Validity of the sonographic longitudinal sagittal image for assessment of the cartilage thickness in the knee osteoarthritis

Abstract

We compared the validity of the sonographic longitudinal sagittal image with the suprapatellar transverse axial image for assessment of thickness of femoral cartilage in osteoarthritis (OA) patients. Fifty-one patients with knee OA were enrolled in this study. Cartilage thicknesses of medial and lateral femoral condyles were measured with longitudinal sagittal and suprapatellar transverse axial image using sonography. Fat-suppressed 3D spoiled gradient-echo magnetic resonance imaging (MRI) was also used to get the reference value. The joint space width (JSW) and Kellgren and Lawrence (K-L) grade were measured in weight-bearing anteroposterior knee radiograph. The kappa and intraclass correlation coefficient (ICC) were used to determine inter- and intra-observer agreement of the ultrasound sonography (US) measurements. In medial femoral condyle, the opportunity to obtain cartilage thickness was increased significantly using the longitudinal US scan as compared with tansverse scan (48 cases vs. 36 cases, p < 0.05). There was a good correlation between longitudinal US scan and MRI in the maximum and minimum cartilage thicknesses of medial condyle (r = 0.568; r = 0.844, respectively, p < 0.01). However, there was no correlation between suprapatellar transverse US scan and MRI in medial condyle. In lateral condyle, both US scans showed good correlations with MRI. In Bland-Altman analysis, longitudinal US scan showed good agreement with MRI except in the minimal cartilage thickness of lateral condyle. There was high overall intra- and inter-observer agreement in US scan. US scan in the longitudinal plane is a more feasible method than suprapatellar transverse scan for measuring cartilage thickness of medial femoral condyle in knee OA patient.

The Application of Imaging in Osteoarthritis

“…For example, in the small joints of the hand, longitudinal and transverse scans in flexion for the dorsal aspects and in neutral to visualize the volar aspects are performed with a high frequency (more than 12 MHz) probe (Moller, Bong et al 2008;Iagnocco 2010;Mancarella, Magnani et al 2010;Wittoek, Carron et al 2010). In order to visualize the weight bearing surfaces of the femoral condyles in the knee, the scan is performed with the knee flexed in the supine position (Moller, Bong et al 2008;Yoon, Kim et al 2008). In the hip the leg is extended and externally rotated to allow visualization of the anterior surface of the femoral head using a lower frequency (8-12 MHz) probe (Backhaus, Burmester et al 2001;Moller, Bong et al 2008;Iagnocco 2010).…”

“…In the knee US probes can also be used arthroscopically to assess cartilage morphology as well as conventional scanning protocols to assess cartilage thickness in the weight bearing areas of the femoral condyles, protrusion of the medial meniscus in the knee and the presence of Baker's cysts (Kuroki, Nakagawa et al 2008;Yoon, Kim et al 2008;Iagnocco 2010). Alternative imaging protocols such as the longitudinal sagittal US scan may also provide visualization of a larger area of femoral condyle than the suprapatellar transverse axial scan (Yoon, Kim et al 2008). Synovial thickening can also be detected but may not correspond to clinical response to intra-articular corticosteroid injections (Hattori, Takakura et al 2005).…”

“…Synovial thickening can also be detected but may not correspond to clinical response to intra-articular corticosteroid injections (Hattori, Takakura et al 2005). Validity of measurements of cartilage thickness in the knee using US has shown good reproducibility in normal to moderately damaged cartilage but is less accurate for severely damaged cartilage where the cartilage-soft tissue interfaces become less clear (Keen, Wakefield et al 2008;Yoon, Kim et al 2008). Ultrasound properties that can be exploited for assessing cartilage structure include the use of signal intensity which correlates to superficial cartilage integrity, echo duration which correlates to surface irregularity and the interval between signals that correlates to thickness (Kuroki, Nakagawa et al 2008).…”

Ultrasonographic Characteristics of Femoral Trochlear Cartilage in Patients with Knee Osteoarthritis

“…When considering the major efforts in developing new medical and surgical treatments for OA, the evaluation of articular cartilage becomes very important (8,9). Therefore, ultrasound (US) is a valid and reliable method for evaluating femoral trochlear cartilage and is used in an appropriate manner (10)(11)(12)(13). The various advantages of sonography (non-invasive, widely used, reproducible, does not include ionizing radiation, dynamic imaging, and comparison) make its immediate application by physicians and ready acceptance by patients possible.…”

Ultrasonographic Evaluation of the Femoral Cartilage Thickness in Patients With Ankylosing Spondylitis

“…In this regard, we used musculoskeletal ultrasound which has been previously shown to be a valid and reliable method for evaluating femoral cartilage (4)(5)(6)(7)(8).…”