Functional discharge readiness and mobility following total knee arthroplasty for osteoarthritis: a comparison of analgesic techniques.

Abstract

To determine if functional discharge readiness and mobility following total knee arthroplasty (TKA) for osteoarthritis is delayed after femoral nerve block (FNB) with or without patient-controlled analgesia (PCA) opioid compared with PCA opioid alone. We analyzed secondary outcomes from a randomized controlled trial with 200 patients undergoing unilateral TKA. Experimental group 1 received single-injection FNB with intravenous PCA opioid, experimental group 2 received continuous FNB, and the control group received PCA opioid alone. FNB was administered using bupivacaine. Patients followed a structured TKA pathway. Discharge readiness outcomes included achievement of 90° knee flexion, independent walking, and stair climbing, and were assessed daily before discharge or day 6, whichever came first. Mobility outcomes included the Timed Up and Go (TUG) test, the 6-Minute Walk Distance (6MWD), and self-reported physical function, and were assessed at weeks 2 and 12. TUG was also assessed on days 3 to 6, postoperation. Both FNB groups (77%) were more likely to achieve 90° knee flexion compared with the control group (59%); odds ratio (OR) 2.3, 95% confidence interval (95% CI) 1.1, 4.8 for single-injection FNB, and OR 2.3, 95% CI 1.1, 4.9 for continuous FNB. There were no significant differences in independent walking and stair-climbing ability before discharge, TUG, 6MWD, or self-reported physical function, between the FNB groups compared with the control group. After TKA, FNB (single-injection with PCA opioid or continuous) does not delay achievement of 90° knee flexion or other measures of functional discharge readiness and mobility compared with PCA opioid alone.