The long plantar ligament is the longest ligament in the foot, running from the calcaneal tuberosity over the cuboid to the metatarsal bases, forming a fibro-osseous tunnel for the peroneus longus tendon as it crosses the cuboid groove. It supports the lateral arch and bridges the calcaneocuboid joint. Its failure contributes to lateral arch collapse in severe flatfoot deformity and in inflammatory arthritis.
| Origin | Plantar calcaneal tuberosity (posterior to the short plantar ligament) |
|---|---|
| Insertion | Deep layer: cuboid. Superficial layer: bases of metatarsals 2 through 5 |
| Actions | Supports the lateral longitudinal arch; the longest plantar foot ligament |
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The long plantar ligament forms the roof of the peroneus longus cuboid groove tunnel — its integrity is important for peroneus longus function. Long plantar ligament tears in association with Lisfranc and calcaneocuboid joint injuries produce lateral midfoot instability. In rheumatoid arthritis, long plantar ligament laxity contributes to the metatarsalgia and forefoot splay seen in severe disease.
Ligament disruption from lateral foot compression or extreme supination force producing lateral foot pain and arch pain, managed with orthotic support and load modification.
