Blood loss following total knee replacement is reduced when using computer-assisted versus standard methods.

Perioperative blood loss was compared in 136 patients (2 groups of 68 patients) who underwent total knee arthroplasty (TKA). Blood loss was significantly lower when using a computer-navigated technique in comparison to a method employing intramedullary femoral rods. Total blood loss was calculated from body weight, height and haematocrit change, using a model that has been shown to reliably estimate true blood loss. Average total blood loss was 1362 ml in the standard TKA group, and 1137 ml in the computer navigated TKA group. This difference was statistically significant (p = 0.016). This study, as compared to previous papers assessing the effects of navigation, used a larger sample size and a more reliable method of assessing blood loss, which takes account of "hidden" losses, and confirms their findings.