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Study on the Effects of Botulinum Toxin Type A and Sodium Chloride Injections for Adults with Painful Thumb Osteoarthritis

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What is this trial about?

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

This clinical trial is focused on studying the effects of a treatment for base-of-thumb osteoarthritis, a condition that causes pain at the base of the thumb due to joint wear and tear. The treatment being tested involves the use of onabotulinumtoxinA, commonly known as Botox, which is a protein used in various medical treatments. The study will compare the effects of two injections of Botox with one injection of Botox and one injection of a placebo, as well as two injections of the placebo.

The purpose of the study is to evaluate how these different treatments affect thumb pain over a period of six months. Participants will receive their injections directly into the joint at the base of the thumb, guided by ultrasound to ensure accuracy. The study will also involve the use of a custom-made rigid splint, which is a supportive device designed to help manage the condition by keeping the thumb in a stable position.

Throughout the study, participants will be monitored to assess changes in their pain levels. The main goal is to determine which treatment option provides the most relief from pain associated with base-of-thumb osteoarthritis. This information will help in understanding the potential benefits of using Botox for this specific type of arthritis.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    The trial begins with an initial assessment to confirm eligibility. This includes verifying age, pain intensity, and specific medical conditions related to the base of the thumb.

    An X-ray is conducted to check for signs of osteoarthritis in the thumb joint, such as bone spurs or joint space narrowing.

  2. Step 2

    First injection

    The first injection is administered using ultrasound guidance to ensure accurate placement in the thumb joint.

    The injection may contain either onabotulinumtoxinA (Botox®) or a saline solution, depending on the group assignment.

  3. Step 3

    Custom-made splinting

    A custom-made rigid splint is provided to support the thumb and reduce pain during daily activities.

    Instructions on how to use the splint effectively are given.

  4. Step 4

    Second injection

    A second injection is administered, again using ultrasound guidance.

    This injection may also contain either onabotulinumtoxinA or saline, based on the group assignment.

  5. Step 5

    Follow-up assessments

    Regular follow-up assessments are conducted to monitor pain levels and the effectiveness of the treatment.

    Pain is measured using a numeric scale from 0 (no pain) to 100 (maximum pain).

  6. Step 6

    Final evaluation

    A final evaluation occurs six months after the first injection to assess changes in thumb pain.

    The primary goal is to determine the average change in pain levels from the start of the trial.

Who can join the trial?

7 criteria

  • Individuals must be at least 18 years old.
  • They should have a pain intensity of at least 30 on a self-administered 11-point pain scale, where 0 means no pain and 100 means the worst possible pain.
  • The pain should be located at the base of the thumb.
  • There must be X-ray evidence of **trapezometacarpial osteoarthritis**, which is a type of arthritis affecting the joint at the base of the thumb. The X-ray should show at least two of the following: **osteophytes** (bony growths), **joint space narrowing** (reduced space between bones), **subchondral bone sclerosis** (hardening of the bone just below the cartilage), or **subchondral cysts** (fluid-filled sacs in the bone).
  • Participants should meet the 1990 ACR classification criteria for hand osteoarthritis, adapted for trapezometacarpial osteoarthritis. This is a set of guidelines used to diagnose arthritis in the hand.
  • Participants must be affiliated with a mode of social security, meaning they have some form of health insurance or entitlement.
  • Women of childbearing potential must have a negative pregnancy test.

Who cannot join the trial?

8 criteria

  • Patients who are under 18 years old cannot participate.
  • Patients who do not have painful base-of-thumb osteoarthritis are not eligible.
  • Patients who are unable to receive injections in the thumb area are excluded.
  • Patients who have allergies to the substances used in the study, such as onabotulinumtoxinA or normal saline, cannot join. OnabotulinumtoxinA is a type of medication used to relax muscles, and normal saline is a saltwater solution often used in medical treatments.
  • Patients who are pregnant or breastfeeding are not allowed to participate.
  • Patients who are part of a vulnerable population, meaning they might need special protection or care, are excluded.
  • Patients who are currently participating in another clinical trial are not eligible.
  • Patients with any other medical condition that might interfere with the study or put them at risk are excluded.
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Investigated drugs

  • OnabotulinumtoxinA (Botox®)

    is used in this trial to help reduce pain in the base of the thumb caused by osteoarthritis. It is administered through two ultrasound-guided injections directly into the joint. The goal is to see if this treatment can provide medium- and long-term relief from pain.

  • Custom-made rigid splinting

    is also part of the trial. This involves using a specially designed splint to support the thumb and reduce movement that might cause pain. The splint is tailored to fit each participant's hand, aiming to improve comfort and effectiveness in managing osteoarthritis symptoms.

What is already known about the treatment

OnabotulinumtoxinA (Botox®) – This medication is administered through ultrasound-guided intra-articular injections, specifically targeting the base of the thumb. It is currently being studied in clinical trials for its effectiveness in treating painful base-of-thumb osteoarthritis in adults. The main therapeutic indication is to alleviate pain associated with this condition. OnabotulinumtoxinA works by blocking the release of certain neurotransmitters at the nerve endings, which reduces muscle contractions and pain. It is classified as a neurotoxin and is widely recognized in medical literature for its various therapeutic uses, including muscle relaxation and pain management.

Investigated diseases

Osteoarthritis of the Base of the Thumb – This condition involves the degeneration of the cartilage at the base of the thumb, leading to pain and stiffness in the joint. It is a common form of arthritis that typically affects adults over the age of 18. As the disease progresses, the cartilage wears down, causing bones to rub against each other, which can result in swelling and reduced range of motion. Over time, the joint may become deformed, and gripping or pinching objects can become difficult. The condition can vary in severity, with some individuals experiencing mild discomfort and others facing significant pain and functional limitations.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515028-35-00Protocol codeAPHP230823Estimated enrolment120 patientsSponsorAssistance Publique Hopitaux De Paris

sourced from the EU Clinical Trials Register and site verification

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