Today, I'll be presenting the findings from a cadaveric study entitled Anatomy of the Tibial Nerve in Relation to the Tarsal Tunnel. These are the relevant disclosures. Tarsal tunnel syndrome is a compressive neuropathy of the tibial nerve at the level of the tarsal tunnel. Surgical outcomes vary depending on the etiology. To date, there has been a lack of studies investigating the anatomy of the tibial nerve in relation to the tarsal tunnel. The purpose of our cadaveric study was to describe the anatomy and variations of the tibial nerve and its branches in relation to the tarsal tunnel. So 40 specimens were obtained, 16 were bilateral, 8 were unilateral, 11 were male, 18 were female, 18 were right-sided lower limbs, and 22 were left-sided lower limbs. Dissection began 20 cm proximal to the delamacunal line towards the medial aspect of the navacular cuneiform joint distally. Anteriorly, the dissection went from the tibiotalar medial cotter to the medial aspect of the Achilles tendon. The plantar aspect of the dissection extended from medial to lateral, ending at the level of the psychometatarsal. We found that the flexor retinaculum was an undistinguished extension of creole fascia in 77.2% of specimens. It had a denser consistency in 22.5% of specimens, and the average length was 51.9 mm. We found that the lateral plantar nerve and abductor digiti minimi nerve shared a common origin in 80% of specimens. The bifurcation, rather than the delamacunal line, occurred proximal in 34% of patients. The bifurcation occurred at the same level as the delamacunal line in 35% of patients. And bifurcation at the distal to the delamacunal line occurred in 31% of patients. We found that the medial calcaneal nerve emerged proximal to the delamacunal line in all specimens, and the medial plantar nerve emerged proximal to the delamacunal line in 95% of specimens. So, we feel that having a denser flexor retinaculum may predispose patients to tarsal tunnel syndrome, which may indicate that more aggressive surgical intervention would be required in these patients. As already stated, the lateral plantar nerve and abductor digiti minimi nerve shared a common origin in 80% of patients. Compression at or proximal to this area could lead to both altered sensation in the distribution in the lateral plantar nerve and a motor deficit in fifth toe abduction. Conversely, we found that the lateral plantar nerve and abductor digiti minimi nerve had no common origin in 12.5% of patients. This could present with an isolated motor deficit in fifth toe abduction and would be more amenable to a more distal dissection. Interestingly, we found that all patients had a medial calcaneal nerve that emerged proximal to the delamacunal line, and 95% of patients had a medial plantar nerve that emerged proximal to the delamacunal line, which conflicts with prior studies. A previous calibric study by Torres et al. found that the tibial nerve branches with proximal origins may not penetrate the tarsal tunnel. In our series, 100% of the medial calcaneal nerves were located within the tarsal tunnel. This indicates that further calibric studies are required. So in conclusion, we found that the flexor-retinaculum may not be an independent structure, variation in density of the flexor-retinaculum may predispose patients to tarsal tunnel syndrome, we found that variation in the origins of the lateral plantar nerve and abductor digiti minimi nerve and the distribution of the medial calcaneal nerve and medial plantar nerve may have implications on both clinical presentation and management. Further research is wanted. Thank you.

cadaveric study

tibial nerve

tarsal tunnel syndrome

anatomy

nerve variations