**2. Context and paper targets**

In pregnancy, a large number of changes are observed in the female body. The main reason for the changes is to cope with the growing foetus's demands and also to protect the

### 4 Injury and Skeletal Biomechanics

woman's health. The changes are mostly controlled by the endocrine system (hypnosis, adrenal, and thyroid glands, placenta, etc.). The system modifies the production of hormones which influence the whole body. The hormonal activity changes the mechanical properties of tissues and together with anatomical modification (growing) affect body posture. One of the organs that are directly impacted is the pelvic floor.

The Women's Pelvic Floor Biomechanics 5

In pregnancy the whole musculoskeletal system is influenced by relaxin, which is produced by the placenta, and corpus luteum. They both control the ligamentary apparatus by inhibiting collagen synthesis that amplifies the activity of collagenase and consequently the ligaments of the pelvic girdle and spine become looser. The loose ligaments and weight of the pregnant uterus increase lumbar lordosis. The whole process results in modifications of movement stereotypes. The modification does not only arise from mechanical principles but in particular form the urgency of seeking a relieving posture. A significant role also played by the fact that m. levatoru ani and the thoracic muscles are functionally engaged in the active muscle chain. In the conducted experiments, the activity of chosen muscles was detected by EMG testing and the performance of movements or the quality of posture was

Nowadays, the topic of normal gait is discussed worldwide by academics (mid gait - Young, 1997). It is an activity which is hardly avoided by pregnant women even in the latter stages of pregnancy. In addition, a unified methodology for evaluating gait has not been invented

Atkinson (1999) compared 3D analysis of gait among one pregnant and one non-pregnant woman. The gait was recorded on video. The subjects were labelled with markers on the acromion, the most distal rib, trochanter major, epicondylus lateralis femoris, malleolus laterilis, and the navel. The data were evaluated by using Motion Capture software and Motion analysis. The results showed that there were significant differences neither in the lumbar spine curvature (the maximum difference about 10 °), gait speed nor flexion and

Bird et al (1999) observed gait among 25 pregnant women at the beginning of gravidity. The

Butler et al (2006) studied the ability of keeping balance and stability. Moreover, it was tested if falling in pregnancy was related to the decreased postural stability. The reason for that was the fact that almost one quarter of pregnant women suffered a fall. The number is comparable with people who are over 65 years old. Twelve pregnant and non-pregnant women (average age 31) took part in the experiment. At the 11th – 14th, 19th – 22nd, and 36th – 39th week of pregnancy and 6 – 8 weeks after birth the markers were placed on the participants and their gait was recorded by a 3D device. The observed parameters stayed relatively the same within both groups of participants. However, both the extension of the hip joint and the flexion of the knee joint increased at the end of the standing phase (this phenomenon is usually guided by greater extension of the knee joint between the half and the end of standing phase). The results also showed no difference in the width of the base and the position of the thorax during walking cycles. The speed of gait was increasing together with the length of steps from the first to the third trimester (p 0.05). There was found no difference in the postural stability between the groups of the women in the first trimester of pregnancy. Furthermore, the women were also tested standing with closed eyes.

results showed dilatation of the weight-bearing base in pregnancy.

yet and therefore the published data about gait in pregnancy has varied dramatically.

measured by the kinematic-dynamic analysis.

*3.1.1. Gait* 

extension in the hip joint.

The women's pelvic floor is traditionally defined as a ligament-muscular apparatus that provides a dynamic support to the urethra, bladder, vagina and rectum. It can be divided into the supporting and suspensory parts.

The supporting part is formed by muscles (m. coccygeus, m. levator ani) that create a thin funnel. The funnel is ended by a hole which establishes a corridor for above mention organs. M. levator ani is directly connected to the vaginal muscle. According to the phylogenetic view, the coccygeus muscle (m. coccygeus) is a skeletal muscle and therefore it is directly connected to the musculoskeletal system.

The suspensory part is a fibrous component that is termed the endopelvic fascia. It is a coherent system that surrounds the vagina and connects to the pelvic walls. The fascia's segments are conservatively named the pubocervical fascia, rectovaginal fascia, cardinal ligaments, and sacrouterine ligaments.

The aforementioned muscles and ligaments guarantee the proper function of the pelvic floor. When the function is unbalanced, it causes a fall and disorganization of organs. These changes strongly affect body posture. While muscular problems are usually solved by suitable physiotherapy treatment, problems of the suspensory apparatus are mostly fixed by surgical approaches when an implant is frequently installed.

This paper discusses the influence of pregnancy on the pelvic floor. In and after pregnancy the pelvic floor is even more loaded and stressed and therefore the eventual dysfunctions multiply related unpleasant effects. The main goal is to discover the structural disorders of suspensory apparatus and rheological expression of endopelvic fascia properties. The outcome of this study helps to design better implants and which mechanical properties are not dangerous due to increasing local mechanical stress.
