Neurovascular structures in human vastus lateralis muscle and the ideal biopsy site

A density model of neurovascular structures was generated from 28 human vastus lateralis muscles isolated from embalmed cadavers. The intramuscular portion of arteries, veins, and nerves was dissected, traced on transparencies, and digitized before adjustment to an average muscle shape using Procrustes analysis to generate density distributions for the relative positions of these structures. The course of arteries, veins, and nerves was highly variable between individual muscles. Nevertheless, a zone of lower average neurovascular density was found between the tributaries from the lateral circumflex femoral and the deep femoral arteries. While the area with the lowest density was covered by the iliotibial tract and would therefore not be suitable for biopsies, another low-density area was located in the distal portion of vastus lateralis. This was just anterior to the iliotibial tract, in a zone that has been described as a good needle biopsy site. The reported complication rates of needle biopsies (0.1%-4%) are in the range of expectations when simulated based on this model. It is concluded that the optimal human vastus lateralis biopsy site is in the distal portion of the muscle, between ½ and ¾ of the length from the greater trochanter to the lateral epicondyle, just anterior to the iliotibial band.