Efficacy of continuous catheter analgesia of the sciatic nerve after total knee arthroplasty

PURPOSE: This study investigated and compared the outcomes after continuous femoral nerve block alone, continuous femoral nerve analgesia combined with single-shot sciatic nerve analgesia, and continuous femoral and sciatic nerve analgesia in patients with total knee replacement. METHODS: The retrospective study evaluated three groups: continuous femoral nerve analgesia alone, continuous femoral nerve analgesia combined with single-shot sciatic nerve analgesia and continuous femoral nerve analgesia combined with continuous sciatic nerve analgesia. All patients had a hemi-or total knee arthroplasty (TKA), which were performed by a single surgeon. The postoperative analgesia was managed by the same team. A total of 362 patient charts were evaluated from the years 2005-2012. Pain scored with a visual analogue scale (VAS) was recorded 8 hours and 24 hours postoperatively on a standardised form. The amount of opioids required with and without additional sciatic nerve analgesia was documented by monitoring the VAS. RESULTS: Overall, 364 patient files could be assessed. The VAS scores after 8 and 24 hours of patients with an additional continuous sciatic nerve catheter were lower (mean values 1.8 and 4.0, respectively) than those of patients with a continuous femoral catheter alone (mean values 2.7 and 4.9). After 8 and 24 hours, patients with a continuous sciatic nerve catheter had lower VAS scores than those with additional single-shot sciatic nerve anaesthesia (mean values 1.9 and 4.5). Pethidine consumption in the continuous sciatic nerve catheter group was lower (32% of patients) as compared with the two other groups (65%). The side effects of opioids per group consequently were also lower: 24% patients with side effects in the continuous sciatic nerve block group, 52% in the additional single shot sciatic nerve group, 44% in the femoral nerve block group. CONCLUSION: On the basis of these results, which correspond well to other studies of a topic that is under discussion in the literature, we adapted our postoperative pain regimen to continuous sciatic and femoral nerve analgesia for at least 24 hours after hemi-and total knee replacement.