scholarly journals Correlation between different instrumentation variants and the degree of destabilization in treating cervical spondylotic spinal canal stenosis by unilateral hemilaminectomy with bilateral decompression: a biomechanical investigation

2021 ◽  
Author(s):  
Ingo Fiss ◽  
Dorothee Mielke ◽  
Veit Rohde ◽  
Marios Psychogios ◽  
Christoph Schilling
Keyword(s):  
Three Dimensional ◽  
Axial Rotation ◽  
Clinical Results ◽  
Biomechanical Study ◽  
Lateral Bending ◽  
Invasive Treatment ◽  
Canal Stenosis ◽  
Flexion Extension ◽  
Native Condition ◽  
Analysis System

Abstract Purpose Unilateral hemilaminectomy with bilateral decompression (BDZ) was proposed as an alternative decompressive procedure in cervical spondylotic myelopathy (CSM). Despite promising clinical results, the destabilizing effect is yet unknown. We therefore performed a biomechanical study to investigate whether lateral mass screw fixation should follow BDZ. Methods Six human C2–C7 cervical specimens were tested under various conditions: native, unilateral hemilaminectomy with bilateral decompression without/with fixation (BDZ/BDF), unilateral hemilaminectomy with bilateral decompression and unilateral foraminotomy without/with fixation (UFZ/UFF), unilateral hemilaminectomy with bilateral decompression and bilateral foraminotomy without/with fixation (BFZ/BFF), and laminectomy without/with fixation (LAZ/LAF). Instrumention was applied from C3–C6. For each condition, the three-dimensional kinematics of the cervical specimen were measured in three main loading directions with an ultrasonic motion analysis system. ANOVA was used to determine differences between the specific segment conditions to assess the parameter’s range of motion (ROM) and neutral zone (NZ). Results For flexion–extension, lateral bending and axial rotation, ROM of BDZ, UFZ, BFZ and LAZ remained at the level of the native condition (p > 0.74), whereas fixation reduced ROM significantly (p < 0.01). Between BDF, UFF, BFF and LAF, no significant differences in reduction in ROM were seen (p > 0.49). Results for NZ were equivalent to ROM in flexion–extension and lateral bending. For axial rotation, NZ remained almost constant on the native level for all tested conditions. Conclusion Bilateral decompression via a hemilaminectomy, even if combined with foraminotomy, could be a less invasive treatment option for multilevel CSM in patients with lordotic cervical alignment and absence of segmental instability.

Immediate Stiffness of the C5–C6 Segment after Discectomy with the Cloward Technique: An in Vitro Biomechanical Study on a Human Cadaveric Model

Neurosurgery ◽  
2001 ◽  
Vol 49 (6) ◽  
pp. 1399-1408 ◽  
Author(s):  
Andrzej Maciejczak ◽  
Michał Ciach ◽  
Maciej Radek ◽  
Andrzej Radek ◽  
Jan Awrejcewicz
Keyword(s):  
Interbody Fusion ◽  
Spinal Instrumentation ◽  
Axial Rotation ◽  
Postoperative Management ◽  
Biomechanical Study ◽  
Lateral Bending ◽  
Cervical Discectomy ◽  
Cloward Procedure ◽  
Flexion Extension

ABSTRACT OBJECTIVE To determine whether the Cloward technique of cervical discectomy and fusion increases immediate postoperative stiffness of single cervical motion segment after application of interbody dowel bone graft. METHODS We measured and compared the stiffness of single-motion segments in cadaveric cervical spines before and immediately after interbody fusion with the Cloward technique. Changes in range of motion and stiffness of the C5–C6 segment were measured in a bending flexibility test (flexion, extension, lateral bending and axial rotation) before and after a Cloward procedure in 11 fresh-frozen human cadaveric specimens from the 4th through the 7th vertebrae. RESULTS The Cloward procedure produced a statistically significant increase in stiffness of the operated segment in flexion and lateral bending when compared with the intact spine. The less stiff the segment before the operation, the greater the increase in its postoperative flexural stiffness (statistically significant). The Cloward procedure produced nonuniform changes in rotational and extensional stiffness that increased in some specimens and decreased in others. CONCLUSION Our data demonstrate that Cloward interbody fusion increases immediate postoperative stiffness of an operated segment only in flexion and lateral bending in cadaveric specimens in an in vitro environment. Thus, Cloward fusion seems a relatively ineffective method for increasing the stiffness of a construct. This may add to discussion on the use of spinal instrumentation and postoperative management of patients after cervical discectomy, which varies from bracing in hard collars through immobilization in soft collars to no external orthosis.

Stability of the craniovertebral junction after unilateral occipital condyle resection: a biomechanical study

1999 ◽  
Vol 90 (1) ◽  
pp. 91-98 ◽  
Author(s):  
A. Giancarlo Vishteh ◽  
Neil R. Crawford ◽  
M. Stephen Melton ◽  
Robert F. Spetzler ◽  
Volker K. H. Sonntag ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Craniovertebral Junction ◽  
Biomechanical Study ◽  
Occipital Condyle ◽  
Upper Cervical Spine ◽  
Lateral Bending ◽  
Content Type ◽  
Axial Translation ◽  
Flexion Extension ◽  
Fine Print

Object. The authors sought to determine the biomechanics of the occipitoatlantal (occiput [Oc]—C1) and atlantoaxial (C1–2) motion segments after unilateral gradient condylectomy. Methods. Six human cadaveric specimens (skull with attached upper cervical spine) underwent nondestructive biomechanical testing (physiological loads) during flexion—extension, lateral bending, and axial rotation. Axial translation from tension to compression was also studied across Oc—C2. Each specimen served as its own control and underwent baseline testing in the intact state. The specimens were then tested after progressive unilateral condylectomy (25% resection until completion), which was performed using frameless stereotactic guidance. At Oc—C1 for all motions that were tested, mobility increased significantly compared to baseline after a 50% condylectomy. Flexion—extension, lateral bending, and axial rotation increased 15.3%, 40.8%, and 28.1%, respectively. At C1–2, hypermobility during flexion—extension occurred after a 25% condylectomy, during axial rotation after 75% condylectomy, and during lateral bending after a 100% condylectomy. Conclusions. Resection of 50% or more of the occipital condyle produces statistically significant hypermobility at Oc—C1. After a 75% resection, the biomechanics of the Oc—C1 and C1–2 motion segments change considerably. Performing fusion of the craniovertebral junction should therefore be considered if half or more of one occipital condyle is resected.

Effect of Facetectomy on the Three-Dimensional Biomechanical Properties of the Fourth Canine Cervical Functional Spinal Unit: A Cadaveric Study

2017 ◽  
Vol 30 (06) ◽  
pp. 430-437 ◽  
Author(s):  
Nadja Bösch ◽  
Martin Hofstetter ◽  
Alexander Bürki ◽  
Beatriz Vidondo ◽  
Fenella Davies ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Motion Analysis ◽  
Testing Machine ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Biomechanical Properties ◽  
Lateral Bending ◽  
Coupled Motion ◽  
Functional Spinal Unit ◽  
Flexion Extension

Abstract Objective To study the biomechanical effect of facetectomy in 10 large breed dogs (>24 kg body weight) on the fourth canine cervical functional spinal unit. Methods Canine cervical spines were freed from all muscles. Spines were mounted on a six-degrees-of-freedom spine testing machine for three-dimensional motion analysis. Data were recorded with an optoelectronic motion analysis system. The range of motion wasdetermined inall threeprimary motionsaswellasrange of motion of coupled motions on the intact specimen, after unilateral and after bilateral facetectomy. Repeated-measures analysis of variance models were used to assess the changes of the biomechanical properties in the three treatment groups considered. Results Facetectomy increased range of motion of primary motions in all directions. Axial rotation was significantly influenced by facetectomy. Coupled motion was not influenced by facetectomy except for lateral bending with coupled motion axial rotation. The coupling factor (coupled motion/primary motion) decreased after facetectomy. Symmetry of motion was influenced by facetectomy in flexion–extension and axial rotation, but not in lateral bending. Clinical Significance Facet joints play a significant role in the stability of the cervical spine and act to maintain spatial integrity. Therefore, cervical spinal treatments requiring a facetectomy should be carefully planned and if an excessive increase in range of motion is expected, complications should be anticipated and reduced via spinal stabilization.

scholarly journals Biomechanical study of a semi-rigid stabilization system combined with transpedicular intracorporeal bone grafting for thoracolumbar burst fractures

2020 ◽  
Author(s):  
xiaoyong zheng ◽  
qingwen yu ◽  
zhi zhang
Keyword(s):  
Bone Grafting ◽  
Burst Fracture ◽  
Axial Rotation ◽  
Biomechanical Study ◽  
Stabilization System ◽  
Thoracolumbar Burst Fracture ◽  
Lateral Bending ◽  
Thoracolumbar Burst Fractures ◽  
Burst Fractures ◽  
Flexion Extension

Abstract Background: For fresh thoracolumbar burst fracture, a new method which can not only promote the fracture healing, but also retain the movement segment, and restore the spinal movement function to the maximum extent is needed. The purpose of this study is to determine the performance of stabilization of a semi-rigid stabilization system combined with transpedicular intracorporeal bone grafting for thoracolumbar burst fractures.Methods Six thoracolumbar cadaver spines were used for testing. A controlled L2 burst fracture was created. The L1-3 motions were determined.Results In extension, flexion and lateral bending, the semi-rigid fixator stabilized the segment to a range of motion(ROM) and neutral zone(NZ) below the magnitude of the intact spine, but showed increased ROM and NZ of axial rotation (P < 0.05) compared with the intact spine.Conclusions Restoration of stability with the semi-rigid dynamic system combined with transpedicular intracorporeal bone grafting is possible in flexion, extension, right and left lateral bending for thoracolumbar burst fracture but for axial rotation.

scholarly journals Motion preservation surgery for scoliosis with a vertebral body tethering system: a biomechanical study

2021 ◽  
Author(s):  
Luis Fernando Nicolini ◽  
Philipp Kobbe ◽  
Jana Seggewiß ◽  
Johannes Greven ◽  
Marx Ribeiro ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Tracking System ◽  
Axial Rotation ◽  
Biomechanical Study ◽  
Lateral Side ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Pure Moment ◽  
L1 And L2 ◽  
Hybrid Construction

Abstract Purpose There is a paucity of studies on new vertebral body tethering (VBT) surgical constructs especially regarding their potentially motion-preserving ability. This study analyses their effects on the ROM of the spine. Methods Human spines (T10-L3) were tested under pure moment in four different conditions: (1) native, (2) instrumented with one tether continuously connected in all vertebrae from T10 to L3, (3) additional instrumented with a second tether continuously connected in all vertebrae from T11 to L3, and (4) instrumented with one tether and one titanium rod (hybrid) attached to T12, L1 and L2. The instrumentation was inserted in the left lateral side. The intersegmental ROM was evaluated using a magnetic tracking system, and the medians were analysed. Please check and confirm the author names and initials are correct. Also, kindly confirm the details in the metadata are correct. The mentioned information is correct Results Compared to the native spine, the instrumented spine presented a reduction of less than 13% in global ROM considering flexion–extension and axial rotation. For left lateral bending, the median global ROM of the native spine (100%) significantly reduced to 74.6%, 66.4%, and 68.1% after testing one tether, two tethers and the hybrid construction, respectively. In these cases, the L1-L2 ROM was reduced to 68.3%, 58.5%, and 38.3%, respectively. In right lateral bending, the normalized global ROM of the spine with one tether, two tethers and the hybrid construction was 58.9%, 54.0%, and 56.6%, respectively. Considering the same order, the normalized L1-L2 ROM was 64.3%, 49.9%, and 35.3%, respectively. Conclusion The investigated VBT techniques preserved global ROM of the spine in flexion–extension and axial rotation while reduced the ROM in lateral bending.

scholarly journals Surgical nuances and construct patterns influence construct stiffness in C1-2 stabilizations: a biomechanical study of C1-2 gapping and advanced C1-2 fixation

2021 ◽  
Author(s):  
Heiko Koller ◽  
Sebastian Hartmann ◽  
Gmeiner Raphael ◽  
Werner Schmölz ◽  
Christoph Orban ◽  
...  
Keyword(s):  
Surgical Technique ◽  
Axial Rotation ◽  
Significant Loss ◽  
Biomechanical Study ◽  
Lateral Bending ◽  
Cross Link ◽  
Flexion Extension ◽  
Six Degree Of Freedom ◽  
Selection Of ◽  
Joint Gapping

Abstract Purpose Stabilization of C1-2 using a Harms–Goel construct with 3.5 mm titanium (Ti) rods has been established as a standard of reference (SOR). A reduction in craniocervical deformities can indicate increased construct stiffness at C1-2. A reduction in C1-2 can result in C1-2 joint gapping. Therefore, the authors sought to study the biomechanical consequences of C1-2 gapping on construct stiffness using different instrumentations, including a novel 6-screw/3-rod (6S3R) construct, to compare the results to the SOR. We hypothesized that different instrument pattern will reveal significant differences in reduction in ROM among constructs tested. Methods The range of motion (ROM) of instrumented C1-2 polyamide models was analyzed in a six-degree-of-freedom spine tester. The models were loaded with pure moments (2.0 Nm) in axial rotation (AR), flexion extension (FE), and lateral bending (LB). Comparisons of C1-2 construct stiffness among the constructs included variations in rod diameter (3.5 mm vs. 4.0 mm), rod material (Ti. vs. CoCr) and a cross-link (CLX). Construct stiffness was tested with C1-2 facets in contact (Contact Group) and in a 2 mm distracted position (Gapping Group). The ROM (°) was recorded and reported as a percentage of ROM (%ROM) normalized to the SOR. A difference > 30% between the SOR and the %ROM among the constructs was defined as significant. Results Among all constructs, an increase in construct stiffness up to 50% was achieved with the addition of CLX, particularly with a 6S3R construct. These differences showed the greatest effect for the CLX in AR testing and for the 6S3R construct in FE and AR testing. Among all constructs, C1-2 gapping resulted in a significant loss of construct stiffness. A protective effect was shown for the CLX, particularly using a 6S3R construct in AR and FE testing. The selection of rod diameter (3.5 mm vs. 4.0 mm) and rod material (Ti vs. CoCr) did show a constant trend but did not yield significance. Conclusion This study is the first to show the loss of construct stiffness at C1-2 with gapping and increased restoration of stability using CLX and 6S3R constructs. In the correction of a craniocervical deformity, nuances in the surgical technique and advanced instrumentation may positively impact construct stability.

scholarly journals Biomechanical Evaluation of an Interfacet Joint Decompression and Stabilization System

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Jeremi M. Leasure ◽  
Jenni Buckley
Keyword(s):  
Minimally Invasive ◽  
Compressive Load ◽  
Axial Rotation ◽  
Cervical Radiculopathy ◽  
Biomechanical Study ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Attractive Option ◽  
And Performance ◽  
Foraminal Area

A majority of the middle-aged population exhibit cervical spondylosis that may require decompression and fusion of the affected level. Minimally invasive cervical fusion is an attractive option for decreasing operative time, morbidity, and mortality rates. A novel interfacet joint spacer (DTRAX facet screw system, Providence Medical) promises minimally invasive deployment resulting in decompression of the neuroforamen and interfacet fusion. The present study investigates the effectiveness of the device in minimizing intervertebral motion to promote fusion, decompression of the nerve root during bending activity, and performance of the implant to adhere to anatomy during repeated bending loads. We observed flexion, extension, lateral bending, and axial rotation resonant overshoot mode (ROM) in cadaver models of c-spine treated with the interfacet joint spacer (FJ spacer) as stand-alone and supplementing anterior plating. The FJ spacer was deployed bilaterally at single levels. Specimens were placed at the limit of ROM in flexion, extension, axial bending, and lateral bending. 3D images of the foramen were taken and postprocessed to quantify changes in foraminal area. Stand-alone spacer specimens were subjected to 30,000 cycles at 2 Hz of nonsimultaneous flexion-extension and lateral bending under compressive load and X-ray imaged at regular cycle intervals for quantitative measurements of device loosening. The stand-alone FJ spacer increased specimen stiffness in all directions except extension. 86% of all deployments resulted in some level of foraminal distraction. The rate of effective distraction was maintained in flexed, extended, and axially rotated postures. Two specimens demonstrated no detectable implant loosening (<0.25 mm). Three showed unilateral subclinical loosening (0.4 mm maximum), and one had subclinical loosening bilaterally (0.5 mm maximum). Results of our study are comparable to previous investigations into the stiffness of other stand-alone minimally invasive technologies. The FJ spacer system effectively increased stiffness of the affected level comparable to predicate systems. Results of this study indicate the FJ spacer increases foraminal area in the cervical spine, and decompression is maintained during bending activities. Clinical studies will be necessary to determine whether the magnitude of decompression observed in this cadaveric study will effectively treat cervical radiculopathy; however, results of this study, taken in context of successful decompression treatments in the lumbar spine, are promising for the continued development of this product. Results of this biomechanical study are encouraging for the continued investigation of this device in animal and clinical trials, as they suggest the device is well fixated and mechanically competent.

scholarly journals Biomechanical Study of a Novel, Expandable, Non-Metallic and Radiolucent CF/PEEK Vertebral Body Replacement (VBR)

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2732 ◽  
Author(s):  
Daniel Adler ◽  
Michael Akbar ◽  
Anna Spicher ◽  
Stephanie-Alice Goerke ◽  
Werner Schmoelz
Keyword(s):  
Vertebral Body ◽  
Degrees Of Freedom ◽  
Pedicle Screws ◽  
Axial Rotation ◽  
Biomechanical Study ◽  
Vertebral Body Replacement ◽  
Lateral Bending ◽  
Six Degrees Of Freedom ◽  
Peek Rods ◽  
Flexion Extension

Vertebral body replacement is well-established to stabilize vertebral injuries due to trauma or cancer. Spinal implants are mainly manufactured by metallic alloys; which leads to artifacts in radiological diagnostics; as well as in radiotherapy. The purpose of this study was to evaluate the biomechanical data of a novel carbon fiber reinforced polyetheretherketone (CF/PEEK) vertebral body replacement (VBR). Six thoracolumbar specimens were tested in a six degrees of freedom spine tester. In all tested specimens CF/PEEK pedicle screws were used. Two different rods (CF/PEEK versus titanium) with/without cross connectors and two different VBRs (CF/PEEK prototype versus titanium) were tested. In lateral bending and flexion/extension; range of motion (ROM) was significantly reduced in all instrumented states. In axial rotation; the CF/PEEK combination (rods and VBR) resulted in the highest ROM; whereas titanium rods with titanium VBR resulted in the lowest ROM. Two cross connectors reduced ROM in axial rotation for all instrumentations independently of VBR or rod material. All instrumented states in all planes of motion showed a significantly reduced ROM. No significant differences were detected between the VBR materials in all planes of motion. Less rigid CF/PEEK rods in combination with the CF/PEEK VBR without cross connectors showed the smallest reduction in ROM. Independently of VBR and rod material; two cross connectors significantly reduced ROM in axial rotation. Compared to titanium rods; the use of CF/PEEK rods results in higher ROM. The stiffness of rod material has more influence on the ROM than the stiffness of VBR material.

scholarly journals Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

2021 ◽  
pp. 219256822110060
Author(s):  
Jun-Xin Chen ◽  
Yun-He Li ◽  
Jian Wen ◽  
Zhen Li ◽  
Bin-Sheng Yu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Mechanical Stability ◽  
Biomechanical Testing ◽  
Bending Stiffness ◽  
Biomechanical Study ◽  
Torsional Stiffness ◽  
P Value ◽  
Lateral Bending ◽  
Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

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