There were no significant differences regarding the biomechanical axis or frontal femoral and individual tibial component alignment .
Conclusion This systematic review and meta- analysis demonstrate that alignment with MRI-based PSI is at least as good as , if not better than , that with CT-based PSI .
Purpose Patient-specific instruments ( PSIs ) are already in relatively common use , and their post-operative radiographic results are equal to those for total knee arthroplasty ( TKA ) with conventional instrumentation .
PSI use requires a preoperative MRI scan , CT scan , or a combination of MRI and a long-leg st and ing radiograph .
However , there is no consensus as to which of these modalities , MRI or CT , is the preferred imaging modality when performing TKA with PSIs .
Implant positioning in TKA: comparison between conventional and patient-specific instrumentation.
The number of total knee arthroplasty ( TKA ) procedures continuously increases , with good to excellent results . In the last few years , new surgical techniques have been developed to improve prosthesis positioning . In this context , patient-specific instrumentation is included . The goal of this study was to compare the perioperative parameters and the spatial positioning of prosthetic components in TKA procedures performed with patient-specific instrumentation vs traditional TKA . In this prospect i ve comparative r and omized study , 15 patients underwent TKA with 3-dimensional magnetic resonance imaging ( MRI ) preoperative planning ( patient-specific instrumentation group ) and 15 patients underwent traditional TKA ( non-patient-specific instrumentation group ) . All patients underwent postoperative computed tomography ( CT ) examination .  In the patient-specific instrumentation group , preoperative data planning regarding femoral and tibial bone resection was correlated with intraoperative measurements . Surgical time , length of hospitalization , and intraoperative and postoperative bleeding were compared between the 2 groups . Positioning of implants on postoperative CT was assessed for both groups . Data planned with 3-dimensional MRI regarding the depth of bone cuts showed good to excellent correlation with intraoperative measurements . The patient-specific instrumentation group showed better perioperative outcomes and good correlation between the spatial positioning of prosthetic components planned preoperatively and that seen on postoperative CT . Less variability was found in the patient-specific instrumentation group than in the non-patient-specific instrumentation group in spatial orientation of prosthetic components . Preoperative planning with 3-dimensional MRI in TKA has a better perioperative outcome compared with the traditional method . Use of patient-specific instrumentation can also improve the spatial positioning of both prosthetic components
There were no significant differences regarding the biomechanical axis or frontal femoral and individual tibial component alignment .
Conclusion This systematic review and meta- analysis demonstrate that alignment with MRI-based PSI is at least as good as , if not better than , that with CT-based PSI .
Purpose Patient-specific instruments ( PSIs ) are already in relatively common use , and their post-operative radiographic results are equal to those for total knee arthroplasty ( TKA ) with conventional instrumentation .
PSI use requires a preoperative MRI scan , CT scan , or a combination of MRI and a long-leg st and ing radiograph .
However , there is no consensus as to which of these modalities , MRI or CT , is the preferred imaging modality when performing TKA with PSIs .