SLR - October 2010 - Stacie Buck

Tibial Nerve Decompression in Patients with Tarsal Tunnel Syndrome: Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels

Reference: Rosson GD, Larson AR, Williams EH, Dellon AL. (2009). Tibial Nerve Decompression in Patients with Tarsal Tunnel Syndrome: Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels.  Plastic and Reconstructive Surgery, 124 (4), 1202-1210.

Scientific Literature Reviews

Reviewed by:  Stacie Buck
Residency Program: OCPM/UHHS Richmond Medical Center

Podiatric Relevance:
This article evaluates the pressure in the tarsal, medial plantar, and lateral plantar tunnels with the foot in various positions in patients with tarsal tunnel sydrome before and after surgical release of the tunnel roofs and intertunnel septum.

Methods:
Ten patients with tarsal tunnel syndrome underwent tibial nerve decompression for this study.  Using an IntraCompartmental Pressure Monitor System, the tarsal, medial plantar, and lateral plantar tunnel pressures were measured before and after surgical release of the roof  of each tunnel and the intertunnel septum.  Each of these measurements was taken with the foot in neutral, dorsiflexion, plantarflexion, pronation, supination, and pronation with plantarflexion.  The average of three readings in each position in every tunnel was recorded.  An identical study was done on tweleve cadaveric models to compare these results with those of symptomatic patients.

Results: 
Of the six foot positions tested, significantly higher pressures were found in the medial plantar (by 24 mmHg) and lateral plantar (by 26 mmHg) tunnels during pronation and all three tunnels had significantly higher pressures during pronation with plantarflexion compared to the neutral position.  The pressure during pronation in the tarsal tunnel was significantly lower than with pronation with plantarflexion.  Decompression of each tunnel significantly decreased the pressure in all positions except neutral where (p=0.01)  Excision of the septum led to a further decrease in the medial and lateral plantar tunnel pressures during pronation.  Although cadaveric models had similar pressure readings as the patients, the lateral plantar tunnels during pronation were significantly higher in symptomatic patients.

Conclusions:
This study demonstrates the need to release the tarsal, medial plantar, and lateral plantar tunnels and the intertunnel septum when performing a tibial nerve decompression in order to reduce the pressure in each compartment.  Since the pressure is greatest at pronation or pronation and plantarflexion in each tunnel, it is suggested to control the amount of pronation, through custom orthoses, post operatively or as a non-operative treatment.  

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