About this trial
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.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
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).
Disqualifiers
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
Trial design
Parallel
Treatments tested in this trial
Low-Dose External Beam Irradiation
RadiationA 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.
Hinged Revision Total Knee Arthroplasty
Procedure/SurgeryFull 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.
Treatment groups
Trial outcomes
Primary outcomes
Total arc of knee range of motion (ROM)
Goniometric measurement of total arc of motion (flexion minus extension deficit) performed by treating surgeon at each follow-up visit, per standard clinical protocol.
Secondary outcomes
Oxford Knee Score (OKS)
EQ-5D-5L (health-related quality of life)
Visual Analogue Scale (VAS) - Pain
Patient Satisfaction (numeric rating)
Sponsors and contacts
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