PT  - JOURNAL ARTICLE
AU  - Michael Yancey
AU  - Nada Rbil
AU  - Abhi Chatterjee
AU  - Hannah Lin
AU  - Hallie L Wyles
AU  - Lydia M Ko
AU  - Ogonna K Nwawka
AU  - Sariah Khormaee
TI  - Ultrasound Shear Wave Elastography Quantitatively Assesses Tension Changes of Supraspinous/Interspinous Ligament Complex Under Varied Loads
AID  - 10.14444/8479
DP  - 2023 Aug 01
TA  - International Journal of Spine Surgery
PG  - 502--510
VI  - 17
IP  - 4
4099  - http://ijssurgery.com//content/17/4/502.short
4100  - http://ijssurgery.com//content/17/4/502.full
SO  - Int J Spine Surg2023 Aug 01; 17
AB  - Background Although interspinous and supraspinous ligaments of the lumbar spine are thought to contribute to spinal stability, little is known about their dynamic biomechanics. We demonstrate that shear wave elastography (SWE) offers a novel technique to noninvasively and quantitatively evaluate posterior spinous ligament complex functional loading and stiffness in different physiologic positions.Methods We performed SWE and measured the length of the interspinous/supraspinous ligament complex in cadaveric torsos (N = 5), isolated ligaments (N = 10), and healthy volunteers (N = 9) to obtain length and shear wave velocity measurements. For cadavers and volunteers, SWE was utilized in 2 lumbar positions: lumbar spine flexion and extension. In addition, SWE was performed on isolated ligaments undergoing uniaxial tension to correlate shear wave velocities with experienced load.Results Average shear wave velocity in cadaveric supraspinous/interspinous ligament complexes increased for lumbar levels (23%–43%) and most thoracic levels (0%–50%). This corresponded to an average increase in interspinous distance from extension to flexion for the lumbar spine (19%–63%) and thoracic spine (3%–8%). Volunteer spines also demonstrated an average increase in shear wave velocity from extension to flexion for both the lumbar spine (195% at L2-L3 to 200% at L4-L5) and thoracic spine (31% at T10-T11). There was an average increase in interspinous distance from extension to flexion for the lumbar spine (93% at L2-L3 to 127% at L4-L5) and thoracic spine (11% at T10-T11). In isolated ligaments, there was a positive correlation between applied tensile load and average shear wave velocity.Conclusion This study creates a foundation to apply SWE as a noninvasive tool for assessing the mechanical stiffness of posterior ligamentous structures and has potential applications in augmenting or evaluating these ligaments in patients with spine pathology.Clinical Relevance The interspinous and supraspinous ligaments are critical soft tissue supports of the posterior lumbar spine. Disruption of these structures is thought to have a negative impact on spinal stability in trauma and spine deformities.Level of Evidence 4.