Lateral ankle ligament anesthesia significantly alters single limb postural control

Area of Science:

• Biomechanics
• Neuroscience
• Orthopedics

Background:

• Lateral ankle anesthesia models ligament deafferentation effects on postural control.
• Conflicting results exist regarding its impact on single limb postural control.
• Time-to-boundary (TTB) is sensitive to subtle postural control deficits, particularly in chronic ankle instability.

Purpose of the Study:

• To investigate the effects of lateral ankle ligament anesthesia on TTB measures of single limb postural control in healthy adults.
• To determine if anesthesia-induced deafferentation mimics deficits seen in chronic ankle instability.

Main Methods:

• Twenty-two healthy adults underwent lidocaine injection to lateral ankle structures.
• Subjects performed barefoot single limb stance on a forceplate under eyes open and closed conditions.
• Time-to-boundary (TTB) minima magnitude and variability in mediolateral (ML) and anteroposterior (AP) directions were analyzed.

Main Results:

• Anesthesia significantly reduced TTBAP magnitude (p=0.008) and variability (p=0.044) compared to the control condition.
• These effects were observed regardless of visual input (eyes open/closed).
• No significant differences were found in the mediolateral (ML) direction.

Conclusions:

• Anesthesia of lateral ankle ligaments impairs anteroposterior (AP) postural control magnitude and variability.
• These findings suggest that ligament deafferentation may contribute to postural control deficits similar to those in chronic ankle instability.