METHODS: This was a cross-sectional study in which patients who had undergone a polysomnographic study for diagnosis of OSAS were recruited. Included patients were grouped according to apnea-hypopnea index (AHI) as mild (AHI between 5 and 14.9) and moderate (AHI between 15 and 29,9) severe OSAS (AHI ≥ 30). Patients with AHI < 5 served as control group. Kellgren-Lawrence scoring system was used for evaluation of OA severity and graded as Grade 0, 1, 2, 3 and 4. Body-mass index (BMI) was calculated and high-sensitive C-reactive protein was measured.