Local infiltration anesthesia with high dose ropivacaine and dexmedetomidine in major knee surgery is safe

BACKGROUND: The role of local infiltration anesthesia (LIA) in knee surgery is significant. LIA can be more potent than a nerve block, but without the downsides. A wide range of agents are used for LIA, including some off-label medications such as dexmedetomidine and ropivacaine. Dexmedetomidine has recently received attention for decreasing demand for anesthetic agents and prolonged effect of anesthesia. The purpose of this study was to demonstrate safety of dexmedetomidine and ropivacaine as LIA.

METHODS: This is a retrospective analysis of 200 patients receiving 300 mg of ropivacaine, 100 µg of dexmedetomidine and 10 mL of saline solution as LIA. Both agents are off-label for this use. The LIA applied prior to skin closure as a pertiarticular block. Major knee surgery was defined as ligament reconstruction of at least one ligament, fracture of the femur and the tibia, knee replacement and osteotomy. We evaluated short-term major side-effects of these agents, and evaluated 30-day complications.

RESULTS: Included were 77 arthroplasties, 10 fracture fixations, 19 osteotomies, 55 primary and revision ACL, 10 isolated medial patellar femoral ligament reconstructions, 2 ACLs combined with a partial knee arthroplasty, 4 cartilage transplantations and 23 multiligament knee reconstructions. We observed one transitory discoloration after an ACL reconstruction that disappeared by the 48 h mark. We had no 30-day superficial or deep infections. Cardiac or allergic reactions were not observed.

CONCLUSIONS: LIA in a combination of single high-dose ropivacaine and dexmedetomidine is safe in knee surgery. Further studies evaluating pain relief with this LIA combination are needed.