Association of Single-Dose Intravenous Vitamin C with Inpatient Hydromorphone Use After Total Hip and Knee Arthroplasty: A Retrospective Cohort Study

Background Postoperative pain control after total knee arthroplasty (TKA) and total hip arthroplasty (THA) commonly includes opioids, which are associated with adverse effects. Vitamin C is reported to reduce postoperative opioid requirements in several surgical settings. Objective To determine whether a single postoperative vitamin C dose added to an established pain management protocol was associated with reduced inpatient hydromorphone use following THA/TKA. Methods Charts of patients who underwent primary TKA (n=100) or THA (n=69) by a single surgeon were retrospectively reviewed. In March 2025, a single 5g intravenous vitamin C dose was incorporated into the postoperative multimodal analgesia protocol. Patients prior to March 2025 were controls (n=122); patients after vitamin C introduction were intervention cohort (n=47). Analgesics and antiemetics were recorded for postoperative day (POD) 0, 1, and 2. Results TKA patients required significantly less hydromorphone than THA patients on POD0 (control: p=0.001; vitamin C: p=0.003). TKA patients in both cohorts had similar total daily hydromorphone use on POD0 and POD2. On POD1, control TKA patients required more hydromorphone (6.1±3.2 mg) than vitamin C TKA patients (4.4±3.0 mg, p=0.036). THA patients in both cohorts had similar total daily hydromorphone use on POD0, 1, and 2. In a linear mixed-effects model, vitamin C administration was associated with reduced hydromorphone/hour of hospital stay (beta coefficient -0.0159, p=0.003). Conclusion A single postoperative 5g intravenous vitamin C dose was associated with reduced inpatient hydromorphone consumption following TKA. Prospective randomized studies are warranted to confirm this association and define the optimal perioperative vitamin C protocol. Level of Evidence III (retrospective cohort study)