A relatively rare injury. Usual mechanism is a hyper-dorsiflexion leading to to dorsal dislocation of the 1st MTPJ.
Type 1: Sesamoids not disrupted, 1MT head prolapses between them and is incarcerated, often irreducible unless open reduction done.
Type 2: Sesamoids disrupted, closed reduction usually possible.
Nice line drawing illustration of the pathology in Jahss’s classic 1980 paper; recently re-published.(Foot & Ankle International/Vol. 27, No. 6/June 2006,401-406. Paper emphasises rarity, no outcomes quoted.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2971641/pdf/najspt-05-131.pdf
Cora L. Maglaya, Chad Cook, Hap Zarzour, Claude T. Moorman.
RETURN TO DIVISION IA FOOTBALL FOLLOWING A
1 ST METATARSOPHALANGEAL JOINT DORSAL
DISLOCATION. Six-week rehab programme; back to sport by 6 months.. No long term results.