Does Tourniquet Use in TKA Increase Postoperative Pain? A Systematic Review and Meta-analysis
Authors: McCarthy Deering Eoin , Hu Shu Yang , Abdulkarim Ali 
Published: November 2018

Abstract

Background
Although tourniquets are commonly used during TKA, that practice has long been surrounded by controversy. Quantifying the case for or against tourniquet use in TKA, in terms of patient-reported outcomes such as postoperative pain, is a priority.

Questions/purposes
The purpose of this study was to meta-analyze the available randomized trials on tourniquet use during TKA to determine whether use of a tourniquet during TKA (either for the entire procedure or some portion of it) is associated with (1) increased postoperative pain; (2) decreased ROM; and (3) longer lengths of hospital stay (LOS) compared with TKAs performed without a tourniquet.

Methods
We completed a systematic review and meta-analysis using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines to assess the impact of tourniquet use on patients after TKA. We searched the following databases from inception to February 1, 2015, for randomized controlled trials meeting prespecified inclusion criteria: PubMed, Embase, and Cochrane Central Register of Controlled Trials. Postoperative pain was the primary outcome. Secondary outcomes were postoperative ROM and LOS. The initial search yielded 218 studies, of which 14 met the inclusion criteria. For our primary analysis on pain and ROM, a total of eight studies (221 patients in the tourniquet group, 219 patients in the no-tourniquet group) were meta-analyzed. We also performed a subgroup meta-analysis on two studies that used the tourniquet only for a portion of the procedure (from osteotomy until the leg was wrapped with bandages) and defined this as half-course tourniquet use (n = 62 in this analysis). The Jadad scale was used to ascertain methodological quality, which ranged from 3 to 5 with a maximum possible score of 5. Statistical heterogeneity was tested with I2 and chi-square tests. A fixed-effects (inverse variance) model was used when the effects were homogenous, which was only the case for postoperative pain; the other endpoints had moderate or high levels of heterogeneity. Publication bias was assessed using a funnel plot, and postoperative pain showed no evidence of publication bias, but the endpoint of LOS may have suffered from publication bias or poor methodological quality. We defined the minimum clinically important difference (MCID) in pain as 20 mm on the 100-mm visual analog scale (VAS).

Results
We found no clinically important difference in mean pain scores between patients treated with a tourniquet and those treated without one (5.23 ± 1.94 cm versus 3.78 ± 1.61 cm; standardized [STD] mean difference 0.88 cm; 95% confidence interval [CI], 0.54-1.23; p < 0.001). None of the studies met the MCID of 20 mm in VAS pain scores. There was also no clinically important difference in ROM based on degrees of flexion between the two groups (49 ± 21 versus 56 ± 22; STD mean difference 0.8; 95% CI, 0.4-1.1; p < 0.001). Similarly, we found no difference in mean LOS between groups (5.8 ± 4.4 versus 5.9 ± 4.6; STD mean difference -0.2; 95% CI, -0.4 to 0.1; p = 0.25). A subgroup meta-analysis also showed no clinically important difference in pain between the full-course and half-course tourniquet groups (5.17 ± 0.98 cm versus 4.09 ± 1.08 cm; STD mean difference 1.31 cm; 95% CI, -0.16 to 2.78; p = 0.08).

Conclusions
We found no clinically important differences in pain or ROM between patients treated with and without tourniquets during TKA and no differences between the groups in terms of LOS. In the absence of short-term benefits of avoiding tourniquets, long-term harms must be considered; it is possible that use of a tourniquet improves a surgeon’s visualization of the operative field and the quality of the cement technique, either of which may improve the long-term survivorship or patient function, but those endpoints could not be assessed here. We recommend that the randomized trials discussed in this meta-analysis follow patients from the original series to determine if there might be any long-term differences in pain or ROM after tourniquet use.

Level of Evidence
Level I, therapeutic study.