Plantar interphalangeal ligaments

The plantar interphalangeal ligaments (plantar plate of the interphalangeal joint of the toe) are fibrocartilaginous structures located on the plantar aspect of the joint.

They are anatomically distinct from the plantar plates of the metatarsophalangeal (MTP) joints, but share similar histological features. The plantar plate is composed primarily of dense longitudinally oriented collagen bundles, with a central region that withstands significant tensile and compressive forces during gait and weight-bearing activities.

At the interphalangeal joint, the plantar plate is firmly attached proximally to the base of the proximal phalanx and distally to the head of the distal phalanx. It merges laterally with the collateral ligaments and is closely associated with the flexor tendon sheath, forming a stabilizing complex for the joint. The plate also serves as a distal attachment for the plantar aponeurosis, contributing to the windlass mechanism and supporting the longitudinal arch of the foot.

Histologically, the plantar plate transitions from a fibrocartilaginous structure centrally to a more ligamentous composition at its borders, with fewer chondrocytes and more fibroblasts distally. The enthesis at the phalangeal attachment is characterized by interdigitating collagen bundles, which provide resistance to the high mechanical loads experienced during toe dorsiflexion.