The Ultrasonographic Findings Related to Pain and FunctionalStatus in Patients with Knee Osteoarthritis

ABSTRACT

OBJECTIVE: To evaluate the usefulness of ultrasonographic (US) examination in patients with knee osteoarthritis (OA) and determine US findings associated with pain and functional status. METHOD: 45 patients with primary knee OA classified by the American College of Rheumatology (ACR) criteria were recruited. The severity of pain and functional status were measured by Lequesne index and Western Ontario and McMaster Universities Osteoarthritis Scores (WOMAC). All patients underwent US examination of their knees and plain radiography for Kellgren and Lawrence (KL) grade. RESULTS: Even in mild OA cases (KL G1, 2), patients had evidence of distended suprapatellar pouch (effusion) (32%), synovial thickening (12%), cartilage degeneration (32%) and medial capsular distension (72%). The severity of pain and functional status were found to be correlated with following US findings: amount of suprapatellar effusion (gamma=0.514, p<0.01), degree of synovial thickness (gamma=0.520, p<0.01), cartilage degeneration grade (gamma=0.594, p<0.01), length of medial capsular distension (gamma=0.426, p<0.01). However, the length of medial and lateral osteophytes, size of Baker's cyst, and clinical parameter such as age, disease duration and BMI score were not correlated with the severity of pain and functional status in OA patients. Following multiple regression analysis, the amount of effusion, synovial thickness and length of medial capsular distension were correlated with Lequesne and WOMAC functional status score (gamma2=0.635, p<0.05). CONCLUSION: Ultrasonographic assessment was useful for diagnosing knee OA. The severity of pain and function were highly associated with the amount of suprapatellar effusion, degree of synovial thickness, the length of medial capsular distension and grade of cartilage degeneration.