Stiffness and Low Dose Irradiation RCT

Overview

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.

Acquired idiopathic stiffness (AIS), or arthrofibrosis, is a rare but potentially devastating complication after total knee arthroplasty (TKA), occurring in approximately 1-6% of cases. It is characterized by pathological fibroblast and myofibroblast proliferation leading to excessive scar tissue deposition within and around the knee joint, resulting in restricted range of motion (ROM), pain, and functional impairment. When conservative management (physiotherapy, manipulation under anesthesia) fails, operative intervention is required. Full component revision to a hinged prosthesis - which permits complete synovectomy, posterior capsule release, and debridement of fibrosed collateral ligaments - has demonstrated superior ROM outcomes compared to partial revision strategies. Perioperative low-dose irradiation (LDI) has an established role in the prophylaxis of heterotopic ossification following total hip arthroplasty and is used as adjunctive therapy for keloid prevention. Mechanistically, LDI at 700-800 cGy inhibits myofibroblast proliferation and modulates fibrotic signaling pathways, addressing the underlying pathophysiology of arthrofibrosis. A retrospective review of 60 patients undergoing hinged revision TKA with LDI demonstrated a median ROM improvement of 60°, with acceptable complication rates. Despite this evidence, no prospective randomized controlled trial has compared hinged revision TKA with and without LDI.