Spine · 2007
The strength of the osteoporotic sacrum.
СтатьяПоддержка исследования: вне правительства СШАНазвание и аннотация: Перевод в очереди
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Waites Matthew D, Mears Simon C, Mathis John M, Belkoff Stephen M
Аннотация
STUDY DESIGN: Biomechanical cadaveric bench study.
OBJECTIVE: To determine the strength of the osteoporotic sacrum subjected to vertical force.
SUMMARY OF BACKGROUND DATA: Sacral insufficiency fractures are thought to be caused by vertical shear forces acting in the sacral ala. The force required to fracture the osteoporotic sacrum is unknown.
METHODS: Eighteen osteoporotic cadaveric pelves were potted and mounted on a materials testing machine so that the anterior superior spine was aligned with the symphysis in the sagittal plane. The lumbar spine (L3-L4) was displaced vertically downward until failure occurred. Failure loads were recorded, and fracture patterns were identified via computed tomography.
RESULTS: Mean (+/-SD) failure load was 3200 +/- 1262 N. In 3 of 18 specimens, sacral fractures were not apparent on computed tomography. In 15 of 18 specimens, fractures were produced lateral to the neural foramina. Of those 15 specimens, 8 were unilateral (1 with horizontal extension) and 7 were bilateral. In 13 of 15 cases, fractures were located in Denis Zone 1.
CONCLUSION: The osteoporotic sacrum failed under vertical forces of approximately 4.5 times body weight. Imaged fracture patterns resembled sacral insufficiency fractures seen clinically. In 1 case, a horizontal fracture line was produced. Vertical compression forces appear to cause insufficiency fractures in the osteoporotic sacrum.
OBJECTIVE: To determine the strength of the osteoporotic sacrum subjected to vertical force.
SUMMARY OF BACKGROUND DATA: Sacral insufficiency fractures are thought to be caused by vertical shear forces acting in the sacral ala. The force required to fracture the osteoporotic sacrum is unknown.
METHODS: Eighteen osteoporotic cadaveric pelves were potted and mounted on a materials testing machine so that the anterior superior spine was aligned with the symphysis in the sagittal plane. The lumbar spine (L3-L4) was displaced vertically downward until failure occurred. Failure loads were recorded, and fracture patterns were identified via computed tomography.
RESULTS: Mean (+/-SD) failure load was 3200 +/- 1262 N. In 3 of 18 specimens, sacral fractures were not apparent on computed tomography. In 15 of 18 specimens, fractures were produced lateral to the neural foramina. Of those 15 specimens, 8 were unilateral (1 with horizontal extension) and 7 were bilateral. In 13 of 15 cases, fractures were located in Denis Zone 1.
CONCLUSION: The osteoporotic sacrum failed under vertical forces of approximately 4.5 times body weight. Imaged fracture patterns resembled sacral insufficiency fractures seen clinically. In 1 case, a horizontal fracture line was produced. Vertical compression forces appear to cause insufficiency fractures in the osteoporotic sacrum.