The plantar intermetatarsal ligaments are short, stout ligamentous bands connecting the plantar surfaces of adjacent metatarsal bases in the Lisfranc complex, supplementing the deeper Lisfranc ligament (between the first cuneiform and second metatarsal base). They contribute to the transverse stability of the tarsometatarsal joint complex, resisting separation between adjacent metatarsal bases during forefoot loading.
Resist plantar and lateral separation of adjacent metatarsal bases, maintain the transverse metatarsal arch at the Lisfranc level, and distribute axial loads across the forefoot.
The plantar intermetatarsal ligaments are disrupted in Lisfranc injuries together with the primary Lisfranc ligament, explaining the complete instability of the tarsometatarsal complex in high-grade injuries. In subtle Lisfranc injuries on weight-bearing radiograph, plantar ligament disruption can be detected by MRI demonstrating marrow oedema at the ligament insertions. Surgical repair of Lisfranc injuries addresses the primary Lisfranc ligament and the second tarsometatarsal joint, with the plantar intermetatarsal ligaments healing secondarily once the primary instability is corrected.
High-energy Lisfranc fracture-dislocation disrupts the plantar intermetatarsal ligaments alongside the primary Lisfranc ligament, producing complete tarsometatarsal instability; weight-bearing radiograph demonstrating diastasis between the first and second metatarsal bases confirms the injury and primary ORIF or arthrodesis is required for high-grade instability.
