Abstract
Up to 5% of knee fractures do not heal primarily at the expected time (delayed union) or fail to achieve healing (nonunion). The causes and treatment of disturbed bone healing in the distal femur, proximal tibia, and patella and in an increasing number of periprosthetic fractures have been discussed. Infection exclusion and/or eradication, reestablishment of axis, alignment and rotation, rigid fixation with fixed-angle devices and interfragmentary screws, bone grafting, arthrolysis, and early range of motion exercises are all necessary steps for good recovery. Illustrative cases have been presented with authors' preferences in the surgical treatment supported by recent publications.