[Proximal tibial aspect ratio and matching of tibial component in total knee arthroplasty: a narrative review]

Abstract

Proximal tibial aspect ratio (PTAR) is closely related to age, disease status and cutting parameters with considerable inter-individual variation independent of gender and race, nevertheless the aspect ratio of tibial components from different manufacturers remains relatively constant from smallest to largest size. As a result, component mismatching is an unavoidable dilemma during tibia preparation in total knee arthroplasty (TKA). Various prosthesis systems all can achieve more than 80% coverage on proximal tibia, whereas their optimal fit rates are generally not more than 50%. It is difficult for symmetrical components to avoid anteroposterior mismatch, internal malrotation tends to occur when maximum coverage is pursued on the resected surface with a medial dominant plateau or lower PTAR. Although it is easier to achieve a balance of rotation and coverage with anatomical components, significant anteromedial overhang tends to appear on the resected surface with a symmetrical or lateral dominant plateau. Further researches should focus on the law of inter-individual variability of proximal tibial morphology, the quantitative definition of "ideal matching" safety zone of key morphological parameters on different areas of proximal tibia and the methodology of realizing"ideal matching"in the majority patients with the least amount of component sizes. In addition, with the rapid development of additive manufacturing and digital orthopedic technology, individual customized implant is expected to become a breakthrough point in the field of TKA component fitting.