Retrograde drain-based analgesic cocktail injection for pain control and early mobilization after total knee arthroplasty: a prospective observational study.

BACKGROUND

Effective postoperative pain management is essential for enhanced recovery following total knee arthroplasty (TKA). Although the routine use of drains in TKA is declining, they can provide a sterile conduit for local analgesic administration. Multimodal analgesia is widely used, but optimal delivery methods remain under evaluation. This study investigates the efficacy and safety of retrograde drain-based injection of an analgesic cocktail for early pain relief and mobilization after TKA.

METHODS

A prospective observational study was conducted in 30 patients undergoing primary unilateral TKA at a single center between January and June 2024. All surgeries were performed under spinal anesthesia without peripheral nerve blocks or periarticular infiltration. Following wound closure and drain placement, a multimodal cocktail (bupivacaine, ketorolac, dexamethasone, normal saline; total 30 mL) was injected retrogradely via the drain, which was then clamped for two hours. Visual Analog Scale (VAS) pain scores were recorded at 6, 12, 24, and 48 h postoperatively. Functional outcomes included time to first mobilization, active knee range of motion (ROM) on day 3, and quadriceps activation by straight leg raise (SLR). Safety outcomes were drain-related complications assessed up to two weeks postoperatively.

RESULTS

Mean VAS scores were 2.6 ± 0.9 at 6 h, 3.1 ± 1.1 at 12 h, 3.8 ± 1.0 at 24 h, and 3.5 ± 0.8 at 48 h. The mean time to first mobilization was 15.2 ± 3.1 h. By day 3, the mean active ROM was 78.6° ± 6.4, and quadriceps activation improved from 60.0% on day 1 to 93.3% on day 3. No drain-related infections or hematomas were observed.

CONCLUSION

Retrograde injection of a multimodal analgesic cocktail via the drain appears to be a safe and feasible adjunct for postoperative analgesia in TKA, providing encouraging early results in terms of pain control and mobilization. Further controlled studies are warranted to validate its comparative efficacy.