One hundred eighty elderly patients scheduled for lower-extremity orthopedic procedures were randomized to bupivacaine + fentanyl 25 µg (BF1, n=77), bupivacaine + fentanyl 50 µg (BF2, n=77), or bupivacaine alone (B, n=37). The primary outcome was opioid use rate; secondary outcomes included NRS pain (≥4) and overall analgesic use on POD1–3. Outcomes were assessed daily to POD3. Overall, the results showed lower opioid use by POD3 with fentanyl versus bupivacaine, and fewer patients with NRS ≥ 4 in fentanyl groups on POD2–3 and for BF1 on POD1. High-dose fentanyl (50 µg) did not outperform 25 µg and was associated with more nausea/vomiting. These findings suggest intrathecal fentanyl (particularly 25 µg) as an adjunct may reduce pain and late-early (POD3) opioid requirements in this population.