We found that there was no significant benefit from using PS instrumentation in primary knee arthroplasty to aid in the positioning of either the tibial or femoral components .
Furthermore sagittal plane tibial component positioning was worse in the PS than the traditional ST group .
Our results suggest that at present PS instrumentation is not superior to ST instrumentation in primary total knee arthroplasty .
OBJECTIVE The aim of this study was to review the radiological alignment outcomes of patient Specific ( PS ) cutting blocks and St and ard Instrumentation in Primary Total Knee Arthroplasty .
METHODS We hypothesized that the use of PS techniques would significantly improve sagittal , coronal and rotational alignment of the prosthesis on short term .
The accuracy of component alignment in custom cutting blocks compared with conventional total knee arthroplasty instrumentation: prospective control trial.
BACKGROUND The purpose of this study was to assess whether custom cutting blocks improve accuracy of component alignment compared to conventional TKA instrumentation . METHODS Eighty primary TKA patients were enrolled in an open-label r and omized prospect i ve clinical trial and were divided into two groups , 40 custom cutting blocks and 40 conventional TKA instrumentations . The primary outcome was prosthetic alignment with respect to mechanical axis and epicondylar axis . Secondary outcomes included operative time , 24-hour postoperative blood loss and hemoglobin at discharged . RESULTS There were no statistical significant differences in the postoperative mechanical axis between the custom cutting blocks group and conventional TKA group , ( 95 % vs. 87.5 % within 3 ° of neutral mechanical alignment , p=0.192 ) . The average rotational alignment was statistically significantly different in the custom cutting blocks group ( 1.0 ° ±0.6 ° vs. 1.6 ° ±1.8 ° external rotation from epicondylar axis , p<0.001 ) . There were statistical significant differences in operation time  between custom cutting blocks group and conventional group , skin to skin [ 57.5±2.3 min vs. 62.1±1.5 , p<0.001 ] . We found an improvement in group 1 compared with group 2 regarding the proportion of patients with postoperative blood loss within 24 h. CONCLUSIONS Custom cutting blocks technique was a surgical procedure which provided better accuracy in rotational alignment but no statistical differences in mechanical axis , less operative time and reduced blood loss  than the conventional TKA instrumentation in the majority of patients
We found that there was no significant benefit from using PS instrumentation in primary knee arthroplasty to aid in the positioning of either the tibial or femoral components .
Furthermore sagittal plane tibial component positioning was worse in the PS than the traditional ST group .
Our results suggest that at present PS instrumentation is not superior to ST instrumentation in primary total knee arthroplasty .
OBJECTIVE The aim of this study was to review the radiological alignment outcomes of patient Specific ( PS ) cutting blocks and St and ard Instrumentation in Primary Total Knee Arthroplasty .
METHODS We hypothesized that the use of PS techniques would significantly improve sagittal , coronal and rotational alignment of the prosthesis on short term .