Biomechanic measures and sense motor control of body posture after plastic surgery

Plastic surgery offers a quite unique window on abrupt and permanent modifications of a human´s body schema. Its impact is comparable to amputations or other severe injuries, with the evident advantage from the experimenter´s (and patient´s) point of view that it is planned, allowing longitudinal studies and quantification of the weight and distribution of modified bodily masses (e.g., weight of the prosthesis).The position and orientation through space of body parts can be reliably assessed with the Fastrak™ system (Polhemus, Colchester, Vermont, USA) that is used for static and dynamic biomedical evaluations. It is an electromagnetic three-dimensional tracking system locating the position and orientation of up to four sensors placed on relevant body parts. It provides real-time, with six degrees of freedom, measurements, determining sensor position and orientation through space. The Fastrak system gives two modalities for posture evaluation, the visualization of the relative angles and the study of COM (the best parameter for comparisontime). It has been used to assess the reproduction of a neutral lumbo-pelvic position following flexion movements, primary and coupled rotations of the thoracic spine and to assess the reproducibility of spine position sense measurements. Stabilometry is a reliable method to quantify the position of body centre of pressure (COP). The aim of our study is to measure the capability of the body schema to readapt to significant and abrupt changes, such as distribution of mass centers, and in particular to assess what is the time course of such re adaptation. For this reason, we have conducted a longitudinal study on postural modifications on a population of women patients who were subject to additive or reductive plastic surgery.