Evaluation of a New Method of Sciatic Nerve Block: A Prospective Pilot Study

Abstract

Purpose

The location of the sciatic nerve deep within the thigh tissue makes it challenging to locate while the patient is in a supine position. The posterior intermuscular septum of the thigh, which encircles the posterior surface of the adductor magnus muscle (AMM), is where the sciatic nerve is located. Our hypothesis was that administering local anesthetic injections into this area could block the sciatic nerve. Therefore, our aim was to evaluate the effectiveness of sciatic nerve block achieved by injecting local anesthetic into the posterior intermuscular septum of the thigh, named the AMM approach.

Methods

Twenty-six patients undergoing total knee arthroplasty were included in the study. We performed an ultrasound-guided sciatic nerve block by injecting 20 mL of 0.25% ropivacaine into the posterior surface of the adductor magnus muscle, using the AMM approach. Additionally, we administered a femoral nerve block with 20 mL of 0.4% ropivacaine. We assessed the sensory and motor effects of the blockade in the operated lower limb and recorded postoperative pain scores at 0, 4, 8, 12, 24, and 48 hours after the operation.

Results

The AMM approach successfully block the sciatic nerve in all 26 patients. The onset of the sensory and motor blockades was achieved within 5.4 ± 1.9 min and 8.7 ± 3.5 min, respectively. We achieved a satisfactory position with the first puncture in 19 of 26 patients (73.1%). The muscle strength of the tibialis anterior immediately after surgery was 4 (ranging from 2 to 5). Additional rescue analgesics were required in 5 of the 26 patients (19.2%) during the first 24 hours postoperatively.

Conclusion

The AMM approach is an innovative and effective method for sciatic nerve block. When combined with simultaneous femoral nerve block in patients undergoing total knee arthroplasty, it provides a useful analgesic treatment option.

Keywords:

• sciatic nerve block
• adductor magnus muscle
• tibialis anterior
• femoral nerve block

Data Sharing Statement

We agree to share all the data for this study. The data that support the findings of this study are available from the corresponding author upon any reasonable request.

Acknowledgments

The authors want to thank the Department of Anesthesiology and Department of Orthopaedics, Peking University Third Hospital for the help and support in preparation of the manuscript and research studies.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by Innovation & Transfer Fund of Peking University Third Hospital (BYSYZHKC2022103), and the National Natural Science Foundation of China (82271289).