Tourniquet time in total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Surgical Outcomes

Background:

• The use of arterial tourniquets in total knee arthroplasty (TKA) remains a subject of debate.
• Prolonged ischemia can lead to hypoxic damage, while shorter durations may impact surgical outcomes.
• Understanding tourniquet-induced metabolic changes in TKA is crucial for optimizing patient safety and outcomes.

Purpose of the Study:

• To quantify time-dependent alterations in skeletal muscle metabolism during TKA.
• To establish a safe tourniquet duration for TKA procedures.
• To investigate the differential ischemic effects on muscle tissue.

Main Methods:

• Microdialysis was employed to measure metabolic markers in the femoral quadriceps muscle of 12 TKA patients.
• Lactate, pyruvate, glucose, and glycerol levels were assessed in muscle tissue both under and distal to the tourniquet, as well as in a reference muscle.
• Time-dependent ischemic responses were analyzed.

Main Results:

• The lactate-to-pyruvate (L/P) ratio increased significantly after 15 minutes of ischemia, with a faster rise observed in tissue directly beneath the tourniquet.
• Elevated glycerol levels under the tourniquet correlated with individual ischemic responses.
• Minor increases in creatine kinase, aspartate aminotransferase, and lactate dehydrogenase were noted, with lactate levels normalizing after 30 minutes of reperfusion.

Conclusions:

• Muscle tissue directly under the tourniquet experienced more severe ischemia compared to distal ischemic tissue.
• Ischemia markers remained unchanged with less than 15 minutes of tourniquet application.
• Any muscle damage from extended tourniquet use appears reversible and primarily occurs under the tourniquet, suggesting 15 minutes as a safe threshold.