SLR - January 2018 - Michael Huchital

Anatomic Delineation of Tarsal Tunnel Innervation via Ultrasonography

Reference: Iborra A, Villanueva M, Barret SL, Rodriguez-Collazo E, Sanz P. Anatomic Delineation of Tarsal Tunnel Innervation via Ultrasonography. J Ultrasound Med. 2017 Dec 4.

Reviewed By: Michael Huchital, DPM
Residency Program: NYU Langone Hospital Systems, Brooklyn, NY

Podiatric Relevance: Ultrasound is a powerful imaging modality for the podiatric physician. It benefits both patient and clinician in that it can be conducted in real time in the office setting. In this article, the effectiveness of ultrasound in the area of the tarsal tunnel is demonstrated with correlation to cadaveric dissection revealing that the tibial nerve and its branches can be accurately identified on ultrasound.

Methods: The correlation between US mapping and real anatomy following cadaveric dissection. Distribution of nerves and variation were assessed using the imaging modality and dissection. Twelve fresh specimens at the foot and ankle, including the calf, were used. High-resolution ultrasound was used to map the tibial nerve and its branches.

Results: Each arm of examination were drawn as paper diagrams and placed in collection tables. The cadavers were firstly mapped with US and secondly under anatomic dissection. By this approach, they were able to accurately measure the value of each method using the same control specimen. The authors found almost total agreement between the ultrasound and dissection results with no significant differences.

Discussion: The authors sought to validate ultrasonography of the tarsal tunnel as a viable means of diagnosing tarsal tunnel syndrome and to guide subsequent surgical intervention. Upon examination of existing literature, other studies used latex or dye injection in cadaveric specimens to correlate finding on ultrasound. The authors chose to use dye as they felt that anatomic dissection would prove more problematic. They state that their resultant variation from previous studies was largely due to sample size. Additionally, they point out that their main objective was not to describe anatomic variation but to determine the efficacy of ultrasonography via subsequent anatomic dissection. There were no previous studies validating ultrasound and the topography of the tarsal tunnel branches. They further state that determining the location of tibial nerve branches is essential in avoiding iatrogenic damage during invasive procedures at this location, reducing postprocedural complications.

Conclusions: On the basis of this study, high-resolution ultrasound is proven to be an effective means of mapping nerve branches at the tarsal tunnel. The authors further implicate that because of how closely the ultrasound was able to map in comparison to anatomic dissection, the modality could be used further to plan surgical intervention.

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