Robert A Hartman1, Robert E Tisherman2, Cheng Wang3, Kevin M Bell2, Joon Y Lee4, Gwendolyn A Sowa1,2,5, James D Kang2. 1. Department of Physical Medicine and Rehabilitation, University of Pittsburgh, 3471 5th Avenue, Pittsburgh, PA, 15213, USA. 2. Department of Orthopaedic Surgery, University of Pittsburgh, 200 Lothrop Street, E1641 Biomedical Science Tower, Pittsburgh, PA, 15261, USA. 3. The First Affiliated Hospital of University of South China, 69 Huanshan Road, 421001, Hengyang City, Hunan Province, People's Republic of China. 4. Department of Orthopaedic Surgery, University of Pittsburgh, 200 Lothrop Street, E1641 Biomedical Science Tower, Pittsburgh, PA, 15261, USA. leejy@upmc.edu. 5. Department of Bioengineering, University of Pittsburgh, 300 Technology Drive, 360B Center for Bioengineering, Pittsburgh, PA, 15219, USA.
Abstract
PURPOSE: To quantify the mechanical role of posterior column components in human cervical spine segments. METHODS: Twelve C6-7 segments were subjected to resection of (1) suprasinous/interspinous ligaments (SSL/ISL), (2) ligamenta flavum (LF), (3) facet capsules, and (4) facets. A robot-based testing system performed repeated flexibility testing of flexion-extension (FE), axial rotation (AR), and lateral bending (LB) to 2.5Nm and replayed kinematics from intact flexibility tests for each state. Range-of-motion, stiffness, moment resistance and resultant forces were calculated. RESULTS: The LF contributes largely to moment resistance, particularly in flexion. Facet joints were primary contributors to AR and LB mechanics. Moment/force responses were more sensitive and precise than kinematic outcomes. CONCLUSIONS: The LF is mechanically important in the cervical spine; its injury could negatively impact load distribution. Damage to facets in a flexion injury could lead to AR or LB hypermobility. Quantifying the contribution of spinal structures to moment resistance is a sensitive, precise process for characterizing structural mechanics.
PURPOSE: To quantify the mechanical role of posterior column components in human cervical spine segments. METHODS: Twelve C6-7 segments were subjected to resection of (1) suprasinous/interspinous ligaments (SSL/ISL), (2) ligamenta flavum (LF), (3) facet capsules, and (4) facets. A robot-based testing system performed repeated flexibility testing of flexion-extension (FE), axial rotation (AR), and lateral bending (LB) to 2.5Nm and replayed kinematics from intact flexibility tests for each state. Range-of-motion, stiffness, moment resistance and resultant forces were calculated. RESULTS: The LF contributes largely to moment resistance, particularly in flexion. Facet joints were primary contributors to AR and LB mechanics. Moment/force responses were more sensitive and precise than kinematic outcomes. CONCLUSIONS: The LF is mechanically important in the cervical spine; its injury could negatively impact load distribution. Damage to facets in a flexion injury could lead to AR or LB hypermobility. Quantifying the contribution of spinal structures to moment resistance is a sensitive, precise process for characterizing structural mechanics.
Entities:
Keywords:
Cervical spine; Ligamentum flavum; Posterior column; Robotics; Serial resection
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