TOURNIQUET USE
Comparison between Groups 1 (tourniquet use) and 2 (selective tourniquet use) revealed similar rates of overall and specific GA injury, intraoperative blood loss, and 24-hour postoperative drain output (Table 10). Group 1 demonstrated a 29% (9/31) rate of any GA injury versus 40% (27/67) in Group 2 (P = .37). For the specific lateral inferior GA injury, there was an equivalent rate of injury at 29% (9/31 in Group 1, 20/67 in Group 2; P = 1.0). Similarly, Group 1 patients had a 10% (3/31) rate of middle GA injury compared to 16% (11/67) in Group 2 patients (P = .53). Intraoperative estimated blood loss was lower in Group 1 (140 mL; range 25–400 mL) than in Group 2 (171 mL; range 40–500 mL) (P = .07), whereas the average 24-hour postoperative drain output was similar for Groups 1 (484 mL; range 75–1800 mL) and 2 (488 mL; range 100–1980 mL) (P = .46). Total estimated output was slightly less for Group 1 (593 mL; range 75–1900 mL) than for Group 2 (626 mL; range 125–2130 mL) (P = .38). A post hoc power analysis showed that with these rates of GA injury in Groups 1 and 2 and given a 2:1 ratio of the number of patients in Group 2 versus Group 1, a total of 185 patients in Group 1 and 370 patients in Group 2 would be needed to detect a statistically significant difference (P < .05) with a power of 80%.
| Table 10. Factors Associated with Tourniquet Use | ||||
Injury | Group 1 (n = 31) | Group 2 (n = 67) | Difference | P Value |
Overall GA injury | 9 (29%) | 27 (40%) | 11% | .3687 |
Lateral inferior GA | 9 (29%) | 20 (29%) | 0% | 1.0 |
Middle GA | 3 (10%) | 11 (16%) | 6% | .5382 |
Blood loss (mL) | 140 (25-400) | 171 (40-500) | 31 | .0661 |
24-Hour drain output (mL) | 484 (75-1800) | 488 (100-1980) | 4 | .4580 |
Total output (mL) | 593 (75-1900) | 626 (125-2130) | 33 | .3776 |
Differences in outcomes separated based on use of a tourniquet for the entire case (Group 1) vs use of a tourniquet only during cementation (Group 2). Note that there were no significant differences. Values are reported as n (%) or average (range). GA = geniculate artery.
DISCUSSION
Major arterial injury associated with TKA is a well-known, rare, and potentially devastating complication.1-13 However, the rate of injury to smaller periarticular vessels and the clinical significance of such injury have not been studied. The present study found a high rate of GA injury but no clinically significant difference in intraoperative blood loss or postoperative drain output between patients with GA injury (which was identified and managed with cautery) and those without GA injury. In addition, tourniquet use did not affect the rate of injury or the associated blood loss. To our knowledge, this is the first study that has critically evaluated the rate of GA injury occurring during TKA.
The overall rate of GA injury occurring during primary TKA was 38% with a higher predominance of lateral inferior than middle GA injury (31% vs 15%). Anatomically, it would follow that the lateral GA could be injured at a higher rate as it courses on top of the lateral meniscus, thus being susceptible to injury during cutting of the tibial plateau and meniscectomy. In addition, because the meniscectomy is performed longitudinally along the course of the artery, it may also be potentially lacerated in multiple locations and lengthwise. In theory, there should be a 100% rate of middle GA injury during posterior-stabilized TKA as this artery runs through the cruciate ligaments, which are resected during these cases. However, vessel injury was defined in this study as the visualization of pulsatile bleeding or vessel lumen. It is probable that in the cases in which injury to the middle GA was not visualized, it was cut but simultaneously cauterized. Thus, a lower rate (15%) of injury was detected. Nonetheless, these results still suggest that these periarticular arteries are injured at a higher rate; therefore, it is important for surgeons to specifically identify these injuries intraoperatively and adequately cauterize these vessels. As long as these arteries are cauterized, additional blood loss and potential vascular pseudoaneurysms should be prevented.
The effect of GA injury on intraoperative blood loss, 24-hour postoperative drain output, and total estimated blood loss showed no significant clinical findings in the present study cohort. In addition, examining the injury rate and blood loss based on TXA use also revealed no detrimental clinical associations. Although GA injury could inherently be associated with higher levels of blood loss and drain output, it is important to note that all GA injuries were also effectively coagulated, thus explaining the indifferent results. Accordingly, it should be recommended to surgeons performing primary TKAs to carefully evaluate for GA injury to prevent excessive blood loss or painful pseudoaneurysms. However, there is also a potential for beta error in this study in which a true difference did exist but no statistical difference was found due to the study being underpowered.
Full or selective tourniquet use during TKA did not appear to have any effect on the rate of GA injury, intraoperative blood loss, or 24-hour postoperative drain output. The similarity between GA injury rates perhaps further indicates an equivalent ability to detect these injuries between these two methods because of operative inspection for such injuries. With regard to intraoperative blood loss and drain output, the present findings are similar to previous studies demonstrating equivocal results despite variable tourniquet utilization in TKA.15,30 However, these results differ from those of Harvey and colleagues31, who demonstrated that blood loss inversely correlated with intraoperative tourniquet time. There are risks and benefits related to the use of both full and selective tourniquet methods, but either method does not appear to be advantageous in decreasing the rate of GA injury.
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