The collateral ligaments of the second through fifth metatarsophalangeal joints extend from the dorsolateral and dorsomedial metatarsal head to the base of the proximal phalanx on each side, stabilising each joint against coronal-plane instability. Together with the plantar plate and joint capsule they form the capsuloligamentous complex of each lesser MTP joint.
Resist medial and lateral deviation of the proximal phalanx on the metatarsal head, maintaining sagittal alignment of the lesser toes during stance and propulsion. They are taut in extension and lax in flexion, analogous to the collateral ligaments of finger MCP joints.
Collateral ligament attenuation at the second MTP joint is a primary contributor to crossover toe deformity, where the second toe drifts medially and eventually overrides the hallux. Clinical assessment uses the transverse drawer (Lachman equivalent) test for the MTP joint, assessing dorsoplantar stability as a proxy for plantar plate integrity. Treatment ranges from taping and shoe modification to surgical plantar plate repair and tendon transfer.
Progressive attenuation of the medial second MTP collateral ligament, usually combined with plantar plate failure, allows the second toe to drift medially and dorsally, overriding the hallux and causing forefoot pain and shoe fit problems.
Complete failure of the plantar plate and collateral ligaments results in dorsal dislocation of the proximal phalanx on the metatarsal head, most common at the second MTP joint, requiring open reduction and ligament reconstruction.
