Correlation of Sonographic Findings with Knee Joint Pain in Knee Osteoarthritis Patients

Kang, Hyo Jong; Lee, Sang Bae; Lee, Myeung Su; Hong, Seung Jae; Park, Kyung Su; Yoon, Chong Hyeon; Kim, Wan Uk; Min, Do June; Min, Jun Ki; Lee, Sang Heon; Park, Sung Hwan; Cho, Chul Soo; Kim, Ho Youn

Abstract

OBJECTIVE
To investigate the ultrasonographic findings in knee OA patients and to examine the possible causes of pain in osteoarthritis by ultrasonography.
METHODS
Ultrasonography was performed with 7.5 MHz linear probe in 64 knee OA patients who fulfilled the ACR criteria. All patients were graded according to the Kellgren-Lawrence grades and then classified into group 1 (K/L I and II) and Group 2 (K/L III and IV). Also WOMAC score, BMI, laboratory finding (ESR, CRP) were checked. Ultrasonographic findings was examined; effusion, thickening of synovium, vertical length of medial and lateral osteophyte (longitudinal view), length of capsular distension (medial longitudinal view), evidence of bursitis and articular cartilage.
RESULTS
50.0% of patients had effusion, among whom 68.7% patients also had synovial thickening. In all patients, the severity of pain was correlated with 4 variables; the presence of effusion, disease duration, the length of medial osteophyte, the length of capsular distension (r=0.279, r=0.415, r=0.537, r=0.608, respectively, p<0.05). The length of medial osteophyte, the degree of capsular distension and disease duration were significantly correlated with WOMAC pain score in Group 1 (p<0.05). After multiple regression analysis, the length of medial osteophyte alone had correlation with the pain severity in Group 1 (r2= 0.396 p<0.05) and the only length of capsular distension was significantly correlated with WOMAC pain score in Group 2 (r=0.609, p<0.05).
CONCLUSION
The length of osteophyte may be more related with pain severity in mild cases (K/L score I and II) while capsular distension could be an important factor causing knee pain in more advanced knee OA (K/L score III and IV).