lidström classification lidström classification lidström classification is a system of categorizing colles' fractures. in the lidström classification system there are six types of fractures. the classification system is based on fracture line, direction and degree of displacement, extent of articular involvement and involvement of the distal radioulnar joint, and was first published in 1959. classification group 1: minimal displacement group 2-a: extra-articular, dorsal angulation group 2-b: intra-articular, dorsal angulation, joint surface not comminuted group 2-c: extra-articular, dorsal angulation and dorsal displacement group 2-d: intra-articular, dorsal angulation and displacement, joint surface not comminuted group 2-f: intra-articular, dorsal angulation and displacement, joint surface comminuted