Continuous intra-articular local anesthetic drug instillation versus discontinuous sciatic nerve block after total knee arthroplasty

•Sciatic nerve block was compared with continuous intraarticular local anesthetic drug instillation after TKA.•Main endpoints were pain intensity levels and postoperative opioid consumption.•Sciatic nerve block resulted in a superior and better pain relief.•Continuous intraarticular anesthetic drug instillation is no adequate alternative.•No differences in functional outcome or length of hospital stay were found.

Study objectiveSciatic nerve block (SNB) is commonly used as adjunct to femoralis nerve block (FNB) to achieve high-quality pain relief after total knee arthroplasty (TKA). However, this combination is associated with considerable muscle weakness, foot drop and surgically related nerve injuries may be masked. The purpose of this study was to assess whether low risk continuous intra-articular anesthetic drug instillation is an adequate alternative to SNB when adding to FNB after TKA.DesignRetrospective investigational follow-up study.SettingUniversity teaching hospital. Interdisciplinary postoperative anesthetic and orthopedic survey.PatientsFor this investigational analysis, 34 of 50 consecutive patients were available.InterventionsAll patients underwent primary unilateral TKA. Group A (18 patients) received a continuous intra-articular 0.33% ropivacaine (5 mL/h) instillation for the first 48 h postoperatively. In Group B (16 patients) a discontinuous SNB was used. Both groups were treated with a continuous FNB.MeasurementsMain endpoints were mean and maximum postoperative pain intensity levels for both anterior and posterior knee side, amount of postoperative administered opioid drugs, differences in functional outcome or hospital stay and rate of postoperative complications.Main resultsGroup A showed higher pain intensity levels for the posterior knee side (P ≤ .042). Merely on the second postoperative day there were no differences within either study group. No differences were found regarding anterior knee pain. Group A showed a significant higher postoperative piritramid consumption (P ≤ .007). Length of hospital stay or postoperative functional outcome was not significant different. Postoperative complications were not related to anesthesia techniques.ConclusionsSNB technique resulted in superior pain relief in comparison to continuous intra-articular local anesthetic drug instillation as adjunct to continuous FNB after TKA.