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

Sciatic 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.

Retrospective investigational follow-up study.

University teaching hospital. Interdisciplinary postoperative anesthetic and orthopedic survey.

For this investigational analysis, 34 of 50 consecutive patients were available.

All 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.

Main 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.

Group 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.

SNB technique resulted in superior pain relief in comparison to continuous intra-articular local anesthetic drug instillation as adjunct to continuous FNB after TKA.