Decoupling of laxity and cortical activation in functionally unstable ankles during joint loading

Area of Science:

• Neuroscience
• Orthopedics
• Kinesiology

Background:

• Ligamentous injuries can alter central nervous system function, potentially impacting joint stability.
• Previous research has not examined cortical responses to joint loading or sensory changes in individuals with joint laxity.

Purpose of the Study:

• To investigate cortical somatosensory responses during ankle joint loading in healthy individuals, those with ankle instability, and copers.
• To determine if joint laxity influences the central nervous system's response to mechanical joint stress.

Main Methods:

• Forty-two participants were divided into healthy (CON), unstable (UNS), and coper (COP) groups based on ankle injury history.
• Electroencephalography (EEG) measured event-related desynchronization (ERD) to quantify somatosensory cortex activity during controlled ankle loading via an arthrometer.

Main Results:

• Ankle joint loading significantly increased somatosensory cortex activation across all participants (F = 63.05, p < 0.001).
• No significant differences in the magnitude of cortical activation were found between the CON, UNS, and COP groups (F = 1.387, p = 0.268).
• The unstable (UNS) group exhibited significantly greater ankle laxity compared to the other groups (F = 3.58, p = 0.038).

Conclusions:

• Joint loading elicits increased somatosensory cortex activity, irrespective of ankle instability or copers status.
• Despite mechanical instability in the UNS group, cortical activation patterns during loading did not differ from healthy or coper groups.
• Further investigation is warranted to elucidate the relationship between cortical activation, joint stiffness, and ligamentous injury outcomes.