Low-dose radiotherapy may be effective as a short-term therapeutic option in knee osteoarthritis
1. A single course of 3 Gy low-dose radiotherapy (LDRT) significantly improved short-term responder rate in patients with knee osteoarthritis (OA) compared to sham radiation, while a single course of 0.3 Gy LDRT did not.
Evidence Rating Level: 1 (Excellent)
OA is an increasingly prevalent degenerative disorder that most frequently affects the knee. Although it is a leading cause of global disability and escalating healthcare costs, there is a notable treatment gap between conservative therapies and joint replacement surgery. LDRT is a non-invasive alternative for pain reduction that works through anti-inflammatory mechanisms such as polarizing macrophages towards an anti-inflammatory phenotype, modulating regulatory T cells, and reducing the production of reactive oxygen species, nitric oxide, and pro-inflammatory cytokines. While data show the overall absolute risk for radiation-induced solid tumors is low, apprehension regarding secondary malignancies remains a barrier to wider adoption. This study focused on dose optimization and implementation of a single-course LDRT strategy. This is a multicenter, single-blind, sham-controlled, randomized trial that included participants aged 50-85 years with a diagnosis of primary knee OA, a baseline walking visual analog scale (VAS) pain score between 50 and 90 mm at the time of screening, and a willingness to discontinue all current analgesic medications, except for prescribed rescue medication. 114 participants were randomized to sham RT (n = 39; mean [SD] age, 67.6 [6.7] years; 71.8% female), total 0.3 Gy LDRT (n = 37; mean [SD] age, 69.4 [7.3] years; 78.4% female), and total 3 Gy LDRT (n = 38; mean [SD] age, 67.3 [6.9] years; 76.3% female). Treatments were delivered in six fractions (two fractions per week) to the most symptomatic knee. The primary endpoint was the Outcome Measures in Rheumatology-Osteoarthritis Research Society International (OMERACT-OARSI) responder rate at 4 months after LDRT. At 4 months, the 0.3 Gy group responder rate did not differ significantly from sham (58.3% vs. 41.7%; p=0.168). The 3 Gy group had a significantly higher responder rate at 4 months (70.3% vs. 41.7%; p=0.021) and 8 months (76.5% vs. 45.5%; p = 0.013), but not at 12 months (66.7% vs. 50.0%; p > 0.05). There were no significant changes between groups in Western Ontario and McMaster Universities Osteoarthritis Index subscales, Patient Global Assessment, inflammatory markers (erythrocyte sedimentation rate and C-reactive protein), and MRI-based parameters. No treatment toxicities or local reactions were reported.
Click here to read this study in BMC Medicine
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