The primary purpose of this proof-of-concept quality improvement effort was to evaluate the practicality of using near-infrared spectroscopy (NIRS) to measure tissue oxygen saturation (Sto2) during total knee arthroplasty (TKA) with use of a tourniquet. NIRS sensors were applied to the biceps femoris (BF) and gastrocnemius (GS) muscles of both lower extremities of patients undergoing TKA procedures. For a convenience sample of 15 patients, measurement of Sto2 was attempted at baseline, following subarachnoid block administration, and after tourniquet inflation and deflation. Mean baseline Sto2 (SD) was 71% (6%) in the BF muscle and 66% (7%) in the GS muscle. Significant changes in Sto2 values were observed following subarachnoid block, tourniquet inflation, and tourniquet deflation. The Sto2 returned to or above baseline in the BF muscle but did not return to baseline in the GS muscle following tourniquet deflation. Changes in tissue oxygen saturation resulting from use of a tourniquet can be continuously monitored with the use of an NIRS device. Further evaluation of the use of NIRS should be undertaken to determine if it could be used to guide safe duration and pressure limits for tourniquet inflation.