Metatarsophalangeal joint of great toe

The metatarsophalangeal joint of the great toe (first MTPJ) is a synovial condyloid joint formed by the articulation between the head of the first metatarsal and the base of the proximal phalanx of the hallux. The joint is stabilized by a complex array of osseous, cartilaginous, and soft tissue structures.

Key anatomical components include:

• Articular surfaces: The rounded head of the first metatarsal and the concave base of the proximal phalanx, both covered by hyaline cartilage.

• Capsule: A fibrous capsule encloses the joint, reinforced dorsally and plantarly.

• Collateral ligaments: Medial and lateral collateral ligaments provide stability against varus and valgus stresses.

• Plantar plate complex: Unlike the lesser toes, the first MTPJ does not have a single dominant plantar plate. Instead, the plantar aspect features a fibrocartilaginous pad that envelops the sesamoid bones and is inseparable from the plantar capsule. This complex includes the intersesamoid ligament, metatarsosesamoid ligaments, sesamoid phalangeal ligaments, and associated musculotendinous structures

• Sesamoid bones: Medial (tibial) and lateral (fibular) sesamoids are embedded within the tendons of the flexor hallucis brevis and are integral to the plantar plate complex, acting as pulleys for the flexor hallucis longus tendon.

• Musculotendinous attachments: The abductor hallucis and flexor hallucis brevis insert on the medial sesamoid, while the adductor hallucis and lateral head of flexor hallucis brevis insert on the lateral sesamoid. The extensor hallucis longus and brevis cross dorsally.

• Other ligaments: The deep transverse metatarsal ligament connects the first MTPJ to adjacent joints.