Use of Spine Robot Employing Real Time Force Control to Simulate a Pure Moment Protocol for the Subaxial Cervical Spine: An In Vitro Biomechancial Study

2011 ◽  
Author(s):  
Daniel M. Wido ◽  
Denis J. DiAngelo ◽  
Brian P. Kelly
Keyword(s):  
Cervical Spine ◽  
Real Time ◽  
Force Control ◽  
Biomechanical Testing ◽  
Subaxial Cervical Spine ◽  
Experimental Artifact ◽  
Pure Moment ◽  
Robotic Testing ◽  
Spine Robot

A standard biomechanical testing protocol for evaluation of the sub-axial cervical spine is the application of pure bending moments to the free end of the spine (with opposing end fixed) and measurement of its motion response. The pure moment protocol is often used to compare spinal fusion instrumentation and has also been used to evaluate non-fusion instrumentation (e.g. disc arthroplasty devices) [1,2]. A variety of different testing systems have been employed to implement pure moment application. In cases where the loading is applied quasi-statically using a series of weights and pulleys the spine may relax between intermittent loading phases and/or unintended loading may be applied causing experimental artifact. Our objective was to use an existing programmable robotic testing platform (Spine Robot) to develop a novel real time force control strategy to simulate pure moment loading under precisely controlled continuous movement conditions. This would serve to advance robotic testing capabilities with an end goal to simulate different protocols in the same platform, and to potentially minimize fixturing and quasi-static artifacts.

Robotic Simulation of an Eccentric Lever Arm Protocol and a Novel Head Weight Protocol for Evaluation of the Subaxial Cervical Spine: An In Vitro Biomechancial Comparison

2011 ◽  
Author(s):  
Daniel M. Wido ◽  
Denis J. DiAngelo ◽  
Brian P. Kelly
Keyword(s):  
Cervical Spine ◽  
Muscle Activation ◽  
Vertical Force ◽  
Follower Load ◽  
Testing Platform ◽  
Lever Arm ◽  
Subaxial Cervical Spine ◽  
Head Weight ◽  
Robotic Testing

In vitro testing provides a critical tool for understanding the biomechanics of the subaxial cervical spine. Previous common testing protocols used to evaluate the subaxial cervical spine include pure moment, follower load, and eccentric lever arm (EL) loading methods [1,2,3]. Although these methods are widely accepted, there is always a goal to try to better simulate physiologic loading conditions. While the follower load attempts to simulate compression due to muscle activation, no previous protocol has taken into account the constant vertical force vector applied to C2 produced by the weight of the human head. Furthermore, we are unaware of previous direct protocol to protocol comparisons using the same testing platform and test specimens. Our multi-axis programmable robotic testing platform (Spine Robot) provides the means to explore such comparisons. The objectives of this study were: 1) to develop a novel head weight influenced loading protocol (HWL), 2) simulate and compare the EL protocol and the HWL protocol on a single programmable robotic testing frame with a consistent specimen sample group.

Analysis of adjacent-segment cervical kinematics: the role of construct length and the dorsal ligamentous complex

2020 ◽  
Vol 32 (1) ◽  
pp. 15-22
Author(s):  
Daniel Lubelski ◽  
Andrew T. Healy ◽  
Prasath Mageswaran ◽  
Robb Colbrunn ◽  
Richard P. Schlenk
Keyword(s):  
Cervical Spine ◽  
Industrial Robot ◽  
Adjacent Segment ◽  
Segmental Motion ◽  
Lateral Mass ◽  
Subaxial Cervical Spine ◽  
Flexion Extension ◽  
Cervical Kinematics

OBJECTIVELateral mass fixation stabilizes the cervical spine while causing minimal morbidity and resulting in high fusion rates. Still, with 2 years of follow-up, approximately 6% of patients who have undergone posterior cervical fusion have worsening kyphosis or symptomatic adjacent-segment disease. Based on the length of the construct, the question of whether to extend the fixation system to undisrupted levels has not been answered for the cervical spine. The authors conducted a study to quantify the role of construct length and the terminal dorsal ligamentous complex in the adjacent-segment kinematics of the subaxial cervical spine.METHODSIn vitro flexibility testing was performed using 6 human cadaveric specimens (C2–T8), with the upper thoracic rib cage and osseous and ligamentous integrity intact. An industrial robot was used to apply pure moments and to measure segmental motion at each level. The authors tested the intact state, followed by 9 postsurgical permutations of laminectomy and lateral mass fixation spanning C2 to C7.RESULTSConstructs spanning a single level exerted no significant effects on immediate adjacent-segment motion. The addition of a second immobilized segment, however, created significant changes in flexion-extension range of motion at the supradjacent level (+164%). Regardless of construct length, resection of the terminal dorsal ligaments did not greatly affect adjacent-level motion except at C2–3 and C7–T1 (increasing by +794% and +607%, respectively).CONCLUSIONSDorsal ligamentous support was found to contribute significant stability to the C2–3 and C7–T1 segments only. Construct length was found to play a significant role when fixating two or more segments. The addition of a fused segment to support an undisrupted cervical level is not suggested by the present data, except potentially at C2–3 and C7–T1. The study findings emphasize the importance of the C2–3 segment and its dorsal support.

Cervical spine locking plate: in vitro biomechanical testing

1993 ◽  
Vol 1 (4) ◽  
pp. 222-225 ◽  
Author(s):  
Stephen A. Smith ◽  
Ronald W. Lindsey ◽  
Brian J. Doherty ◽  
Jerry W. Alexander ◽  
Jessie H. Dickson
Keyword(s):  
Cervical Spine ◽  
Locking Plate ◽  
Biomechanical Testing

A Multi-Axis Programmable Spine Robot: Application Towards Kinematic Assessments of the Lumbar MSU

2008 ◽  
Author(s):  
Brian P. Kelly ◽  
Nephi A. Zufelt ◽  
Elizabeth J. Sander ◽  
Denis J. DiAngelo
Keyword(s):  
Biomechanical Testing ◽  
Dynamic State ◽  
Limited Data ◽  
Instantaneous Axis Of Rotation ◽  
New Methods ◽  
Methods Of Evaluation ◽  
Mechanical Devices ◽  
Spine Robot ◽  
Testing Protocols

Current in vitro testing methodologies remain limited in the ability to explore spinal dynamics. The gold standard of flexibility testing has traditionally focused on evaluating MSU rotational ranges of motion only. While such data may be applied towards evaluation of the Instantaneous Axis of Rotation (IAR), many systems lack the needed sensitivity. The result is that there is currently no consensus on the location of the IAR. Further, very limited data or insight can be gathered as to the precise kinematic or dynamic state of the MSU, or the influence of surgically implanted motion restoration devices. For example, total disc arthroplasty devices are typically rigid mechanical devices that impose an IAR or IAR range. How might this imposed IAR affect MSU mechanics? How might variations in surgical placement of an implant be scientifically quantified? More recently an emerging group of compliant motion restoration devices are being developed that require new methods of evaluation. How well does a compliant device restore the native mechanics of the disc or MSU? To address and understand these increasingly important issues, novel, more advanced biomechanical testing protocols need to be developed.

In-Vitro Biomechanical Testing of the AO Cervical Spine Locking Plate

1993 ◽  
Vol 7 (2) ◽  
pp. 171
Author(s):  
Stephen A. Smith ◽  
Ronald W. Lindsey ◽  
Brian J. Doherty ◽  
Jerry W. Alexander ◽  
Jessie H. Dickson
Keyword(s):  
Cervical Spine ◽  
Locking Plate ◽  
Biomechanical Testing

Adaptive Hybrid Control Algorithm With Iterative Learning for Robotic In Vitro Biomechanical Testing of Spine

2012 ◽  
Author(s):  
T. F. Bonner ◽  
L. Gilbertson ◽  
R. W. Colbrunn
Keyword(s):  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Dynamic Testing ◽  
Biomechanical Testing ◽  
Testing Methods ◽  
Robotic Technology ◽  
Control Schemes ◽  
Pure Moment

In spine testing, methods have been developed to apply pure moments to a single axis of the spine to elucidate the mechanical properties of the spine. The application of those concepts continues to be applied with custom loading frames, custom robotics systems, and adaptation of commercial robotic technology. With these systems and pure moment testing, spinal biomechanics variables such as the neutral zone and range of motion can be determined. As more complex testing systems with higher degrees of freedom (DOF) capabilities are developed, dynamic testing becomes a possibility. However, these more complex testing systems require more complex control schemes.

Assessing the biofidelity of in vitro biomechanical testing of the human cervical spine

2020 ◽  
Author(s):  
Richard A. Wawrose ◽  
Forbes E. Howington ◽  
Clarissa M. LeVasseur ◽  
Clair N. Smith ◽  
Brandon K. Couch ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Biomechanical Testing
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