**1. 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

<sup>\*</sup> Corresponding Author

The Role of Altered Connective Tissue in the Causation of Pelvic Floor Symptoms 5

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

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

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

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 and Ulmsten

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

1993, Petros and Ulmsten 1997) and their significant role in pelvic floor dysfunctions.

al. 2011) can be avoided at least with some patients.

example, due to lax connective tissue attachments.

**3. Pelvic floor muscles and their functions (figure 2)** 

leakage ceased.

2010):

avulsions have been reported at the pelvic floor (Dietz and Lanzarone 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 and Ulmsten 1990, 1993). The new developments and the recent focus on connective tissue are important, not least because looseness of tissues can be repaired surgically..
