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Radio- KO Radiotherapy for Knee Osteoarthritis Clinical Trial

Low-dose RADIOtherapy for Knee Osteoarthritis (RADIO-KO): Protocol for a Single-center, Sham-controlled, Randomized Clinical Trial

Status
Recruiting
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT06887829
Acronym
RADIO-KO
Enrollment
128
Registered
2025-03-20
Start date
2025-06-04
Completion date
2027-10-29
Last updated
2026-09-02

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Osteoarthritis, Knee

Keywords

osteoarthritis, knee, Radiotherapy, Randomized controlled trial, Pain Management, Placebos

Brief 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.

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.

Interventions

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).

OTHERSham comparator

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.

Sponsors

Mayo Clinic
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Subject)

Intervention model description

Single-center, single-blinded, sham-controlled, superiority randomized controlled trial

Eligibility

Sex/Gender
ALL
Age
50 Years to 100 Years
Healthy volunteers
No

Inclusion criteria

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

Exclusion criteria

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

Design outcomes

Primary

MeasureTime frameDescription
Change in Area Under the Curve (AUC) of ICOAP ScoresBaseline, 6 monthsChange 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 participants6 monthsDifferences in the rate of improvement between the 2 groups with analysis to include time points of 2 months and 4 months after intervention.

Countries

United States

Contacts

CONTACTFamily Medicine Research Study Coordinators
RSTFMSC@mayo.edu507-422-6823
PRINCIPAL_INVESTIGATORStephen P. Merry, M.D.

Mayo Clinic

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Sep 3, 2026