Objective To study high-frequency ultrasonic features of pigmented villonodular synovitis (PVNS).Methods High-frequency ultrasonic findings in 17 cases with PVNS were analyzed and a comparison between surgical and pathological results was made.Results Of 17 cases,10 cases were diffuse type,7 cases were local type.The main high-frequency ultrasonic signs were as follows: the diffused type synovial PVNS demonstrated as hypoecho,local synovial proliferation was revealed as nodulated and heterogeneous echo,hydrarthrosis of the knee joint was present in 10 cases,the involvement of meniscus occurred in 4 cases,intra-articular cartilage and cortex erosion were showed in 5 cases.Local type PVNS was mainly demonstrated as the nodulated and hypoechoic proliferation of synovium,hydrarthrosis of the joint and cartilage erosion were not found.Conclusions High-frequency ultrasound is a valuable imaging method for diagnosing PVNS in preoperative routine screening.

BACKGROUND:The knee joint acts as the body’s largest and most complex joint, which is a commonly seen perplex in patients because of synovium and cartilage diseases. Moreover, clinical physicians are often confused on the ultrasonic diagnosis of synovium and cartilage diseases.
OBJECTIVE: To review the ultrasound misdiagnosed cases of knee cartilage and synovial lesions and to summarize the common misconceptions and discrimination methods.
METHODS: A retrospective analysis was performed in the ultrasound misdiagnosed cases of knee cartilage and synovial lesions reported from 2002 to 2014, and then the common misconceptions and corresponding identification methods were summarized.
RESULTS AND CONCLUSION: High-frequency ultrasound is most likely to have six “mistaken ideas” addressing knee cartilage and synovial lesions: (1) cartilage degeneration; (2) synovial calcification; (3) echo intensity from synovial lesions; (4) blood flow in the synovium; (5) synovial effusion; (6) lesions involving intraarticular structures. High-frequency ultrasound runs through dynamical observation and contrast observation of bilateral knee joint lesions, which is a valuable imaging method for diagnosis of cartilage and synovial diseases based on vigilance at the “mistaken ideas” and mastery of the distinguishing ideas and methods.