Ultrasound imaging for the rheumatologist XLI. Sonographic assessment of the hip in OA patients

Objectives: To investigate the prevalence of ultrasound (US) detectable abnormalities in the hip joints of patients with osteoarthritis (OA) and correlate them with clinical findings and measures of disease severity. Methods: Consecutive patients with hip OA were investigated by clinical and US examinations. Bilateral US of the hip joints was performed by using a Logiq9 machine, equipped with a multifrequency linear probe, operating at 9 MHz; in addition, power Doppler (PD) was applied (frequency 7.5 MHz; PRF 750 Hz). Clinical evaluation included the registration of demographic data, disease duration, current and previous joint pain and Lequesne index. US study included the assessment of both inflammatory and structural abnormalities at the level of hip joint (joint effusion, synovial hypertrophy, local pathologic vascularisation at PD, osteophytes) and periarticular soft tissues (ilio-psoas bursitis, trochanteric bursitis, iliopsoas tendinopathy, gluteus medius tendinopathy and gluteus minimus tendinopathy). Results: One hundred and fifty hips of 75 patients were studied. Clinical examination demonstrated the presence of current hip pain in 80% of patients and previous hip pain in 85.7% of cases. The mean Lequesne Index was 11.9±4.9. US detected effusion in 50% of the joints, synovial hypertrophy in 41.3%, PD signal in 0.7%, osteophytes in 773%; at periarticular level, trochanteric bursitis was found in 24.7% of patients, gluteus tendinopathy in 22.7%, iliopsoas tendinopathy in 7.3% and finally iliopsoas bursitis in 13%. The presence of current and previous hip pain significantly correlated with the presence of effusion (p=0.01); age and disease duration significantly correlated with the presence of osteophytes (p=0.01). Various US-detected abnormalities were found also in asymptomatic patients. Statistically significant differences between the 2 subgroups of symptomatic and asymptomatic patients were registered for effusion (p=0.003). Conclusions: In hip OA, US is a useful imaging tool for analysing both inflammatory and structural damage lesions as well as for differentiating the involvement of joint structures and periarticular soft tissues. In addition, US was able to detect a wide set of abnormalities even in asymptomatic patients, confirming that it is more sensitive than clinical examination in detecting musculoskeletal involvement.