Biomechanical comparison of seven internal fixation devices for the lumbosacral junction.

For comparison purposes, seven different internal fixation systems were applied sequentially to each of six fresh-frozen cadaver spines at the lumbosacral junction. The spines were loaded to a maximum flexion bending moment of 12 Newton meters and an extension moment of 6 Nm. Resultant angular motion was recorded with an electrogoniometer. The Synthes and Kaneda devices provided the most rigid fixation in flexion and extension testing. The Luque internal fixation system was as effective as the Kaneda and Synthes systems at limiting extension but was slightly less successful at limiting flexion. The Knodt system was effective at limiting extension but less effective in limiting flexion. The interfacet screws were effective at limiting flexion but less effective at limiting extension. Harrington rods to the sacral alae were the least effective system in both directions. Sublaminar wires did little to improve their performance.

Functional vs. organic pain: a meaningful distinction?

This study examined the statistical and clinical validity of the distinction frequently made between "functional" pain and "real" pain. Earlier work has relied on the MMPI exclusively and results have been inconclusive, yet the distinction continues to be made and treatment is recommended on the basis of the label. Sixty-seven chronic back pain patients were administered questionnaires that assessed quantity and quality of depression, dimensions of illness behavior, and psychogenic attitudes. Scores of chronic pain patients were compared to normal subjects, and results indicate that the pain subjects experienced high levels of depression, anxiety, and social alienation. However, organic pain subjects did not differ from subjects with no organic findings. The authors suggest that the distinction between organic and functional pain be discarded in favor of an approach that assesses current emotional stressors and available coping mechanisms.