Reliability of quadriceps and hamstring muscle stiffness measured by ultrasound shear wave elastography in patients with knee osteoarthritis

This study aimed to assess the intra- and inter-examiner reliability of shear wave elastography (SWE) in measuring the stiffness of quadriceps and hamstring muscles in individuals diagnosed with knee osteoarthritis (KOA). Thirty-two individuals diagnosed with KOA underwent evaluations of the quadriceps and hamstring muscles. Shear-wave elastography (SWE) quantified shear-wave speed (m/s) in the rectus femoris, vastus lateralis, vastus medialis, quadriceps tendon, semimembranosus, hamstring tendon, and biceps femoris. Two independent examiners conducted SWE assessments to determine muscle stiffness, with measurements repeated after 6 to 8 days. In the initial test session, mean shear-wave speeds ranged from 2.00 to 2.47 m/s for the quadriceps muscle and from 2.06 to 2.60 m/s for the hamstrings across testers 1 and 2. During the retest session, mean shear-wave speeds ranged from 1.98 to 2.48 m/s for the quadriceps and from 2.07 to 2.57 m/s for the hamstrings. The intraclass correlation coefficients (ICCs) indicated good to excellent reliability for both intra-examiner reliability (0.88–0.98) and inter-examiner reliability (0.78–0.93). Additionally, the ICCs and standard errors of measurement (SEM) for inter-examiner reliability varied from 0.78 to 0.93 and 0.04 to 0.14 for hamstring muscle stiffness, and from 0.84 to 0.91 and 0.08 to 0.12 for quadriceps muscle stiffness, respectively. Shear-wave elastography is a reliable technique for assessing muscle stiffness in the quadriceps and hamstrings of patients suffering from knee osteoarthritis.