The temporal effects of variable tourniquet use on pain after total knee arthroplasty.

Background: Tourniquet use in total knee arthroplasty (TKA) remains controversial. While widely studied, any temporal effects on pain and opioid utilization have not been investigated. We hypothesized that postoperative opioid utilization increases with increasing tourniquet times in TKA.

Methods: We retrospectively reviewed 1110 TKAs by three arthroplasty surgeons from October 2016 through September 2019. Exclusion criteria included ambulatory surgery, undocumented tourniquet times, simultaneous bilateral TKA, and diagnoses other than osteoarthritis, inflammatory arthritis, or osteonecrosis. Postoperative opioid medications were converted to daily morphine milligram equivalents (MME/day). Secondary outcomes included range of motion (ROM) at 1-month, 3-month, and 1-year visits as well as patient reported outcomes measures (PROMs) at 3 and 12 months.

Results: Nine-hundred and eleven patients were included and stratified based on tourniquet use. Three-hundred and four patients were assigned to a "No Use" group (≤10'); 138 patients to "Low Use" (11-60'); 177 patients to "Medium Use" (61-90'); and 292 patients to "Prolonged Use" (91-120). Compared to No Use, MME/day was significantly increased with Medium Use (+7.676 MME/day, p = 0.001) and Prolonged Use (+12.44 MME/day, p =< 0.001). No significant differences were found between No Use and Low Use groups. Estimated blood loss (EBL) in Low Use and No Use groups was significantly increased compared to other groups (+120 mL, p < 0.001, +109 mL, p < 0.001 respectively). Post-operative ROM and complication rates were similar between groups at 1 year post-TKA.

Conclusions: A threshold of 60 min of tourniquet time is associated with increased MME/day postoperatively compared to No Tourniquet. Functional and patient-reported outcomes are comparable between groups at 1 year follow-up.