Matziolis G, et al. - Although the spacer block technique has been recommended for the implantation of unicompartmental knee arthroplasty (UKA), there is still a lack of data concerning the resulting component positioning. In this current investigation, it was demonstrated that in patients who had undergone medial UKA, results of spacer block technique were comparable to the intramedullary guided technique. However, the precision was low and outlier frequent. Greater attention ought to be paid to the precision of tibial resection due to the possibility of transferring a tibial malalignment to a femoral malalignment.