Anatomy of the Lateral Plantar Ligaments of the Transverse Metatarsal Arch

Abstract

Background: While the anatomy of the Lisfranc complex is well understood, the lateral tarsometatarsal ligamentous structures, in contrast, are less well studied. Our aim in this study was to identify an anatomical explanation as to why the second to fifth metatarsals function as a unit in homolateral and divergent midfoot injuries. Methods: Eleven cadaveric lower limbs, preserved in formaldehyde, were examined at the University of Liverpool Human Anatomy and Resource Centre. Each of the lower limbs was dissected to identify the plantar aspect of the transverse metatarsal arch. Results: On removal of the long plantar ligament, the peroneal longus tendon was visible, as was its insertion onto the first metatarsal base. A lateral Lisfranc ligament (which was a transverse suspensory metatarsal ligament) spanned between the bases of the second and fifth metatarsals in all specimens with an average length of 33.7 mm and width of 4.6 mm. This ligament has not previously been described. It was noted that in all specimens, the long plantar ligament blended with the lateral Lisfranc ligament. In addition to the lateral Lisfranc ligament, separate intermetatarsal ligaments were identifiable connecting each metatarsal. The long plantar ligament provided a connection through the lateral Lisfranc ligament connecting the transverse and longitudinal arches of the foot. Conclusion: We found a plantar ligament that provided connection through the long plantar ligament of both the transverse and the longitudinal arches. It spanned from the second to the fifth metatarsal, which we believe may explain that in some cases, lateral instability can be overcome when the middle column is stabilized. Clinical Relevance: We suspect that in the majority of homolateral and divergent types of tarsometatarsal injuries that the lateral Lisfranc ligament remains intact and thus it has significant clinical ramifications.

Morphological features of the lateral plantar ligament of the transverse metatarsal arch

“…Previous studies reported that dorsal tarsometatarsal ligaments occurred in 7–9 distinct bands, interosseous intermetatarsal ligaments occurred in 4 distinct bands, and plantar tarsometatarsal bands occurred in 9 separate bands (Castro et al, 2010; Sarrafian, 2011; Ulbrich et al, 2013; Won et al, 2019). Further, Mason et al (2020) identified a well‐defined ligament originating from the base of M5 and inserting on the lateral plantar aspect of M2, and that this ligament was present in all 11 specimens; however, the sample size was very small (n = 11) compared with that in the present study (n = 100). Factors related to dissection also need to be considered: Mason et al (2020) reported that the LPL blended partially with the lateral plantar ligament in the medial third of the ligament in all specimens.…”

“…The morphological characteristics of the lateral plantar ligament were assessed and its length, width, and thickness of the fiber bundles were measured according to a method described previously (Mason et al, 2020). Measurements were made at the center of all ligaments using digital calipers (Shinwa Rules, Niigata, Japan).…”

“…The tarsometatarsal articulation (Lisfranc joint) of the midfoot is a complex interplay of articular congruity, ligaments, tendons, and supporting tendons (Mason et al, 2020). The Lisfranc joint includes all articulations between the tarsal bones (three cuneiforms [C1–3] and the cuboid) and the bases of the five metatarsals, termed M1–5 (de Palma, Santucci, Sabetta, & Rapali, 1997).…”

“…However, new ligaments have recently been reported on the lateral side. Mason et al (2020) identified a well‐defined ligament originating from the M5 base and inserting on the lateral plantar aspect of M2, that was present in all 11 of their specimens. They termed this ligament the lateral Lisfranc ligament (a transverse suspensory metatarsal ligament).…”

Updates on Lisfranc Complex Injuries

“…42 As a result, the lateral column is generally not fused in the treatment of Lisfranc injuries and is allowed to remain mobile. Recently, Mason et al 36 described the lateral Lisfranc ligament, a transverse suspensory metatarsal ligament that connects the long plantar ligaments of both the transverse and longitudinal arches. In cadavers, they noted that this ligament allowed M2 through M5 to act as a single unit.…”