Toggle

Lateral distal approach

Print

Anatomical landmarks

Superior edge of the patella, vastus lateralis muscle, long head of the biceps femoris muscle

lateral distal

 

Block technique

This technique affords a block of the sciatic nerve just superior to its bifurcation without any complicated positioning. The patient is supine on his back, with the leg in a neutral position; padding is placed distally under the lower leg to allow the knee to hang suspended. The compartment between the vastus lateralis muscle and the sinewy part of the biceps femoris muscle is identified by palpation approx. 5 cm (3 – 8 cm) above the patella. This site is marked. A needle of 50 mm in length is usually sufficient for puncture. The insertion direction points 30° dorsally and 5 – 10° cranially. Again, the positive stimulatory response is elicited from muscles on the lower leg or foot innervated by the peroneal or tibial nerves. Once the threshold electrical current is reached, 30 – 50 ml of local anaesthetic are injected. Compared to the proximal sciatic nerve blocks, onset of action is significantly longer, between 20 – 40 min. A pain catheter can be positioned easily. Under certain circumstances, it may be helpful for localizing the muscle compartment to actively tense the ventral and dorsal thigh muscles against resistance. One common error is made by searching for the nerve too ventrally and too deeply. (The nerve‘s position is always more superficial and dorsal than one thinks).