Mechanical Pain is a Main Type of Pain in Patients With Advanced Knee Osteoarthritis

This study aimed to investigate the prevalence and risk factors of mechanical pain in patients with advanced knee osteoarthritis (KOA), providing insights for targeted treatment approaches.

We conducted a cross-sectional study involving 920 patients with KOA. The sample size was determined using the formula n=(Z ²∗P∗(1 - P))/E ², assuming a 95% confidence interval (CI) and a 5% margin of error. Data on demographics and affected knee parameters, including age, sex, body mass index (BMI), affected side, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, range of motion, degree of varus, and numeric rating scale (NRS) were collected. Pain was categorized using the painDETECT questionnaire and WOMAC scores to differentiate between simple mechanical pain, mixed mechanical pain, and probable neuropathic pain (NP).

Among participants, 43.48% experienced simple mechanical pain, 33.48% had mixed mechanical pain, and 23.04% reported probable NP. Significant differences were observed in the total WOMAC scores, range of motion (bend), and NRS across the three groups. Gender distribution varied significantly, with a higher proportion of female patients in each pain category. Notably, NRS on the affected side was moderately correlated with the total WOMAC pain score (r = 0.500, ^∗ p < 0.05). Moreover, female patients exhibited significantly higher WOMAC pain scores (6.28) compared with males (6.08), and women with a WOMAC pain score > 4 had an odds ratio (OR) of 2.462 (95% CI: 1.766-3.433, ^∗ p < 0.05) compared with those with a score ≤ 4.

Mechanical pain is highly prevalent in patients with advanced KOA. Identifying the specific type of mechanical pain and associated risk factors, such as female gender and higher NRS score, can facilitate personalized pain management.