LDRT Retreatment for Knee Osteoarthritis

November 4, 2026 updated by: University of Wisconsin, Madison

UW26092: Low-Dose Radiation Therapy for Osteoarthritis of the Knee: A Phase 2 Randomized Trial of Dual-Course Versus Single-Course Radiation

The goal of this clinical trial is to learn if one course of low-dose radiation therapy (LDRT) helps as much as two courses of LDRT in people with osteoarthritis.

The main questions it aims to answer are whether pain control, joint function, and quality of life are the same with one course of LDRT.

Participants will receive LDRT and can expect to be in the study for up to 3 months.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This study is being done to evaluate the degree of symptom improvement after dual-course low-dose radiation therapy (LDRT) compared to single-course LDRT in participants with osteoarthritis (OA) of the knee.

Study Type

Interventional

Enrollment (Estimated)

112

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • Wisconsin
      • Madison, Wisconsin, United States, 53705
        • University of Wisconsin - Madison
        • Contact:
        • Principal Investigator:
          • Jessica Schuster, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

40 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Clinical diagnosis of osteoarthritis of the knee
  • Age ≥40 years at the time of consent
  • Joint pain which has persisted for ≥3 months
  • Completed imaging of the involved joint in the past 3 months (including MRI, CT, X-ray, or bone scan)
  • Negative pregnancy test

Exclusion Criteria:

  • Previous surgery to the affected joint or planned surgery to the affected joint in the next 6 months
  • Previous radiation treatment targeting the affected joint. Previous radiation targeting any other body site does not exclude from participation as long as there is no clinically meaningful overlap, as determined at the discretion of the treating physician.
  • Current use of prescription medications containing opioids
  • Confirmed prior diagnosis of rheumatoid arthritis, pseudogout, or gout in the affected joint

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: One course of LDRT

Participants will receive one course of LDRT
Radiation: Low Dose Radiation Therapy

Treatments will be given twice weekly over a duration of approximately 3 weeks.
Experimental: Two courses of LDRT

Participants will receive two courses of LDRT
Radiation: Low Dose Radiation Therapy

Treatments will be given twice weekly over a duration of approximately 3 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score - 6 months
Time Frame: Baseline to 6 months

WOMAC is a 24 item questionnaire that evaluates pain, stiffness, and physical function in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 96 points. Higher scores indicate worse symptoms and greater functional limitation.
Baseline to 6 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score - 9 months
Time Frame: Baseline to 9 months

WOMAC is a 24 item questionnaire that evaluates pain, stiffness, and physical function in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 96 points. Higher scores indicate worse symptoms and greater functional limitation.
Baseline to 9 months
Change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score - 12 months
Time Frame: Baseline to 12 months

WOMAC is a 24 item questionnaire that evaluates pain, stiffness, and physical function in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 96 points. Higher scores indicate worse symptoms and greater functional limitation.
Baseline to 12 months
Change in WOMAC pain sub-domain score
Time Frame: Baseline to 12 months

Pain sub-domain has 5 items that evaluate pain in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 20 points. Higher scores indicate worse pain.
Baseline to 12 months
Change in WOMAC stiffness sub-domain score
Time Frame: Baseline to 12 months

Stiffness sub-domain has 2 items that evaluate stiffness in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 8 points. Higher scores indicate worse stiffness.
Baseline to 12 months
Change in WOMAC joint function sub-domain score
Time Frame: Baseline to 12 months

Stiffness sub-domain has 17 items that evaluate joint function in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 68 points. Higher scores indicate greater physical limitations.
Baseline to 12 months
Incidence of adverse events
Time Frame: 6 months

Evaluated by CTCAE, v6.0.
6 months
Change in use of pain relievers
Time Frame: Baseline to 12 months

Participants will self-report how much and what pain relief medication they used while on study.
Baseline to 12 months
Change in WOMAC score in one-joint treatment compared to two-joint treatment.
Time Frame: Baseline, 6 months, 9 months, 12 months

WOMAC is a 24 item questionnaire that evaluates pain, stiffness, and physical function in patients with hip or knee osteoarthritis. Typically rated using a 0 to 4 scale (0 = none, mild, moderate, severe, 4 = extreme), scores range from 0 to 96 points. Higher scores indicate worse symptoms and greater functional limitation.
Baseline, 6 months, 9 months, 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Wisconsin, Madison

Collaborators

Radiation Oncology Institute

Investigators

  • Principal Investigator: Jessica Schuster, MD, University of Wisconsin, Madison

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

January 1, 2027

Primary Completion (Estimated)

January 1, 2033

Study Completion (Estimated)

January 1, 2033

Study Registration Dates

First Submitted

November 4, 2026

First Submitted That Met QC Criteria

November 4, 2026

First Posted (Actual)

November 12, 2026

Study Record Updates

Last Update Posted (Actual)

November 12, 2026

Last Update Submitted That Met QC Criteria

November 4, 2026

Last Verified

November 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026-1510
  • UWMSN | SMPH | Radiation Medic (Other Identifier: UW Madison)
  • Protocol Version 9/29/2026 (Other Identifier: UW Madison)
  • UW26092 (Other Identifier: UW Madison)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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