Systemic embolic phenomena are well recognised during total knee replacement (TKR) and are widely believed to be the cause of intra-operative hypotension and reduced cardiac output, which may lead to circulatory collapse and sudden death.

We undertook a prospective, double-blind, randomised study comparing the cardiac embolic load during computer-assisted and conventional (intramedullary-aligned) TKR, as measured by transoesophageal echocardiography. 26 consecutive procedures were performed by a single surgeon at a single site. Embolic load was scored using the modified Mayo grading system for echogenic emboli.

Patients undergoing conventional TKR (n=12) had a mean embolic score of 6.15 (SD 0.83) on release of the tourniquet. Those undergoing computer-assisted TKR (n=14) had a mean embolic score of 4.89 (SD 1.10). Comparison of the groups using a two-tailed t-test confirmed a highly significant reduction (p=0.004) in embolic load when performing computer-assisted TKR. The groups were otherwise well matched and there were no complications.

In conclusion, this study demonstrates that computer-assisted TKR results in the release of significantly fewer systemic emboli than conventional TKR using intra-medullary alignment. There is evidence that this should reduce perioperative morbidity and neurological dysfunction. This would appear to add to the ever-growing list of arguments in favour of computer-assisted total knee replacement.