Lower limb length discrepancy and malalignment in paediatric orthopaedics constitute a set of acquired or malformative structural pathologies. These anomalies, which may alter statics of lower limbs, are susceptible to engender an asymmetry of mechanical constraints' distribution across joints, and thus to promote the onset of arthritic phenomenons. The purpose of this review's article is to define the limits of tolerance of the various malformations and describe the innovative techniques available in order to correct them.