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 ?
Patient specific cutting blocks are currently of no proven value.
Patient specific cutting guides generated by preoperative Magnetic Resonance Imaging ( MRI ) of the patient 's extremity have been proposed as a method of improving the consistency of Total Knee Arthroplasty ( TKA ) alignment and adding efficiency to the operative procedure . The cost of this option was evaluated by quantifying the savings from decreased operative time and instrument processing costs compared to the additional cost of the MRI and the guide .  Coronal plane alignment was measured in an unselected consecutive series of 200 TKAs , 100 with st and ard instrumentation and 100 with custom cutting guides .  While the cutting guides had significantly lower total operative time and instrument processing time , the estimated $ 322 savings was overwhelmed by the $ 1,500 additional cost of the MRI and the cutting guide . All measures of coronal plane alignment were equivalent between the two groups . The data does not currently support the proposition that patient specific guides add value to TKA
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 ?