A radiologic survey of various configurations of the lumbar spine.

This paper reports an investigation to determine whether or not human spine configurations can be categorized into types by which one could predict the possibility of disablement at one specific level more than another. Configurations of the lumbar spine, the shape of the lower two lumbar discs, the anterior and posterior heights of discs, the sizes of the transverse processes of L4-5, the presence or absence of rudimentery ribs, and the presence of transitional vertebrae were studied in roentgenograms of 554 subjects. They concluded that the probable criteria for development of L4-5 degeneration were 1) high intercrestal line passing through the upper half of L4, 2) long transverse process on L5, 3) rudimentary rib, and 4) transitional vertebra. Criteria for development of L5-S1 degeneration were 1) intercrestal line passing through the body of L5, 2) short transverse process on L5, 3) no rudimentary rib, 4) no transitional vertebrae. A high intercrestal line and long transverse process probably act as antitorsional devices protecting the L5-S1 disc; hence the likelihood of degeneration at L4-5 is increased.