Extended-release epidural morphine vs continuous peripheral nerve block for management of postoperative pain after orthopedic knee surgery: a retrospective study.

The purpose of this study was to compare the efficacy and safety of extended-release epidural morphine (EREM) and perineural infusion (PNI) to control pain after total knee arthroplasty. A convenience sample of 200 patients was obtained using a retrospective chart review of patients who underwent a total knee arthroplasty. Institutional review board approval was obtained, and 100 charts of patients who received EREM and 100 patient charts for PNI were reviewed.