Current concepts for aligning knee implants: patient-specific or systematic?

Mechanical or anatomical alignment techniques create a supposedly 'biomechanically friendly' but often functionally limited prosthetic knee.Alternative techniques for alignment in total knee arthroplasty (TKA) aim at being more anatomical and patient-specific, aiming to improve functional outcomes after TKA.The kinematic alignment (KA) technique for TKA has shown good early clinical outcomes. Its role in extreme anatomical variation remains to be defined.The restricted KA technique for TKA might be a reasonable option for patients with extreme anatomical variation.While unicompartmental knee arthroplasty (UKA) has many advantages over TKA, the revision rate remains higher compared with TKA. One major explanation is the relative ease with which a UKA can be converted to a TKA, compared with revising a TKA. This can be considered as an additional advantage of UKA. Another reason is that surgeons favour revising a UKA to a TKA in cases of degeneration of the other femorotibial compartment rather than performing a relatively simple re-operation of the knee by doing an additional UKA (staged bi-UKA). Cite this article: 2018;3:1-6. DOI: 10.1302/2058-5241.3.170021.