Do Audible Sounds During a Metacarpophalangeal and Metatarsophalangeal Thrust Manipulation Have an Impact on Intra-Articular Joint Space and Brainwave Activity?

Background: Joint manipulation is commonly used to manage musculoskeletal dysfunctions. Joint manipulation can result in audible sounds. The clinical significance and cause of manipulation sound remain unclear. This study aimed to identify intra-articular distance following a metacarpophalangeal (MCP) II and metatarsophalangeal (MTP) II joint manipulation in healthy subjects. Additionally, the cortical response pattern was measured.

Methods: Twenty-five subjects completed this quasi-experimental repeated-measures study protocol. Musculoskeletal ultrasound was used to measure intra-articular joint distance, and a portable EEG device captured brainwave activity. The environment was controlled during testing. Initially, the joint distance of the MCP II and MTP II was measured followed by the recording of initial brainwaves. Following a pre-manipulation hold, a second brainwave measure was taken. After this, each subject underwent a thrust manipulation of either MCP II or MTP II, immediately followed by the next brainwave measurement. One minute later, the final and fourth measurement took place.

Results: All subjects regardless of audible sound increased in joint space following both the MCP and MTP joint manipulation. The audible group had more significant EEG changes ( < 0.05) following the MCP manipulation but less following the MTP manipulation.

Conclusions: This study supports the tribonucleation theory explaining audible joint manipulation sounds. The manipulation of the MCP II joint resulted in increased Theta wave activity, indicating a state of relaxation, which was larger in the audible group. The MTP II manipulation had decreased cortical effects regardless of the presence of a sound. Despite these findings, the clinical usefulness of audible sounds remains questionable.