Background Osteoarthritis (OA) is one of the most frequent chronic diseases with a lifetime prevalence estimated between 30% and 50% (1). The diagnosis of OA is usually performed by radiographs and suggestive clinical symptoms. Recently ultrasound (US) has shown to be an accurate and predictive tool for assessing the presence and severity of OA in symptomatic subjects (2,3).
Objectives To evaluate the prevalence of inflammatory and structural signs of knee OA by US in a long-term population-based cohort, and to evaluate their correlation to demographic, clinical and laboratory parameters.
Methods Study design: prospective population-based study evaluated clinically and by laboratory parameters every 5 years since 1990 in Brunek (Italy). During the 4th follow up in 2010, subjects were also submitted to an US examination of both knees. Data collected: (1) inflammatory US changes such as hypoechoic synovial hypertrophy (SH), Doppler signal, effusion (E); (2) structural US changes such as cartilage damage, and osteophytes. US was performed by an independent examiner using an ESAOTE My Lab 25 (Genova, Italy); (3) physical examination of knees; (4) demographic characteristics, physical activity, comorbidities, medications, pain and functional scales related to knee joint; (5) blood tests. Statistical analysis: univariate, multivariate.
Results 488 subjects (mean age of 72.5 years) were examined by US, 53.5% were females. In the total population only 10% (N=49) did not present any abnormality at US. Prevalence of inflammatory and structural signs was high (72% and 86% of subjects respectively, and 31% had both). Presence of inflammation was statistically associated with age (>70 yrs), male gender, diabetes, knee pain, knee swelling, history of arthroplasty, high WOMAC and Barthel index (P value <0.05 or <0.0001). Structural signs were associated with age (>70), female gender, BMI>25, high WOMAC as well as US signs SH and E (P value <0.05 or <0.0001). In the multivariate analysis only age >70, male gender and knee pain were independent predictors of the presence of inflammation (OR of 1.99,184 and 1.80 respectively), whereas female gender, age and BMI were predictors of structural signs (OR of 0.49 for male gender, 1.69 for age and 2.22 for BMI).
Conclusions The prevalence of inflammatory and structural lesions in knee joints of a population aged over 60 years is high. Since these changes are related to risk factors of OA such as age, BMI and diabetes as well as symptoms of OA and joint failure (arthroplasty) in the univariate and multivariate analyses, US appears as an effective tool for detecting OA.
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Disclosure of Interest None Declared