Hawkin's classification of talar neck fractures

Hawkin's classification system divides fractures of the neck of talus into four types according to the degree of displacement and resulting risk of avascular necrosis. Higher type implies greater risk of complications.

Type	Description	Subluxation	Avascular necrosis
Type I	Undisplaced fracture of talar neck	no	rare
Type II	Fracture of talar neck with mild displacement	subtalar joint	occasional
Type III	Fracture of talar neck with moderate displacement	subtalar and ankle joint	frequent
Type IV	Fracture of talar neck with severe displacement	subtalar, ankle and talonavicular joint	common

References:

1. Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg Am. 1970 Jul;52(5):991–1002.
2. Juliano PJ, Dabbah M, Harris TG. Talar neck fractures. Foot Ankle Clin. 2004 Dec;9(4):723–736, vi.
3. Singh S, Tsai C-H, Kim A, Dailey T. Talar Neck Fracture Reduced and Stabilized with an Ilizarov External Fixator: A case report with three year follow up. The Foot and Ankle Online Journal 2010
4. Rammelt S, Zwipp H. Talar neck and body fractures. Injury. 2009 Feb;40(2):120–35.

Images:

Hawkin's type I to IV (left to to right)
$Hawkin's classification of talar neck fractures - type I$ $Hawkin's classification of talar neck fractures - type II$ $Hawkin's classification of talar neck fractures - type III$ $Hawkin's classification of talar neck fractures - type IV$