Osteoarthritis, KneeRADIO-KONCT06887829
Radio- KO Radiotherapy for Knee Osteoarthritis Clinical Trial
A study testing Low dose radiotherapy in people with Osteoarthritis, Knee, run by Mayo Clinic at 1 site in United States.
Trial summary
The primary aim of this study is to investigate whether low-dose radiotherapy is an effective treatment to reduce the pain of knee osteoarthritis. A secondary aim is to determine whether patients experience any more measurable side effects than those receiving sham treatments. Read more about this study
- Who is it for?
- Ages 50 to 100 years
- Conditions the study is for
- Osteoarthritis, Knee
- What is being tested?
- Low dose radiotherapy
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 128 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Jun 2025to 29 Apr 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 50 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 50-100 years with a Mayo Clinic Rochester primary care provider At least moderate constant (ICOAP item A1) or intermittent (ICOAP item B6) pain Diagnosis of primary knee OA (ICD-10 M17.x) without recurrent acute inflammatory flares Joint-line tenderness on examination co-localizes with the reported pain and without a primary extra-articular pain generator Radiographic KL grade 2-3 within the preceding year Ability to complete electronic surveys
Who cannot join
- Pregnancy or childbearing potential without surgical sterilization Recent knee trauma is causing the current pain History of inflammatory arthritis or hemarthrosis Symptomatic hip OA KL grade 1 or 4 Uncontrolled psychiatric illness Prior ipsilateral intra-articular knee surgery Corticosteroid injection within 3 months or hyaluronic acid injection within 6 months in the ipsilateral knee (or 1 month if no sustained improvement after either) Fibromyalgia Active malignancy requiring treatment Regular current use of opioids, platelet-rich plasma, or acupuncture use for the knee
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Mayo Clinic
Rochester, Minnesota, 55905
Family Medicine Research Study Coordinators, 507-422-6823, RSTFMSC@mayo.edu
About this study
Official title: Low-dose RADIOtherapy for Knee Osteoarthritis (RADIO-KO): Protocol for a Single-center, Sham-controlled, Randomized Clinical Trial
The primary aim of this study is to investigate whether low-dose radiotherapy is an effective treatment to reduce the pain of knee osteoarthritis. A secondary aim is to determine whether patients experience any more measurable side effects than those receiving sham treatments.
Read the detailed description
This is a single-center, single-blinded, sham-controlled, superiority randomized controlled trial at Mayo Clinic, Rochester, Minnesota. A total of 128 adults aged 50-100 years with primary knee OA, Kellgren-Lawrence (KL) grade 2-3, and at least moderate pain will be randomized 1:1 to receive either low dose radiotherapy (LDRT) to the affected knee or an identical sham procedure. LDRT will be delivered at 0.5 Gray (Gy) per fraction x 6 fractions (3 Gy total, delivered over 2 weeks). Non-responders at 2 months will receive an identical second course according to the original allocation. The primary endpoint is the area under the curve (AUC) of the Intermittent and Constant Osteoarthritis Pain (ICOAP) scale collected weekly for 6 months. Secondary and exploratory endpoints include analgesic use, durability of response at 9 and 12 months, and effect modification by age and body mass index. The trial has 80% power (two-sided alpha level of 0.05) to detect a half-standard-deviation difference in AUC between groups on the ICOAP scale over 6 months.
- Conditions
- Osteoarthritis, Knee
- Being tested
- Low dose radiotherapy, Sham comparator
- Keywords
- osteoarthritis, knee, Radiotherapy, Randomized controlled trial, Pain Management, Placebos
- Medical subject headings
- Osteoarthritis, Knee, Agnosia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Low dose radiotherapyRadiation
Low-Dose Radiation Therapy (LDRT) delivered at 0.5 Gy per fraction for 6 fractions, administered on a Monday-Wednesday-Friday schedule over 2 weeks, for a total cumulative dose of 3 Gy. Delivered to the more symptomatic (index) knee. Participants who report no improvement in knee pain at their 2-month assessment will receive a second identical round of LDRT (totaling an additional 3 Gy).
Sham comparatorOther
An identical sham procedure without radiation delivery, administered to the more symptomatic (index) knee on a Monday-Wednesday-Friday schedule over 2 weeks (6 sessions total). Participants who report no improvement in knee pain at their 2-month assessment will receive a second identical round of the sham procedure.
| Study group | Role | What they receive |
|---|---|---|
| Low dose radiotherapy | Active comparator | Low dose radiotherapy for knee osteoarthritis Receives: Radiation: Low dose radiotherapy |
| Placebo | Sham comparator | No radiation therapy Receives: Other: Sham comparator |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Area Under the Curve (AUC) of ICOAP Scores
Change in the Intermittent and Constant Osteoarthritis Pain (ICOAP) outcome scale weekly for six months after intervention analyzed as area under the curve of patients with Kellgren-Lawrence grade 2-3 knee OA.
Measured: Baseline, 6 months
Analgesic use frequency in treatment vs. sham participants
Differences in the rate of improvement between the 2 groups with analysis to include time points of 2 months and 4 months after intervention.
Measured: 6 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Mar 2025
- Study start4 Jun 2025
- Primary completion28 Mar 2028 (estimated)
- Study completion29 Apr 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Osteoarthritis, KneeStudies of the same condition, open and under way.
- More trials run by Mayo ClinicThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Single-center, single-blinded, sham-controlled, superiority randomized controlled trial
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 128 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Mayo Clinic
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Stephen P. Merry, Mayo Clinic
- Investigators
- Stephen P. Merry, M.D., Principal investigator, Mayo Clinic
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06887829
- Sponsor's protocol ID
- 24-006759
- Acronym
- RADIO-KO
- Status last verified
- Aug 2026
- First submitted
- 7 Mar 2025
- Last updated
- 26 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- Yes: The datasets used and/or analyzed during the current study, including the trial protocol and statistical analysis plan, will be available from the corresponding author on reasonable request after completion and publication of the trial results.
Study at a glance
From the registry record, last updated by the sponsor on 26 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Low-dose RADIOtherapy for Knee Osteoarthritis (RADIO-KO): Protocol for a Single-center, Sham-controlled, Randomized Clinical Trial
- ClinicalTrials.gov ID
- NCT06887829
- Acronym / sponsor ID
- RADIO-KO / 24-006759
- Conditions
- Osteoarthritis, Knee
- Keywords
- osteoarthritis, knee, Radiotherapy, Randomized controlled trial, Pain Management, Placebos
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 128 participants (estimated)
- Lead sponsor
- Mayo ClinicUniversity, hospital or other
- Study start
- 4 Jun 2025 (actual)
- Primary completion
- 28 Mar 2028 (estimated)
- Study completion
- 29 Apr 2028 (estimated)
- First posted
- 20 Mar 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary aim of this study is to investigate whether low-dose radiotherapy is an effective treatment to reduce the pain of knee osteoarthritis. A secondary aim is to determine whether patients experience any more measurable side effects than those receiving sham treatments.
Detailed description
This is a single-center, single-blinded, sham-controlled, superiority randomized controlled trial at Mayo Clinic, Rochester, Minnesota. A total of 128 adults aged 50-100 years with primary knee OA, Kellgren-Lawrence (KL) grade 2-3, and at least moderate pain will be randomized 1:1 to receive either low dose radiotherapy (LDRT) to the affected knee or an identical sham procedure. LDRT will be delivered at 0.5 Gray (Gy) per fraction x 6 fractions (3 Gy total, delivered over 2 weeks). Non-responders at 2 months will receive an identical second course according to the original allocation. The primary endpoint is the area under the curve (AUC) of the Intermittent and Constant Osteoarthritis Pain (ICOAP) scale collected weekly for 6 months. Secondary and exploratory endpoints include analgesic use, durability of response at 9 and 12 months, and effect modification by age and body mass index. The trial has 80% power (two-sided alpha level of 0.05) to detect a half-standard-deviation difference in AUC between groups on the ICOAP scale over 6 months.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- Single-center, single-blinded, sham-controlled, superiority randomized controlled trial
| Arm | Type | Receives |
|---|---|---|
| Low dose radiotherapy | Active comparator | Radiation: Low dose radiotherapyLow dose radiotherapy for knee osteoarthritis |
| Placebo | Sham comparator | Other: Sham comparatorNo radiation therapy |
Who may qualify
- Ages
- 50 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Age 50-100 years with a Mayo Clinic Rochester primary care provider At least moderate constant (ICOAP item A1) or intermittent (ICOAP item B6) pain Diagnosis of primary knee OA (ICD-10 M17.x) without recurrent acute inflammatory flares Joint-line tenderness on examination co-localizes with the reported pain and without a primary extra-articular pain generator Radiographic KL grade 2-3 within the preceding year Ability to complete electronic surveys
Key exclusion criteria (1 listed)
- Pregnancy or childbearing potential without surgical sterilization Recent knee trauma is causing the current pain History of inflammatory arthritis or hemarthrosis Symptomatic hip OA KL grade 1 or 4 Uncontrolled psychiatric illness Prior ipsilateral intra-articular knee surgery Corticosteroid injection within 3 months or hyaluronic acid injection within 6 months in the ipsilateral knee (or 1 month if no sustained improvement after either) Fibromyalgia Active malignancy requiring treatment Regular current use of opioids, platelet-rich plasma, or acupuncture use for the knee
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Low dose radiotherapyLow-Dose Radiation Therapy (LDRT) delivered at 0.5 Gy per fraction for 6 fractions, administered on a Monday-Wednesday-Friday schedule over 2 weeks, for a total cumulative dose of 3 Gy. Delivered to the more symptomatic (index) knee. Participants who report no improvement in knee pain at their 2-month assessment will receive a second identical round of LDRT (totaling an additional 3 Gy). | Radiation | Low dose radiotherapy |
| Sham comparatorAn identical sham procedure without radiation delivery, administered to the more symptomatic (index) knee on a Monday-Wednesday-Friday schedule over 2 weeks (6 sessions total). Participants who report no improvement in knee pain at their 2-month assessment will receive a second identical round of the sham procedure. | Other | Placebo |
Primary outcome
Change in Area Under the Curve (AUC) of ICOAP Scores
Time frame: Baseline, 6 months
Change in the Intermittent and Constant Osteoarthritis Pain (ICOAP) outcome scale weekly for six months after intervention analyzed as area under the curve of patients with Kellgren-Lawrence grade 2-3 knee OA.
Analgesic use frequency in treatment vs. sham participants
Time frame: 6 months
Differences in the rate of improvement between the 2 groups with analysis to include time points of 2 months and 4 months after intervention.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Oct 2026.
- Individual participant dataSharing planned: Yes. The datasets used and/or analyzed during the current study, including the trial protocol and statistical analysis plan, will be available from the corresponding author on reasonable request after completion and publication of the trial results.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Stephen P. Merry, M.D. principal investigator
Mayo Clinic
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Low dose radiotherapy in people with Osteoarthritis, Knee, run by Mayo Clinic at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 26 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Family Medicine Research Study Coordinators (507-422-6823, RSTFMSC@mayo.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Area Under the Curve (AUC) of ICOAP Scores (time frame: Baseline, 6 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Oct 2026.