The effect of tibial implant size on post-operative alignment following medial unicompartmental knee replacement.

We have retrospectively reviewed a consecutive series of 71 medial unicompartmental knee replacements in 56 patients performed between 1991 and 1996 by a single surgeon. The aim of this study was to quantify the amount of correction in the tibiofemoral angle, which is achievable with each thickness of polyethylene tibial insert. Our results have shown that the amount of correction which can be expected with an 8 mm, 10 mm, 12 mm and 14 mm insert are 5.3 degrees, 4.8 degrees, 6.6 degrees and 9.5 degrees, respectively. These results will act as a useful reference for surgeons who perform this procedure.