The following is a summary of the “Effects and mechanotransduction pathways of therapeutic ultrasound on healthy and osteoarthritic chondrocytes: a systematic review of in vitro studies,” published in the March 2023 issue of Osteoarthritis and Cartilage by Oliveira, et al.

To investigate the effects and mechanotransduction pathways of therapeutic ultrasound on chondrocytes. To find in vitro studies exploring the use of ultrasound to stimulate chondrocytes for the treatment of osteoarthritis (OA), the databases PubMed, EMBASE, and Web of Science were searched until the 19th of September, 2021. Study characteristics, ultrasound parameters, in vitro setup, and mechanotransduction pathways were collected. In addition, the Risk of Bias Assessment in Non-Randomized Studies (RoBANS) instrument was used to determine the potential for bias.

The 31 studies included either healthy or OA chondrocytes or explants. Lack of temperature control, setup calibration, adequate semi-quantitative analyses, and independent experiments contributed to a high risk of performance, detection, and pseudoreplication bias in most studies. Acoustic gel, a water bath, or culture media were used to transmit ultrasound to the culture plate. Regardless of the experimental design, ultrasound increased cartilage production and decreased degradation. 

In OA chondrocytes, ultrasound suppressed apoptosis, inflammation, and matrix degradation by activating phosphoinositide-3-kinase/akt (PI3K/Akt), extracellular signal-regulated kinase (ERK), and p38 and JNK pathways, while activating PI3K/Akt, ERK, p38, and JNK in healthy chondrocytes to boost matrix synthesis. According to the included research, ultrasound has a healing effect on chondrocytes. However, these results should be interpreted cautiously because a high risk of performance, detection, and pseudoreplication bias was identified. Additional research is needed to determine the efficacy of ultrasound in regenerating cartilage in OA knees by studying its effects on human chondrocyte cultures.