The effects of bone resection depth and malalignment on strain in the proximal tibia after total knee arthroplasty

The clinical significance of tibial resection depth in total knee arthroplasty (TKA) is not clearly understood. The purpose of this study was to quantify the effect of tibial resection depth in TKA on tibial loading. Tibiae were coated with a photoelastic resin enabling full-field dynamic shear strain quantification in the tibial metaphysis during TKA loading. A standard resection level (5 mm) was compared to a resection level 15 mm distal to the joint line. Both had appropriate-sized tibial components. With 15 mm of tibial resection, strains increased up to 281% in the proximal and peripheral regions of the tibia during neutral loading and up to 315% anteriorly and 197% peripherally during varus loading. Distal resection levels result in significant smaller component size and relatively posterior and peripheral displacement of the implant. Changes in loading patterns in specimens with increased tibial resection depths have not previously been described.