MR imaging-anatomical correlation of the metatarsophalangeal joint of the hallux: Ligaments, tendons, and muscles.

OBJECTIVE: To perform an MR imaging-anatomical correlation to elucidate the anatomy of muscles, tendons, and ligaments about the hallux as seen on MR imaging.

MATERIALS AND METHODS: Four fresh and 4 embalmed cadaver specimens were used for this study. The embalmed specimens and one fresh specimen were dissected by three investigators. The fresh specimens were preserved deep frozen. They were thawed and imaged with a 3 T MR system. Proton density weighted images were obtained. The specimens were refrozen and sectioned with a band saw into 3 mm thick slices.

RESULTS: Musculotendinous structures were equally well seen in the fresh and embalmed specimens. The capsular ligaments could best be studied in the fresh specimens. Proximal to the sesamoids the following muscle and tendon anatomy was delineated: the abductor hallucis tendon inserted on the medial sesamoid bone together with the medial belly of the flexor digitorum brevis; the adductor hallucis (transverse and oblique heads) inserted on the lateral sesamoid together with the lateral head of the flexor hallucis brevis. At the level of the sesamoid bones and distally, the ligaments making up the plantar plate were delineated, including the presesamoid band, the flexor hallucis longus pulley, the sesamometatarsal ligaments, the sesamophalangeal ligaments, and the capsular ligaments.

CONCLUSION: MRI allows for accurate assessment of the complex anatomy of the hallux. At the level proximal to the sesamoids the muscle and tendon insertions are well demonstrated. At the level of the sesamoids and distally, the ligaments making up 'the plantar plate' are well demonstrated.