Fig. 3From: Management of proximal femur fractures in the elderly: current concepts and treatment optionsAO classification of femoral neck fractures. AO 31-B1 includes impacted fractures. With decreasing impaction from grade 1 to grade 3, B2 consists of a larger femoral head fragment with a fracture line increasing in slope from grade 1 to grade 3, and B3 describes a small head fragment with increasing dislocation and instability with increasing gradeBack to article page