Ultrasonographic evaluation of needle electromyography insertion into the tibialis posterior using a posterior approach

Objective: To estimate the safety window for needle insertion in the posterior approach to the tibialis posterior by ultrasonography, particularly in a clinical setting.

Design: Cross-sectional study.

Setting: University hospital.

Participants: Healthy volunteers (108 legs, from 22 men and 32 women).

Interventions: Not applicable.

Main outcome measures: Distance between the tibia and neurovascular bundles in the posterior aspect of the tibia on a transverse ultrasonographic scan.

Results: The safety window at the midpoint was significantly larger than the upper third (0.62-2.16 cm, average 1.47 ± 0.38 cm vs 0.51-1.62 cm, average 1.16 ± 0.31 cm). The depth at the midpoint was significantly more shallow than the upper third (1.57-3.16 cm, average 2.31 ± 0.34 cm vs 1.76-3.66 cm, average 2.52 ± 0.38 cm). Body weight, height, tibial length, and leg circumference showed positive correlation with the safety window at both points.

Conclusions: The midpoint may be more favorable than the upper third for needle insertion to the tibialis posterior with a posterior approach.