Precise localization of motor branching and motor points: A cadeveric study

Abstract

In order to facilitate precise localization of motor nerves and motor points, and to increase effectiveness and minimize complications of neurolytic blocks. Locations of motor branching points and motor points of 31 cadavers were measured as relative to medial femoral condyle and mid posterior calf line. Needle insertion points 1.5 centimeters and 0.5 centimeters proximal to the level of medial femoral condyle yielded the best chance(66.25%-76.19%) of finding motor branches to medial gastrocnemius muscles and lateral gastrocnemius respectively. The points with greatest chance of success (67.69%-86.41%) for soleus, tibialis posterior and flexor hallucis longus motor branches blocks were found to be at 2.5, 6, and 11 centimeters distal to the level of medial femoral condyle respectively. However,even if these points are used as guidelline when performing motor branch block prodedure, the risk of sensory nerve fiber injury are still as high as 20.98% upto 50.0%. To avoid such complication,the authors have proposed a set of landmarks that would make it possible to access all of the motor branches of any single calf muscle with only three or less needle insertions, and still maintaining about 1% risk of sensory fiber injury.