Custom-fit kinematic alignment in total knee arthroplasty using PSI. The story of ShapeMatch technology

Background. The story of ShapeMatchA (R) custom-fit cutting guides for primary total knee arthroplasty (TKA) is special compared to other available techniques. First, it was the first such patient-specific instrument (PSI) on the market. Second, the underlying philosophy of kinematic alignment is unique compared to other competitors. Finally, it is the only PSI technique that has been withdrawn from the market. Objectives and methods. The objective of this paper is to summarize the history of the ShapeMatchA (R) technology and to review the current literature regarding clinical evidence for kinematically aligned TKA. Results and conclusions. In the recent literature, faster rehabilitation, better knee function and higher patient satisfaction are described for kinematically aligned TKA compared to conventional alignment. However, there is also evidence for inaccuracies by using the PSI technology as a possible cause of treatment failures. Due to those problems, this technology was recalled from the market. As an alternative method to achieve kinematic alignment in TKA, manual as well as computer-assisted techniques are currently under development and are discussed here.