Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P14. Variations among human spine segments and their relationships to in vitro kinematics: a retrospective analysis of experimental data including 581 cervical motion segments from 147 donor spines

Abstract

BACKGROUND CONTEXT Kinematic data from in vitro flexibility tests involving cadaveric spines are often used to validate finite element models of human spine segments. However, data describing relationships between motion segment features (ie, dimensions of vertebrae and discs, subject height) and kinematics are lacking. PURPOSE To retrospectively investigate the relationships between cadaveric cervical spinal motion segments and their biomechanical characteristics, including coupled motion. STUDY DESIGN/SETTING Standard nondestructive in-vitro flexibility tests were performed on intact cervical spine segments (Occ-C3 and C3-T1). Relationships between donor spine features and in vitro kinematic parameters were studied using Pearson correlation and multiple regression analyses. PATIENT SAMPLE A total of 581 cadaveric cervical motion segments from 147 donor spines [86M/61 F, range: 20-69years, mean age 53.5+10.6years, BMD 0.558+0.101 g/cm2, mean height 173.4+12.0 cm]. OUTCOME MEASURES Spinal flexibility of intact motion segments were assessed using intervertebral mean range of motion (ROM) during flexion–extension (FE), lateral bending (LB, average right and left), and axial rotation (AR, average right and left). Coupled motion (CM), that is LB during AR (LB/AR) and AR during LB (AR/LB) were also assessed. METHODS General spine tissue donor information (age, gender, height, and weight at time of death) was obtained from medical histories provided by tissue banks. Bone mineral densities (BMD) were obtained from DEXA scans. Dimensions of vertebrae and discs were measured using ImageJ. Kinematic data were retrieved from studies involving intact testing of the fresh cervical spine segments (Occiput-T1), with all tests performed in the same lab using the same protocol. Loads of 1.5 Nm were applied while optoelectronically measuring intervertebral rotations in three planes (FE, LB and AR) at all spinal levels. Relationships between donor information (vertebrae and disc dimensions, subject height, weight, gender), bone quality (BMD) and kinematic data (ROM, CF LB/AR and CF AR/LB) were studied using Pearson correlation and multiple regression analyses (p RESULTS Overall values for ROM for intact motion segments were within typical values as reported in the literature. There were significant negative correlations between BMD and ROM, starting at C4–C5 and continuing caudally (R .4). Multiple linear regression analysis showed that ROM of cervical motion segments can be predicted using relationships between subject cervical level, gender, age, weight and/or BMD [FL-EX: R=0.321, P CONCLUSIONS Significant relationships exist between cervical spine segments’ dimensions, BMD and biomechanical properties (ROM and CM) at mid- and lower cervical levels. These relationships are of value during the validation process of finite element models involving human cervical spine segments, especially in studies focusing on motion preservation.