The popliteal block can be quite useful for foot surgery or for pain relief after foot surgery. In this block, the sciatic nerve is blocked in the area of the popliteal fossa. The classic approach to doing this block is by approaching the popliteal fossa from the posterior. This is anatomically reliable and provides good results. However, sometimes it may be impossible or very difficult to position to patient prone to allow this posterior approach (morbid obesity, pregnancy, mechanical ventilation, etc.)

The lateral approach to the popliteal block offers an alternative to the posterior approach in those patients where prone positioning is impossible or difficult. Studies in cadavers have shown that the lateral approach is also extremely reliable and allows access to the sciatic nerve in the supine position.

Here are the steps to performing this block utilizing the lateral approach:

1. Patient is placed in the supine position with the leg normally extended at the knee.

2. The most prominent point of the lateral epicondyle is identified.

3. The groove between the biceps femoris and the vastus lateralis muscle is identified.

4. The needle is inserted in this groove at a point seven centimeters above the most prominent point. Use a 10 cm long, insulated stimulating needle attached to a nerve stimulator.

5. The needle is initially inserted horizontally - and advanced until the femur is contacted. If the femur is not contacted at a depth of about 5 cm, it is re-inserted slightly above the initial insertion point.

6. Once the femur is contacted, the needle is withdrawn to the skin and then directed posteriorly at a 30 degree angle.

7. Use the nerve stimulator to elicit stimulation of the sciatic nerve. If unsuccessful, adjust the angle of the needle 5 degrees at a time until stimulation is obtained.

8. Once the nerve is located, inject 30-40 cc of local anesthetic incrementally after aspirating to make sure that no blood is returned.