Racial variations in spinal anatomy
It should be no surprise that among all of the variable phenotypes that inhabit the earth with a myriad of eye shapes, colors, facial features that the spine should be any exception and in fact what has been found is that the variations in key anatomical components of the spine differ significantly between racial groups. This set of findings is significant in that it forces the treating physician to employ alternative diagnostic therapeutic strategies. The realization that despite the fact that we are all humans there are clinically relevant differences between members of the same race and without question those of different races. This is one of the factors that explains the exceptional ability that man of African origin have vastly improved athletic ability compared to most Caucasian men. The many advantages that their increased sacro-pelvic angles include the ability to more rapidly generate and employ greater forces of hip-pelvic extension which translates to a increased ground speed and ability to attain greater heights.
The African-American male has had a very challenging last 300 hundred years and only the fittest of those that were sold into slavery survived and it is today that we see their genetically fitter progeny dominate the sports of basketball, American football and athletics.
One of the key anatomical features of the AA male is the generally increased bone density particularly within the vertebral bodies. This feature protects them against vertebral fractures which would be more likely encountered in the Caucasian male. The spinal column of the modern AA also benefitted from the selection that occurred on the plantations when only those with the physical strength survived to reproduce.
The modern clinical significance of the marked anatomical variations relates to the increased musculature surrounding the spine which if an aggressive wide dissection were used would result in significant blood loss and so the argument could be made that the MISS approach the perfect technique for this subset of patients. Another anatomical variation relates to angle of sacro-pelvic junction which is steep and can pose a visualization problem when placing tubes and trocars for surgical work on the L5-S1 disc. Quite often in these instances a direct posterior approach is utilized.
The curvature of the AA spine differs markedly in the lumbar and thoracic region with a pronounced lumbar curve and exaggerated thoracic curve that have to be fully appreciated when multi-level fusions are performed.
The spinal columns of people from the far east of oriental origin are characterized by being significantly smaller than those found in the west but the most defining feature tends to be the narrowness of the neural canals which predispose these patient populations to an increased incidence of stenotic syndromes. In addition the pedicles are smaller and narrower than those of a western spine. The bone density of this patient population is weaker than that an individual raised in the west and is a factor in the increased incidence of intervertebral fractures in a younger subset of the population.
One theory for the smaller density and size indices relates to the fact that most people of Oriental origin are slim and about half the weight of the average American. This lack of weight lessens the stresses placed on the spinal structures which leads to smaller bone growth. If the population started to gain weight then it would be expected that those individuals that adapt with increasing bone density will flourish and survive as compared to those that don’t who will likely die early deaths associated with increased spinal fractures consistent with a spinal column unable to cope with the rapid increase in weight.