Tibial implant design in primary TKA: retrospective comparison of two designs for the occurrence of radiolucent lines and aseptic loosening.

Abstract

The purpose of this retrospective study was to study the effect of tibial implant design on the occurrence of radiolucent lines (RLLs) and aseptic loosening (AL) by comparing two different total knee arthroplasty (TKA) designs. Two types of total knee arthroplasty,different for tibial shape, size andkeeldesign were compared, 255 for the first and 774 for the second. The occurrence of RLLs and radiological signs of micro- and macro-mobility and aseptic looseningwas analyzed. Demographic data were compared, as well as the type and rate of RLLs, occurrence of aseptic loosening and the presence of potential risk factors. The first implant designis morphometric and has a squarer keel than the second implant TKA. The overall rate of RLLs was similar(21%vs 23%), despite of a significantly lower rates of radiological signs of macro-mobility of the tibial component with the first implant(2% vs 17%). Survivorship of both designs was overall comparable(99.6% vs 98.8 %) the first implantgroup had more potential risk factors for poor bone quality than the secondgroup (p<0.05). A morphometric design is more anatomic and offers better bone coverage of the epiphyseal tibial surface. RLLs, as a sign of implant micro-mobility, were equally present in both designs. Radiological signs of macro-mobility at the metaphysiswere less frequently observed in squared keel design. The morphometric implant did not show improved survivorship compared with a symmetric implant. III.