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 .
Patient-specific total knee arthroplasty: the importance of planning by the surgeon
Abstract Purpose The purpose of the study was to evaluate the accuracy of the planning of the patient-specific pin guides in total knee arthroplasty ( TKA ) . This planning was performed primarily by a technician of the company and offered to the surgeon . All parameters of the implantation can either be modified or accepted by the surgeon . The hypothesis was that the plan needs preoperative intervention by the surgeon . Methods A prospect i ve study in 50 patients was carried out . All patients received the same posterior-stabilised implant with patient-specific instrumentation . All surgical parameters ( coronal , sagittal , rotational alignment , femoral and tibial resection levels and implant sizes ) were checked by the orthopaedic surgeon and changed if necessary . Results Preoperatively , the femoral size was changed in 8 patients ( 16 % ) , the femoral flexion in 23 patients ( 46 % ) , the femoral shift in 34 patients ( 68 % ) , the tibial size in 24 patients ( 48 % ) and the tibial rotation in all patients . The epicondylar axis was accepted in 47 patients ( 94 % ) in the technician plan . Mean planning time was 8 ± 4 min . Intraoperatively , the femoral anterior – posterior size was in 50 patients ( 100 % ) the same as in the surgeon and in 42 patients ( 84 % ) the same as in the technician plan ( p = 0.003 ) . The tibial component implanted was in 42 patients ( 84 % ) the same as in the surgeon and in 19 patients ( 38 % ) the same as in the technician plan ( p < 0.0001 ) . A femoral distal recut was necessary in 31 patients ( 62 % ) and a change of the tibial proximal cut in 17 patients ( 34 % ) during surgery . Intraoperatively , no changes of the femoral and tibial alignment , the femoral anterior – posterior size , the femoral flexion , the femoral shift , the femoral and tibial rotation were necessary . Postoperatively , the coronal mechanical overall axis was within ±3 ° in 47 patients ( 94 % ) with a maximum deviation of 5.6 ° . Conclusions Significant changes of the technician plan were necessary to get an accurate preoperative plan . Intraoperative changes were significant less compared to the surgeon than to the technician plan . No major changes ( alignment , femoral anterior – posterior size and rotation ) of the surgeon plan were necessary . Surgeons using patient-specific pin guides in TKA may verify the default plan provided by the technician . A blind reply on the technician plan may be not recommended . Level of evidence Therapeutic study , Level III
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 .