The hallux sesamoid complex is maintained by three groups of ligaments: the intersesamoid ligament (connecting the two sesamoids to each other), the metatarsosesamoid ligaments (connecting each sesamoid to the first metatarsal head), and the phalangosesamoid ligaments (connecting each sesamoid to the base of the proximal phalanx via the plantar plate). The FPB tendons embed the sesamoids within the ligamentous complex.
The sesamoid ligament complex distributes load across the first metatarsophalangeal joint, maintains sesamoid position beneath the first metatarsal head, protects the FHL tendon, and transmits FPB muscle force to the hallux for toe-off.
Turf toe injury disrupts the sesamoid ligament complex from a forced hyperextension mechanism, producing plantar MTP joint pain from plantar plate-sesamoid injury. The severity grading distinguishes Grade I (sprain), Grade II (partial tear), and Grade III (complete disruption with sesamoid migration). Sesamoid fracture or diastasis of the bipartite sesamoid (in patients with congenital sesamoid division) can be assessed by comparison to the contralateral foot. First MTP joint arthrodesis for severe turf toe or hallux rigidus requires excision of the sesamoids or their preservation within the fusion mass.
Forced hyperextension of the first MTP joint ruptures the plantar plate and sesamoid ligament complex at the metatarsosesamoid or phalangosesamoid junction, producing plantar MTP pain, swelling, and inability to push off on turf surfaces; MRI grades the plantar plate and sesamoid ligament disruption and guides conservative versus surgical management.
