The posterior/medial dry needling approach of the tibialis posterior muscle is an accurate and safe procedure: a cadaveric study

BACKGROUND: Evidence suggests that tibialis posterior muscle plays an important role in equinovarus foot deformity in patients who had suffered a stroke and it is one of the most frequently injected lower-extremity muscles for the management of spasticity. Our aim was to assess if a needle accurately and safely penetrates the tibialis posterior muscle during the application of dry needling. METHODS : We conducted a cadaveric descriptive study. Needling insertion of the tibialis posterior was conducted in 11 cryopreserved cadavers with a 70 mm needle. The needle was inserted using two common approaches, at midpoint (posterior/medial approach) and at upper third (anterior approach) of the leg towards the tibialis posterior. The needle was advanced into the tibialis posterior based upon clinician judgement. Cross-sectional anatomical dissections were photographed and analyzed by photometry. Safety was assessed by calculating the distances from the tip and the path of the needle to proximate neurovascular structures. RESULTS: Accurate needle penetration of the tibialis posterior muscle was observed in all cadavers with both approaches. In general, distances from the needle to the neurovascular bundles were larger with the posterior/medial approach than with the anterior approach, reaching statistically significance for needle tip to nerve (mean difference: 0.6 cm, 95%CI 0.35 to 0.85 cm) and vascular bundle (mean difference: 0.55 cm, 95%CI 0.3 to 0.8 cm) distances (P < 0.001) and needle path to vascular bundle distance (difference: 0.25 cm, 95%CI 0.1 to 0.4 cm, P = 0.045). Age and gender did not influence the main results. CONCLUSIONS: This cadaveric study suggests that needling of the tibialis posterior muscle can be accurately and safely conducted. Safety seems to be larger with the posterior/medial approach when compared with the anterior approach.