A randomized trial of controlled-release oxycodone during inpatient rehabilitation following unilateral total knee arthroplasty

Background: Reliance on "as-needed" analgesia following total knee arthropl asty may lead to inadequate control of pain and delayed recovery of functio n. Preemptive use of controlled-release opioids may improve pain control, a ccelerate recovery, and reduce the need for inpatient rehabilitative servic es. This study was designed to determine whether controlled-release opioids enhance post-arthroplasty pain control and facilitate functional recovery during rehabilitation. Methods: Fifty-nine patients admitted for inpatient rehabilitation followin g unilateral total knee arthroplasty were randomized to receive OxyContin ( controlled-release oxycodone) (twenty-nine patients) or a placebo (thirty p atients) every twelve hours. Both groups could receive on-request, immediat e-release oxycodone (5 mg every four hours). The dose of study medication w as increased on the basis of the frequency of requests for immediate-releas e oxycodone. Measures of interest included pain ratings as determined with a visual-analog scale, changes in the range of motion of the knee and quadr iceps strength, and improvements in selected Functional Independence Measur e scores during the first eight physical therapy sessions. The duration of the hospital stay for rehabilitation also was compared between the two grou ps. Results: Baseline demographic, clinical, and functional characteristics wer e similar between the OxyContin and placebo groups. Compared with the place bo group, the patients who received OxyContin reported significantly less p ain as well as significantly greater range of motion of the knee (passive m otion, p = 0.036; active motion, p < 0.001) and quadriceps strength (p = 0. 001) by the eighth physical therapy session. The patients who received OxyC ontin also were discharged from the rehabilitation hospital at an average o f 2.3 days earlier than the patients in the placebo group (p = 0.013). Conclusions: Preemptive use of controlled-release oxycodone during rehabili tation following total knee arthroplasty leads to improved pain control, mo re rapid functional recovery, and a reduced need for inpatient rehabilitati ve services.