Femoral nerve block improves analgesia outcomes after total knee arthroplasty: a meta-analysis of randomized controlled trials.

Background: Femoral nerve blockade (FNB) is a common method of analgesia for postoperative pain control after total knee arthroplasty. We conducted a systematic review to compare the analgesia outcomes in randomized controlled trials that compared FNB (with and without sciatic nerve block) with epidural and patient-controlled analgesia (PCA).

Methods: We identified 23 randomized controlled trials that compared FNB with PCA or epidural analgesia. These studies included 1,016 patients, 665 with FNB, 161 with epidural, and 190 with PCA alone.

Results: All 10 studies of single-shot FNB (SSFNB) used concurrent PCA opioids. SSFNB was found to reduce PCA morphine consumption at 24 h (-19.9 mg, 95% credible interval [CrI]: -35.2 to -4.6) and 48 h (-38.0 mg, 95% CrI: -56.0 to -19.7), pain scores with activity (but not at rest) at 24 and 48 h (-1.8 visual analog pain scale, 95% CrI: -3.3 to -0.02 at 24 h; -1.5 visual analog pain scale, 95% CrI: -2.9 to -0.02 at 48 h) and reduce the incidence of nausea (0.37 odds ratio, 95% CrI: 0.1 to 0.9) compared with PCA alone. SSFNB had similar morphine consumption and pain scores compared with SSFNB plus sciatic nerve block, and SSFNB plus continuous FNB.

Conclusions: SSFNB or continuous FNB (plus PCA) was found to be superior to PCA alone for postoperative analgesia for patients having total knee arthroplasty. The impact of adding a sciatic block or continuous FNB to a SSFNB needs to be studied further.