Dexmedetomidine-Based Versus Opioid-Containing Periarticular Infiltration in High Tibial Osteotomy: A Retrospective Comparative Cohort Study

Background/Objectives: High tibial osteotomy (HTO) is a joint-preserving procedure for selected patients with medial compartment knee osteoarthritis and varus malalignment. Postoperative pain after HTO may impair early mobilization and increase systemic opioid requirements. Periarticular infiltration analgesia is commonly used as part of multimodal analgesia; however, comparative evidence regarding opioid-containing and opioid-free infiltration protocols in HTO remains limited. This study compared postoperative pain, systemic opioid consumption, PCA demand, rescue analgesic requirement, and analgesia-related adverse events between a modified opioid-containing Ranawat cocktail and an opioid-free dexmedetomidine-based periarticular infiltration protocol. Methods: This single-center retrospective comparative cohort study included 80 patients who underwent medial opening-wedge HTO between March 2021 and March 2025. Patients were categorized according to the documented periarticular infiltration protocol: modified Ranawat cocktail (n = 40) or dexmedetomidine-based cocktail (n = 40). Postoperative VAS scores were recorded at 6, 12, 18, and 24 h and on postoperative days 7 and 14. Secondary outcomes included 24 h systemic opioid consumption expressed as morphine milligram equivalents, PCA demand count, rescue analgesic use, and analgesia-related adverse events. Longitudinal postoperative VAS trajectories were analyzed using unadjusted and adjusted linear mixed-effects models. The adjusted model included the available covariates of age, body mass index, preoperative VAS score, operative time, and tourniquet time. Results: Baseline demographic and perioperative variables were comparable between groups. The dexmedetomidine group demonstrated lower adjusted postoperative VAS scores during the early postoperative period, with statistically significant between-group differences at 12, 18, and 24 h, whereas pain trajectories converged by postoperative day 14. Twenty-four-hour systemic opioid consumption was lower in the dexmedetomidine group than in the modified Ranawat group (9.78 ± 1.99 vs. 13.92 ± 1.79 MME, p < 0.001). PCA demand was also lower in the dexmedetomidine group (6.30 ± 3.16 vs. 9.63 ± 2.92, p < 0.001). No significant between-group differences were observed in rescue NSAID use, rescue tramadol requirement, nausea/vomiting, hypotension, bradycardia, allergic reactions, or other recorded adverse events. Conclusions: In this retrospective cohort, dexmedetomidine-based opioid-free periarticular infiltration was associated with lower adjusted early postoperative VAS scores, reduced 24 h systemic opioid consumption, and fewer PCA demands compared with a modified opioid-containing Ranawat cocktail after medial opening-wedge HTO. However, because treatment allocation was not randomized and several potentially relevant confounders were not available for adjustment, these findings should be interpreted as associative and hypothesis-generating. Prospective adequately powered randomized studies are needed to confirm these findings and evaluate their effects on functional recovery and osteotomy healing.