To clarify the anatomical characteristics of the lateral plantar ligament (LPL) of the transverse metatarsal arch (TMA) in the population of southwest Shandong Province, so as to complement the anatomical structures of the midfoot and Lisfranc joint complexes.

A total of 100 adult lower limbs were dissected and the types of LPL were divided according to their insertions, among them, 63 were (63%) and 37 were female (37%); 50 were on the left side (50%) and 50 were on the right side (50%). The fiber bundle length, origin width, insertion width, and thickness of the LPL were measured.

(1) According to the insertions of the LPL, they were divided into: ① Type I, the LPL was inserted at the base of the second metatarsal (M2) in 47 cases; ② Type II, the LPL was inserted at the base of M2 and fused with tibialis posterior tendon (TPT) in 16 cases; ③ Type III, the LPL was absent in 16 cases; ④ Type IV, the LPL was inserted at TPT in 6 cases; ⑤ Type V, the LPL was inserted at the intermediate cuneiform (IC) in 1 case; ⑥ Type VI, bifid LPL with one bundle inserted at the base of M2, and the other bundle inserted at the medial cuneiform (MC) in 4 cases; ⑦ Type VII, two bundles of LPL inserted at the base of M2 in 8 cases; ⑧ Type VIII, the LPL consisted of 3 bundles; the distal, middle and proximal bundles was inserted at the base of M2, the TPT and the lateral side of navicular bone in 2 cases, respectively. (2) There was a statistical significance in the length of LPL between male (31.62 ± 3.83) mm and female (28.07 ± 3.46) mm (t=-3.050, P = 0.003). There was no statistical significance in the types of LPL between male and female (Z=-1.721, P > 0.05), and no statistical significance in the types between left and right sides (Z=-0.026, P > 0.05).

According to our research, LPL originates from M5 and is divided into 8 types according to its insertion location, of which insertion at the base of M2 is the most common. In addition, we found that LPL has fibrous fusion with the long plantar ligament and the TPT, which may be involved in maintaining arch stability. The classification of LPL in this study is a supplement to the anatomical structure of the middle foot and Lisfranc joint complex, providing a new direction for the diagnosis and treatment of middle foot and arch injury in the future.