• Therefore, it may be necessary to make use of a medial approach with the patient supine. 2
•Two medically complex patients presented for below-knee amputations (BKA).
•We offered these patients ultrasound-guided popliteal and femoral single-shot nerve blocks and continuous perineural catheters.
•In both instances, the popliteal block was not feasible using the lateral or posterior approach but was successfully performed using a medial approach.
• For this approach, the lower extremity was externally rotated and flexed 45 degrees at the knee. Figure 1
•Patient informed consent was obtained for submission of a case report and all protected health information de-identified.
•AC was a 45-year-old female with multiple comorbidities including obesity (BMI 46).
•We were unable to perform the popliteal nerve block in a prone or lateral position due to her body habitus and limited mobility.
•We attempted to use a supine position with the knee flexed 90 degrees in a positioning block.
•We were unsuccessful at obtaining adequate ultrasound images and needle visualization in this position with a lateral approach and thus made use of a medial approach.
•The medial approach allowed successful popliteal nerve block and catheter placement with a subsequent successful femoral nerve block and catheter placement.
•BD was a 68-year-old female with a history of severe developmental delay, cerebral palsy, and obesity (BMI 46).
•She had severe contractures causing her operative leg to be fixed with slight external rotation and knee flexion with little ability to be re-positioned.
•We attempted the popliteal nerve block in this position using a medial approach.
•We obtained adequate ultrasound images of the sciatic nerve while maintaining needle visualization and successfully performed the block and placed the catheter.
•Without re-positioning, we performed a single shot saphenous nerve block in the adductor canal.
•Unfortunately, a femoral nerve block was not possible for this patient.
•In both cases, using the medial approach to the popliteal nerve block allowed for a successful block and catheter placement.
•It also has some distinct advantages, including quicker positioning and no need for additional support equipment.
•It also allows the anesthesiologist to perform both the popliteal block and either a femoral or saphenous nerve block without re-positioning between blocks.
•This may reduce the time and assistance needed to perform these blocks, especially when leaving a catheter in one or both sites.
•While this approach has been demonstrated as a viable alternative when other approaches are not feasible, further work is needed to fully evaluate it as an alternative to the standard approaches.
Figure 1. Sensory distribution of anesthesia accomplished with the popliteal nerve block. All shaded areas except the medial aspect of the leg (pink, saphenous nerve) are anesthetized with the popliteal block.
Figure 2. Illustration demonstrating two variations in positioning for the medial approach to the popliteal nerve block. On top, the lower extremity is externally rotated and flexed at the knee laying flat on the bed. On bottom the lower extremity is elevated slightly. This allows for a larger sterile field by placing a sterile drape beneath the knee. Original Illustration done by Kristi Whitlow
Figure 3. Ultrasound image of the tibial nerve (right) and common peroneal nerve (left) just distal to the split from the sciatic nerve. This image was taken just after injection of local anesthetic using the medial approach and shows local surrounding both branches of the sciatic nerve.
1. HorlockerT, Kopp S, Wedel D. Chapter 57 - Peripheral Nerve Blocks. In: Miller’s Anesthesia, 2-Volume Set. Eighth. Elsevier; 2015:1745-1747.e3. doi:10.1016/B978-0-7020-5283-5.00057-6.
2. TahaAM, Ahmed AF. Supine ultrasound-guided popliteal block: A medial approach. Br J Anaesth. 2016;116(2):295-296. doi:10.1093/bja/aev462.
3. Peripheral Nerves and Arteries of the Lower Extremity. OrthopaedicsOne Clerkship. In: OrthopaedicsOne - The Orthopaedic Knowledge Network. Created Nov 25, 2010 14:12. Last modified Nov 25, 2010 14:12 ver.3. Retrieved 2018-02-24, from https://www.orthopaedicsone.com/x/RYDEAg.