The team will investigate the user's intention to move by using cortical activity during a sit to stand movement performance in people with a transfemoral amputation and able-bodied individuals. The goal is to get insights in pre-movement onset indicators within the brain that initiate the sit to stand transfer. The hypothesis is that people with a transfemoral amputation use different brain locations for motion planning compared to able-bodied individuals.

The evolution of lower limb prostheses has made considerable progress in the past decades. There has been a transition from passive (e.g. Total knee®, Össur) to quasi-passive (e.g. C-leg®, Otto Bock) and eventually to active prostheses (e.g. Power knee®, Össur). The development always focused on an amputation as a primary peripheral disorder. For example, manufacturers have been searching to compensate the loss of muscle mass by adding torque into the prosthesis. However, few considerations have yet been taken to the fact that central adaptations are also observed after amputation in terms of neuroplasticity and reorganization.

The atypical motion planning strategies of people with a lower limb amputation (LLA) could possibly be related to the challenges that they experience during daily activities, such as the sit to stand transfer. Standing up from a chair is a relevant clinical problem and current devices do not yet relieve the asymmetrical loading. A few studies have already investigated the muscular activity during a sit to stand movement in people with a LLA and able-bodied individuals. The movement is characterized by a forward displacement of the centre of mass with the highest activation of the m. gluteus maximus, m. adductor magnus and m. biceps femoris.The sit to stand transfer is a potential movement to investigate brain activity incorporating the advantages and disadvantages of EEG measurements.

Until now, the development of lower limb prostheses approaches people with a LLA as a peripheral disorder whereas relevant central adaptations are also observed. Therefore, the purpose of this study is to identify the cortical activity that is responsible for successfully completing a sit to stand transfer. The hypothesis is that different brain locations are activated in people with a transfemoral amputation for motion planning compared to able-bodied individuals.

Inclusion Criteria:

• Age: 25 - 75 years
• Gender: men and women
• Level of amputation: unilateral transfemoral
• Vascular or traumatic cause of amputation
• Medicare Functional Classification Level25: K3-4
• Participants are able to stand up from a chair and return to the seated position without support of their hands for ten repetitions
• Participants wear their prosthesis for at least 8 hours/day (Prosthetic use has been shown to have an influence on functional reorganization)
• No cognitive impairment. This will be objectified with the mini-mental state examination (score on 30)

Exclusion Criteria:

• Any neurological disease
• No upper limb or bilateral amputation