Patient case (clinical description): A 47-year-old woman comes to the office complaining of pain in the calf and knee when she bends down. The pain limits her activity. Her medical history is significant for osteoarthritis, for which she uses nonsteroidal anti-inflammatory drugs (NSAIDs) for the past two years. She is living with her husband and has 3 children. She doesn't smoke but drinks alcohol occasionally. Her vital signs are normal. On physical examination, there is a small effusion in the right knee. The effusion grew a little larger and she developed a tender swelling in the popliteal fossa and calf. Both the pain and swelling worsened as she bent and straightened her knee.

Patient's own account: I'm a 47-year-old woman, married with 3 kids. I don't smoke and I drink occasionally. I went to the doctor because of pain in my calf and knee when I was bending down. This has been limiting my daily activities. I have been diagnosed with osteoarthritis for which I have taken anti-inflammatory drugs for the past 2 years. The doctor saw a small fluid buildup in my right knee. This buildup became a bit bigger and I have a swollen calf. The pain is worse when I bend and straighten my knee.

Clinical trial: Comparison of the Efficacy, Tolerability and Safety of actiTENS to Those of Level 2 Analgesic Treatments.

Eligibility criteria:
Inclusion Criteria:

          -  Adult > or = 55 years.

          -  Being monitored by a rheumatologist in private practice or in a hospital.

          -  Presenting nociceptive pain:

               -  chronic (for at least 3 months),

               -  secondary to knee osteoarthritis confirmed by x-ray: stage 2 and over according
                  to Kellgren and Lawrence.

          -  Of moderate to severe intensity equal to or above 4 on a numerical scale of 0-10.

          -  In a situation of analgesic therapy failure for level 1 analgesics:

               -  paracetamol and NSAIDS,

               -  Prescribed at therapeutic dose : 4 g/d of paracetamol and 1200 mg/d of ibuprofen
                  or equivalent (analgesic dose),

               -  For at least 2 weeks,

          -  Requiring a level 2 prescription.

          -  Affiliated to social security insurance.

          -  Informed of the concept and agreeing to use the TENS as a non-medicinal analgesic
             treatment.

          -  Capable of understanding how to use the TENS and the level 2 analgesic treatments.

          -  Intellectually and physically able to participate in the study in the opinion of the
             investigator.

          -  Owns a Smartphone to be able to download the actiTENS application.

        Exclusion Criteria:

          -  Current or previous allergy to the actiTENS electrodes.

          -  On-going or planned pregnancy and absence of effective contraception (except for
             menopausal women).

          -  Neuropathic pain with a DN4 result > 4/10 or with a positive response to one or more
             questions in the DN4 clinical examination.

          -  Osteoarthritis flare.

          -  Surgery planned in the following 6 months.

          -  History of multiple operations on the knee concerned.

          -  Medicinal or non-medicinal treatments which could influence the pathology being
             studied.

          -  Modification of medicinal or non-medicinal treatments planned in the following 6
             months.

          -  Current participation in another study.

          -  Presence of another painful condition which could perturb the evaluation.

          -  Patient with an absolute contraindication to TENS or level 2 systemic analgesic
             treatments recommended for the treatment of chronic pain of moderate or severe
             intensity.

          -  Patient unable to express his/her consent or deprived of liberty.

          -  Patient with cognitive disorder or behaviour rendering him/her unsuitable to follow
             the instructions for this study.

          -  Patient not affiliated to a social security system.
No condition on gender to be admitted to the trial.
No healthy subjects accepted to join the trial.
Subject must be at least 18 Years old.
Subject must be at most 55 Years

Eligibility (NLI label): Entailment