Plantar Tarsometatarsal Ligaments: Anatomy, Function, and Imaging

Topic

Plantar tarsometatarsal ligaments

The plantar tarsometatarsal ligaments are strong fibrous bands located on the plantar (inferior) aspect of the tarsometatarsal joints, connecting the tarsal bones (cuneiforms and cuboid) with the bases of the metatarsals. They form part of the Lisfranc joint complex, providing essential stability to the midfoot and maintaining the integrity of the longitudinal and transverse arches.

These ligaments are thicker and stronger than their dorsal counterparts and are reinforced by the tendons of the tibialis posterior and peroneus longus muscles. Together, they ensure rigid stability during propulsion and weight-bearing.

Synonyms

Plantar Lisfranc ligaments
Plantar tarsometatarsal joint ligaments
Plantar cuneometatarsal and cubometatarsal ligaments

Origin, Course, and Insertion

Origin: Plantar surfaces of the cuneiforms and cuboid bones
Course: Oblique fibrous bands extending distally and laterally across the plantar aspect of the foot
Insertion: Bases of the first to fifth metatarsals on their plantar surfaces

The medial plantar ligament connects the first cuneiform to the first and second metatarsals; the central set spans the intermediate and lateral cuneiforms to the second, third, and fourth metatarsals; and the lateral set connects the cuboid to the fourth and fifth metatarsals. These fibers interweave, forming a continuous, tough sheet of fibrous tissue.

Relations

Superiorly: Dorsal tarsometatarsal ligaments and interosseous (Lisfranc) ligament
Inferiorly: Plantar aponeurosis and tendons of tibialis posterior and peroneus longus
Medially: Medial cuneiform and first metatarsal base
Laterally: Cuboid and fifth metatarsal base

Function

Midfoot stabilization: Maintains alignment between tarsal and metatarsal bones
Arch support: Contributes to both longitudinal and transverse plantar arches
Force transmission: Transfers load from forefoot to hindfoot during gait
Joint integrity: Prevents excessive dorsiflexion and separation at the tarsometatarsal joints
Dynamic stability: Reinforced by surrounding tendons and plantar fascia during push-off phase

Clinical Significance

Lisfranc injury: Involves tearing or avulsion of plantar tarsometatarsal ligaments, often with midfoot instability
Trauma: Axial loading or twisting injuries can cause rupture, leading to joint displacement or collapse of the arch
Chronic degeneration: Repetitive stress may cause thickening, fibrosis, or calcification
Post-traumatic arthritis: Common late complication of untreated Lisfranc ligament injuries
Symptoms: Midfoot pain, swelling, plantar tenderness, inability to push off during gait
Imaging relevance: Crucial in diagnosing Lisfranc joint dislocation and ligament disruption on MRI or CT

MRI Appearance

T1-weighted images:
- Normal ligaments appear as low-signal (dark) linear bands connecting tarsal and metatarsal bases.
- Surrounding fat planes are bright, enhancing contrast and visualization.
- Partial tears show focal thickening or irregularity with mild signal increase.
- Complete tears appear as discontinuity or fluid-filled gap between ligament attachments.
T2-weighted images:
- Normal ligaments remain low signal (darker than on T1).
- Acute injuries appear as bright hyperintense zones with disruption or swelling.
- Adjacent bone marrow edema and joint effusion may be present.
- Chronic injuries may show ligament thinning, wavy contour, or scarring.
STIR:
- Normal: dark linear structures.
- Pathology: hyperintense ligament signal with adjacent soft-tissue edema or effusion.
- Excellent for detecting subtle sprains and marrow changes.
Proton Density Fat-Saturated (PD FS):
- Normal ligaments: low signal, sharply defined.
- Partial tears: focal bright intraligamentous signal with intact fibers.
- Complete tears: bright fluid gap between retracted ligament ends.
- Ideal sequence for assessing Lisfranc ligament disruption.
T1 Fat-Sat Post-Contrast:
- Normal ligaments: minimal or no enhancement.
- Injured ligaments: linear or diffuse enhancement indicating inflammation or scarring.
- Chronic fibrosis may enhance mildly along the plantar aspect.

CT Appearance

Non-Contrast CT:

Ligaments appear as thin, soft-tissue density bands connecting tarsal and metatarsal bones.
Best evaluated indirectly by alignment of tarsometatarsal joint surfaces.
Acute injury: widening of joint spaces, subluxation, or small avulsion fragments.
Chronic changes: calcification, ossification, or irregular cortical remodeling at ligament insertions.

Post-Contrast CT (standard):

Provides better soft-tissue contrast.
Injured ligaments may appear as thickened or indistinct low-density structures with periligamentous enhancement.
Useful for detecting associated midfoot fractures or subtle joint malalignment.

MRI image

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