In vitro elution of local anesthetics from PMMA bone cement

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Pharmacology

Background:

• Effective pain management after total knee arthroplasty (TKA) lacks a gold standard.
• Current drug delivery systems for TKA pain are suboptimal.
• Polymethylmethacrylate (PMMA) bone cement has a history of use as a drug delivery system.

Purpose of the Study:

• To characterize the elution profile of local anesthetics from PMMA bone cement.
• To evaluate the potential of PMMA bone cement as a local anesthetic depot for TKA.

Main Methods:

• Specimens of Palacos® R+G bone cement loaded with lidocaine hydrochloride or bupivacaine hydrochloride were prepared.
• Elution of local anesthetics into phosphate-buffered saline (PBS) was measured over time.
• Liquid chromatography was used to quantify anesthetic concentrations.

Main Results:

• Lidocaine elution reached 9.74% at 72 hours and 18.73% at 336 hours.
• Bupivacaine elution was 2.71% at 72 hours and 2.70% at 336 hours.
• Eluted doses at 72 hours approached those used in anesthetic blocks.

Conclusions:

• Local anesthetics demonstrate in vitro elution from PMMA bone cement.
• PMMA bone cement shows promise as a drug delivery system for localized pain control post-TKA.