We did not find any differences between PSI and SI with respect to any other parameters .
Conclusions PSI  has advantages in axial alignment of the femoral component , operative time , and perioperative blood loss relative to SI .
No significant differences were found between PSI and SI with respect to alignment of the remaining components , number of outliers , or length of hospital stay .
Purpose The purpose of the present study was to compare patient-specific instrumentation ( PSI ) with st and ard instrumentation ( SI ) in patients undergoing total knee arthroplasty ( TKA ) .
PSI is hypothesized to have advantages with respect to component alignment ; number of outliers ( defined as alignment > 3 ° from the target alignment ) ; operative time ; perioperative blood loss ; and length of hospital stay .
This new surgical technique is expected to exhibit superior performance .
Patient-specific instrumentation in total knee arthroplasty: simpler, faster and more accurate than standard instrumentation—a randomized controlled trial
Abstract Purpose This r and omized controlled trial was conducted to compare patient-specific instrumentation ( PSI ) to st and ard instrumentation regarding efficacy to achieve a good coronal alignment and differences in surgical time , blood loss and length of stay . Methods Ninety-five of 100 r and omized patients eligible for total knee arthroplasty were analysed .  PSI with magnetic resonance and long-leg radiograph was performed in 47 patients , while 48 patients received st and ard instrumentation .  Primary outcome measure was coronal alignment , evaluated with long-leg radiograph . Deviation > 3 ° varus/valgus was considered an outlier . Surgical time was compared from skin to skin . Length of stay was a post hoc analysis . Blood loss was evaluated comparing the number of blood units spent , fall in haemoglobin and haematocrit levels . Results St and ard instrumentation had a higher number of outliers in the coronal alignment with a relative risk of 3.015 , compared to PSI . Surgical time was reduced by 18 min ( 24.8 % ) with the  PSI  , as well as length of stay , with a half-day reduction . Number of blood units spent was significantly less in the PSI group . Relative risk of transfusion was 7.09 for patients in the st and ard instrumentation group . Difference in Hg and Htc levels were not significant . No patient had to ab and on PSI . Minor changes to preoperative plan occurred in 14.9 % of the patient : cut review in 4.3 % and insert change in 10.6 % . Conclusions Patient-specific instrumentation ( PSI ) is able to provide important advantages over st and ard instrumentation in total knee arthroplasty : it lowers the risk of outliers and transfusion , is a faster procedure and enables a shorter length of stay with a low rate of intraoperative adjustments . Level of evidence
We did not find any differences between PSI and SI with respect to any other parameters .
Conclusions PSI  has advantages in axial alignment of the femoral component , operative time , and perioperative blood loss relative to SI .
No significant differences were found between PSI and SI with respect to alignment of the remaining components , number of outliers , or length of hospital stay .
Purpose The purpose of the present study was to compare patient-specific instrumentation ( PSI ) with st and ard instrumentation ( SI ) in patients undergoing total knee arthroplasty ( TKA ) .
PSI is hypothesized to have advantages with respect to component alignment ; number of outliers ( defined as alignment > 3 ° from the target alignment ) ; operative time ; perioperative blood loss ; and length of hospital stay .
This new surgical technique is expected to exhibit superior performance .