructions for controlling a stimulator in accordance with claim 23.

27. A computer readable medium, providing a computer program in accordance with claim 26.

28. A data signal, comprising a computer program in accordance with claim 26.

29. A system for a medical application, comprising a stimulator in accordance with claim 23, and a device in accordance with claim 22.

30. A system in accordance with claim 29, further comprising a stimulator programmer in accordance with claim 25.

31. A system in accordance with claim 29 or claim 30, further comprising a stimulator controller in accordance with claim 24.

32. An apparatus for facilitating a medical application, the apparatus comprising a tool arranged to pre-tension contractile tissue intended as an implant for the medical application, so that the contractile tissue will achieve a desired tension post -implantation.

33. An apparatus in accordance with claim 32, comprising a mount for mounting the contractile tissue and a tensioning body connected to the mount and arranged to apply a tensioning force.

34. An apparatus in accordance with claim 33, wherein the tensioning body comprises a resilient tensioning arm.

35. An apparatus in accordance with claim 33, wherein the tensioning body comprises a moveable carriage.

36. An apparatus in accordance with any one of claims 32 to 35, further comprising a measuring device for measuring the length of the pre-tension contractile tissue.

37. An apparatus in accordance with any one of claims 32 to 36, arranged to apply a pre-tension to the contractile tissue having a value of:

2 to 40 percent of AP_max ;

3 to 30 percent of AP_raax;

4 to 25 percent of AP_max; 5 to 20 percent of AP_max;

6 to 18 percent of AP_max ;

7 to 16 percent of AP_max;

8 to 14 percent of AP_max ;

9 to 12 percent of AP_max; 10 percent of AP_max