The main objective of this multicentric, prospective and interventional study is to assess the feasibility of multimodal prehabilitation in patients aged 75 years or older with surgical indication for coxarthrosis or severe gonarthrosis

This study consists of a pre-established surgical preparation program in cooperation with physiotherapists or physical activity instructors, dieticians, psychologists, physical therapists and nurses.

This innovative program improves muscle strength, balance and walking of the study patients. It also allows for faster and better recovery of their physical fitness and intellectual abilities after surgery.

These interventions will be performed in day admission (DA) and at home and will consist of training, a diet program to strengthen the muscles and balance of the patients participating in the study.

Patients who agree to participate in the study will receive interventions for 6 weeks prior to surgery, partly in a day hospital and partly at home, including:

• Muscle rehabilitation developed with a physiotherapist or physical activity instructor
• Nutritional support (dietician at 1st, 3rd, and 6th day admission (DA), referring geriatrician)
• Cognitive and physical stimulation "Exergame" (Genious Healthcare); with only cognitive exercises at home
• Psychological support by a psychologist
• Information in the form of videos on the main risks and important points to know and prepare before and after surgery
• 1 follow-up call per week made by the PRE4OS referent between each day admission (DA) to assess patient satisfaction, any limitations encountered, possible exercises at home, the occurrence of possible adverse effects
• 1 hour per week home adapted physical activity session by the Siel Bleu association

Inclusion Criteria:

• Age ≥ 75 years
• Surgical indication for total hip or knee replacement for hip or knee osteoarthritis.
• Minimum time of 6 weeks between inclusion visit and date of surgery
• Physical (excluding coxarthrosis or knee osteoarthritis) and cognitive capacities to follow a prehabilitation program (assessment by the geriatrician)
• Proximity between place of life and hospital to go to the center for pre-rehabilitation
• Good understanding of the French language
• Benefiting from social coverage
• Have read the information notice and have consented to participate in the study by signing a written consent

Exclusion Criteria:

• Urgent surgery (trauma, acute dislocation)
• Neurocognitive disorders at a moderate or severe stage (Mini Mental State Examination (M.M.S.E) ≤20), or not evaluable and not allowing to participate in the prehabilitation program
• Lack of social coverage (beneficiary or beneficiary)
• Adult persons subject to a legal protection measure (curatorship, guardianship and safeguard of justice)
• Refusal to participate
• Hospitalized patients ( the living space can be the home or thelon term care).