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 ?
The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty
Abstract Purpose The aim of this study was to investigate the post-operative radiological outcomes of patient-specific instrumentation ( PSI ) surgery versus conventional total knee arthroplasty ( TKA ) . Methods Sixty patients scheduled for a primary TKA were prospect ively divided into PSI or conventional technique . Coronal and sagittal radiographic long limb films were taken post-operatively . The accepted values for normal alignment were 180 ° ± 3 ° for hip-knee-ankle angle ; 90 ° ± 3 ° for coronal femoral component angle or coronal tibia component angle ; 0 ° to 3 ° flexion for sagittal femoral component angle and 0 ° to 7 ° posterior slope for sagittal tibia component angle . Results For hip-knee-ankle angle , there were 21 % more outliers in the PSI group compared to the conventional group ( p = 0.045 ) . Most of these outliers had valgus deformity in the PSI group and varus deformity in the conventional group ( p = 0.045 ) . For implant placement , there was no difference in the proportion of outliers between the two groups . There was also no difference in the duration of surgery . Conclusions This study showed that PSI surgery is associated with a larger proportion of outliers for lower limb alignment . PSI surgery as an alternative to conventional TKA is not advisable . Level of evidence 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 ?