Has the lumbar spine a margin of safety in forward bending?

Cadaveric lumbar motion segments (consisting of two vertebrae and the intervening disc and ligaments) were loaded to simulate forward bending movements in life, and the flexion angle at the elastic limit was measured. These flexion angles were then compared with flexion angles obtained from X-rays of healthy volunteers in the erect standing and fully flexed positions. The comparison showed that, when people adopt the static, fully flexed posture, the osteoligamentous lumbar spine is flexed about 10° short of its elastic limit.

[1]  M. Adams,et al.  The Resistance to Flexion of the Lumbar Intervertebral Joint , 1980, Spine.

[2]  Adams Ma,et al.  Prolapsed Intervertebral Disc: A Hyperflexion Injury , 1982 .

[3]  M. Pearcy,et al.  Lumbar intervertebral disc and ligament deformations measured in vivo. , 1984, Clinical orthopaedics and related research.

[4]  W Y Loebl,et al.  Measurement of spinal posture and range of spinal movement. , 1967, Annals of physical medicine.

[5]  P M Reynolds,et al.  Measurement of spinal mobility: a comparison of three methods. , 1975, Rheumatology and rehabilitation.

[6]  L. Twomey,et al.  Sagittal and horizontal plane movement of the human lumbar vertebral column in cadavers and in the living. , 1980, Rheumatology and rehabilitation.

[7]  W. Floyd,et al.  The function of the erectores spinae muscles in certain movements and postures in man * , 1955, The Journal of physiology.

[8]  V. Wright,et al.  Normal range of spinal mobility. An objective clinical study. , 1971, Annals of the rheumatic diseases.

[9]  W C Hutton,et al.  The Effect of Posture on the Fluid Content of Lumbar Intervertebral Discs , 1983, Spine.

[10]  M A FALCONER,et al.  Plain radiography in intraspinal protrusion of lumbar intervertebral disks: A correlation with operative findings , 1949, The British journal of surgery.

[11]  H. Farfan,et al.  Mechanical disorders of the low back , 1973 .

[12]  G. Andersson,et al.  The Influence of Backrest Inclination and Lumbar Support on Lumbar Lordosis , 1979, Spine.

[13]  Adams Ma.  The mechanical properties of lumbar intervertebral joints with special reference to the causes of low back pain. , 1980 .

[14]  M. Pearcy,et al.  Three-Dimensional X-ray Analysis of Normal Movement in the Lumbar Spine , 1984, Spine.