A safe transition to a more personalized alignment in total knee arthroplasty: the importance of a “safe zone” concept

Medicine has been under a constant change. The latest strong and permanent trend in most of the medical fields is personalized medicine. Personalized medicine or theragnostics means targeting your diagnostics and treatment more towards the individual patient than to the mean of your patient population. In contrast, historical and current knee arthroplasty alignment and implantation concepts followed and still follow a systematic approach, mostly the mechanical alignment concept. However, the wind of change has yet arrived in total knee arthroplasty. If one would have asked knee arthroplasty surgeons about their preferred alignment concept following ten years ago, it predominantly would have been mechanical alignment. The most personalized alignment concept in the past was anatomical alignment, which still is a systematic approach and leads to a neutral mechanical alignment, however, puts the tibial joint line in 3° varus and the femoral one in 3° valgus.