The aim of this study is to investigate the possible effects that a motor limitation at the peripheral level might have on the ability to visually discriminate others' actions.

Previous literature has shown that specific motor skills (motor expertise) facilitate the visual discrimination of domain-specific actions, and that these motor experts' superior abilities might be mediated by areas not only responsible for the visual recognition of movements (as it happens in non-expert subjects) but also involved in motor planning. Similarly, impairment in the motor system due to neurological damage modulates not only the ability to perform movements but also the ability to discriminate and predict the temporal course of observed actions.

Based on these findings, it has been hypothesized that the motor representations of gait, despite being a hyper-learned motor pattern, might be subjected to modification as a result of an impairment of walking caused by a peripheral functional limitation in the lower limbs as the one characterizing orthopaedic patients who underwent a surgical operation for total knee arthroprosthesis. In this protocol, patients are thus required to perform visual discrimination tasks based on the observation of movements performed with either the upper or lower limbs, and their performance is expected to correlated with their functional impairments in movement execution.

These results would indicate that the (in)ability to perform a movement might have an impact on its representation at the central level and on internal motion simulation capabilities, which also influence the ability to visual discriminate others' actions through action-perception transfer: this would suggest that rehabilitation in orthopaedic patients should take into account (and restore) such a central impairment in motor representations.

Inclusion Criteria:

• Participants must be able to understand instructions and have no history of neurological or psychiatric disorders.

Exclusion Criteria:

• History of neurological or psychiatric disorders.

Orthopaedic patients and age-matched healthy controls.