Ultrasonographic features of knee osteoarthritis in Chinese population

Abstract

Objective To investigate the musculoskeletal ultrasound (MSUS) findings in Chinese knee osteoarthritis (OA) patients. Methods All the MSUS data were from the outpatients with knee OA who visited Department of Rheumatology and Clinical Immunology, Peking University First Hospital from February 2013 to August 2014. MSUS findings included number and position of osteophyte, synovitis, thickness of cartilage, and so on. Comparisons between groups were made using t test, Chi-square tests. Results Six hundreds and seventy-four patients were included. Almost all the patients (96.1% ) had osteophytes, most patients had both knees osteophytes. The most common osteophyte location was femoral (85.2%), followed by tibia and the upper edge of patella. The number of osteophytes differed from none to ten, and the distribution of bilateral knee osteophytes was symmetrical in most patients. There was no significant difference in the number of osteophytes between male and female, and patients over 60 years old had more osteophytes than the patients aged 60 or below. In all bursae lesions, the suprapatellar bursa were the most commonly affected [effusion, 279(41.4%), synovial hyperplasia, 189(28.0%), synovitis 24 (3.6%)]. There was no significant difference in the cartilage thickness between bilateral knees. But the cartilage thickness of female patients was significantly thinner than that of men [left: (2.0±0.5) mm vs (2.5±0.8) mm, t=3.859, P<0.05; right: (2.0±0.5) mm vs (2.5±0.8) mm, t=4.109, P<0.05], and the patients over 60 years old had thinner cartilage than patients younger than 60 years old [left: (2.0 ± 0.6) mm vs (2.2 ± 0.6) mm, t=2.108, P<0.05; right: (2.0 ± 0.6) mm vs (2.2 ± 0.6) mm, t=2.507, P< 0.05]. None patient had Calcium pyrophosphate dehydrate (CPPD) deposition in the cartilage. Conclusion In the ultrasonographic findings of knee OA in China, osteophyte could be found in 96% patients, the most common location of osteophyte is the femur area. The distribution of bilateral knee osteophytes is symmetrical in most patients. Patients over 60 years old have more osteophytes. Nearly half patients have joint effusion, one third patients have synovial hyperplasia or synovitis. Bilateral knee cartilage degeneration is symmetrical. Women and patients over 60 years old have thinner cartilage. Key words: Osteoarthritis, knee; Osteophyte; Ultrasonography