Anatomical Description of the Spring Ligament Articular Facet.

Background: The spring ligament fibrocartilaginous complex (SLFC), which is essential for stabilizing the medial longitudinal arch, features a little-explored fibrocartilaginous facet within its superomedial aspect, articulating with the talar head. This research aimed to provide a detailed anatomical description of this facet, designated as the spring ligament articular facet (SLAF).

Methods: Nine normally aligned cadaveric lower limbs were dissected, approaching the SLFC from a superior direction. Following talus disarticulation, high-resolution images of the ligament complex were captured and analyzed. ImageJ software was used to determine the areas and dimensions of the superomedial calcaneonavicular (SMCN) spring and SLAF.

Results: The fibrocartilage facet exhibited a trapezoid shape in all specimens. The mean area for SMCN spring was 280.39 mm², and for SLAF, it was 200 mm². The proximal-to-distal length for SLAF averaged 11.78 mm at its longest and 5.34 mm at its shortest. Attachment of the SLAF to the calcaneum and the navicular showed robust fibrous structures, with average measurements of 3.75 and 1.75 mm at the medial and lateral calcaneal margins, and 2.75 and 2.98 mm at the medial and lateral navicular margins, respectively.

Conclusion: This study clearly delineated the individual structural components of the SLFC articulating with the talar head and detailed its dimensions, emphasizing the need for more specific anatomical terminology that respects the intricate anatomy of the SLFC.

Level of evidence: Level III, descriptive study.