Biomechanical Evaluation of the Craniovertebral Junction After Anterior Unilateral Condylectomy: Implications for Endoscopic Endonasal Approaches to the Cranial Base

Neurosurgery ◽  
2013 ◽  
Vol 72 (6) ◽  
pp. 1021-1030 ◽  
Author(s):  
Luis Perez-Orribo ◽  
Andrew S. Little ◽  
Richard D. Lefevre ◽  
Phillip R. Reyes ◽  
Anna G.U.S. Newcomb ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Craniovertebral Junction ◽  
Lateral Bending ◽  
Endoscopic Endonasal ◽  
Intact State ◽  
Flexion Extension ◽  
Upper Cervical ◽  
Craniocervical Fusion ◽  
Biomechanical Evaluation ◽  
Ventral Skull Base

Abstract BACKGROUND: Endoscopic endonasal approaches to the craniovertebral junction and clivus, which are increasingly performed for ventral skull base pathology, may require disruption of the occipitocondylar joint. OBJECTIVE: To study the biomechanical implications at the craniovertebral junction of progressive unilateral condylectomy as would be performed through an endonasal exposure. METHODS: Seven upper cervical human cadaveric specimens (C0-C2) underwent nondestructive biomechanical flexibility testing during flexion-extension, axial rotation, and lateral bending at C0-C1 and C1-C2. Each specimen was tested intact, after an inferior one-third clivectomy, and after stepwise unilateral condylectomy with an anterior approach. Angular range of motion (ROM), lax zone, and stiff zone were determined and compared with the intact state. RESULTS: At C0-C1, mobility during flexion-extension and axial rotation increased significantly with progressive condylectomy. ROM increased from 14.3 ± 2.7° to 20.4 ± 5.2° during flexion and from 6.7 ± 3.5° to 10.8 ± 3.0° during right axial rotation after 75% condyle resection (P < .01). At C1-C2, condylectomy had less effect, with ROM increasing from 10.7 ± 2.0° to 11.7 ± 2.0° during flexion, 36.9 ± 4.8° to 37.1 ± 5.1° during right axial rotation, and 4.3 ± 1.9° to 4.8 ± 3.3° during right lateral bending (P = NS). Because of marked instability, the 100% condylectomy condition was untestable. Changes in ROM were a result of changes more in the lax zone than in the stiff zone. CONCLUSION: Lower-third clivectomy and unilateral anterior condylectomy as would be performed in an endonasal approach cause progressive hypermobility at the craniovertebral junction. On the basis of biomechanical criteria, craniocervical fusion is indicated for patients who undergo > 75% anterior condylectomy.

Biomechanical evaluation of the craniovertebral junction after inferior-third clivectomy and intradural exposure of the foramen magnum: implications for endoscopic endonasal approaches to the cranial base

2013 ◽  
Vol 18 (4) ◽  
pp. 327-332 ◽  
Author(s):  
Andrew S. Little ◽  
Luis Perez-Orribo ◽  
Nestor G. Rodriguez-Martinez ◽  
Phillip M. Reyes ◽  
Anna G. U. S. Newcomb ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Craniovertebral Junction ◽  
Foramen Magnum ◽  
Lateral Bending ◽  
Endoscopic Endonasal ◽  
Flexion Extension ◽  
Upper Cervical ◽  
Biomechanical Evaluation ◽  
Ventral Skull Base ◽  
Modest Degree

Object Endoscopic endonasal approaches to the craniovertebral junction (CVJ) and clivus are increasingly performed for ventral skull-base pathology, but the biomechanical implications of these approaches have not been studied. The aim of this study was to investigate the spinal biomechanics of the CVJ after an inferior-third clivectomy and anterior intradural exposure of the foramen magnum as would be performed in an endonasal endoscopic surgical strategy. Methods Seven upper-cervical human cadaveric specimens (occiput [Oc]–C2) underwent nondestructive biomechanical flexibility testing during flexion-extension, axial rotation, and lateral bending at Oc–C1 and C1–2. Each specimen was tested intact, after an inferior-third clivectomy, and after ligamentous complex dissection simulating a wide intradural exposure using an anterior approach. Angular range of motion (ROM), lax zone, and stiff zone were determined and compared with the intact state. Results Modest, but statistically significant, hypermobility was observed after inferior-third clivectomy and intradural exposure during flexion-extension and axial rotation at Oc–C1. Angular ROM increased incrementally between 6% and 12% in flexion-extension and axial rotation. These increases were primarily the result of changes in the lax zone. No significant changes were noted at C1–2. Conclusions Inferior-third clivectomy and an intradural exposure to the ventral CVJ and foramen magnum resulted in hypermobility at Oc–C1 during flexion-extension and axial rotation. Although the results were statistically significant, the modest degree of hypermobility observed compared with other well-characterized CVJ injuries suggests that occipitocervical stabilization may be unnecessary for most patients.

The cervical end of an occipitocervical fusion: a biomechanical evaluation of 3 constructs

2008 ◽  
Vol 9 (3) ◽  
pp. 296-300 ◽  
Author(s):  
Michael A. Finn ◽  
Daniel R. Fassett ◽  
Todd D. Mccall ◽  
Randy Clark ◽  
Andrew T. Dailey ◽  
...  
Keyword(s):  
Tracking System ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Lateral Mass ◽  
Lateral Bending ◽  
Cross Link ◽  
3D Tracking ◽  
Flexion Extension ◽  
Biomechanical Evaluation ◽  
Rotation Motion

Object Stabilization with rigid screw/rod fixation is the treatment of choice for craniocervical disorders requiring operative stabilization. The authors compare the relative immediate stiffness for occipital plate fixation in concordance with transarticular screw fixation (TASF), C-1 lateral mass and C-2 pars screw (C1L-C2P), and C-1 lateral mass and C-2 laminar screw (C1L-C2L) constructs, with and without a cross-link. Methods Ten intact human cadaveric spines (Oc–C4) were prepared and mounted in a 7-axis spine simulator. Each specimen was precycled and then tested in the intact state for flexion/extension, lateral bending, and axial rotation. Motion was tracked using the OptoTRAK 3D tracking system. The specimens were then destabilized and instrumented with an occipital plate and TASF. The spine was tested with and without the addition of a cross-link. The C1L-C2P and C1L-C2L constructs were similarly tested. Results All constructs demonstrated a significant increase in stiffness after instrumentation. The C1L-C2P construct was equivalent to the TASF in all moments. The C1L-C2L was significantly weaker than the C1L-C2P construct in all moments and significantly weaker than the TASF in lateral bending. The addition of a cross-link made no difference in the stiffness of any construct. Conclusions All constructs provide significant immediate stability in the destabilized occipitocervical junction. Although the C1L-C2P construct performed best overall, the TASF was similar, and either one can be recommended. Decreased stiffness of the C1L-C2L construct might affect the success of clinical fusion. This construct should be reserved for cases in which anatomy precludes the use of the other two.

scholarly journals Biomechanical Evaluation of Unilateral Versus Bilateral C1 Lateral Mass-C2 Intralaminar Fixation

2017 ◽  
Vol 7 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Nitin Bhatia ◽  
Asheen Rama ◽  
Brandon Sievers ◽  
Ryan Quigley ◽  
Michelle H. McGarry ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Axial Rotation ◽  
Biomechanical Properties ◽  
Lateral Mass ◽  
Intact State ◽  
Flexion Extension ◽  
Fixation Techniques ◽  
Rotation Stiffness ◽  
Biomechanical Evaluation ◽  
C2 Fixation

Study Design: Biomechanical, cadaveric study. Objectives: To compare the relative stiffness of unilateral C1 lateral mass-C2 intralaminar fixation to intact specimens and bilateral C1 lateral mass-C2 intralaminar constructs. Methods: The biomechanical integrity of a unilateral C1 lateral mass-C2 intralaminar screw construct was compared to intact specimens and bilateral C1 lateral mass-C2 intralaminar screw constructs. Five human cadaveric specimens were used. Range of motion and stiffness were tested to determine the stiffness of the constructs. Results: Unilateral fixation significantly decreased flexion/extension range of motion compared to intact ( P < .001) but did not significantly affect axial rotation ( P = .3) or bending range of motion ( P = .3). There was a significant decrease in stiffness in extension for both unilateral and bilateral fixation techniques compared to intact ( P = .04 and P = .03, respectively). There was also a significant decrease in stiffness for ipsilateral rotation for the unilateral construct compared to intact ( P = .007) whereas the bilateral construct significantly increased ipsilateral rotation stiffness compared to both intact and unilateral fixation ( P < .001). Conclusion: Bilateral constructs did show improved biomechanical properties compared to the unilateral constructs. However, unilateral C1-C2 fixation using a C1 lateral mass and C2 intralaminar screw-rod construct decreased range of motion and improved stiffness compared to the intact state with the exception of extension and ipsilateral rotation. Hence, a unilateral construct may be acceptable in clinical situations in which bilateral fixation is not possible, but an external orthosis may be necessary to achieve a fusion.

Biomechanical evaluation of a simulated T-9 burst fracture of the thoracic spine with an intact rib cage

2014 ◽  
Vol 21 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Tiffany G. Perry ◽  
Prasath Mageswaran ◽  
Robb W. Colbrunn ◽  
Tara F. Bonner ◽  
Todd Francis ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Posterior Instrumentation ◽  
Burst Fracture ◽  
Axial Rotation ◽  
Segmental Motion ◽  
Lateral Bending ◽  
Rib Cage ◽  
Biomechanical Models ◽  
Flexion Extension ◽  
Biomechanical Evaluation

Object Classic biomechanical models have used thoracic spines disarticulated from the rib cage, but the biomechanical influence of the rib cage on fracture biomechanics has not been investigated. The well-accepted construct for stabilizing midthoracic fractures is posterior instrumentation 3 levels above and 2 levels below the injury. Short-segment fixation failure in thoracolumbar burst fractures has led to kyphosis and implant failure when anterior column support is lacking. Whether shorter constructs are viable in the midthoracic spine is a point of controversy. The objective of this study was the biomechanical evaluation of a burst fracture at T-9 with an intact rib cage using different fixation constructs for stabilizing the spine. Methods A total of 8 human cadaveric spines (C7–L1) with intact rib cages were used in this study. The range of motion (ROM) between T-8 and T-10 was the outcome measure. A robotic spine testing system was programmed to apply pure moment loads (± 5 Nm) in lateral bending, flexion-extension, and axial rotation to whole thoracic specimens. Intersegmental rotations were measured using an optoelectronic system. Flexibility tests were conducted on intact specimens, then sequentially after surgically induced fracture at T-9, and after each of 4 fixation construct patterns. The 4 construct patterns were sequentially tested in a nondestructive protocol, as follows: 1) 3 above/2 below (3A/2B); 2) 1 above/1 below (1A/1B); 3) 1 above/1 below with vertebral body augmentation (1A/1B w/VA); and 4) vertebral body augmentation with no posterior instrumentation (VA). A repeated-measures ANOVA was used to compare the segmental motion between T-8 and T-10 vertebrae. Results Mean ROM increased by 86%, 151%, and 31% after fracture in lateral bending, flexion-extension, and axial rotation, respectively. In lateral bending, there was significant reduction compared with intact controls for all 3 instrumented constructs: 3A/2B (−92%, p = 0.0004), 1A/1B (−63%, p = 0.0132), and 1A/1B w/VA (−66%, p = 0.0150). In flexion-extension, only the 3A/2B pattern showed a significant reduction (−90%, p = 0.011). In axial rotation, motion was significantly reduced for the 3 instrumented constructs: 3A/2B (−66%, p = 0.0001), 1A/1B (−53%, p = 0.0001), and 1A/1B w/VA (−51%, p = 0.0002). Between the 4 construct patterns, the 3 instrumented constructs (3A/2B, 1A/1B, and 1A/1B w/VA) showed comparable stability in all 3 motion planes. Conclusions This study showed no significant difference in the stability of the 3 instrumented constructs tested when the rib cage is intact. Fractures that might appear more grossly unstable when tested in the disarticulated spine may be bolstered by the ribs. This may affect the extent of segmental spinal instrumentation needed to restore stability in some spine injuries. While these initial findings suggest that shorter constructs may adequately stabilize the spine in this fracture model, further study is needed before these results can be extrapolated to clinical application.

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.

Biomechanical studies of an artificial disc implant in the human cadaveric spine

2005 ◽  
Vol 2 (3) ◽  
pp. 339-343 ◽  
Author(s):  
Patrick W. Hitchon ◽  
Kurt Eichholz ◽  
Christopher Barry ◽  
Paige Rubenbauer ◽  
Aditya Ingalhalikar ◽  
...  
Keyword(s):  
Biomechanical Testing ◽  
Axial Rotation ◽  
Load Testing ◽  
Artificial Disc ◽  
Lateral Bending ◽  
Content Type ◽  
Intact State ◽  
Flexion Extension ◽  
Fine Print

Object. The authors compared the biomechanical performance of the human cadaveric spine implanted with a metallic ball-and-cup artificial disc at L4–5 with the spine's intact state and after anterior discectomy. Methods. Seven human L2—S1 cadaveric spines were mounted on a biomechanical testing frame. Pure moments of 0, 1.5, 3.0, 4.5, and 6.0 Nm were applied to the spine at L-2 in six degrees of motion (flexion, extension, right and left lateral bending, and right and left axial rotation). The spines were tested in the intact state as well as after anterior L4–5 discectomy. The Maverick disc was implanted in the discectomy defect, and load testing was repeated. The artificial disc created greater rigidity for the spine than was present after discectomy, and the spine performed biomechanically in a manner comparable with the intact state. Conclusions. The results indicate that in an in vitro setting, this model of artificial disc stabilizes the spine after discectomy, restoring motion comparable with that of the intact state.

Effect of a prosthetic disc nucleus on the mobility and disc height of the L4–5 intervertebral disc postnucleotomy

2001 ◽  
Vol 95 (2) ◽  
pp. 208-214 ◽  
Author(s):  
Hans-Joachim Wilke ◽  
Sinead Kavanagh ◽  
Sylvia Neller ◽  
Christian Haid ◽  
Lutz Eberhart Claes
Keyword(s):  
Intervertebral Disc ◽  
Axial Rotation ◽  
Disc Height ◽  
In Vitro Test ◽  
Lateral Bending ◽  
Content Type ◽  
Intact State ◽  
Device Implantation ◽  
Flexion Extension ◽  
Fine Print

Object. Current procedures for treatment of degenerative disc disease may not restore flexibility or disc height to the intervertebral disc. Recently, a prosthetic device, intended to replace the degenerated nucleus pulposus, was developed. In this biomechanical in vitro test the authors study the effect of implanting a prosthetic nucleus in cadaveric lumbar intervertebral discs postnucleotomy and determine if the flexibility and disc height of the L4–5 motion segment is restored. Methods. The prosthetic disc nucleus device consists of two hydrogel pellets, each enclosed in a woven polyethylene jacket. Six human cadaveric lumbar motion segments (obtained in individuals who, at the time of death, were a mean age of 56.7 years) were loaded with moments of ± 7.5 Nm in flexion—extension, lateral bending, and axial rotation. The following states were investigated: intact, postnucleotomy, and after device implantation. Range of motion (ROM) and neutral zone (NZ) measurements were determined. Change in disc height from the intact state was measured after nucleotomy and device implantation, with and without a 200-N preload. Conclusions. Compared with the intact state (100%), the nucleotomy increased the ROM in flexion—extension to 118%, lateral bending to 112%, and axial rotation to 121%; once the device was implanted the ROM was reduced to 102%, 88%, and 90%, respectively. The NZ increased the ROM to 210%, lateral bending to 173%, and axial rotation to 107% after nucleotomy, and 146%, 149%, 44%, respectively, after device implantation. A 200-N preload reduced the intact and postnucleotomy disc heights by approximately 1 mm and 2 mm, respectively. The original intact disc height was restored after implantation of the device. The results of the cadaveric L4–5 flexibility testing indicate that the device can potentially restore ROM, NZ, and disc height to the denucleated segment.

scholarly journals Biomechanical comparison of a C1 posterior arch clamp with C1 lateral mass screws in constructs for C1-C2 fusion

2021 ◽  
pp. 095441192110324
Author(s):  
Timothy L Lasswell ◽  
John B Medley ◽  
Jack P Callaghan ◽  
Duane S Cronin ◽  
Colin D McKinnon ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Atlantoaxial Instability ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Lateral Bending ◽  
Intact State ◽  
Significant Difference ◽  
Flexion Extension ◽  
Translaminar Screw ◽  
Fresh Frozen

The aim of this experimental study was to assess the biomechanical performance of a novel C1 posterior arch (C1PA) clamp compared with C1 lateral mass (C1LM) screws in constructs used to treat atlantoaxial instability. These constructs had either C2 pedicle (C2P) screws or C2 translaminar (C2TL) screws. Eight fresh-frozen human cadaveric ligamentous spine specimens (C0-C3) were tested under six conditions: the intact state, the destabilized state after a simulated odontoid fracture, and when instrumented with four constructs (C1LM-C2P, C1LM-C2TL, C1PA-C2P, C1PA-C2TL). Each specimen was tested in a spinal loading simulator that separately applied axial rotation, flexion-extension and lateral bending. In each test condition, displacement controlled angular motion was applied in both directions at a speed of 2 deg/s until a resulting moment of 1.5 Nm was achieved. The measured ranges of motion (ROM) of the C1-C2 segments were compared for each test condition using nonparametric Friedman tests. The destabilized state had significantly more C1-C2 motion ( p < 0.05) than the intact state in all cases, and all constructs greatly reduced this motion. C2 pedicle screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension as well as axial rotation and no statistically significant difference was detected in lateral bending. C2 translaminar screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension and no statistically significant difference was detected in axial rotation or in lateral bending. Data from the current study suggested that constructs using the novel C1PA clamp would provide as good, or improved, biomechanical stability to the C1-C2 segment compared with constructs using C1LM screws.

Range of Motion of the Upper Cervical Spine: flexion, extension, lateral bending, and axial rotation

2020 ◽  
Vol 8 ◽  
Author(s):  
Ana I. Lorente ◽  
César Hidalgo García ◽  
Jacobo Rodríguez Sanz ◽  
Mario Maza Frechín ◽  
Albert Pérez Bellmunt
Keyword(s):  
Cervical Spine ◽  
Range Of Motion ◽  
Axial Rotation ◽  
Upper Cervical Spine ◽  
Lateral Bending ◽  
Normal Range ◽  
Range Of Movement ◽  
Flexion Extension ◽  
Upper Cervical ◽  
Life Threatening

Instability is a serious and life-threatening diagnosis in the upper cervical spine (occiput-atlas-axis), and a depth understanding of normal range of movement is required for clinical manual evaluation. To improve this knowledge, ten upper cervical spine specimens have been tested in flexion, extension, lateral bending, and axial rotation. 

Biomechanical evaluation of posterior thoracic transpedicular discectomy

2010 ◽  
Vol 13 (2) ◽  
pp. 253-259 ◽  
Author(s):  
Fatih Ersay Deniz ◽  
Leonardo B. C. Brasiliense ◽  
Bruno C. R. Lazaro ◽  
Phillip M. Reyes ◽  
Anna G. U. Sawa ◽  
...  
Keyword(s):  
Thoracic Spine ◽  
Axial Rotation ◽  
Biomechanical Properties ◽  
Load Control ◽  
Spinal Stability ◽  
Lateral Bending ◽  
Spinal Motion ◽  
Biomechanical Behavior ◽  
Flexion Extension ◽  
Biomechanical Evaluation

Object The authors investigated the biomechanical properties of transpedicular discectomy in the thoracic spine and compared the effects on spinal stability of a partial and total facetectomy. Methods Human thoracic specimens were tested while intact, after a transpedicular discectomy with partial facetectomy, and after an additional total facetectomy was incorporated. Nonconstraining pure moments were applied under load control (maximum 7.5 Nm) to induce flexion, extension, lateral bending, and axial rotation while spinal motion was measured at T8–9 optoelectronically. The range of motion (ROM) and lax zone were determined in each specimen and compared among conditions. Results Transpedicular discectomy with and without a total facetectomy significantly increased the ROM and lax zone in all directions of loading compared with the intact spine (p < 0.008). The segmental increase in ROM observed with the transpedicular discectomy was 25%. The additional total facetectomy created an insignificant 3% further increase in ROM compared with medial facetectomy (p > 0.2). Conclusions Transpedicular discectomy can be performed in the thoracic spine with a modest decrease in stability expected. Because the biomechanical behavior of a total facetectomy is equivalent to that of a medial facetectomy, the additional facet removal may be incorporated without further biomechanical consequences.

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