NCT07767097 · Mount Sinai Hospital, Canada
Stiffness and Low Dose Irradiation RCT
(LDI TKR RCT)
What this study is about
Acquired idiopathic stiffness (AIS) is a common complication following total knee arthroplasty (TKA). It is caused by excessive scar formation, which leads to pain, loss of motion, and functional impairment. When early noninvasive treatments fail, some patients require more surgery.
View original scientific description
Acquired idiopathic stiffness (AIS) is a common complication following total knee arthroplasty (TKA). It is caused by excessive scar formation, which leads to pain, loss of motion, and functional impairment. When early noninvasive treatments fail, some patients require more surgery. In these cases, surgeons often use a special type of replacement called a hinged prosthesis, which allows more thorough removal of scar tissue and stiffened ligaments. Unfortunately, even after more surgery, many patients continue to struggle with stiffness, pain, and impaired function. Low-dose irradiation (LDI) is a safe, established therapy for conditions with abnormal scar formation. Its role in the setting of AIS has not been defined. The goal of this study is to compare outcomes of revision TKA with or without the addition of LDI. The primary outcome is range of motion at one year following surgery. Secondary outcomes include patient-reported functional scores, repeat surgeries, and complications like wound breakdown or infection. This project has the potential to address a common, debilitating complication after TKA, improve outcomes, reduce repeat interventions and healthcare costs, and broader implementation and standardization of care.
Interventions
RADIATION
Low-Dose External Beam Irradiation
A single session of external beam irradiation (800 cGy) delivered to the operative knee on post-operative day 1 (or post-operative day 2 if medically necessary). At Mount Sinai Hospital and Humber River Hospital, LDI is delivered at Princess Margaret Cancer Centre. US sites coordinate through local radiation oncology departments.
PROCEDURE
Hinged Revision Total Knee Arthroplasty
Full component revision to a rotating hinge knee prosthesis, including synovectomy, posterior capsule debridement, and release of fibrosed collateral ligaments, performed by the treating orthopaedic surgeon at each participating site.
Primary outcome measures
Total arc of knee range of motion (ROM)
Time frame: Baseline (pre-operative), intraoperative, 2 weeks, 6 weeks, 3 months, and1 year post-operatively.
Goniometric measurement of total arc of motion (flexion minus extension deficit) performed by treating surgeon at each follow-up visit, per standard clinical protocol.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Adults (≥18 years) undergoing revision TKA with a hinged prosthesis for AIS after primary TKA
- Patient with a ROM arc \<70 degrees or flexion contracture of \>20 degrees without any identifiable cause for stiffness (e.g. component oversizing, malrotation, infection, or periprosthetic fracture).
Exclusion criteria
- Revision for causes other than AIS (e.g., component malposition, infection, periprosthetic fracture)
- Prior ipsilateral knee infection
- Revision to non-hinged prosthesis
- Medical contraindications to surgery
- Medical contraindications to irradiation
- Currently pregnant or planning to become pregnant during the study period
Where
- Los Angeles, California
- Salt Lake City, Utah
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 17, 2026 · Source of record for eligibility and locations