Popliteal

The popliteal block targets the sciatic nerve in the proximal popliteal fossa.  It is the primary block for surgeries of the lower leg and foot.  The major advantage of the popliteal block is that with exception of anteromedial cutaneous distribution of the saphenous nerve, it affords almost complete anesthesia of the lower leg without affecting the hamstring or adductor muscles of the thigh.

Indications: Procedures of the ankle and foot

Patient Position: Prone, Lateral or Supine

Transducer: High frequency transducer (>7 MHz)

Transducer Position: Popliteal crease; location often varies within the crease, slightly rocking the transducer caudal will often improve the image (anistropy)

Needle: 5cm, 22 gauge stimulating needle

Local Anesthetic: 30 -40mls of local anesthetic

Keys To A Successful Block: circumferential spread around both branches of the sciatic

The sciatic nerve arises from the nerve roots L4-5 and S1-3 of the lumbar plexus.  It supplies motor and sensory innervation to the posterior leg and foot.  In the popliteal fossa, the sciatic nerve lies posterior and lateral to the popliteal artery and vein, bordered medially by the semitendinous and semimembranous muscles and laterally by the biceps femoris muscle.  The sciatic nerve divides into the tibial and common peroneal nerves at varying locations along the popliteal fossa, making it important to scan the region proximally and distally to determine the area that offers the greatest chance of success.

 

 

 

In the video below, the sciatic nerve is identified in the proximal popliteal fossa. The transducer is moved caudal past the bifurcation of the tibial and common peroneal nerves. Continuing caudal, the popliteal artery and vein are identified beneath the tibial nerve, the transducer is returned cephalad to its original position.

The optimal position for performing a popliteal block is having the patient in the prone position and using an in-plane or out-of-plane approach.  A high-frequency (>7MHz) transducer is placed at the popliteal crease and moved cephalad to evaluate the region, taking note of major anatomical landmarks such as the femur and popliteal artery.  The practitioner should also note the point at which the sciatic nerve begins to divide as it is the desired location for local anesthetic placement.  Once the correct position is determined, the needle is aimed to slightly to one side of the sciatic, rather than directly at the nerve itself.  If the out-of-plane approach is used, hydrolocation can assist the anesthetist in determining needle tip position.  New practitioners may consider the use of nerve stimulation in conjunction with US.  When proper needle position is confirmed (motor stimulation if used), 20-30 mls of local anesthetic is injected under ultrasound-guidance after negative aspiration.  Circumferential spread will usually result in a complete block.

However, circumstances may prevent placing the patient in this position, requiring an in-plane approach from the supine position.  It is important to remember that when in the patient is in the supine position, the US image is inverted and the orientation should be adjusted to ensure the proper image.

The video below shows a popliteal block performed with the patient in the supine position.  The needle is inserted using an in-plane technique so that it passes between the tibial and peroneal nerves.  Local anesthetic is injected, creating spread on the far aspect of the tibial nerve.  As the needle is slowly withdrawn, local anesthetic is slowly injected causing local anesthetic to be deposited around both nerves.


References

Mulroy MF, Bernards CM, McDonald SB, Salinas FV. A Practical Approach to Regional Anesthesia. 4th. Ed. Baltimore, MD: Lippincott Williams and Wilkins; 2009:253-261.

Pollard BA, Chan VW. An introductory curriculum for ultrasound-guided regional anesthesia: a learner’s guide. Toronto. University of Toronto Press Inc.; 2009:66-69.

Gray AT. Atlas of ultrasound-guided regional anesthesia. Philadelphia, PA. Saunders, Elsevier; 2010:173-175.

Bigeleisen PE, ed, Orebaugh SL, Moayeri N, et al. Ultrasound-guided regional anesthesia ad pain medicine. Baltimore, MD. Lippincott Williams & Wilkins; 2010:132-139.

Morgan GE, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. New York, NY: Lange Medical Books/McGraw-Hill; 2006:350-351.

 

    Legal Disclaimer

  • Provision of education and research information only - always seek professional advice

    The VAULT website was developed by Christian R. Falyar, CRNA, DNAP, to share information related to ultrasound-guided regional anesthesia with other anesthesia providers. It is not intended to be a substitute for accredited regional anesthesia training. Christian R. Falyar CRNA, DNAP does not accept any liability for any injury, loss or damage that results from the use of or reliance on information contained in this website.
  • Quality of information - always check the information

    Christian R. Falyar, CRNA, DNAP has made every effort to ensure the quality of the information presented on this website is current and checks it regularly. However, before relying on the material on this website, users should carefully evaluate its accuracy, currency, completeness and relevance to their practice. Christian R. Falyar, CRNA, DNAP, cannot guarantee and assumes no legal liability or responsibility for the accuracy, currency or completeness of the information.
  • Links to external websites

    This website may contain links to other websites which are external to the VAULT website. Christian R. Falyar, CRNA, DNAP takes reasonable care in selecting linking websites. It is the responsibility of the user to make their own decisions about the accuracy, currency, reliability and correctness of information contained in linked external websites. Linkage to external websites should not be taken to be an endorsement or a recommendation of any third party products or services offered by virtue of any information, material or content linked from or to this website. Users of links provided by this website are responsible for being aware of which organization is hosting the website they visit. Views or recommendations provided in linked websites do not necessarily reflect those of Christian R. Falyar, CRNA, DNAP.