Knowledge of the normal movements of whole lumbar spine and lumbosacral joint is important for evaluating clinical pathologic conditions that may potentially produce unstable situations in these regions. At present there are few studies that report systemic three-dimensional movement analysis of these regions. The purpose of this in vitro study was to quantitatively determine three-dimensional movements of the whole lumbar spine and lumbosacral joint. Ten fresh human cadaveric spine specimens including from L1 to sacrum (six specimens) and ilium (four specimens) were studied. Pure moments of a maximum of 10 N-m were applied incrementally. Parameters of neutral zone, elastic zone, and range of motion for rotations as well as for translations were measured. Neutral zones for flexion-extension, right/left axial torque, and right-left lateral bending were, respectively: 1.6°, 0.9°, and 1.4° (L1-2); 1.0°, 0.8°, and 2.0° (L2-3); 1.4°, 0.7°, and 1.4° (L3-4); 1.8°, 0.4°, and 1.6° (L4-5); 3.0°, 0.4°, and 1.8° (L5-S1). Ranges of motion for flexion, extension, axial torque (one side), and lateral bending (one side) were, respectively: 5.8°, 4.3°, 2.3°, and 4.9° (L1-2); 6.5°, 4.3°, 2.6°, and 7.0° (L2-3); 7.5°, 3.7°, 2.6°, and 5.7° (L3-4); 8.9°, 5.8°, 2.2°, and 5.7° (L4-5); 10.0°, 7.8°, 1.4°, and 5.5° (L5-S1). Neutral zone values were small except for flexion at L5-S1. In flexion and extension, more motion took place at lower levels (L4-5, L5-S1) than at upper levels. In axial rotation of the whole lumbar spine, least motion took place at L5-S1. In lateral bending, least motion took place at L1-2 and biggest motion took place at L2-3, while similar magnitudes of motion were seen at L3-4, L4-5, and L5-S1.
