Article Figures & Data
Figures
- Figure 1
The cadaveric torso and volunteers assumed two positions: (A) lumbar extension/hip extension and (B) lumbar flexion/hip flexion.
- Figure 2
Representative images showing visualization of the interspinous and supraspinous ligaments with superimposed anatomic labeling (A) and example shear wave velocity measurements using a region of interest within the interspinous ligament region in extension (B) and flexion (C).
- Figure 3
Shear wave velocity measurement of excised interspinous ligaments. (A) Tensile testing setup. Shown are no. 8 drywall screws driven through the spinous processes bordering the interspinous ligament and k-wires were used to connect the screws with the tensile tester. (B) Example shear wave image of a ligament pulled by the tensile device.
- Figure 4
Aggregate shear wave velocities of all tested cadavers (N = 5), separated by ligament level. Error bars indicate standard deviations of measurements.
- Figure 5
Shear wave velocities obtained from cadavers (N = 4 or 5), separated into ligament levels T10-T11 (A), T12-L1 (B), L2-L3 (C), and L4-L5 (D). To perform a paired t test, each extension velocity was paired with the flexion velocity from the same cadaver. *P < 0.05, **P < 0.01, ***P < 0.001.
- Figure 6
Aggregate shear wave velocity (SWV) values of excised L2-L3 (A) and L4-L5 (B) interspinous ligaments from all cadavers, dependent on load exerted on the ligament at the time the shear wave measurement was made. Error bars indicate standard deviations of measurements.
- Figure 7
Shear wave velocities obtained from volunteer subjects (N = 7 or 9), separated into ligament levels T10-T11 (A), T12-L1 (B), L2-L3 (C), and L4-L5 (D). To perform a paired t test, each extension velocity was paired with the flexion velocity from the same volunteer to account for physiologic differences between volunteers. *P < 0.05, **P < 0.01, ***P < 0.001.
Tables
- Table 1
Average distances, in cm, between spinous processes at interspaces for 5 cadavers (n = 5) in physiologic extension and flexion positions, with relative percent increases. The designated percent increase was calculated by a paired methodology whereby the increase was calculated in a single ligament moving from flexion to extension prior to being averaged.
Level Extension, Mean ± SD Flexion, Mean ± SD Increase %, Mean ± SD T9-T10 1.48 ± 0.22 1.34 ± 0.30 2.72 ± 10.11 T10-T11 1.37 ± 0.38 1.38 ± 0.22 8.16 ± 17.38 T11-T12 1.91 ± 0.30 1.89 ± 0.52 6.34 ± 12.83 T12-L1 1.45 ± 0.29 1.80 ± 0.28 26.86 ± 18.12 L1-L2 1.44 ± 0.33 1.68 ± 0.21 19.07 ± 16.63 L2-L3 1.22 ± 0.26 1.89 ± 0.32 58.75 ± 25.11 L3-L4 1.38 ± 0.59 2.06 ± 0.24 63.36 ± 41.88 L4-L5 1.30 ± 0.50 1.81 ± 0.54 45.74 ± 37.25 L5-S1 1.29 ± 0.66 1.72 ± 0.76 40.61 ± 28.13 - Table 2
Regression P values and 95% confidence intervals for the relationship between shear wave velocity and load for levels L2-L3 and L4-L5.
Level Samples, N Slope, m/N·s Slope P Value Slope 95% CI, m/N·s R 2 L2-L3 5 0.0259 3.96E−21 0.0212–0.0306 0.4249 L4-L5 5 0.0201 2.47E−28 0.0172–0.0231 0.4953 - Table 3
Collected SWV data from volunteer subjects, including interspinous distances in physiologic extension and flexion, percent increase between the positions, and SWV in both positions.
Level Subjects, N Extension Distance, cm Flexion Distance, cm % Increase Extension SWV, m/s Flexion SWV, m/s % Increase T10-T11 7 1.34 ± 0.12 1.48 ± 0.28 11 2.50 ± 0.97 3.28 ± 1.20 31 T12-L1 9 1.02 ± 0.32 1.61 ± 0.30 58 1.71 ± 0.59 4.08 ± 1.13 139 L2-L3 9 0.96 ± 0.27 1.86 ± 0.34 93 1.70 ± 0.36 5.01 ± 1.58 195 L4-L5 9 0.84 ± 0.31 1.91 ± 0.46 127 1.53 ± 0.37 4.59 ± 2.31 200 Abbreviation: SWV, shear wave velocity.
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