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Correspondence

Femoral block for pain after knee surgery

TARKKILA, P.

Author Information
European Journal of Anaesthesiology: February 1999 - Volume 16 - Issue 2 - p 145

Sir:

We thank Drs Borgeat and Singer for their interest in our article [1]. The positive reports of the efficacy of continuous 3-in-1 block [2,3] after knee surgery induced us to compare it with intrathecal morphine, which had been our routine analgesic for these patients.

(1) The correct placement of the needle was confirmed by the motor response of quadriceps muscle to low current stimulation (0.4-0.8 mA) with a nerve stimulator. Thereafter, the catheter was introduced into the femoral sheath. We agree that we did not check whether the block reached the lateral cutaneous and obturator nerves. The residual effect of the spinal anaesthesia made the sensory testing of these two nerves difficult.

(2) We do not agree that the verbal rating scale (VRS) makes our results unreliable. As far as we know, there are no studies that prove that using a visual analogue scale (VAS) would give more reliable results than VRS. We still believe that, with this mainly older patient population, often having poor eyesight and difficulties in understanding the 10 cm VAS scale, it could have given faulty results in some cases. Also, we do not believe that using a VAS scale would have made any difference to our conclusions.

(3) The location of pain in those patients in whom there was insufficient pain relief came from the posterior part of the knee indicating that branches of the sciatic nerve were involved.

(4) We still believe that the simplicity of the method is lost if more than one puncture is needed. The technique that is described in the letter from Drs Borgeat and Singer necessitates placing the patient in the lateral position and performing two different punctures. More studies of the optimum pain treatment for patients after major knee surgery are still warranted.

(5) We completely agree with Drs Borgeat and Singer that this technique is inadequate for the provision of good post-operative analgesia after major knee surgery. More effective pain treatments are required.

P. TARKKILA

Department of Anaesthesiology, Fourth Department of Surgery, Helsinki University Central Hospital, Kasarmikatu 11-13, FIN-00130 Helsinki, Finland

References

1 Tarkkila P, Tuominen M, Huhtala J, Lindgren L. Comparison of intrathecal morphine and continuous femoral 3-in-1 block for pain after major knee surgery under spinal anaesthesia. Eur J Anaesth 1998; 15: 6-9.
2 Dahl JB, Christiansen CL, Daugaard JJ, Schulz P, Carlsson P. Continuous blockade of the lumbar plexus after knee surgery - postoperative analgesia and bupivacaine plasma concentrations. A controlled trial. Anaesthesia 1988; 43: 1015-1018.
3 Edwards ND, Wright EM. Continuous low-dose 3-in-1 nerve blockade for postoperative pain relief after total knee replacement. Anesth Analg 1992; 75: 265-267.
© 1999 European Academy of Anaesthesiology