An Anatomic Study of the Naviculocuneiform Ligament and Its Possible Role Maintaining the Medial Longitudinal Arch

Weight-bearing radiographic analysis of pes planus deformities show, with varying degree of severity, a break in the Meary line. The break in the Meary line occurs not only at the talonavicular joint but also distal to the spring ligament and reported tibialis posterior insertion. Our aim in this study was to investigate the distal plantar ligaments of the medial longitudinal arch, to try to identify other areas where deformity correction could be affected.

We examined 11 cadaveric lower limbs that had been preserved for dissection in a solution of formaldehyde. The lower limbs were carefully dissected to identify the plantar aspect of the medial longitudinal arch.

In all specimens, the tibialis posterior tendon inserted into the plantar medial aspect of the navicular with separate slips to the intermediate and lateral cuneiform. The navicular cuneiform ligament extended from the navicular to medial cuneiform. This structure was statically inserted between the navicular and medial cuneiform, which would allow the pull of the tibialis posterior to act on the navicular and medial cuneiform in tandem. The average width of the naviculocuneiform ligament was 15.2 mm (range 12.4-18.0) compared to 9.5 mm (range 7.6-11.4) for the tibialis posterior tendon.

The tibialis posterior tendon inserted into the navicular and continued onto the medial cuneiform to provide a static restraint between 2 bony insertions, thus supporting the distal aspect of the medial longitudinal arch.

We are confident that it is a structure of importance in maintaining the distal aspect of the medial longitudinal arch and may therefore have significant clinical and surgical implications when treating the pes planus deformity.