Femoral nerve catheter vs local infiltration for analgesia in fast track total knee arthroplasty: short-term and long-term outcomes.

BACKGROUND: The aim was to compare the effects on short-term and long-term pain and functional outcome of periarticular local anaesthetic infiltration (LIA) with LIA of the posterior knee capsule in combination with a femoral nerve block (FNB) catheter in patients undergoing total knee arthroplasty. METHODS: Eighty patients were randomised to one of two groups: Subjects in group LIA received periarticular LIA with ropivacaine 0.2% for postoperative analgesia; subjects in group FNB received LIA of the posterior capsule and a FNB catheter. The primary outcome parameter was functional capacity of the knee 12 months after surgery. Secondary parameters included mobility as determined by accelerometer data, pain, satisfaction with the analgesic regimen, hospital length of stay, and use of pain medication 3 and 12 months after surgery. RESULTS: There were no differences between groups in long-term functional capacity, patient satisfaction and hospital length of stay. In the first 2 days, subjects in group FNB had slightly lower pain scores and used less opioids, and subjects in group LIA had a higher level of accelerometer activity. Three and 12 months after surgery, subjects in group FNB had lower maximum pain scores and were less likely to use any pain medication 12 months after surgery. CONCLUSIONS: Both techniques were similar regarding long-term functional outcome. Subjects in group FNB had slightly lower pain scores and lower opioid consumption after operation, lower maximum pain scores at 3 and 12 months, and were less likely to use any pain medication at 12 months. CLINICAL TRIAL REGISTRATION: NCT01966263.

Pharmacokinetics of 400 mg ropivacaine after periarticular local infiltration analgesia for total knee arthroplasty.

BACKGROUND: Although considered safe, no pharmacokinetic data of high dose, high volume local infiltration analgesia (LIA) with ropivacaine without the use of a surgical drain or intra-articular catheter have been described. The purpose of this study is to describe the maximum total and unbound ropivacaine concentrations (Cmax , Cu max ) and corresponding maximum times (Tmax , Tu max ) of a single-shot ropivacaine (200 ml 0.2%) and 0.75 mg epinephrine (1000 µg/ml) when used for LIA in patients for total knee arthroplasty. METHODS: In this prospective cohort study, 20 patients were treated with LIA of the knee for primary total knee arthroplasty. Plasma samples were taken at 20, 40, 60, 90, 120, 240, 360 min and at 24 h after tourniquet release, in which total and unbound ropivacaine concentrations were determined. RESULTS: Results are given as median [IQR]. Highest ropivacaine concentration (Cmax ) was 1.06 µg/ml [0.34]; highest unbound ropivacaine concentration (Cu max ) was 0.09 µg/ml [0.05]. The corresponding time to reach the maximum concentration for total ropivacaine was 312 min [120] after tourniquet release, and for the unbound fraction 265 [110] min after tourniquet release. CONCLUSION: Although great inter-individual variability was found between the maximum ropivacaine concentrations, both maximum total and unbound serum concentrations of ropivacaine remained well below the assumed systemic toxic thresholds of 4.3 and 0.56 µg/ml.