Eighty knees from fifty-eight patients with end-stage osteoarthritis were randomized to TKA with a tourniquet (n=40 knees) or without a tourniquet (n=40 knees). The primary outcomes were cellular markers in IPFP sampled intraoperatively: hypoxia (HIF-1α H-score), apoptosis (BAX/Bcl-2 ratio), and oxidative stress (oxidative stress index, OSI). Secondary outcomes included ROM and patient-reported/clinical scores (KOOS, KSS, Kujala) assessed preoperatively and at 3 months. Tissue was sampled at three time points in the tourniquet group (≈5 min after inflation, just before deflation, and before fascia closure) and at two time points in the no-tourniquet group. Overall, the results revealed significantly higher mean HIF-1α, BAX/Bcl-2, and OSI in the tourniquet group across time points, with hypoxia and apoptosis peaking just before deflation; however, 3-month clinical outcomes and ROM did not differ between groups. In short, tourniquet use acutely increases IPFP cellular injury signals without detectable short-term functional detriment.