{'fraction_non_alphanumeric': 0.035652173913043476, 'fraction_numerical': 0.014347826086956521, 'mean_word_length': 5.152406417112299, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Effects of Stepwise Transection of Spinal Components in Lumbar Spine An Experimental Study of One L 1S 1 Cadaver Sample

INTRODUCTION The intervertebral discs, facet joints, and spinal ligaments act together to provide stability and flexibility to the lumbar spine. Disruption of these spinal components may result in an unstable condition, even under normal physiologic loads. Measuring the kinematic response following stepwise anatomical reduction can provide valuable information about contribution of specific anatomical structures [1]. Furthermore, such data can provide useful input for calibration of specimen-specific finite element (FE) model [2-3]. The objectives of the current study were: 1. To quantify the contribution of isolated ligaments, facet joints, and intervertebral discs to kinematic response of the entire L1-S1 construct. 2. To provide input for the calibration of an L1-S1 FE model. METHODS One cadaveric lumbar (L1-S1) spine (53/Male) was radiographed to ensure the absence of fractures, deformities and any metastatic disease. The spine was dissected by carefully denuding the paravertebral musculature avoiding disruption of spinal ligaments, facet joints and disks. The intact specimen was then mounted and tested on a 6 degree of freedom spine simulator with L1 fixed proximally and Sacrum distally [Figure 1A]. After intact testing (Construct 1), the spine was tested for six different surgical constructs (Construct 2-7) with stepwise transection of SSL, ISL, FL, FC (bilateral facetectomy), PLL, and ALL, following the sequence in Figure 1B. Unconstrained pure moments of 10 Nm were applied on the intact spine at 1 degree/sec in FlexionExtension (FE), Lateral Bending (LB), and Axial Rotation (AR) loading modes. Following the intact testing, displacement control was used on the subsequent surgical constructs to achieve the same range of motion (ROM) as the intact spine. Displacement control protocol was adopted to avoid breaking the spine and to achieve similar tissue deformations in the soft tissue [4,5]. A total of three load/unload cycles were performed for each mode with data analysis based on the final cycle. ROM was measured using Optotrak Certus motion analysis system (NDI, Inc. Watrerloo, Canada) with markers at L1, L2 L3, L4, L5 and S1 levels.