Inclusion Criteria:  Pathological group  Adults suffering from a spinal deformity with or without sagittal misalignment presenting at the outdoors spinal clinic in the University Hospitals Leuven campus Pellenberg, Belgium Age > 18 years old and < 79 years old Scoring at least 25 out of 30 on Mini Mental State Examination Ability to walk at least 50 meters distance independently without a walking aid All subjects participating in study number 2 and 3 should also be able to walk 10 minutes on a instrumented treadmill to obtain a complete movement analysis with dynamic EMG Ability and willingness of patient to attend follow-up visits and complete patient questionnaires Completed patient informed consent  Control group  Asymptomatic adults not suffering from a spinal deformity leading to a pathological sagittal alignment presenting as volunteer in the University Hospitals Leuven, Belgium Age >18 years old and < 79 years old Scoring at least 27 out of 30 on Mini Mental State Examination Ability to walk at least 1000 meters distance independently without a walking aid Ability and willingness of patient to attend follow-up visits and complete patient questionnaires Completed patient informed consent  Exclusion Criteria:  Pathological group  Age < 18 years old and > 79 years old Absence of adult spinal deformity Scoring less than 25 out of 30 on Mini Mental State Examination Non-ability to walk at least 50 meters distance independently, with or without a walking aid. Missing patient informed consent Patients presenting with a neurological disease affecting balance other than Parkinson's disease such as stroke and/or Vestibular lesion Patients with a current history of diagnosed musculoskeletal disorders of the trunk and/or lower extremities affecting the motor performance such as severe hip arthrosis with or without flexion contracture, severe knee arthrosis, severe ankle arthrosis, severe leg length discrepancy (> 3 cm)  Control group  Age < 18 years old and > 79 years old Backpain and/or Sciatica at time of the study Presence of adult spinal deformity leading to a pathological sagittal alignment Scoring less than 27 out of 30 on Mini Mental State Examination Non-ability to walk at least 1000 meters distance independently without a walking aid Missing patient informed consent Patients presenting with a neurological disease affecting balance such as Stroke, Parkinson's disease and/or Vestibular lesion Patients with a current history of diagnosed musculoskeletal disorders of the trunk and/or lower extremities affecting the motor performance such as severe hip arthrosis with or without flexion contracture, severe knee arthrosis, severe ankle arthrosis, severe leg length discrepancy (> 3 cm) BMI > 27