Are systemic emboli reduced in computer-assisted knee surgery?

Abstract

We undertook a prospective, randomised study using a non-invasive transcranial Doppler device to evaluate cranial embolisation in computer-assisted navigated total knee arthroplasty (n = 14) and compared this with a standard conventional surgical technique using intramedullary alignment guides (n = 10). All patients were selected randomly without the knowledge of the patient, anaesthetists (before the onset of the procedure) and ward staff. The operations were performed by a single surgeon at one hospital using a uniform surgical approach, instrumentation, technique and release sequence. The only variable in the two groups of patients was the use of single tracker pins of the imageless navigation system in the tibia and femur of the navigated group and intramedullary femoral and tibial alignment jigs in the non-navigated group. Acetabular Doppler signals were obtained in 14 patients in the computer-assisted group and nine (90%) in the conventional group, in whom high-intensity signals were detected in seven computer-assisted patients (50%) and in all of the non-navigated patients. In the computer-assisted group no patient had more than two detectable emboli, with a mean of 0.64 (SD 0.74). In the non-navigated group the number of emboli ranged from one to 43 and six patients had more than two detectable emboli, with a mean of 10.7 (sd 13.5). The difference between the two groups was highly significant using the Wilcoxon non-parametric test (p = 0.0003).Our findings show that computer-assisted total knee arthroplasty, when compared with conventional jig-based surgery, significantly reduces systemic emboli as detected by transcranial Doppler ultrasonography.

Computer navigated total knee arthroplasty: Aspects of a single unit's experience of 777 cases

“…Advocates of conventional TKA cite the increased operative and tourniquet times [24][25][26] associated with navigated TKA, whilst proponents of navigated TKA have yet to identify a significant clinical advantage over conventional TKA that justifies the significant hardware costs perceived to be associated with using such techniques [27]. Studies do exist which show reduced blood loss [14,28,29], fewer systemic emboli [24,30,31] and fewer clinically detectable thromboembolic events [32] in navigated TKA compared with conventional TKA, and this is thought to be directly related to the avoidance of femoral and/or tibial intramedullary instrumentation.…”

“…Studies do exist which show reduced blood loss [14,28,29], fewer systemic emboli [24,30,31] and fewer clinically detectable thromboembolic events [32] in navigated TKA compared with conventional TKA, and this is thought to be directly related to the avoidance of femoral and/or tibial intramedullary instrumentation. Cohorts in all these studies were, however, very small and offer low levels of evidence, and contradictory evidence does exist showing no difference in blood loss [25,33] and thromboembolic phenomena [13] between the two groups.…”

Navigation knee replacement

“…The risk of fat embolism during knee replacement has been shown to be significantly reduced when an extramedullary femoral alignment guide [27] or computerassisted surgery is used [7,15]. Studies using non-invasive [15] and invasive monitoring [7] have shown that significantly fewer emboli are detected in the systemic circulation during computer-assisted TKR compared with conventional TKR.…”

“…Studies using non-invasive [15] and invasive monitoring [7] have shown that significantly fewer emboli are detected in the systemic circulation during computer-assisted TKR compared with conventional TKR. However, most studies comparing these two methods have not shown any significant difference in post-operative thromboembolic events [2].…”

“…However, these complications have not been shown to occur to any significant level [2,5,12,33]. Furthermore, although CASTKRs increase the duration of surgery significantly by between 15 and 17 min compared with conventional TKRs [15,17,22,39], they have not been shown to increase the risk of deep infections [20].…”