ULTRASOUND EXAMINATION OF KNEE JOINT: A COMPARISON BETWEEN PSORIATIC ARTHRITIS AND RHEUMATOID ARTHRITIS

Introduction: The knee joint is frequently involved in psoriatic arthritis (PsA) and in rheumatoid arthritis (RA). Very little is known about the possible differences of such involvement in these arthritides. Aim of the Study: To investigate the features of knee involvement in PsA and RA by ultrasound examination (US). Methods: Bilateral US examination of the knee was performed by the same rheumatologist, experienced in US, in 30 PsA patients (F:M15:15; disease dura- tion: 78.41±79.45 months) and in 30 RA patients (F:M23:7; disease duration: 123.12±79.56 months) using a Logiq 9 (General Electrics Medical Systems, Mil- waukee, WI) with a linear probe operating at 10MHz for the evaluation of joints and 14MHz for the assessment of tendons. Results: Joint effusion with synovial proliferation was observed in 31 out of 60 (51) knees of PsA patients and in 41 out of 60 (68) knees of RA patients. In 7 PsA and in 4 RA patients also a positive PD signal was visualized. Baker’s cyst was detected in 24 knees in the RA group and in 11 knees in the PsA. No bone erosions were imaged in any of the PsA patients while 2 out of the 30 (6.7) RA subjects showed erosions. Quadricipital tendon enthesopathy was present in 20 PsA (66) and 5 RA (16), while patellar tendon enthesopathy was visualized in 3 RA (10) and 11 PsA patients (36). Conclusion: We observed a more frequent prevalence of enthesopathy in the PsA than in the RA group. No significant difference in the occurrence of joint effusion and synovitis was de- tected. Further investigations on knee involvement, by US technique, in a larger number of PsA and RA patients would be useful to establish the prevalence and the features of articular and periarticular involvement