Ultrasound palpation for fast in-situ quantification of articular cartilage stiffness, thickness and relaxation capacity

Visualizing tactile feedback: an overview of current technologies with a focus on ultrasound elastography

Tissue elasticity remains an essential biomarker of health and is indicative of irregularities such as tumors or infection. The timely detection of such abnormalities is crucial for the prevention of disease progression and complications that arise from late-stage illnesses. However, at both the bedside and the operating table, there is a distinct lack of tactile feedback for deep-seated tissue. As surgical techniques advance toward remote or minimally invasive options to reduce infection risk and hasten healing time, surgeons lose the ability to manually palpate tissue. Furthermore, palpation of deep structures results in decreased accuracy, with the additional barrier of needing years of experience for adequate confidence of diagnoses. This review delves into the current modalities used to fulfill the clinical need of quantifying physical touch. It covers research efforts involving tactile sensing for remote or minimally invasive surgeries, as well as the potential of ultrasound elastography to further this field with non-invasive real-time imaging of the organ's biomechanical properties. Elastography monitors tissue response to acoustic or mechanical energy and reconstructs an image representative of the elastic profile in the region of interest. This intuitive visualization of tissue elasticity surpasses the tactile information provided by sensors currently used to augment or supplement manual palpation. Focusing on common ultrasound elastography modalities, we evaluate various sensing mechanisms used for measuring tactile information and describe their emerging use in clinical settings where palpation is insufficient or restricted. With the ongoing advancements in ultrasound technology, particularly the emergence of micromachined ultrasound transducers, these devices hold great potential in facilitating early detection of tissue abnormalities and providing an objective measure of patient health.

Characterization of intra-tissue strain fields in articular cartilage explants during post-loading recovery using high frequency ultrasound

This study aims to demonstrate the potential of ultrasound elastography as a research tool for non-destructive imaging of intra-tissue strain fields and tissue quality assessment in cartilage explants. Osteochondral plugs from bovine patellae were loaded up to 10, 40, or 70 N using a hemi-spherical indenter. The load was kept constant for 15 min, after which samples were unloaded and ultrasound imaging of strain recovery over time was performed in the indented area for 1 h. Tissue strains were determined using speckle tracking and accumulated to LaGrangian strains in the indentation direction. For all samples, strain maps showed a heterogeneous strain field, with the highest values in the superficial cartilage under the indenter tip at the bottom of the indent and decreasing values in the deeper cartilage. Strains were higher at higher load levels and tissue recovery over time was faster after indentation at 10 N than at 40 N and 70 N. At lower compression levels most displacement occurred near the surface with little deformation in the deep layers, while at higher levels strains increased more evenly in all cartilage zones. Ultrasound elastography is a promising method for high resolution imaging of intra-tissue strain fields and evaluation of cartilage quality in tissue explants in a laboratory setting. In the future, it may become a clinical diagnostic tool used to identify the extent of cartilage damage around visible defects.

Research on quantitative measurement method of articular cartilage thickness change based on MR image

In order to study the quantitative measurement method of articular cartilage thickness change based on MR image, 140 patients with no knee joint symptoms and 17 patients with knee joint damage were studied. FLASH, SE and FISP 3 sequences were scanned for all normal knee joints to determine the articular cartilage thickness. 17 patients with knee joint damage were followed up for six months. The thickness of their femoral condyle and femoral trochlea cartilage was measured by FLASH sequence and thickness changes are recorded. The results show that the thickness distribution of normal knee articular cartilage in different parts is not equal, and the thickness of articular cartilage will be gradually thinner in different ages; MR image technique can observe the change of articular cartilage thickness in patients with knee joint damage, reflecting the recovery status of the patient's condition. The results of quantitative measurement of changes in articular cartilage thickness based on MR images are presented herein, and the results are as expected. Experimental data were provided for the clinical treatment of acute knee injury and osteoarthritis. Although there are still some shortcomings in the research process, the research results still provide some reference and guidance for the future exploration of the use of MR images to monitor the condition of arthritis, so this study is a significant research topic.

Inhibition of myostatin signal pathway may be involved in low-intensity pulsed ultrasound promoting bone healing

PURPOSE

Low-intensity pulsed ultrasound (LIPUS) is effective in promoting bone healing, and a myostatin deficiency also has a positive effect on bone formation. In this study, we evaluated the effects of LIPUS on bone healing in rats in vivo and investigated the mechanisms in vitro, aiming to explore whether LIPUS promotes bone healing through inhibition of the myostatin signaling pathway.

METHODS

Rats with both drill-hole defects and MC3T3-E1 cells were randomly assigned to a LIPUS group and a control group. The LIPUS group received LIPUS treatment (1.5 MHz, 30 mW/cm²) for 20 min/day.

RESULTS

After 21 days, the myostatin expression in quadriceps was significantly inhibited in the LIPUS group, and remodeling of the newly formed bone in the drill-hole site was significantly better in the LIPUS group than that in the control group, which was confirmed by micro-CT analysis. After 3 days, LIPUS significantly promoted osteoblast proliferation; inhibited the expression of AcvrIIB (the myostatin receptor), Smad3, p-Smad3, and GSK-3β; and increased Wnt1 and β-catenin expression. Moreover, translocation of β-catenin from the cytolemma to the nucleus was observed in the LIPUS group. However, these effects were blocked by treatment with myostatin recombinant protein.

CONCLUSIONS

The results indicate that LIPUS may promote bone healing through inhibition of the myostatin signal pathway.