With traditional ‘off-the-shelf’ implants for knee replacement surgery, 15–20% of patients end up unhappy with their knee. At least part of the reason for this may be the significant differences that can exist between individuals in their distal femoral and proximal tibial geometries. This article explains how patient-specific customized knee implants can address many of the deficiencies that may exist with off-the-shelf designs. Evidence is presented of how customized knee implants can lead to better alignment, better coverage, better knee kinematics, less bone resection, improved efficiency in theatre, fewer complications, better patient-reported outcomes and increased long-term prosthetic survivorship, all without any significant overall additional costs. This article also dispels some of the myths and the hype that surround the current trend towards robotic-assisted knee replacement surgery.