The full-length standing radiograph in an anteroposterior projection is the primary tool for defining and measuring limb alignment with definition of the physiological axes and mechanical and anatomic angles of the lower limb. We define the deformities of the lower limb and the importance of correct surgical planning and execution. For patients with torsional malalignment of the lower limb, computerized tomography scan evaluation is the gold standard for preoperative assessment. Cite this article: EFORT Open Rev 2021;6:487-494. DOI: 10.1302/2058-5241.6.210015