Prevalence of knee pain and factors influencing its risk in ambulatory chronic stroke survivors

Background Gait alterations after stroke may lead to knee pain, limiting rehabilitation and reducing quality of life.Objectives To estimate the prevalence of knee pain and identify associated factors in ambulatory chronic stroke survivors.Methods We conducted a cross-sectional study in 12 outpatient rehabilitation units in Vietnam, enrolling 212 patients with stroke. We recorded demographics, morbidities, knee pain, clinical examination findings and gait parameters. Weight-bearing asymmetry was measured using a two-scale method. Minimal knee flexion during the stance phase was derived from markerless gait analysis. Factors associated with knee pain were assessed using modified Poisson regression with robust standard errors to estimate adjusted prevalence ratios (aPRs). Multinomial logistic regression was performed to identify factors associated with pain laterality.Results The prevalence of knee pain was 19.8%. The following factors were independently associated with knee pain: age (aPR: 1.03; 95% CI: 1.01–1.06), stroke type (aPR: 2.51; 95% CI: 1.55–4.09), time since stroke onset (aPR: 1.08; 95% CI: 1.04–1.12), prior knee osteoarthritis (aPR: 2.27; 95% CI: 1.31–3.91), obesity (aPR: 1.84; 95% CI: 1.14–2.96), and quality of life (aPR: 0.02; 95% CI: 0.01–0.06). Smaller minimal knee flexion was associated with a higher risk of ipsilateral knee pain (p = 0.009).Conclusion The prevalence of knee pain among ambulatory chronic stroke survivors was approximately 20%. Older age, hemorrhagic stroke, longer poststroke time, obesity, prior knee osteoarthritis, and poorer quality of life were independently associated with knee pain. Greater hyperextension during stance was associated with a higher risk of knee pain in the affected limb.