Multimodal Bio-mechanical Analysis of Adult Spinal Deformity With Sagittal Plane Misalignment

Inclusion Criteria: * Pathological group 1. Age \>= 45 years 2. Diagnosis of adult congenital, degenerative, idiopathic or iatrogenic spinal deformity 3. Scoring at least 25 out of 30 on Mini Mental State Examination 4. Ability to walk at least 50 meters distance independently without a walking aid 5. Sagittal malalignment: PI-LL ≥ 25 degrees; sagittal vertical axis \>5cm; pelvic tilt \>25° and/or thoracic kyphosis \> 60° and/or coronal malalignment: thoracic scoliosis 30 ≥ degrees; thoracolumbar/lumbar scoliosis ≥ 30 degrees; global coronal malalignment \>3cm, posterior spinal fusion \> 4 levels + iliac fixation. 6. Ability and willingness of patient to attend follow-up visits and complete patient questionnaires 7. Completed patient informed consent * Control group 1. Asymptomatic adults not suffering from a spinal deformity leading to a pathological sagittal alignment presenting as volunteer in the University Hospitals Leuven, Belgium 2. Age \>=45 years old 3. Scoring at least 27 out of 30 on Mini Mental State Examination 4. Ability to walk at least 1000 meters distance independently without a walking aid 5. Ability and willingness of patient to attend follow-up visits and complete patient questionnaires 6. Completed patient informed consent Exclusion Criteria: * Pathological group 1. Age \< 45 years old 2. Absence of adult spinal deformity 3. Scoring less than 25 out of 30 on Mini Mental State Examination 4. Non-ability to walk at least 50 meters distance independently, with or without a walking aid. 5. Missing patient informed consent 6. Patients presenting with a neurological disease affecting balance other than Parkinson's disease such as stroke and/or Vestibular lesion 7. 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) 8. BMI\>30 * Control group 1. Age \< 45 years old 2. Backpain and/or Sciatica at time of the study 3. Presence of adult spinal deformity leading to a pathological sagittal alignment 4. Scoring less than 27 out of 30 on Mini Mental State Examination 5. Non-ability to walk at least 1000 meters distance independently without a walking aid 6. Missing patient informed consent 7. Patients presenting with a neurological disease affecting balance such as Stroke, Parkinson's disease and/or Vestibular lesion 8. 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) 9. BMI \> 27