Ultrasound Imaging of the Trapeziometacarpal Articular Cavity to Investigate the Presence of Intraarticular Gas Bubbles After Chiropractic Manipulation

Abstract Objective The purpose of this study was to investigate the presence of intraarticular gas bubbles in the trapeziometacarpal joint cavity after chiropractic manipulation with audible cavitation and to assess the state of the gas bubbles after a 20-minute refractory period. Methods This investigation included 18 asymptomatic male and female participants between the ages of 21 and 26 years. High-resolution (15 MHz) sonograms of the trapeziometacarpal articular cavity were obtained by an experienced musculoskeletal ultrasonographer at 3 intervals: premanipulation, within 30 seconds postmanipulation, and at 20 minutes postmanipulation. The sonograms were saved as digital copies for subsequent reports that were correlated with reports compiled during dynamic visualization of the articular cavity. Data were extracted from the reports for analysis. Results The premanipulative sonograms showed that 27.78% of joints contained minute gas bubbles, also known as microcavities, within the synovial fluid before the joint was manipulated. The remaining 72.22% of joints contained no intraarticular microcavities. All of the postmanipulative sonograms revealed numerous large conspicuous gas bubbles within the synovial fluid. The postrefractory sonograms showed that, in 66.66% of the synovial fluid, gas bubbles were still visible, whereas the remaining 33.34% had no presence of gas bubbles or microcavities, and the synovial fluid had returned to its premanipulative state. Conclusion The findings of this study suggest that synovial fluid may contain intraarticular microcavities even before a manipulation is performed. Numerous large intraarticular gas bubbles are formed during manipulation due to cavitation of the synovial fluid and were observed in the absence of an axial distractive load at the time of imaging. In most cases, these gas bubbles remained within the joint for longer than 20 minutes.