A randomized double-blind placebo-controlled trial investigating pain characteristics in response to diclofenac or placebo in symptomatic knee osteoarthritis.
Osteoarthritis is a common condition that causes joint pain, swelling, and stiffness in the knee. While anti-inflammatory pain medicines like diclofenac are often used, doctors want to learn more about how they work on different types of pain, such as constant ache versus sudden sharp pain. In this trial, adult volunteers with painful knee osteoarthritis will take either a 50 mg diclofenac tablet or a dummy pill (placebo) containing harmless starch and lactose. Neither you nor the study team will know which tablet you receive until the end. Over the course of the study, researchers will measure changes in your knee pain and everyday movement using questionnaires, gentle pain-sensitivity checks, and a short 40-metre walking test. The findings will help doctors choose better, more targeted pain treatments for people with knee osteoarthritis in the future.
At a glance
What is this study about?
Knee osteoarthritis happens when the protective cartilage inside the knee joint wears down over time. This can make the joint painful, stiff, and difficult to move, having a major impact on day-to-day activities like walking, climbing stairs, or simply getting out of a chair.
Diclofenac is a well-known non-steroidal anti-inflammatory drug (NSAID) that doctors routinely prescribe to lower inflammation and ease joint pain. However, knee pain is complex. Some people feel a dull, constant ache, while others get sudden, sharp pain during movement. People also process pain signals in different ways.
This study compares diclofenac directly against a placebo (an inactive dummy pill) to see how each affects these different types of pain. By measuring walking ability and how sensitive the knee is to touch and pressure, researchers hope to uncover clear patterns in how people respond to medication. This could help healthcare professionals give the right pain relief to the right person in the future.
Key takeaways
- Testing how diclofenac eases knee osteoarthritis pain compared to a dummy pill.
- Open to adults aged 18 and over who have painful knee osteoarthritis.
- Involves questionnaires, simple walking tests, and gentle touch checks.
- Helps doctors learn how to match future arthritis treatments to specific types of pain.
- Completely voluntary with the freedom to leave the study at any time.
Who may be eligible?
This trial is open to adults aged 18 and over who have been diagnosed with knee osteoarthritis and are currently experiencing knee pain that affects their daily life. Men and women are both welcome to take part.
Because the study uses diclofenac and an inactive tablet that contains lactose, people with certain medical conditions—such as a history of stomach ulcers, severe heart or kidney problems, or known allergies to anti-inflammatory drugs—may not be able to join.
A doctor or research nurse will review your full medical history and current medicines to confirm whether the trial is safe and suitable for you.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- I am aged 18 or over.
- I have been diagnosed with knee osteoarthritis.
- I currently have ongoing knee pain or stiffness.
- I do not have a known allergy to diclofenac or anti-inflammatory drugs.
- I am able to attend clinic visits and take daily study tablets.
What does participation involve?
Taking part involves taking a study capsule by mouth each day for the planned trial period. You will be randomly chosen by a computer to receive either diclofenac (50 mg) or a placebo capsule containing starch and lactose. Neither you nor your study doctor can choose which one you take.
During the trial, you will attend appointments at the clinic where the team will check on your health. You will be asked to fill in simple questionnaires about your knee pain, stiffness, and daily activities. The team will also carry out simple physical checks, including a 40-metre walking test to see how well you move, and gentle tests to measure how sensitive your skin and joint are to pressure.
The study team will monitor your progress closely and arrange follow-up checks to see how you are doing throughout the treatment period.
Potential risks and benefits
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Common questions
What is a placebo?
A placebo is a dummy pill that looks identical to the real medicine but contains no active ingredients, using only harmless substances like lactose and starch.
Can I choose to receive diclofenac instead of the placebo?
No. A computer randomly decides who receives the active medicine and who receives the placebo so that the test results remain fair and unbiased.
Will taking part cure my knee osteoarthritis?
No. There is currently no cure for osteoarthritis. This trial looks at how well diclofenac manages your pain and symptoms.
What happens if my knee pain gets worse during the trial?
The research team will monitor you closely. If your pain becomes severe or unmanageable, you can leave the trial and return to your usual pain management plan.
Do I have to pay to take part?
No. Clinical trial treatments and study-related tests are provided free of charge, and some trials offer help with travel expenses.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
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