Results: The mean age of primary and secondary OA was 76 and 63 years old, respectively. The occurrence of primary OA was found in a significantly older age group than secondary OA. The primary OA patients had significantly higher levels of leucocytes, fasting blood sugar (FBS), and fibrinogen than patients with secondary OA. There was an increasing number of spinal bodies with DISH in patients with primary OA. Despite the absence of statistical significance, the patients with primary OA tended to have higher body mass index (BMI), alkaline phosphatase, erythrocyte sedimentation rate, and C-reactive protein. In patients with primary OA, bilateral enthesophytes in the iliac crest tended to be longer, and the degree of sacroiliac joint degeneration tended to be higher.