Neuropathic pain in knee osteoarthritis: Prevalence, diagnosis, and clinical implications

Objectives: This study aims to explore the prevalence of neuropathic pain (NP) in patients with knee osteoarthritis (KOA) and to assess its correlation with functional status. Patients and methods: Between December 2023 and May 2024, a total of 193 patients (48 males, 145 females; mean age: 58.7 +/- 12.8 years; range, 22 to 89 years) who were diagnosed with KOA and had persistent knee pain for more than three months were included. The painDETECT and Douleur Neuropathique en 4 Questions (DN4) questionnaires were utilized to evaluate NP. The Visual Analog Scale (VAS) was used to assess pain severity, while the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was utilized to assess functional status. Results: The painDETECT indicated NP in 27.5% of patients, while the DN4 scale showed 30.6%. Patients with NP exhibited significantly elevated VAS and WOMAC scores to patients without NP, indicating a greater severity of pain and functional impairment in this subgroup (p<0.05). The agreement between the painDETECT and DN4 was moderate (k=0.472). There were significant correlations between the painDETECT and DN4 scores with the WOMAC total score (r=0.371 and r=0.242, respectively, p<0.001). Conclusion: Neuropathic pain is common in KOA patients and is associated with higher pain intensity and poorer functional outcomes. The moderate agreement between the painDETECT and DN4 scores may lead to a certain degree of diagnostic variation. Combining more than one method may increase the diagnostic accuracy.