Use of patient-specific cutting blocks reduces blood loss after total knee arthroplasty.

Total knee arthroplasty (TKA) is associated with substantial blood loss. Sources of bleeding are the femoral and tibial intramedullary canals, which are violated during implantation using standard instrumentation. Patient-specific instrumentation (PSI) and computer-assisted surgery (CAS) do not require violation of the intramedullary canals. Therefore, we sought to assess the impact of these methods on blood loss and transfusion requirement. A retrospective cohort study was conducted in a series of 107 consecutive primary TKAs. The first group (n = 32) was operated with standard instrumentation, the second group (n = 35) with CAS and the third group (n = 40) with PSI. A tourniquet was used in all cases. Mean (standard deviation) calculated total blood loss was 442 (160), 750 (271) and 700 (401) ml for the PSI, CAS and standard instrumentation groups, respectively (p < 0.001), with no significant differences between CAS and standard instrumentation (p = 0.799). Significant differences were found in terms of transfusion requirements, with 12.5, 42.9 and 21.8% of the patients requiring transfusion (p = 0.010). Post hoc analysis revealed that only the difference between PSI and CAS were statistically significant (p = 0.003). In conclusion, PSI reduces blood loss when compared to both CAS and standard instrumentation TKA performed with the use of a tourniquet.