The investigators believe that the application of non-linear methods of analysis using the ganglion and neural network technique will make it possible to analyse all of the complex data obtained in patients with hip osteoarthritis before and then after total hip replacement, and should allow us to identify a combination of objective variables to classify the surgery as " successful " or " unsuccessful ".

To this end, the study will take place as follows:

Step 1: Screening, and inclusion. Step 2: Evaluation of the hip osteoarthritis and analysis of locomotor activity Step 3: Total hip replacement Step 4: Clinical evaluation of locomotor activity carried out between 6 months and 1 year after the THR Step 5: Data analysis

Inclusion Criteria:

Control group:

• Subjects who have provided written informed consent
• Subjects covered by the national health insurance scheme
• Men or women aged between 25 and 85 years
• able to understand simple instructions and packaging instructions and able to give informed consent

Patients group:

• Patients who have provided written informed consent
• Patients covered by the national health insurance scheme
• Men or women aged between 25 and 85 years
• able to understand simple instructions and packaging instructions and to give their informed consent
• Suffering from hip osteoarthritis defined according to ACR criteria
• Most recent radiography examination less than 6 months earlier
• Radiological stage II, III or IV hip osteoarthritis according to the Kellgren and Lawrence classification
• Presenting with an indication for total hip replacement, according to the surgeon's usual criteria

Exclusion Criteria:

Control group:

• Hip osteoarthritis or other arthrosis in the lower limbs
• Pregnant or breast-feeding women
• Disorders that may interfere with gait analysis
• Disorder that may be destabilized by gait analysis
• Neurological disease and/or motor neuron disease

Patients group:

• Contra-indication for total hip replacement
• Repeat surgery for total hip replacement
• Impossibility to use a standard implant
• Pregnant or breast-feeding women
• Inflammatory flare of the hip osteoarthritis
• Disorder that may interfere with gait analysis
• Disorder that may be destabilized by gait analysis
• Rapidly destructive hip osteoarthritis
• Neurological disease and/or motor neuron disease
• Hip dysplasia requiring THR to be completed using a graft

hip osteoarthritis indication for total hip replacement