Effects of low-dosage radiotherapy for knee osteoarthritis on the incidence of knee arthroplasty: Results of a randomized controlled trial with 9-year follow-up

Abstract

The aim. To compare the incidence of knee arthroplasty in patients receiving standard treatment with non-steroidal anti-inflammatory drugs (NSAIDs) in combination with symptomatic slow acting drugs for osteoarthritis (SYSADOA), or combination of NSAIDs and SYSADOA with low-dose radiation therapy (LDRT) in patients with stage 0–2 knee osteoarthritis (OA). Materials and methods. The article presents the results of randomized controlled study of 292 patients with confirmed knee OA according to Altman’s criteria (1991) and Kellgren – Lawrence radiographic stages 0–2 who were randomized into two groups. The control group (n = 146) received standard therapy of NSAIDs + SYSADOA. Patients of the study group (n  =  146) received combination of standard therapy and  LDRT up to a total dose of 4.5  Gy. The  cumulative risk of knee arthroplasty was assessed using actuarial analysis and the Kaplan – Meier method. Attributable (AF) and population attributable (PAF) fractions were calculated to assess LDRT preventive potential. Results. The total observation period was 2131.2 person-years. Knee arthroplasty was performed in 4.1 % (n = 6) of patients in the study group against 7.5 % (n = 11) in the control group. The  incidence density ratio was 0.60 (95%  CI: 0.18–1.88), which corresponds to a risk reduction by 67 %, but the differences were not statistically significant due to the small number of cases (p = 0.340). The AF was 40 % while the PAF was 21 %. Conclusions. The use of LDRT reduces the risk of knee arthroplasty by two-thirds and has the potential to prevent 21 % cases of knee arthroplasty in patients with knee OA. A study on a larger sample is required.