Predictors of Knee Osteoarthritis Progression Following Low-Dose Radiation Therapy: a 10-Year Randomized Controlled Trial

BACKGROUND: Osteoarthritis is the most prevalent joint disease, characterized by its progressive nature. Risk factors for radiographic progression remain poorly understood and inconsistently reported in the literature. The influence of low-dose radiation therapy on the baseline predictors of osteoarthritis progression has not been previously investigated.

AIM: This study aimed to identify predictors of knee osteoarthritis progression over a 10-year follow-up period following low-dose radiation therapy.

METHODS: Predictors of knee osteoarthritis progression over a 10-year follow-up period were identified based on baseline clinical, demographic, and magnetic resonance imaging (MRI) parameters in patients treated with symptom-modifying slow-acting drugs (glucosamine and chondroitin sulfate) in combination with low-dose radiation therapy (experimental group) and in those who received only symptom-modifying slow-acting drugs (control group). This randomized controlled trial initially enrolled 292 patients with clinically confirmed knee osteoarthritis (according to the Altman criteria) and radiographically verified Kellgren–Lawrence stage 0–2. At the time of analysis, 274 patients remained: 139 in the experimental group and 135 in the control group (18 were excluded for various reasons). Radiographic imaging of the knee joint was done in two projections prior to therapy, and a follow-up imaging was done ten years later. An analytical approach for magnetic resonance imaging evaluation was used to analyze baseline MRI data. Progression was classified into two types: any progression (an increase of ≥ 1 radiographic grade) and marked progression (an increase of ≥ 2 grades). Multivariate logistic regression was used in three stages to analyze the determinants of osteoarthritis progression.

RESULTS: After 10 years, osteoarthritis progression was noted in 209 patients (76.2%): 86 (31.3%) in the experimental group and 123 (44.9%) in the control group. Marked progression was observed in 3 patients (3%) in the experimental group and in 39 patients (36.1%) in the control group. Overall, the most significant predictors of marked knee osteoarthritis progression were age over 60 years, body mass index over 30 kg/m², presence of pain (as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index), subchondral plate thinning, treatment type, and initial radiographic stage.

CONCLUSION: The presence of synovitis increased the risk of osteoarthritis progression 2.6 times in patients with grade 0–2 disease. Low-dose radiation therapy exhibited a protective effect on disease progression.