Objectives: Low-dose radiation therapy (LDRT) for benign disorders such as knee osteoarthritis (OA) is widely used in some parts of the world, despite absence of controlled studies. We evaluated the effect of LDRT on symptoms and inflammation in patients with knee OA.
Methods: In this randomised, double-blinded, sham-controlled clinical trial (RCT), we recruited patients with knee OA (clinical ACR criteria) in the Netherlands, aged ≥50 years, pain score ≥5/10 and non-responding to analgesics and exercise therapy. Patients were randomised 1:1 to receive LDRT (1 Gray per fraction) or sham intervention six times in 2 weeks, stratified by pain (<8 versus ≥8/10). Primary outcome was the proportion of OMERACT-OARSI responders, 3 months postintervention. Secondary outcomes included pain, function and inflammatory signs assessed by ultrasound, MRI and serum inflammatory markers.
Results: We randomly assigned 55 patients: 27 (49%) to LDRT and 28 (51%) to sham. At 3 months postintervention, 12/27 patients (44%; 95% CI 26% to 63%) in the LDRT vs 12/28 patients (43%; 95% CI 25% to 61%) in the sham group responded; difference 2% (95% CI 25% to 28%), OR adjusted for the stratifying variable was 1.1 (95% CI 0.4 to 3.2). Also, for clinical and any of the inflammatory signs, no differences were observed.
Conclusions: We found no substantial beneficial effect on symptoms and inflammatory signs of LDRT in patients knee OA, compared with sham treatment. Therefore, based on this RCT and the absence of other high-quality evidence, we advise against the use of LDRT as treatment for knee OA.
Trial registration number: NTR4574.
Keywords: anti-inflammatory; epidemiology; knee osteoarthritis; radiation therapy; randomised controlled clinical trial.
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