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

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
112

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Wisconsin, Madison

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Radiation Oncology Institute

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 1, 2027

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2033

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 1, 2033

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 4, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 4, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 12, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 4, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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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