The use of patient-specific instruments does not reduce blood loss during minimally invasive total knee arthroplasty?

Blood loss can be substantial and will influence morbidity and mortality after total knee arthroplasty. This study evaluated whether patient-specific instruments (PSI) can reduce blood loss because the intramedullary canal is not opened during the procedure and whether hidden blood loss can be reduced by its use. Seventy-five patients operated with the Signature PSI technique were compared with a matched group operated with conventional instruments. Maximal drop in haemoglobin (Hb) and hematocrit (HTC) level were compared at day 2 and day 4. Transfusions were noted. Clinical outcomes like range of motion and knee society scores were studied as secondary outcomes. No statistically significant difference for calculated blood loss, maximal drop in Hb or HTC and transfusions were found. No clinical differences in range of motion or knee society scores were observed. The use of PSI-assisted total knee arthroplasty (TKA) did not result in less blood loss compared with conventional minimally invasive TKA with tourniquet. No reduction in hidden blood loss was observed either. According to this study, the argument of reduced transfusion cost should not be used in cost-effectiveness calculations of PSI-assisted TKA. III.