A series of 400 vertebral columns of whites and Negroes of both sexes and of various ages were examined for the presence of osteophytes. These were classified according to four degrees of development. Osteophytes were first found in the twenties, and the proportion of affected spines increased directly thereafter. In the forties, 100 per cent of skeletons showed first-degree osteophytes. The other degrees of osteophytes were found in 100 per cent of skeletons of people who were over eighty years of age. The distribution of the osteophytes in the different regions of the spine, as well as their localization on each vertebral body, was found to follow characteristic patterns. The most outstanding features of these patterns were:
1. The incidence of osteophytes is greater on the anterior aspect than on the posterior aspect of the vertebral body.
2. Anterior or posterior osteophytes tend to develop more in the concavities of the normal vertebral column or within the concavities of scoliosis or kyphosis.
3. Peaks of regional distribution are seen and are related to the normal curvatures of the vertebral column and to the line of gravity crossing them. The presence of osteophytes on the superior or inferior borders of the vertebrae is also related to the spinal curvatures.
These findings indicate that osteophytes tend to appear more where pressure is greatest. This leads to the concept that osteophytes develop as a defense mechanism in response to pressure. Further support for this theory is provided by the fact that osteophytes are composed of more compact, stronger bone than the rest of the vertebral body and by the fact that the form and position of the osteophytes on the vertebral body resemble the capitals and bases of pillars designed by architects to increase the resistance of these pillars to compression. The thoracic spine is characterized especially by the predominance of osteophytes on the right side, a distribution caused by the aorta which runs down on the left. This general pattern of development of osteophytes is similar in all the race and sex groups examined. However, some differences are found: In anterior osteophytes, whites of both sexes show a greater incidence than Negroes, but the difference is not significant; whereas males of both races show a greater prevalence than females, the difference being statistically significant. Regarding posterior osteophytes, a significantly higher incidence is found in whites of both sexes; the slightly higher incidence in males than in females of both races was found to be non-significant.
The soft tissues into which osteophytes may grow and the different pathological conditions which may be produced by osteophytes pressing on viscera related to the vertebral column are reviewed.