Peripheral Nerve Blocks: A Color Atlas, 3rd Edition

42.Ultrasound Guided Posterior Tibial Nerve Block

Luiz Guilherme L. Soares

Colin McCartney

Patient Position: The patient is positioned supine with the anesthesiologist facing the lateral aspect of the foot.

Indication: Surgery of the forefoot.

Needle Size: 50-mm stimulating needle.

Surface Landmarks: The medial malleolus (Fig. 42-1).

Ultrasound Landmarks: The medial malleolus is an hyperechoic curvilinear structure. The posterior tibial artery and hyperechoic tibial nerve are found posterior and superficial to the medial malleolar bony shadow (Figs. 42-2, 42-3).

Transducer Position: In the axial plane, posterior to the medial malleolus.

Volume: 3 to 5 mL.

Technique: Sterile prep of the skin. A 13-MHz linear transducer is placed posterior to the medial malleolus. The needle is placed anterior to the probe in the longitudinal plane at an angle which is nearly tangential to the skin. The needle is advanced with a current of 0.5 mA until plantar flexion of the toes is elicited or until a paresthesia is obtained. Injection of 3 to 5 mL of local anesthetic should surround the nerve with a block hypoechoic ring (Fig. 42-4).

 

Figure 42-1. Illustration of needle and probe position for ultrasound guided posterior tibial nerve block.

Figure 42-2. Sonogram (with color Doppler) of anatomy posterior to the medial malleolus. Ant, anterior; N, posterior tibial nerve; A, posterior tibial artery.

Figure 42-3. Anatomy of the nerves at the ankle.

Figure 42-4. Sonogram (with color Doppler indicating arterial pulse) demonstrating local anesthetic spread surrounding the posterior tibial nerve. N, posterior tibial nerve; LA, local anesthetic.

 

Tips

1.   Some practitioners prefer to perform the block without a stimulating needle.

2.   For anesthesia of the forefoot, the deep peroneal, saphenous, sural, and superficial peroneal nerves must also be blocked. The later three are best blocked with simple infiltration as described elsewhere in the text.