Aim:  To determine the risk factors of symptomatic osteoarthritis (OA) of the knee.

Methods:  Two hundred and thirty‐nine cases of symptomatic OA of the knee (ACR Criteria for OA 1986) with radiographic OA (Kellgren‐Lawrence I or more) taken from a rheumatology outpatient clinic were compared to 279 controls without radiographic (Kellgren‐Lawrence 0) OA taken from general internal medicine outpatient clinic at the same hospital. Independent variables to be assessed were age, sex, ethnic group, body mass index (BMI), education, marital status, parity, smoking, and history of acute trauma, hysterectomy, anatomical abnormality of knee, diabetes mellitus, and uric acid levels. Multiple logistic regression analysis was done to assess the independent risk factors.

Results:  After going through the steps of multiple logistic regressions analysis, the results were: symptomatic cases compared to controls: age > 50 (OR: 1.86, 95% CI = 1.78–2.82), being female (OR: 2.08, 95% CI = 1.35–3.50), BMI > 25 units (OR: 3.28, 95% CI = 2.20–4.89), elementary education (OR: 0.29, 95% CI = 0.14–0.61) and genu valgus (OR: 4.07, 95% CI = 2.43–7.93). For the female subset of symptomatic cases compared with controls: age > 50 (OR: 9.34, 95% CI = 4.77–18.24), BMI > 25 units (OR: 5.27, 95% CI = 2.85–9.73) and genu valgus (OR: 13.64, 95% CI = 4.58–41.44).

Conclusions:  Age > 50, being female, BMI > 25 units and genu valgus, may be the risk factors for symptomatic OA of the knee.