The femoral component alignment resulting from spacer block technique is not worse than after intramedullary guided technique in medial unicompartimental knee arthroplasty.

The spacer block technique produces results comparable to the intramedullary guided technique. However, the precision is low and outlier frequent. Due to the possibility of transferring a tibial malalignment to a femoral malalignment, even greater attention should be paid to the precision of tibial resection.