7 randomized control trials (RCTs) and 11 non-randomized control trials (nRCTs) assessing differences between patient-specific instrumentation (PSI) and conventional instrumentation (CONV), in terms of incidences of component misalignment in primary total knee arthroplasty (TKA), were included in this study. Results determined that the occurrence of outliers - defined as those with alignment 3° from the desired position - was similar between the two groups. No significant difference was seen in the incidence of malalignment in terms of the mechanical axis, femoral and tibial components in the coronal and sagittal planes, and femoral component rotation in TKA.