The Possible Pathophysiological Outcomes and Mechanisms of Tourniquet-Induced Ischemia-Reperfusion Injury during Total Knee Arthroplasty

Figure 1

Effects of tourniquet- (TQ-) induced I/R injury on localized skeletal muscle, circulation, and remote organs and the effects of therapeutic interventions on the skeletal muscle I/R in cases of surgery for knee arthroplasty (TKA). The skeletal muscle I/R condition results in (1) preserved cellular bioenergy and mitochondrial function, (2) upregulation of genes related to cell stress pathways, (3) endothelial dysfunction as indicated by an increase in endothelin 1 and NOS levels, (4) alteration in protein metabolism, (4) increased oxidative stress and inflammatory responses, and (5) injury to distant organs including the kidney. Ischemic preconditioning (IPC), propofol, and vitamin C demonstrated positive or protective effects in the cases of I/R injury in this setting, while elevated O₂ tension aggravated the injury and N-acetylcysteine may have dose-dependent responses. Other interventions including remote ischemic preconditioning (rIPC), volatile anesthetic agents, mannitol, and nitric oxide possibly produce positive outcomes, and additional studies in this I/R condition should be investigated. ⊕: positive effect; ⊖: negative effect; ?: inadequate evidence; ↑: increase; ↓: decrease; ↔: no change; ATP: adenosine triphosphate; CPK-MB: creatinine phosphokinase-MB; Cr: creatinine; eNOS: endothelial nitric oxide synthase; nNOS: neuronal nitric oxide synthase; O₂: oxygen.