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.