Correlation between ultrasonographic findings and symptoms of knee osteoarthritis

Knee osteoarthritis (OA) is mainly diagnosed by clinical and radiographic findings. The aim of this study was to evaluate the correlation between ultrasonography (US) findings during flexion and knee loading and symptoms of knee OA.

We studied 33 knees with OA in 21 patients. Using US, the medial meniscal protrusion was measured at the midpoint of the medial joint space with the patient standing and the knee in maximum extension and flexion. With the knee in extension, the thickness of the synovial membrane at the suprapatellar area and the size of the osteophytes at the medial joint space were measured. Radiography was performed to determine the Kellgren-Lawrence (K-L) scores. The correlations between US findings and the visual analog scale (VAS) score, Japanese Knee Osteoarthritis Measure (JKOM) score, K-L score, and range of motion (ROM) were analyzed.

Medial meniscal protrusion was significantly correlated with K-L score and ROM limitation. Synovial membrane thickness was also significantly correlated with the total JKOM and usual activity scores. There was no correlation between the VAS scores and US findings. Multigroup comparisons of the patients' positions during US did not reveal significant intergroup differences.

US was able to detect a change in medial meniscal protrusion during knee flexion and loading. Although medial meniscal protrusion was not correlated with pain, it was related to structural changes of the knee, similar to radiographic findings. Synovial membrane thickness detected by US correlated with pain and a disturbance in the usual activity of patients with OA.