Assessment of blood flow around the knee joint in patients with knee osteoarthritis by color Doppler ultrasound.

OBJECTIVE: To explore a method for early diagnosis of knee osteoarthritis (OA) by comparing vascular morphology and hemodynamic parameters between healthy controls and patients, and explore the effects of age on the blood flow of healthy subjects. MATERIAL AND METHODS: 80 healthy subjects and 106 patients with knee OA were recruited. Color Doppler ultrasound was used to measure the vascular morphology and hemodynamic parameters of 11 blood vessels around the knee joint. A general linear model was used to analyze the difference of blood flow parameters between healthy controls and patients, and to explore the effects of sex and age on the blood flow of healthy subjects. RESULTS: Age has no significant effect on the vessel diameter of healthy subjects, and it only affect the blood flow velocity (P ＜ 0.05) and blood flow volume (P ＜0.0083) of a few blood vessels. There was no significant difference in vascular morphological parameter between healthy controls, patients with mild OA and moderate/severe OA, but there was significant difference in vascular hemodynamic parameters (P ＜ 0.0167). Specifically, in the early stage of knee OA, hemodynamic parameters of main arteries in patients did not change significantly, but those of branch vessels changed significantly (P ＜ 0.0167). With the development of knee OA, the difference of hemodynamic parameters of branch vessels in patients increased gradually. CONCLUSION: Hemodynamic parameters of branch vessels around the knee joint have changed significantly in the early stage of knee OA, which can be treated as an important index to screening the early patients.

In vivo assessment of material properties of muscles and connective tissues around the knee joint based on shear wave elastography.

Previous studies on knee biomechanics have mainly focused on the joint structure itself, largely neglecting the material properties of the muscles and connective tissues around the knee joint. Therefore, this study was purposed to conduct a systematic in vivo examination of the material properties of muscles, tendons, and ligaments, and investigated the respective influences of gender and age on the material properties. The participants were 50 healthy males and females within the following four age groups: 21-30 years, 31-40 years, 41-50 years, and above 51 years. The Young's moduli of the muscles, tendons, and ligaments around the knee joint were measured by shear wave elastography (SWE). Analysis of the Young's modulus results showed that excellent repeatability could be achieved by using SWE. For muscles, the intraclass correlation coefficient (ICC) and 95% confidence interval (CI) ranged between 0.952 and 0.987, and 0.923 and 0.992, respectively. The ICC ranged from 0.920 to 0.941, and the 95% CI was between 0.872 and 0.969 for tendons and ligaments. Additionally, the Young's moduli of the muscles, tendons, and ligaments of males were greater than those of females. With the exception for medial patellar retinaculum (MPR), the Young's moduli of other observed tissues decreased with age for both males and females, indicating that age has a significant impact on the Young's moduli of muscles, tendons, and ligaments. Hence, SWE is a reliable and repeatable technique that can be used to assess the Young's moduli of the muscles, tendons, and ligaments around the knee joint. Furthermore, gender and age affects the material properties. The results of this study provide an in vivo database of the material properties of muscles and connective tissues, and thus may prove useful for the prevention and treatment of knee joint injuries and diseases.

Non-invasive Quantitative Assessment of Muscle Force Based on Ultrasonic Shear Wave Elastography.

The objective of this study was to investigate the feasibility of using shear wave elastography (SWE) to indirectly measure passive muscle force and to examine the effects of muscle mass and scan angle. We measured the Young's moduli of 24 specimens from six muscles of four swine at different passive muscle loads under different scan angles (0°, 30°, 60° and 90°) using SWE. Highly linear relationships between Young's modulus E and passive muscle force F were found for all 24 muscle specimens at 0o scan angle with coefficients of determination R2 ranging from 0.984 to 0.999. The results indicate that the muscle mass has no significant effect on the muscle E-F relationship, whereas E-F linearity decreases disproportionately with increased scan angle. These findings suggest that SWE, when carefully applied, can provide a highly reliable tool to measure muscle Young's modulus, and could be used to assess the muscle force quantitatively.