Biomechanical modification 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). One potential drawback is that modifications due to (aesthetic) plastic surgery are often too little to be revealed by motor control tasks, making it difficult to measure the time course of body schema readaptation. The aim of our study is measuring the capability of the body scheme to re-adapt to significant and abrupt changes, such as the distribution of mass centers, and in particular to assess what is the time course of such re-adaptation. For this reason, we have carried out a longitudinal study on postural modifications on a population of female patients (N = 30) who were subjected to additive or reductive plastic surgery. Posture and stabilometry evaluations were performed before surgery (T0), and after 1 months (T1), 4 months (T2), and 1 year (T3). Posture was reconstructed from spatial tracking system (FastrackTM Polhemus) recordings. Stabilometry analysis was performed by force platform (Globus Italia). The results document a modification in posture and a significant increase in the sway area after body mass alterations. Posture and stabilometry data return to equilibrium after 1 year. Our data suggest that posture control relies on, at least in part, feedforward than only on feedback strategies.