Background: Currently, the duration of tourniquet time in total knee arthroplasty is chosen by the surgeons and varies between 0 and 120 min. Studies evaluating the effect of tourniquet time in this surgery are heterogeneous, and there is limited information on molecular/complement profiling. The purpose of this study was, therefore, to determine whether the duration of tourniquet-induced limb ischemia during total knee arthroplasty influences reperfusion injury, resulting in pain, swelling, and the release of pro-inflammatory markers. Methods: In 40 patients undergoing total knee arthroplasty, a tourniquet was applied for up to 30 min (group A, short tourniquet) or 90–120 min (group B, long tourniquet). Postoperative pain and swelling served as primary outcome parameters. The levels of pro- and anti-inflammatory markers before surgery and 4 h, 24 h, and 48 h after surgery were used as secondary outcome parameters for exploratory testing. Results: There were no differences in numeric rating pain scale (NRS) scores and calf circumference between groups A and B. Patients in group B required patient-controlled intravenous analgesia more frequently than group A patients (47% versus 5%, group B vs. group A, p < 0.0001). In group B, a significantly higher increase in C3a and MIG levels between 4 h and 48 h, and a significantly higher increase for MIG and M-CSF between 24 h and 48 h, were observed. Conclusions: Tourniquet times between 90 and 120 min were not associated with higher pain levels or more swelling, but an increased need for intravenous analgesia and a higher increase in pro-inflammatory markers. This might be a consequence of a more pronounced ischemia/reperfusion injury with tourniquet times longer than 90 min.
Pfeiffer et al. (Wed,) studied this question.