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Randomized double‑blind trial of harpagophytum procumbens and arnica montana mother tincture cream for knee osteoarthritis pain in adults

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on knee osteoarthritis, a long‑lasting joint condition that causes knee pain, stiffness and reduced ability to move. The investigational treatment is a topical cream called ARTENSIUM. The cream contains two plant extracts, harpagophytum procumbens and arnica montana, which are thought to have soothing properties. A matching placebo cream that looks the same but does not contain the active extracts is also used for comparison.

The purpose of the trial is to see whether the active cream reduces pain more than the placebo after two weeks of use. Participants will be randomly assigned to receive either the active cream or the placebo and will apply the assigned product to the painful knee twice daily for 14 days. Pain will be recorded using a simple 0‑to‑10 rating called a VAS and a questionnaire called the KOOS that asks about pain, symptoms, daily activities, quality of life and overall function. Use of any extra pain‑relieving medicines, such as analgesic tablets, NSAIDs or opioids, will be noted in a diary. The study does not involve any invasive procedures and participants will be asked to visit the clinic at the start, after one week and after two weeks for brief check‑ins.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Receive medication and instructions

    You will be given a tube that looks identical whether it contains artensium cream (the test product) or placebo cream (the inactive product). the label will not indicate which one you have.

    The study staff will explain how to store the tube, how much cream to use, and the schedule for applying it to your knee.

  2. Step 2

    Baseline assessment (day 0)

    You will complete questionnaires that measure knee pain, symptoms, daily activities, quality of life, and overall satisfaction. These questionnaires are known as the KOOS (knee injury and osteoarthritis outcome score) and a visual analogue scale (pain VAS) for pain intensity.

    The most painful knee will be identified, and all measurements will refer to that knee.

    You will also be asked to record any pain medication you have taken before the study starts.

  3. Step 3

    First cream application (morning of day 0)

    Apply a thin layer of the cream to the skin of the identified knee. The recommended amount is three dose units per application (the amount indicated on the packaging).

    The cream is for cutaneous use only; do not apply to broken skin or other body areas.

    After applying the cream, you will wait and record your pain level before application, then again 2 hours and 4 hours after the first use.

  4. Step 4

    Daily cream application (days 1–14)

    Each morning, apply the same amount of cream (three dose units) to the same knee.

    Continue this routine for a total of 14 days, including the first day.

    If you miss a dose, do not double the next one; simply continue with the regular schedule.

  5. Step 5

    Pain recording during the study

    On the first day, you will note your pain level before the cream, then 2 hours and 4 hours after application using the pain VAS scale.

    On day 7 and day 14, you will record your pain level before the morning application and after the application in the same way.

    These records help evaluate how the cream affects your knee pain over time.

  6. Step 6

    Use of rescue medication

    If you need additional pain relief, you may take standard analgesics such as paracetamol, non‑steroidal anti‑inflammatory drugs (NSAIDs), or opioids.

    Every dose taken must be written in the patient diary, including the type of medication, amount, and time of intake.

    The study will track the total amount of rescue medication used, the maximum daily amount, and the number of days you needed it.

  7. Step 7

    Mid‑study visit (day 7)

    You will complete the KOOS subscales (pain, symptoms, activities of daily living, quality of life) and the pain VAS again.

    You will also fill out the Patient Global Impression of Change (PGIC) questionnaire, which asks how your knee feels compared with the start of the study.

    The diary you have been keeping will be reviewed for completeness.

  8. Step 8

    Final visit (day 14)

    You will repeat all questionnaires performed on day 0 and day 7, including KOOS, pain VAS, and PGIC.

    You will answer additional questions about overall satisfaction with the product, ease of spreading, texture, odor, visual appearance, and intention to reuse the cream.

    Any remaining cream will be returned, and the study staff will collect your diary for final analysis.

Who can join the trial?

8 criteria

  • Be between 50 and 75 years old.
  • Have knee osteoarthritis diagnosed according to the American College of Rheumatology (ACR) criteria, which are standard doctor guidelines; a knee radiograph (X‑ray) must have been taken within the last 24 months.
  • Feel mild to moderate knee pain, measured with a VAS (Visual Analogue Scale) score of at least 30 mm and no more than 60 mm.
  • Report that knee pain has increased over the past 15 days compared with the usual level.
  • Have not changed any non‑pharmacological treatments such as physiotherapy in the three weeks before joining; if physiotherapy is ongoing, it must have stayed the same.
  • Receive, read, and understand the study information sheet and sign the informed consent form.
  • Be able to attend scheduled study visits, walk without a wheelchair or walking frame, and apply the study cream independently or with assistance.
  • Be able to follow all other study rules and requirements.

Who cannot join the trial?

25 criteria

  • Taking any opioid pain medication right now, no matter how it is given or why you use it.
  • Having excess fluid swelling inside the study knee (known as knee joint effusion).
  • Feeling pain that actually comes from the lower back, the sacroiliac joint (where the spine meets the pelvis), or the hip instead of the knee.
  • Having active cancer at the time you join the study.
  • Receiving any cancer treatment such as chemotherapy, hormone therapy, targeted therapy, or immunotherapy, even if it is maintenance treatment.
  • Having had surgery on the study knee within the past 3 months.
  • Having had mesotherapy (small injections of medicine into the skin) on the study knee within the past 3 months.
  • Having any acute skin problem that is inflamed or infected, such as open wounds, eczema, or a skin rash.
  • Having any chronic or acute health problem that the doctor thinks would make the study unsafe for you (for example, nerve‑related pain called neuropathic pain) or a serious infection that could affect short‑term health.
  • Having a suspected or confirmed acute infection or inflammation when you start the study, shown by symptoms or a blood test called CRP that is three times higher than normal.
  • Having received an injection directly into the study knee (intra‑articular injection) within the past 3 months.
  • Taking aspirin at doses used for pain relief or anti‑inflammation (low‑dose aspirin for blood thinning is allowed).
  • Being a woman who could become pregnant and is not using effective birth control, or being pregnant or breastfeeding.
  • Having a known allergy to any ingredient in the study cream or its placebo, especially the cleaning agent chlorhexidine. A small skin test will be done on the first day.
  • Being in prison or under legal protection measures as defined by French law.
  • Not being covered by the French social security system.
  • Having any condition that the doctor believes would make participation unsafe or would prevent you from following the study rules.
  • Being enrolled in another clinical study at the same time.
  • Using non‑steroidal anti‑inflammatory drugs (NSAIDs) either systemically or on the skin that cannot be stopped when you join the study.
  • Taking the pain medicines nefopam or metamizole, no matter how they are given or why.
  • Being on any form of corticosteroid therapy (steroid medicines), regardless of how they are taken.
  • Having a total or partial knee replacement (prosthesis) in the study knee.
  • Having chronic rheumatologic diseases such as chronic low back or hip pain, rheumatoid arthritis, systemic lupus erythematosus, psoriatic arthritis, spondyloarthritis, chronic bone infection of the knee (osteomyelitis), loss of blood supply to the femur or tibia (avascular necrosis), nerve root problems in the lower back (lumbo‑radiculopathy), bone or cartilage tumors, gout, Paget’s disease, calcium pyrophosphate crystal disease (chondrocalcinosis), tendinitis, bursitis, patellofemoral syndrome, iliotibial band syndrome, or patellar/quadriceps tendinopathy.
  • Having a recent (less than 6 weeks old) traumatic knee injury such as a sprain, meniscus tear, swelling, or fracture.
  • Having a knee infection called septic arthritis or a single‑joint inflammation (monoarthritis) of the knee.
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Investigated drugs

ARTENSIUM cream is a topical medication applied to the skin over the knee. It contains two natural extracts: harpagophytum (also known as devil’s claw) and arnica. These ingredients are thought to help reduce inflammation and relieve pain. In the study, participants used the cream on the painful knee for two weeks, and researchers measured how much the pain improved compared with a placebo cream. The cream was applied directly to the affected area, allowing the active substances to work locally where they are needed.

What is already known about the treatment

  • Placebo cream (identical in appearance to ARTENSIUM® cream, without active substances)

    It is a skin‑applied cream used only as a control in the study and contains no active ingredients. It is not an approved medicine and is used solely for research purposes. Its purpose is to look the same as the test cream so participants cannot tell which one they receive. Because it has no pharmacological effect, it does not belong to any drug class.

  • ARTENSIUM, crème

    It is a topical cream applied to the knee, usually three times a day, and contains extracts of Harpagophytum procumbens (devil’s claw) and Arnica montana. These plant extracts are known from medical literature to have anti‑inflammatory and pain‑relieving effects and are sold in some over‑the‑counter ointments. The cream is intended to reduce pain and improve movement in people with knee osteoarthritis. The extracts work by blocking inflammatory chemicals and decreasing swelling at the application site, classifying the product as an herbal anti‑inflammatory topical.

Investigated diseases

Knee osteoarthritis - A chronic degenerative joint disease that gradually wears away the cartilage covering the ends of the knee bones. As the cartilage thins, the joint surface becomes rough and the underlying bone may develop small growths. This process leads to increasing pain, stiffness, and loss of flexibility in the knee. Over time, the surrounding structures such as ligaments and the joint capsule may also change, further limiting movement. The condition typically worsens slowly, causing a steady decline in the ability to perform everyday activities.
Trial detailsLast updated 10 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-527647-18-00Protocol codeARTHROSITEstimated enrolment200 patients

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