Gait alterations occur as a result of postural adaptations undertaken by the body to accommodate the increase in body mass during pregnancy. This includes changes in the alignment of the musculoskeletal system and an anterior displacement of the centre of gravity.
With a major part of the body mass gain concentrated in the abdominal area, some of the more prominent postural changes include increased lumbar lordosis, hyperextension of the knee, anterior tilt of the pelvis and a weakening of the medial longitudinal arch.
Changes in foot morphology over the course of pregnancy are triggered primarily by the enlarged contact area between the arches of the foot and the ground. This results in modifications in the foot structure such as an increase in foot width, foot length and a decrease in arch height.
Accumulation of fluid in the soft tissues of the foot causes edema and a subsequent expansion in foot volume leading to increased discomfort and difficulty while walking.
Wen-Ko Chiou, of the Department of Industrial Design at the Chang Gung University, published an in-depth study on the influence of body mass on foot dimensions during pregnancy.
A hundred pregnant women were asked to complete a self-report questionnaire to evaluate subjective foot complaints. Thirty of these women had their feet measured from the twentieth week of the gestation period until labour.
Body mass was found to account for more than 90% of the variation in foot dimensions with a lowering of the medial arch and a gradual increase in foot length, foot width and foot surface area from the beginning of the twentieth week until the thirty-eighth week of gestation.
Plantar pressure modifications during gait in pregnant women were analysed in detail by Bertuit et al. by performing gait trials on 58 women in their last 4 months of pregnancy, nine postpartum women and 23 healthy nonpregnant women.
Peak pressure, contact area and peak time were observed to decrease for the forefoot and rearfoot whilst increasing significantly for the midfoot.
Regarding the gait strategy adopted by pregnant women, Bertuit et al. concluded that there “seemed to be a significant lateralisation of gait with an increased contact area of the lateral midfoot, and reduced pressure with a late peak time on the medial forefoot.”
The implication of these findings can help in successfully establishing a gait pattern specific to late pregnancy as plantar pressures are determined to have characteristics that could help maintain a stable and safe gait.
Hormonal changes induced by pregnancy such as an increase in the production of the hormone relaxin leads to enhanced ligament laxity, increasing the mobility of the pelvic complex and the peripheral joints. There is also an increase in subtalar and first metatarsophalangeal joint ranges of motion.
Customised orthotics provide the support needed by the feet to adjust to the biomechanical changes produced in relation to body mass gain during pregnancy, particularly gait modifications through the gestation period.
In addition to optimally supporting the medial longitudinal arch, custom made orthotics such as MASS4D® can help in the even distribution of plantar pressure and re-alignment of the musculoskeletal system to manage postural imbalances in the body such as increased lumbar lordosis and sagittal pelvic tilt.
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