Where Are We Now?
Tourniquet use during TKA is controversial. While using a tourniquet improves visualization by providing a bloodless field and improving cement interdigitation into cancellous bone, its disadvantages include soft-tissue compression under the tourniquet, and diminished blood flow during surgery.
Soft-tissue compression and ischemia may contribute to adverse effects on the skin, muscle, or nerves [2, 4, 8]. Indeed, muscle ischemia has been identified in tissues directly under the tourniquet  and nerve injuries have been reported following prolonged tourniquet times . Large, echogenic venous emboli have been observed ultrasonographically after tourniquet deflation during TKA , although whether these are clinically important remains unknown.
Retained cement fragments, component malposition, and ligament laceration may be a function of inadequate visualization of the surgical field [3, 5], and advocates of tourniquet use believe that the clearer view of the field can reduce these sorts of complications. A tourniquet also provides a better (drier) surface for cementing compared to when one is not used , although it has not been established whether this decreases the risk of longer-term loosening at the cement-bone interface.
The current study by Deering and colleagues  compares tourniquet use for the entire procedure with tourniquet use for a portion of the procedure, and with no tourniquet use during TKA. The authors did not identify any clinically relevant differences in pain and functional outcomes between the groups , which shows that transient ischemia to soft tissues does not result in clinically relevant impairment in muscle function after surgery.
Where Do We Need To Go?
While the current study provides compelling evidence that tourniquet use does not compromise muscle or knee function after TKA , the patient population that may be at risk for tourniquet-related complications has not been clearly established nor has the potential benefit of tourniquet use on long-term cemented implant fixation. Future studies should assess the relative risk of tourniquet related adverse effects in presumed high- and low-risk patient populations. Patients at increased risk of complications related to soft-tissue ischemia and poor blood flow may include those with peripheral vascular disease, diabetes, and venous stasis. Patients at increased risk of clinical manifestations of fat embolism may include those with underlying pulmonary disease.
The studies included in the meta-analysis by Deering and colleagues  report postoperative pain, ROM, and hospital length of stay. But if tourniquet use improves cement fixation, then long-term studies are needed to determine whether tourniquets have any effect on the durability of cemented implant fixation in TKA.
How Do We Get There?
An assessment of those at risk for tourniquet-related complications after TKA could be developed with a regression analysis of large TKA patient populations that includes patients’ comorbidities, demographics, and use (or nonuse) of tourniquets. Large, national registries might be the best source of data for such a study, as they also track those other relevant patient variables, which would need to be managed statistically as potentially confounding variables. However, to my knowledge, the use of a tourniquet currently is not tracked as a variable in those registries; adding it in the future could help us get the answer to the important questions that remain on this topic, particularly whether tourniquet use improves survivorship free from aseptic loosening in cemented TKA.
Important shorter-term studies of cemented implant fixation in which patients are not followed to aseptic loosening includes radiographic analyses of cemented implant fixation and radiostereometric analysis studies of implant migration. Both types of studies could be helpful to predict the durability of cemented TKA with or without a tourniquet.
1. Deering EM, Hu SY, Abdulkarim A. Does tourniquet use in TKA increase postoperative pain? A systematic review and meta-analysis. Clin Orthop Relat Res. [Published online ahead of print]. DOI: 10.1097/CORR.0000000000000572
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3. Gandhi R, Smith H, Lefaivre KA, Davey JR, Mahomed NN. Complications after minimally invasive total knee arthroplasty as compared with traditional incision techniques: A meta-analysis. J Arthroplasty. 2011;26;29-35.
4. Horlocker TT, Hebl JR, Gali B, Jankowski CJ, Burkle CM, Berry DJ, Zepeda FA, Stevens SR, Schroeder DR. Anesthetic, patient, and surgical risk factors for neurologic complications after prolonged total tourniquet time during total knee arthroplasty. Anesth Analg. 2006;102:950-955.
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6. Parmet JL, Horrow JC, Berman AT, Miller F, Pharo G, Collins L. The incidence of large venous emboli during total knee arthroplasty without pneumatic tourniquet use. Anesth Analg.
7. Pfitzner T, von Roth P, Voerkelius N, Mayr H, Perka C, Hube R. Influence of the tourniquet on tibial cement mantle thickness in primary total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2016;24:96-101.
8. Rasmussen LE, Holm HA, Kristensen PW, Kjaersgaard-Andersen P. Tourniquet time in total knee arthroplasty. Knee. 2018;25:306–313.