Prevalence of Neuropathic Pain Varies in Patients With Knee Osteoarthritis in Different Treatment Stages
Abstract Background: Pain is the main symptom of knee osteoarthritis (KOA) and can be classified as nociceptive pain and neuropathic pain (NP). However, the prevalence and risk factors of NP in patients with KOA at different treatment stages vary in countries and are still unclear in China.Methods: Patients in this retrospective study were divided into three groups according to treatment stage, including outpatient stage, preoperative total knee arthroplasty (pre-TKA) stage and postoperative TKA stage (post-TKA). A numeric rating scale (NRS) and PainDETECT questionnaire were used to evaluate nociceptive pain and NP. Patient demographics, radiological assessments using Kellgren-Lawrence (K-L) grades, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were analyzed.Results: Of the 921 patients, the prevalence of possible and likely NP was 17.5% (56/320) and 2.5% (8/320) in the pre-TKA group compared with 3.4% (8/233) and 0.4% (1/233) in the outpatient group and 1.4% (5/368) and 0.5% (2/368) in the post-TKA group, respectively. In the pre-TKA group, higher NRS (NRS>3; OR=10.65, 95% CI: 3.25-34.92, p<0.001) and WOMAC pain (WOMAC>10; OR=4.88, 95% CI: 2.38-10.01, p<0.001) scores conferred an increased risk of unclear pain. Age, gender, BMI and K-L grade showed no significant differences among the unlikely, possible and likely NP groups.Discussion: Different prevalence of NP occur in KOA patients at different treatment stages. Due to the low prevalence of NP in the outpatient and post-TKA groups, we suggest not regularly screening for NP in these patients, while it may be essential to screen for NP in patients waiting for TKA. In the latter group, higher NRS and WOMAC pain scores are important risk factors of NP.