Results The majority of studies did not show an improvement in overall limb alignment when PSI was compared with st and ard instrumentation .
The studies demonstrated mixed results regarding the influence of PSI on operative times .
Decreased operative times were not uniformly observed , and when noted , they were found to be of minimal clinical or financial significance .
PSI did reliably reduce the number of instrument trays required for processing perioperatively .
The accuracy of the preoperative plan , generated by the PSI manufacturers , was found lacking , often leading to multiple intraoperative changes , thereby disrupting the flow of the operation and negatively impacting efficiency .
Neither of the two studies we identified provided strong evidence to support an advantage favoring the use of PSI .
Conclusions PSI for TKA has not reliably demonstrated improvement of postoperative limb or component alignment when compared with st and ard instrumentation .
Although decisive evidence exists to support that PSI requires fewer surgical trays , PSI has not clearly been shown to improve overall surgical efficiency or the cost-effectiveness of TKA .
Limited available literature does not clearly support any improvement of postoperative pain , activity , function , or ROM when PSI is compared with traditional instrumentation
Background Patient-specific cutting blocks have been touted as a more efficient and reliable means of achieving neutral mechanical alignment during TKA with the proposed downstream effect of improved clinical outcomes .
However , it is not clear to what degree published studies support these assumptions .
Questions / purpose sWe asked : ( 1 ) Do  patient-specific cutting blocks  achieve neutral mechanical alignment more reliably during TKA when compared with conventional methods ? (
2 ) Does patient-specific instrumentation ( PSI ) provide financial benefit through improved surgical efficiency ? (
3 ) Does the use of patient-specific cutting blocks translate to improved clinical results after TKA when compared with conventional instrumentation ?
Rotation in total knee arthroplasty: no difference between patient-specific and conventional instrumentation
Abstract Purpose It was our hypothesis that patient-specific instrumentation ( PSI ) can improve the accuracy of the rotational alignment in TKA based on the concept of the system and on the potential to clearly identify pre-operatively during planning the classical anatomical l and marks that serve as references to set-up the rotation both for the femur and tibia . Material s and methods In this prospect i ve comparative r and omized study , 40 patients ( 20 in each group ) operated in our institution between September 2012 and January 2013 by the 2 senior authors were included . R and omization of patients into one of the two groups was done by the Hospital Informatics Department with the use of a systematic sampling method . All patients received the same cemented high-flex mobile bearing TKA . In the PSI group , implant position was compared to the planed position using previously vali date d dedicated software . The position of the implants ( frontal and sagittal ) was compared in the 2 groups on st and ard X-rays , and the rotational position was analysed on post-operative CT-scan . Results 90 % of the patients add < 2 ° or mm of difference between the planned position of the implants and the obtained position , except for the tibial rotation where the variations were much higher . Mean HKA was 179 ° ( 171–185 ) in the PSI group with 4 outliers ( 2 varus : 171 ° and 172 ° :184 ° and 185 ° ) and 178.3 ° with 2 outliers ( 171 ° and 176 ° ) in the control group . No difference was observed between the two groups concerning the frontal and sagittal position of the implants on the ML and AP X-rays . No significant difference of femoral rotation was observed between the two groups with a mean of 0.4 ° in the PSI group and 0.2 ° in the control group ( p : n.s ) . Mean tibial rotation was 8 ° of internal rotation in the PSI group and 15 ° of internal rotation in the st and ard group ( p : n.s ) . Conclusion Based on our results , we were unable to confirm our hypothesis as PSI can not improve rotation in TKA . More work needs to be done to more clearly define the place of PSI in TKA , to keep on improving the accuracy of the system and to better define the individual targets in TKA in terms of frontal , sagittal and rotational positioning of the implant for each patient . Level of evidence Prospect i ve comparative r and omized study , Level II
Results The majority of studies did not show an improvement in overall limb alignment when PSI was compared with st and ard instrumentation .
The studies demonstrated mixed results regarding the influence of PSI on operative times .
Decreased operative times were not uniformly observed , and when noted , they were found to be of minimal clinical or financial significance .
PSI did reliably reduce the number of instrument trays required for processing perioperatively .
The accuracy of the preoperative plan , generated by the PSI manufacturers , was found lacking , often leading to multiple intraoperative changes , thereby disrupting the flow of the operation and negatively impacting efficiency .
Neither of the two studies we identified provided strong evidence to support an advantage favoring the use of PSI .
Conclusions PSI for TKA has not reliably demonstrated improvement of postoperative limb or component alignment when compared with st and ard instrumentation .
Although decisive evidence exists to support that PSI requires fewer surgical trays , PSI has not clearly been shown to improve overall surgical efficiency or the cost-effectiveness of TKA .
Limited available literature does not clearly support any improvement of postoperative pain , activity , function , or ROM when PSI is compared with traditional instrumentation
Background Patient-specific cutting blocks have been touted as a more efficient and reliable means of achieving neutral mechanical alignment during TKA with the proposed downstream effect of improved clinical outcomes .
However , it is not clear to what degree published studies support these assumptions .
Questions / purpose sWe asked : ( 1 ) Do  patient-specific cutting blocks  achieve neutral mechanical alignment more reliably during TKA when compared with conventional methods ? (
2 ) Does patient-specific instrumentation ( PSI ) provide financial benefit through improved surgical efficiency ? (
3 ) Does the use of patient-specific cutting blocks translate to improved clinical results after TKA when compared with conventional instrumentation ?