Functional recovery best after femoral nerve block for knee arthroplasty
MedWire News: Patients show better functional recovery at 6 weeks after total knee arthroplasty if they are given continuous femoral nerve block for postoperative pain relief rather than periarticular infiltration, research suggests.
Periarticular infiltration and continuous femoral nerve block are both known to provide better pain relief and knee flexion than systemic opioids in patients recovering from total knee arthroplasty.
But, at the time of the current study, these two techniques had not been directly compared in a randomized, double-blind trial.
A previous randomized open study reported that periarticular infiltration was superior to continuous femoral nerve block, so Franco Carli (McGill University Health Center, Montreal, Quebec, Canada) and colleagues expected their blinded trial to produce similar results.
Instead, continuous femoral nerve block was superior to periarticular infiltration for reducing postoperative opioid consumption and across several functional outcome measures, the team reports in the British Journal of Anaesthesia.
The 20 patients assigned to receive 48 hours of postoperative femoral block (ropivacaine 0.2%) used 14.5 mg of morphine during the first 24 hours after surgery and 12.0 mg during the second 24-hour period. The 20 patients given 48 hours of periarticular infiltration (ropivacaine 0.2%, ketorolac 30 mg/ml, epinephrine 1 mg/ml) used 26.0 and 22.5 mg in the corresponding time periods, significantly more than the femoral block group.
There was a trend toward less pain at rest among patients in the femoral block versus periarticular groups. Otherwise, patients reported similar levels of pain.
Six weeks after surgery, the average 6-minute walk test time had significantly improved from a pre-operative value of 231.6 meters to 267.5 m among patients given femoral block. The improvement in the periarticular infiltration group, from 229.0 to 248.0 m, was not statistically significant.
Patients in the femoral block group had a greater improvement in physical activity levels, as assessed by Community Health Activities Model Program for Seniors scores, at a 135.7% increase compared with a 44.6% increase in the periarticular infiltration group.
Both groups of patients made significant improvements in knee function, but 6-week Knee Society scores were better in the femoral block versus periarticular infiltration groups, at 156.6 versus 137.7, as were Western Ontario and McMaster Universities Osteoarthritis scores, at 19.7 versus 28.0.
"Such findings not only confirm the positive impact of analgesia on late outcome measures specific to knee function, but also report the beneficial effects on measures of general health and recovery such as physical activity and mobilization," say Carli et al.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Eleanor McDermid