Lumbar surgery is the most common treatment for chronic disabling low back pain with degenerative disc disease. There are few elements to objectively evaluate the improvement of the motor control after surgery and the motor adaptation capacities of the patients.

The impact of lumbar surgery on complexity in this painful context has never been studied. Theoretically, the restriction of mobility imposed by lumbar surgery should limit the subject's adaptive capacities (of one or more lumbar segments) and thus reduce complexity. Nevertheless, improvement in pain intensity levels could allow the patient to find better motor adaptation capacities, necessary for a positive evolution in the long-term.

The aim of this study was to investigate the evolution of gait complexity in chronic low back pain patients pre- and post-surgery. If surgery improves the adaptability of walking through an antalgic benefit exceeding the induced stiffness, the complexity of walking should be superior after surgery.

This is a proof-of-concept study in which the study investigators hypothesize that measuring complexity by fractal analysis during a walking task will show the increase in gait complexity induced by lumbar surgery at 3 and 6 months after surgery.

Inclusion Criteria:

• Patients with chronic low back pain requiring prosthesis or arthrodesis surgery on one or two levels
• Subject affiliated or beneficiary of a health insurance plan.
• The patient must have given their free and informed consent

Exclusion Criteria:

• Patients with organic low back pain (infection, tumor, inflammatory rheumatism)
• Patient with a neurological deficit (cauda equina syndrome or motor testing MRC < 3 on a muscle group of the lower limbs)
• Patient who has already undergone lumbar surgery (except single discectomy)
• Patient with serious concomitant pathologies
• Patients participating in a therapeutic study prohibiting participation in another study
• Patient in an exclusion period from a different study
• It is impossible to give the subject informed information
• Patient is unable to express consent
• The patient is under safeguard of justice or state guardianship
• Patient is pregnant, parturient or breastfeeding

Patients with chronic low back pain requiring prosthesis or arthrodesis surgery for their lumbar pathology (surgery on one or two levels) followed at the Nîmes University Hospital or at the Grand Sud Polyclinic.