The Role of Altered Connective Tissue in the Causation of Pelvic Floor Symptoms

The pelvic floor consists of muscles and connective tissue. In the past, the components’ relative contribution to the structural support of the pelvic floor and its functions has been a subject of controversy (Corton 2009). With increasing age women can develop vaginal and pelvic organ prolapse as well as symptoms such as stress urinary incontinence, voiding dysfunction, urgency and frequency and nocturia, and may also develop fecal incontinence, obstructive defecation and pelvic pain (Petros 2010). All of these symptoms can be associated to a greater or lesser extent with pelvic floor defects.


Introduction
The pelvic floor consists of muscles and connective tissue.In the past, the components' relative contribution to the structural support of the pelvic floor and its functions has been a subject of controversy (Corton 2009).With increasing age women can develop vaginal and pelvic organ prolapse as well as symptoms such as stress urinary incontinence, voiding dysfunction, urgency and frequency and nocturia, and may also develop fecal incontinence, obstructive defecation and pelvic pain (Petros 2010).All of these symptoms can be associated -to a greater or lesser extent -with pelvic floor defects.
What events are responsible for these defects?One theory says that an important cause of prolapse and pelvic floor dysfunction is likely to be partial denervation (Swash et al 1985, Smith et al. 1989).But Pierce et al. (2008) demonstrated in nulliparous monkeys that bilateral transection of the levator ani nerve resulted in atrophy of denervated levator ani muscles but not in failure of pelvic support.This indicates that connective tissue components could compensate for weakened pelvic floor muscles.According to South et al. (2009), in up to 30 percent of all vaginal childbirths, pelvic floor muscles are partially denervated.However, such functions are known to recover and reinnervate often within months (Snooks et al 1984, Lin et al. 2010) .
In a direct test of the question, "connective tissue or muscle damage?",Petros et al 2008 performed a blinded prospective study with muscle biopsies of m.pubococcygeus taken at the same time as a midurethral sling operation for urinary stress incontinence (USI) was done, an operation which works by creating an artificial collagenous neoligament (Petros PE, Ulmsten U, Papadimitriou 1990).Out of 39 patients with histological evidence of muscle damage, 33 (85%) were cured immediately after surgery, indicating that connective tissue, not muscle damage was most likely the major cause of the USI.
Further, the muscle itself can change.It is known that the number and density of urethral striated muscle fibers declines with age (Huisman 1983, Perucchini et al. 2002), an idea that has been confirmed in studies about the vastus lateralis muscle (Lexell et al. 1988).Muscle avulsions have been reported at the pelvic floor (Dietz andLanzarone 2005, Dietz et al. 2007), but it is more likely that the insertion areas of muscles are dislocated by connective tissue alterations than muscle tears (Petros 2008).
From a mechanical point of view, the pelvic floor is composed of both muscles and connective tissue.The muscles are the active components that are -through their contractions -responsible for all functions of the pelvic floor.The connective tissues, with their elastic and collagen fibres and their extracellular matrices, provide structural support for the vagina and other organs such as uterus, urethra, bladder and rectum (Abramowitch 2009).It has been shown, that connective tissue changes occur during pregnancy (Rechberger et al. 1988, Harkness 1959).Weakening of collagen cross bonding (Rechberger et al. 1988) added to dilatation of the vaginal canal at childbirth can lead to overdistension or rupture of connective tissue.Extracellular matrix proteases contribute to progression of pelvic organ prolapse in mice and humans (Budatha et al. 2011, Connell 2011).The first vaginal birth is especially associated with the development of a prolapse, whereas additional vaginal births do not show significant increases in the odds of prolapse (Quiroz et al. 2011).Aging is characterized by a loss of collagen, degeneration of the elastic fibre network and a loss of hydration as a result of imbalance between biosynthesis and degradation (Uitto und Bernstein 1998, Campisi 1998) In addition to that, there is a significant variability of tissue due to inborn variations (Dietz et al 2004) and collagen-associated disorders (Lammers et al. 2011, Campeau et al. 2011).
Surgical procedures can reduce structural support of the organs, especially those which cut or displace the uterosacral and cardinal ligaments during hysterectomy or which partially resect vaginal tissue or perineal body during colporrhaphy.Petros and Ulmsten (1993) stated that looseness or laxity of the vagina and its supporting ligaments can cause stress incontinence as well as urge.Since then the theory has been expanded to include other symptoms such as pelvic pain, voiding dysfunction and more recently, fecal incontinence and constipation (Petros & Swash 2008).In order to fix such loose ligaments Petros et al. (1990) have introduced alloplastic material for planned formation of an artificial neo-ligament.From this rather basic research, new surgical techniques have been developed, such as tapes for midurethral slings (TVT, TOT) and for repair of other pelvic floor ligaments (Petros andUlmsten 1990, 1993).The new developments and the recent focus on connective tissue are important, not least because looseness of tissues can be repaired surgically.. Gordon (1966) studied the relation between muscle force and sarcomere length (figure 1).As a muscle fiber consists of a distinct number of sarcomeres, the determined relation can be leveraged for the full length of the muscle, for which the same relation can be assumed.This implies that a muscle has a special range of lengths, in which it can perform its peak force.If the muscle is shortened, its force decreases and goes down towards zero.If a muscle is overlengthened, its force goes down, too, sometimes even all the way to zero, at a length half of the one that gives optimal force.This means that a fully innervated muscle with normal morphology can have very low or even no force when it is over-stretched.The same process occurs in women with descending or prolapsing vaginal wall and pelvic organs.The muscles which attaches directly or indirectly to the vagina or the pelvic organs change their length and their direction of action.This alters muscle force and function according to the relation shown in Figure 1.After re-positioning of the prolapsed organs, the muscle can reach its normal length and function.Hence, atrophy of muscle by immobilization (Hvid et al. 2011) can be avoided at least with some patients.

Basic effect of altered connective tissues (looseness) on muscle function
A prime example of this principle is restoration of urethral closure by a midurethral sling which restores the integrity of the pubourethral ligament.In the original description of the "tension-free" sling (Ulmsten et al 1996), the operation was performed under local anesthesia and the tape was lifted upwards while the patient was coughing, until the urine leakage ceased.Fig. 1.Relationship of maximal muscle force to muscle (sarcomere)length (modified after Gordon 1966).Maximal muscle strength is exerted over a very short length (between red lines).Contractile strength falls rapidly with muscle lengthening and shortening, for example, due to lax connective tissue attachments.

Pelvic floor muscles and their functions (figure 2)
In many studies morphology of pelvic floor muscles has been explained with only few limited reference to muscle action.There is no doubt that the pelvic floor muscles and ligaments have immense importance for stress incontinence, micturition and anorectal functions.It was P. Petros who explained the directional muscle forces (Petros andUlmsten 1993, Petros andUlmsten 1997) and their significant role in pelvic floor dysfunctions.
From a functional and clinical aspect, it is important to consider 4 major muscle groups of the pelvic floor which are able to move the vaginal wall and pelvic floor organs (Petros 2010): 1.The anterior and medial portions of the pubococcygeus muscle (PCM) arise on either side from the inner surface of the pubic bone and attach to the lateral walls of the distal vagina (Zacharin 1963, Petros und Ulmsten 1997, Corton 2009).This muscle portion, called pubococcygeus muscle (PCM) by Petros and Ulmsten (1993) and pubovaginal muscle by Corton (2009) can pull the distal vagina forward to close the distal urethra during effort (coughing or straining).This muscle needs intact pubourethral ligaments for optimal action.2. The levator plate in the upper layer runs horizontally, goes into the posterior wall of the rectum, and thus plays a major role in any backward movement of this organ.This muscle needs intact pubourethral and uterosacral ligaments and an intact perineal body to optimize its various actions.3. The conjoint longitudinal muscle of the anus (LMA) is a striated muscle which constitutes the middle layer.It is vertically oriented, creates the downward force for bladder neck closure during effort and stretches open the outflow tract during micturition.It takes fibers superiorly from the levator plate (LP), the lateral part of the pubococcygeus and puborectalis muscle.It is well anchored by extra-anal sphincter (Courtney 1950).This muscle needs intact uterosacral ligaments for optimal action.4. The puborectalis muscle (PRM) originates just medially to PCM and traverses all three muscle layers.It is orientated vertically and runs forward medially below PCM.It is closely applied to the lateral walls of the rectum and surrounds them (Courtney 1950).
The lower layer of pelvic floor muscles is an important anchoring layer.It consists of perineal membranes and component muscles -bulbocavernosus, ischiocavernosus and the deep and superficial transverse perinei muscles.The deep transverse perinei muscle anchors the upper part of the perineal body to the descending pubic ramus.It is a strong muscle and it stabilizes the perineal body laterally.The external anal sphincter acts as a tensor of the perineal body and represents the principal insertion point of the LMA.The bulbocavernosus muscle stretches and anchors the distal part of the urethra.The ischiocavernosus muscle helps stabilize the perineal membrane and may act to stretch the external urethral meatus laterally via its effect of the bulbocavernosus.Between the extra-anal sphincter and the coccyx lies the postanal plate, a tendinous structure which also contains striated muscles inserting into the extra-anal sphincter (Petros 2010).
The striated rhabdosphincter of the urethra surrounds the urethra in the middle third of its length for approximatly 1,5 cm (Oelrich 1983).

Important connective tissue structures at the pelvic floor (figures 2 and 8)
At the pelvic floor at least 9 sites of connective tissue can be defined as loose.With regard to its function, P. Petros (2010) divides the connective tissue defects in three zones (figure 2).
The anterior zone, which reaches from the external meatus of the urethra to the bladder neck, embraces three important structures: The extraurethral ligament runs from the pubis anteriorly to the meatus urethrae anterior to the perineal membrane.
The pubourethral ligament, a ligament with key relevance for stress urinary continence, originates from the lower end of the posterior surface of the pubic symphysis and descends like a fan to insert into the pubococcygeus muscle and lateral part of the mid urethra (Zacharin 1963, Petros 1998).
The suburethral vagina acts as a hammock for the urethra.The antero-medial portion of the pubococcygeus muscles is attached laterally on each side of the hammock In the middle zone, which reaches from the bladder neck to the cervix, three further structures are important: The arcus tendineus fascia pelvis (ATFP) are horizontal ligaments which arise just superior to the pubourethral ligaments at the pubis symphysis and insert into the ischial spine.The vagina is suspended from the ATFP by its fascia, much like a sheet slung across two washing lines (Nichols 1989).The cardinal ligaments are attached to the cervical ring and pubocervical fascia and extend laterally towards and above the ischial spine.The cervical ring surrounds the cervix and acts as an attachment point for the cardinal and uterosacral ligaments as well as the pubocervical and rectovaginal fascia.It consists mainly of collagen.
The "pubocervical fascia" -a term still used by surgeons -stretches from the lateral sulci of the vagina to the anterior part of the cervical ring, it is a vaginal muscularis and fibromuscular wall (Corton 2009).
In the posterior zone, which reaches from the cervix to the anal canal, the following 3 structures can be loose.
The uterosacral ligaments arise from the sacral vertebrate S2,3,4 and attach to the cervical ring posteriorly.It is an effective insertion point of the downward muscle force, the longitudinal muscle of the anus (LMA).The rectovaginal fascia extends as a sheet between the lateral rectal pillars, from the perineal body below to the levator plate above.
It is attached to the uterosacral ligaments (USL) and the fascia surrounding the cervix.The perineal body lies between the distal third of the posterior vaginal wall and the anus below the pelvic floor.It is 3-4 cm long.According to DeLancey (1999), it is formed primarily by the midline connection between the halves of the perineal membrane.It is the insertion point of bulbocavernosus muscle and deep and superficial transverse perinei muscles.

Stress urinary continence and incontinence
During stress (coughing or straining) the intraurethral pressure rises in normal patients.The rise in pressure within the urethra precedes the rise in pressure in the bladder by 160-240 milliseconds (Enhorning 1961, Constantinou and Govan 1982, van der Kooi et al. 1984, Pieber et al. 1998).This means, that the increased pressure within the urethra during stress must be due to an active muscle contraction and cannot be a passive transmission of the abdominal pressure.
In addition to the contraction of the rhabdosphincter at midurethra, the PCM pulls the distal vagina forward to close the distal urethra (figure 3).Furthermore, the bladder and posterior vaginal wall is pulled backwards (by levator plate) and downwards (by LMA).
With intact pubourethral ligament the urethra is stretched and angulated to "kink" the proximal urethra (Petros and Ulmsten 1995).This action is an important closing mechanism, which, as known, helps many patients maintain continence after excision of the distal urethra.
The Integral Theory (1990Theory ( , 1993) ) states that "stress urinary incontinence ... derives mainly from laxity in the vagina or its supporting ligaments, a result of altered collagen/elastin".A hypermobile urethra results from loose connective tissue.In stress situations, abdominal forces stretch loose tissues in the anterior zone (pubourethral ligament, extraurethral ligament, hammock), leading to overlengthening of the rhabdosphincter.
According to Gordon`s relation between muscle length and muscle force, as soon as the muscle force diminishes … (by half/etc), the patient is stress incontinent.Overstretched connective tissue leads also to an increased radius within the rhabdosphincter and the urethra.According to Laplace's law, the pressure within the urethra correlates inversely to the radius within the rhabdosphincter.In loose connective tissue, the pressure within the urethra thus diminishes in line with the increasing radius.The Hagen-Poiseuille`s law is also helpful in describing continence.The resistance to flow within the urethra in stress situations correlates directly to the length of the urethra and indirectly to the radius within the urethra in the 4th power (Bush et al. 1997).Stress in patients with loose connective tissue will open the urethra.The stress flow then correlates to the radius of the urethra in 4th power.
In other words, loose connective tissue can lead to reduced muscle force by overstretching the muscle, reduced urethral pressure by increasing the radius within the rhabdosphincter, and reduced resistance to flow by widening the urethral radius.
These correlations have a major impact on interpretation of urodynamic results and should be considered in the future.

Normal micturition and abnormal emptying of the bladder
Micturition is another complex mechanism that has to be understood when performing pelvic floor surgery.Thus, not only sphincter relaxation and detrusor contraction have to be taken into consideration.EMG-measurements in the posterior fornix have demonstrated commencement of muscle contraction prior to commencement of voiding (Petros 2010).
Radiologically, it was shown that the anterior vaginal wall is stretched and moved backward and downward during micturition (figures 4b).The bladder also moves backward and downward and the proximal urethra funnels (figure 4a).This The posterior muscles (LP and LMA) only contribute in opening the bladder neck and urethra when the connective tissue architecture and its insertion points are intact in a way that they can pull normally (see figure 1).If the uterosacral ligaments are loose (insertion points of the LMA) or a cystocele is present the posterior forces cannot pull normally, the muscles are shortened or overstretched and have reduced force.Even a minor degree of prolapse can be the cause of defective micturition.Kinking of the urethra by prolapse can also be a cause of abnormal emptying of the bladder.A location of the tape too high up the bladder neck or proximal urethra as well as anterior fixation of the bladder neck after colposuspension can disturb funnelling of the urethra.

Stability at the bladder base by a tensioned vaginal wall, urgency and frequency
In their first publication of the "Integral theory" Petros and Ulmsten (1990) stated that "symptoms of stress and urge derive mainly from laxity in the vagina or its supporting ligaments, a result of altered collagen/elastin".Following their publication, evidence was increasingly found that supported their claim that a correlation between the prolapse and an overactive bladder exists (de Boer et al. 2010).
Figures 2, 3b and 5 show that the bladder lies on the vaginal wall.With effort the posterior vaginal wall is orientated horizontally and the bladder lies on this part of tensioned vaginal wall (figure 3b), which acts as a "trampoline".The vagina is attached to the pelvic rim by the uterosacral ligaments posteriorly, the arcus tendineus and the cardinal ligaments laterally as well as the pubourethral ligament anteriorly.Anterior and posterior muscle forces (red arrows in figure 5) add to tension the vaginal wall.While the slow twitch fibres are active when at rest, the fast twitch fibres are active during effort.At the bladder base stretch receptors are present which are connected by afferent nerves to the cortex (Wyndaele et al. 2008, Everaerts et al. 2008, Petros & Ulmsten 1990).Efferent nerves can activate the pelvic floor musculature (figure 5).Petros and Ulmsten (1993) postulated that urgency could lead to a premature activation of the micturition reflex.A lax vagina at the anterior, middle or posterior zone reduces the tension of the vagina below the bladder base, the stretch receptors can be activated by afferent nerves, the cortex gets the information of full bladder and this creates the sensation of urge.Prematurely the micturition reflex can be activated and even urge incontinence can occur.

Nocturia
Many patients with vaginal vault or uterine prolapse -even if of a minor degree -complain about nocturia.Figure 6 explains the mechanism that leads to nocturia..When the patient is asleep, the force of gravity pulls down the bladder base.Normally, with firm uterosacral ligaments, the bladder is held high (dotted line in Figure 6).When the patient is asleep and the uterosacral ligaments are loose, the pelvic floor muscles are relaxed, the bladder descends posteriorly, the bladder base is stretched and the stretch receptors "N" are stimulated.
Fig. 6.Mechanism of nocturia-schematic view-patient asleep.The pelvic muscles (arrows) are relaxed.As the bladder fills, it is pulled downwards by the force of gravity 'G'.In the normal patient, bladder descent is limited by the uterosacral ligaments "USL".If "USLs" are loose, the bladder descends more, the stretch receptors "N" are stimulated, the micturition reflex is activated at a low bladder volume, "nocturia".(from P Petros 2010, by permission)

Anorectal function, fecal incontinence and obstructive defecation
The anecdotal observation that midurethral slings and repair of loose uterosacral ligaments can cure fecal incontinence has led Petros and Swash (2008) to establish a new theory of anorectal function.A new complex musculo-elastic sphincter mechanism was detected.Its mechanism is similar to that of bladder neck closure.Directional muscle forces stretch the rectum backwards and downwards around an anus firmly anchored by the puborectalis muscle.Anorectal closure occurs when the backward muscle forces of LP and LMA stretch the rectum around the anus, which is anchored by PRM-contraction.Upon comparing Figure 3b with Figure 3a, the rectum above the anal canal has been markedly angulated (and closed) by muscle actions during effort.Upon relaxation of PRM, LP/LMA vectors open out the anal canal for evacuation (broken lines, Fig2) Fecal incontinence can occur when connective tissue at the anterior zone is loose.Then the insertion points of the puborectalis muscle are dislocated and the muscle is weak.Furthermore, the anterior insertion points of the levator plate are loose and the muscle is weak and the anorectal closure is weak, also.
When connective tissue at the posterior zone is loose, the muscles also cannot act optimally and fecal incontinence can occur.Lax uterosacral ligaments can explain rectal intussusception and obstructive defecation.The levator plate cannot tension the rectovaginal fascia.The perineal body is an important anchoring point and, if loose, it can contribute to fecal incontinence and obstructive defecation (Petros 2010, Abendstein andPetros 2008).

Pelvic pain
Many patients with vaginal vault prolapse or uterus prolapse report pelvic pain, a low abdominal dragging pain which occurs mainly in an upright position and is generally relieved in a lying position.This pain may be associated with vulvodynia.Both types of pain have been temporarily relieved by injection of local anaesthetic into the uterosacral ligaments (Bornstein et al 2005, Petros et al 2004), supporting the hypothesis that this pain is a referred pain arising from the inability of lax uterosacral ligaments to support the nerves running along the ligament (figure 7).These nerves are stretched by gravity or during intercourse to cause pain.This pain is almost invariably associated with other symptoms deriving from posterior zone laxity, Figure 8.In a recent study, restoration of uterosacral ligament tension using a posterior tensioned sling showed improvement in posterior zone symptoms as follows: nocturia >2/night 83%; urge-incontinence >2/day 78%; abnormal emptying, 73% ; pelvic pain, 86% fecal incontinence, 87% (Petros PEP, Richardson PA, 2010) 11.The association of pelvic floor dysfunctions and different zones of connective tissue looseness at the pelvic floor (figure 8) The three zones of connective tissue looseness (see above) are associated with different symptoms.Petros (2010) developed the diagnostic algorithm (Figure 8) through considering the pathophysiology of dysfunctions and through practical experiences with the patients that had different forms and degrees of descensus/prolapse of the vaginal wall.
Many symptoms are associated with these different forms of descensus/prolapse: stress urinary incontinence, abnormal emptying of the bladder, urgency and frequency, nocturia, faecal incontinence, obstructed defecation and pelvic pain.

Consequences of the diagnostic algorithm for surgical treatments
In the past surgery has only been performed for prolapse and stress incontinence.We now recognise that symptoms of different degrees and combinations can be present in different forms and degrees of prolapse, as seen in Figure 8.Because of the peripheral neurological origin of some symptoms such as urgency and pain, major symptoms may occur with only minimal prolapse.Therefore the new anatomical and functional findings, as summarized in Figure 8 have to be considered in modern pelvic floor surgery.
In daily practice, first, the different symptoms have to be identified with the help of a standardized questionnaire, for instance using Petros`s questionnaire (Petros 2010, pages 270-273).Then the existing pelvic floor defects are assessed.Very helpful are the diagnostic algorithm (Figure 8) and "simulated operations" (Petros 2010) to indicate the appropriate surgery.An example of a "simulated operation" is the controlled urine loss on coughing by applying unilateral digital pressure at midurethra (Pinch-Test).Another is exposure of latent stress incontinence by pushing the prolapse back into the vagina, and asking the patient to cough.
"Restoration of form (structure) leads to restoration of function" (Petros 2010).This principle directly applies Gordon's Law: exact restoration of the insertion points of the pelvic floor muscles allows the muscles to act optimally.The function -even if complex -should thus have the optimal chance to recover.
When repair of weak tissues by conventional techniques such as suturing is not possible (for example repair of a pubourethral ligament for cure of USI), or the recurrence rate is too high, the use of alloplastic materials is an option.Because normal function requires a neurologically complex co-ordination of smooth and striated muscle, any surgery must mimic the natural anatomy as closely as possible if it is to restore function.
The axis of the posterior vagina is nearly horizontal because the uterosacral ligaments insert dorsally between S2-4.Elevation of the vagina to the promontorium is too cranial, while fixation of the vagina to the sacrospinous ligament is too caudal.It is a surgical compromise to use these areas for easy and safe fixation but the site of the uterosacral ligament remains the optimal site for its reconstruction.The uterus needs to be conserved whenever possible.It is the central anchoring point for the posterior ligaments, the rectovaginal fascia and the pubocervical fascia.The descending branch of the uterine artery is a major blood supply for these structures, and should be conserved where possible even if subtotal hysterectomy is performed.
It is important to understand that tissue structure is often displaced laterally (e. g. cardinal ligaments, uterosacral ligaments, rectovaginal fascia, pubocervical fascia, hammock, perineal body).Surgical techniques, which bring the tissues together in the midline or bridge it with alloplastic tapes at the anatomically correct position, should be applied and further developed.Simply applying a large mesh provides a barrier to the prolapse and does not restore the damaged anatomy or function.Instead, such meshes have the tendency to shrink and reduce elasticity of tissues.Furthermore, they obliterate the organ spaces.This may cause pain, dyspareunia, and erosions and may negatively affect the dissection required in cases where the patient develops rectal or bladder carcinoma.The use of alloplastic materials has to be reduced to the necessary amount and their application sites carefully considered.The conventional techniques have to be evaluated following these fundamental principles (Liedl 2010, Wagenlehner et al. 2010) In order to minimize pain, surgery to the perineal skin and tension when suturing the vagina should be avoided.Vaginal excision should be avoided even in patients with large bulging prolapse.After repair of underlying ligamentous fascial defects, the vaginal wall contracts and will be more elastic than after excision.Tightness or elevation of the bladder neck area of the vagina as well as indentation of the urethra with a midurethral sling should be avoided in order to avoid urinary retention.
Looking at the bladder neck closure mechanism the midurethral tape should be positioned along the pubourethral ligament, which inserts retropubically.This seems especially important in patients with severe stress urinary incontinence or recurrence.The transobturatoric approach for tape insertion may be an option for mild and moderate cases.New techniques using mini tissue anchors are promising.The TFS (Tissue Fixation System) tensioned tapes (Petros 2010) accurately reinforce the main suspensory ligamentspubourethral (PUL), uterosacral (USL), cardinal (CL), arcus tendineus fascia pelvis (ATFP) and perineal body (PB) while bringing the laterally displaced tissues towards the midline (figure 9).This action more precisely restores the musculoelastic tension required to also restore function.The meshes with sling fixation transobturatorially or at the sacrospinous ligaments only produces long lasting barriers.At the moment the pelvic floor surgery is in a Fig. 2. Important muscles and connective tissue structure at the pelvic floor (from P. Petros 2010, by permission) Broken line below bladder signifies relaxation of PCM; LP/LMA vectors actively open out the urethra exponentially decreasing frictional resistance to micturition Defecation Broken line behind rectum signifies relaxation of PRM; LP/LMA vectors actively open out the anorectum, exponentially decreasing frictional resistance to defecation Petros has been developing the midurethral sling since 1986 based on research on the laxities of the vagina and supporting ligaments and loose connective tissue.; V=vagina; CX=cervix; R=rectum; PUL=pubourethral ligament; Bv=attachment of bladder base to vagina; LMA= conjoint longitudinal muscle of the anus; LP=levator plate; USL=uterosacral ligament.

Fig. 3 .
Fig. 3. Directional movements of bladder and urethra during effort.a) Lateral xray in resting position, sitting.b) Lateral xray during straining, same patient, shows forward movement of distal vagina and urethra and backward/downward rotation of proximal vagina and urethra ,around the pubourethral ligament (PUL) at the midurethral point.c) Muscle actions during effort-schematic view.PCM pulls the distal vagina forwards to close the distal urethra; LP/LMA stretch the proximal vagina and urethra backwards/downwards to close off the proximal urethra.(From PPetros 2010, by permission).

Fig. 4 .
Fig. 4. Normal micturition.a) Lateral xray, same patient as fig.3.During micturition, the bladder and vagina move backwards and downward, opening out the posterior urethral wall.b) Superimposed lateral xray.sAt rest (unbroken lines) and micturition (broken lines) vascular clips placed at midurethra "1", bladder neck "2" and bladder base "3".c) Muscle actions during micturition .PCM relaxes.This allows the posterior muscle forces LP/LMA (red arrows) to stretch vagina and posterior urethral wall backwards/downwards to open out the outflow tract.Same labelling as fig.3. (From P Petros 2010, by permission).

Fig. 7 .
Fig. 7. Pelvic pain caused by loose uterosacral ligaments (USL).Especially in the standing position, the uterus or vaginal vault prolapses under the influence of gravity 'G'.The unmyelinated nerves which run along the USLs are stretched by 'G', causing pain.(from P Petros 2010, by permission) This algorithm summarizes the relationship between structural damage (prolapse) in the three zones and the respective functions (symptoms).The size of the bar gives an approximate

Fig. 8 .
Fig. 8. Diagnostic algorithm.Pictorially elaborates the association between connective tissue looseness at different zones, their relationship with specific prolapses and symptoms, and how repair of the ligaments/fascia in each zone may cure or improve both the prolapse and the symptom(s).The size of the bars gives an approximate indication of the prevalence (probability) of the symptom.(modified after Petros 2010, by permission)

Fig. 9 .
Fig. 9.The use of tensioned tapes to strengthen the principal connective tissue structures which support the vagina, bladder, uterus and rectum: pubourethral ligament (PUL), arcus tendineus fascia pelvis (ATFP), cardinal ligament (CL), uterosacral ligaments (USL), perineal body (PB).These 5 structures are the effective insertion points of the directional muscle forces (arrows) which support the organs, and which open and close the urethra and anorectum, anteromedial part of pubococcygeus muscle (PCM), levator plate (LP) and longitudinal muscle of the anus (LMA).(from P Petros 2010, by permission)