Floor plan - 2013 Annual Meeting - American Association for Hand ...

Pressure Changes in the Medial and Lateral Plantar and Tarsal Tunnels Related to Ankle
Position: a Prospective Intra-Operative Study in Patients with Underlying Neuropathy
Institution where the work was prepared: Johns Hopkins University School of Medicine, Baltimore, MD, USA
Gedge D. Rosson, MD1; Eric H. Williams, MD2; Allison R. Barker, BA1; A. Lee Dellon, MD3; (1)Johns Hopkins
University School of Medicine, (2)Dellon Institute for Peripheral Nerve Surgery: Baltimore. Clinical Instructor; Johns
Hopkins University School of Medicine, (3)Dellon Institute for Peripheral Nerve Surgery: Baltimore. Professor; Johns
Hopkins University School of Medicine
BACKGROUND:
Pressure in the tarsal tunnel has been shown to be elevated in pronation. We hypothesized that this result would hold for the medial
and lateral plantar tunnels since they are also potential sites of nerve compression. Additionally we hypothesized that decompression
surgery would decrease these pressures. We have previously presented that these pressures are decreased by surgery in a cadaver
model. We further hypothesized that the pressures in symptomatic patients would be higher than in our cadaver study. Thus, we sought
to study the pressure changes in the medial and lateral plantar and tarsal tunnels in actual symptomatic patients with co-existing peripheral
neuropathy and evidence of superimposed nerve compressions.
METHODS:
10 patients were enrolled. Intra-operative pressure measurements were made in the medial and lateral plantar and tarsal tunnels before
and after decompression surgery, including excision of the septum between the medial and lateral plantar tunnels, in a variety of foot
positions. Approval for this prospective study was obtained from The Johns Hopkins Medicine IRB.
RESULTS:
Pronation and pronation with plantar flexion gave significantly higher pressures than the other foot positions in the medial and lateral
plantar tunnels. This was the same as seen in the cadaver study. Surgery significantly decreased the pressures in the three tunnels in all
foot positions except pronation in the tarsal tunnel and supination in the lateral plantar tunnel. Significant decreases in pressure were
seen with simple roof incision in all tunnels in all positions except the two mentioned above. Septum excision gave further significant
decreases in pressure in the medial and lateral plantar tunnels when compared with roof incision alone. These patients did have significantly
higher pressures in several foot positions in the medial and lateral plantar tunnels than the cadaver study limbs.
CONCLUSION:
Pressures within the medial and lateral plantar tunnels, and the tarsal tunnel, increase significantly with changes in ankle position. These
pressure changes are significantly decreased by surgical release of these three tunnels, including excision of the septum between the
medial and lateral plantar tunnels. Pressures within the medial and lateral plantar tunnels are significantly higher in living symptomatic
patients versus presumably asymptomatic cadaver limbs.
CLINICAL RELEVANCE:
Symptoms related to chronic compression of the tibial nerve and its branches may potentially be relieved by custom orthotics and proper
gait mechanics, and, when necessary, by a surgical strategy targeting release of multiple anatomic regions rather than focusing upon
the tarsal tunnel alone.
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