OCT Detects Collagen Fiber Alignment in Human Cadaveric Lumbar Facet Capsular Ligament During Mechanical Loading

The lumbar facet capsular ligament (FCL) is a highly collagenous structure that functions to constrain lumbar spinal motion. Two FCLs are found at each level of the spine, flanking the spinous process. The ligament spans from the inferior articular process (IAP) of the superior vertebra to the superior articular process (SAP) of the inferior vertebra forming the posterior portion of the facet capsule (Figure 1). Along with the anteriorly located ligamentum flavum, the FCL contains the synovial fluid that lubricates the facet joint. The facet capsule is highly innervated [1] and may be involved in low back pain or proprioception. Thus, changes in collagen fiber alignment from mechanical loading may activate mechanoreceptors leading to proprioception or nociceptors leading to pain.