1
|
Bohl MA, McBryan S, Newcomb AGUS, Lehrman JN, Kelly BP, Nakaji P, Chang SW, Uribe JS, Turner JD, Kakarla UK. Range of Motion Testing of a Novel 3D-Printed Synthetic Spine Model. Global Spine J 2020; 10:419-424. [PMID: 32435561 PMCID: PMC7222693 DOI: 10.1177/2192568219858981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
STUDY DESIGN Biomechanical model study. OBJECTIVE The Barrow Biomimetic Spine (BBS) project is a resident-driven effort to manufacture a synthetic spine model with high biomechanical fidelity to human tissue. The purpose of this study was to investigate the performance of the current generation of BBS models on biomechanical testing of range of motion (ROM) and axial compression and to compare the performance of these models to historical cadaveric data acquired using the same testing protocol. METHODS Six synthetic spine models comprising L3-5 segments were manufactured with variable soft-tissue densities and print orientations. Models underwent torque loading to a maximum of 7.5 N m. Torques were applied to the models in flexion-extension, lateral bending, axial rotation, and axial compression. Results were compared with historic cadaveric control data. RESULTS Each model demonstrated steadily decreasing ROM on flexion-extension testing with increasing density of the intervertebral discs and surrounding ligamentous structures. Vertically printed models demonstrated markedly less ROM than equivalent models printed horizontally at both L3-4 (5.0° vs 14.0°) and L4-5 (3.9° vs 15.2°). Models D and E demonstrated ROM values that bracketed the cadaveric controls at equivalent torque loads (7.5 N m). CONCLUSIONS This study identified relevant variables that affect synthetic spine model ROM and compressibility, confirmed that the models perform predictably with changes in these print variables, and identified a set of model parameters that result in a synthetic model with overall ROM that approximates that of a cadaveric model. Future studies can be undertaken to refine model performance and determine intermodel variability.
Collapse
Affiliation(s)
- Michael A. Bohl
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Sarah McBryan
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Anna G. U. S. Newcomb
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Jennifer N. Lehrman
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Brian P. Kelly
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Peter Nakaji
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Steve W. Chang
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Juan S. Uribe
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - Jay D. Turner
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA
| | - U. Kumar Kakarla
- Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA,U. Kumar Kakarla, c/o Neuroscience Publications, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, 350 W Thomas Road, Phoenix, AZ 85013, USA.
| |
Collapse
|
2
|
Tumialán LM, Lehrman JN, Mulholland CB, de Andrada Pereira B, Newcomb AGUS, Kelly BP. Dimensional Characterization of the Human Cervical Interlaminar Space as a Guide for Safe Application of Minimally Invasive Dilators. Oper Neurosurg (Hagerstown) 2020; 19:E275-E282. [DOI: 10.1093/ons/opaa013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/15/2019] [Indexed: 11/13/2022] Open
Abstract
Abstract
BACKGROUND
The risk of interlaminar passage of a dilator into the cervical spinal canal in minimally invasive approaches is currently unknown. Among the various anthropometric data reported in the literature, there is no report of the interlaminar dimensions in the cervical spine.
OBJECTIVE
To report the cervical interlaminar dimensions in neutral, flexion, and extension.
METHODS
A total of 8 spines were sectioned into cervical (C2-T1) segments. Digitized coordinate data defining the locations and movements of chosen anatomic points on the laminar edges at a given spinal level were used to compute the dimensions during a static neutral posture, flexion, and extension positions to mimic the positions during surgery. Interlaminar dimensions were averaged and categorized for each vertebral level and spinal posture.
RESULTS
Based on the reported measurements, the smallest diameter dilator in commonly used dilator sets has the potential to traverse the interlaminar space at all levels in flexion. In a neutral posture, the average interlaminar distance at C2-3, C6-7, and C7-T1 was still greater than 2.0 mm, the smallest diameter of the initial dilator. The largest interlaminar distance was at C6-7 in flexion (7.68 ± 1.60 mm).
CONCLUSION
Because dilators pass directly onto the cervical lamina without visualization of the midline structures, the interlaminar distances have increased relevance in the minimally invasive cervical approaches of foraminotomy and laminectomy. The data in this report demonstrate the theoretical risk of interlaminar passage with small diameter dilators in posterior minimally invasive approaches to the cervical spine.
Collapse
Affiliation(s)
- Luis M Tumialán
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Jennifer N Lehrman
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Celene B Mulholland
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Bernardo de Andrada Pereira
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
3
|
Godzik J, Pereira BDA, Newcomb AGUS, Lehrman JN, Mundis GM, Hlubek RJ, Uribe JS, Kelly BP, Turner JD. Optimizing biomechanics of anterior column realignment for minimally invasive deformity correction. Spine J 2020; 20:465-474. [PMID: 31518683 DOI: 10.1016/j.spinee.2019.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Anterior column realignment (ACR) is a powerful but destabilizing minimally invasive technique for sagittal deformity correction. Optimal biomechanical design of the ACR construct is unknown. PURPOSE Evaluate the effect of ACR design on radiographic lordosis, range of motion (ROM) stability, and rod strain (RS) in a cadaveric model. STUDY DESIGN/SETTING Cadaveric biomechanical study. PATIENT SAMPLE Seven fresh-frozen lumbar spine cadaveric specimens (T12-sacrum) underwent ACR at L3-L4 with a 30° implant. OUTCOME MEASURES Primary outcome measure of interest was maximum segmental lordosis measured using lateral radiograph. Secondary outcomes were ROM stability and posterior RS at L3/4. METHODS Effect of grade 1 and grade 2 osteotomies with single-screw anterolateral fixation (1XLP) or 2-screw anterolateral fixation (2XLP) on lordosis was determined radiographically. Nondestructive flexibility tests were used to assess ROM and RS at L3-L4 in flexion, extension, lateral bending, and axial rotation. Conditions included (1) intact, (2) pedicle screw fixation and 2 rods (2R), (3) ACR+1XLP with 2R, (4) ACR+2XLP+2R, (5) ACR+1XLP with 4 rods (4R) (+4R), and (6) ACR+2XLP+4R. RESULTS Segmental lordosis was similar between ACR+1XLP and ACR+2XLP (p>.28). ACR+1XLP+2R was significantly less stable than all other conditions in flexion, extension, and axial rotation (p<.014); however, adding an extra screw improved stability to levels equal to 4R conditions (p>.36). Adding 4R to ACR+1XLP reduced RS in all directions of loading (p<.048), whereas adding a second screw did not (p>.12). There was no difference in strain between ACR+1XLP+4R and ACR+2XLP+4R (p>.55). CONCLUSIONS For maximum stability, ACR constructs should contain either fixation into both vertebral bodies (2XLP) or accessory rods (4R). 2XLP can be used without compromising the maximal achievable lordosis but does not provide the same RS reduction as 4R. CLINICAL SIGNIFICANCE ACR is a highly destabilizing technique that is increasingly being used for minimally invasive deformity correction. These biomechanical data will help clinicians optimize ACR construct design.
Collapse
Affiliation(s)
- Jakub Godzik
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Bernardo de Andrada Pereira
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Jennifer N Lehrman
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Gregory M Mundis
- Division of Orthopedic Surgery, San Diego Spine Foundation, Scripps Clinic, La Jolla, CA, USA
| | - Randall J Hlubek
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Juan S Uribe
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Jay D Turner
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA.
| |
Collapse
|
4
|
Lehrman JN, Narayanan M, Cavallo C, Newcomb AGUS, Zhao X, Kelly BP, Crawford NR, Nakaji P. Evaluation of abnormal styloid anatomy as a cause of internal jugular vein compression using a 3D-printed model: a laboratory investigation. J Clin Neurosci 2019; 72:386-391. [PMID: 31883814 DOI: 10.1016/j.jocn.2019.11.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/30/2019] [Indexed: 11/27/2022]
Abstract
This study used a 3-dimensional (3D) craniocervical junction model of styloidogenic jugular venous compression (SJVC) syndrome to simulate and evaluate intracranial pressure (ICP) after internal jugular vein (IJV) compression by an elongated styloid process during axial rotation. The 3D-printed model created using data from an SJVC-syndrome patient included an articulating occipital-cervical junction, simplified arteriovenous system, gauge to measure simulated ICP, fixed obstruction simulating left-sided venous occlusion, and right-sided vascular tubing to simulate IJV compression. The model was rotated axially to its extreme right and left; maximum degree of motion and pressure were recorded for 3 cycles. Measurements were repeated after styloid resection in 25% increments. The extreme right rotation (11°) of the intact styloid condition yielded a mean pressure of 15.34 ± 2.85 mmHg. After 25% styloid resection, extreme rotation (11°) yielded 13.96 ± 2.88 mmHg. After 50%, extreme rotation increased to 16° yielding 17.41 ± 3.52 mmHg; 11° rotation was 2.76 ± 1.96 mmHg. After 75%, extreme rotation increased to 19° yielding -0.86 ± 1.08 mmHg; 16° and 11° rotation yielded -0.69 ± 1.19 and -0.86 ± 1.08 mmHg, respectively. After 100%, extreme rotation to 19° yielded -1.21 ± 0.60 mmHg; 16° and 11° rotation yielded -0.34 ± 0.30 and 0.00 ± 0.00 mmHg, respectively. Extreme left rotations (11°) yielded mean pressures of -0.17 ± 0.00 (intact), -0.17 ± 0.30 (25%), 2.24 ± 0.79 (50%), 0.34 ± 0.30 (75%), and 0.17 ± 0.30 mmHg (100%). Simulated ICP increased proportionally to maximum ipsilateral axial rotation, and was highest after 50% styloid resection. Contralateral axial rotation did not increase pressure. IJV compression was relieved at 75% resection, suggesting that partial (75%) or complete styloidectomy is a potentially efficacious treatment for SJVC syndrome.
Collapse
Affiliation(s)
- Jennifer N Lehrman
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | - Mohan Narayanan
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | - Claudio Cavallo
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | - Xiaochun Zhao
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States
| | | | - Peter Nakaji
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, United States.
| |
Collapse
|
5
|
Savardekar AR, Rodriguez-Martinez NG, Newcomb AGUS, Reyes PM, Soriano-Baron H, Chang SW, Kelly BP, Crawford NR. Comparing the Biomechanical Stability of Cortical Screw Trajectory Versus Standard Pedicle Screw Trajectory for Short- and Long-Segment Posterior Fixation in 3-Column Thoracic Spinal Injury. Int J Spine Surg 2019; 13:245-251. [PMID: 31328088 DOI: 10.14444/6033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background Information on the performance of posterior fixation with cortical screw (CS) versus pedicle screw (PS) trajectories for stabilizing thoracolumbar burst fractures is limited. Therefore, we sought to analyze stability with CS versus PS in short- and long-segment fixations using a 3-column spinal injury model. Methods Nondestructive flexibility tests: (1) intact, (2) intact + short fixation, (3) intact + long fixation, (4) after burst fracture, (5) short fixation + burst fracture, and (6) long fixation + burst fracture using thoracic spine segments (7 CS, 7 PS). Results With CS, the range of motion (ROM) was significantly greater with short-segment than with long-segment fixation in all directions, with and without burst fracture (P ≤ .008). With PS and burst fracture, ROM was significantly greater with short fixation during lateral bending and axial rotation (P < .006), but not during flexion-extension (P = .10). Groups with CS versus PS were not significantly different after burst fracture during flexion-extension and axial rotation, with short (P ≥ .58) or long fixation (P ≥ .17). During lateral bending, ROM was significantly greater with CS versus PS, without burst fracture (long fixation, P = .02) and with burst fracture (short and long fixation, P ≤ .001). Conclusions CS trajectory is a valid alternative to PS trajectory for thoracic spine fixation in 3-column spinal injuries, and long-segment fixation is superior to short-segment fixation with either.
Collapse
Affiliation(s)
- Amey R Savardekar
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Nestor G Rodriguez-Martinez
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Phillip M Reyes
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Hector Soriano-Baron
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Steve W Chang
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Neil R Crawford
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
6
|
Snyder LA, Lehrman JN, Menon RK, Godzik J, Newcomb AGUS, Kelly BP. Biomechanical implications of unilateral facetectomy, unilateral facetectomy plus partial contralateral facetectomy, and complete bilateral facetectomy in minimally invasive transforaminal interbody fusion. J Neurosurg Spine 2019; 31:447-452. [PMID: 31075766 DOI: 10.3171/2019.2.spine18942] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/13/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Minimally invasive transforaminal interbody fusion techniques vary among surgeons. One decision point is whether to perform a unilateral facetectomy (UF), a unilateral facetectomy plus partial contralateral facetectomy (UF/PF), or a complete bilateral facetectomy (CBF). The authors therefore compared the biomechanical benefits of all 3 types of facetectomies to determine which approach produces improved biomechanical outcomes. METHODS Seven human cadaveric specimens (L3-S1) were potted and prepped for UF, with full facet removal, hemilaminectomy, discectomy, and pedicle screw placement. After distraction, a fixed interbody spacer was placed, and compression was performed. A final fixation configuration was performed by locking the rods across the screws posteriorly with bilateral compression. Final lordosis angle and change and foraminal height were measured, and standard nondestructive flexibility tests were performed to assess intervertebral range of motion (ROM) and compressive stiffness. The same procedure was followed for UF/PF and CBF in all 7 specimens. RESULTS All 3 conditions demonstrated similar ROM and compressive stiffness. No statistically significant differences occurred with distraction, but CBF demonstrated significantly greater change than UF in mean foraminal height after bilateral posterior compression (1.90 ± 0.62 vs 1.00 ± 0.45 mm, respectively, p = 0.04). With compression, the CBF demonstrated significantly greater mean ROM than the UF (2.82° ± 0.83° vs 2.170° ± 1.10°, p = 0.007). The final lordosis angle was greatest with CBF (3.74° ± 0.70°) and lowest with UF (2.68° ± 1.28°). This finding was statistically significant across all 3 conditions (p ≤ 0.04). CONCLUSIONS Although UF/PF and CBF may require slightly more time and effort and incur more risk than UF, the potential improvement in sagittal balance may be worthwhile for select patients.
Collapse
Affiliation(s)
| | - Jennifer N Lehrman
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Ram Kumar Menon
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | - Anna G U S Newcomb
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
7
|
Hlubek RJ, Godzik J, Newcomb AGUS, Lehrman JN, de Andrada B, Bohl MA, Farber SH, Kelly BP, Turner JD. Iliac screws may not be necessary in long-segment constructs with L5-S1 anterior lumbar interbody fusion: cadaveric study of stability and instrumentation strain. Spine J 2019; 19:942-950. [PMID: 30419290 DOI: 10.1016/j.spinee.2018.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/05/2018] [Accepted: 11/05/2018] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Lumbosacral pseudoarthrosis and instrumentation failure is common with long-segment constructs. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. The influence of iliac screws and interbody type on range of motion (ROM), rod strain (RS), sacral screw strain (SS) is not well-established. PURPOSE Investigate the effects of transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and iliac screws on long-segment lumbosacral construct biomechanics. STUDY DESIGN Biomechanical study. PATIENT SAMPLE Fourteen human cadaveric spine specimens. OUTCOME MEASURES Lumbosacral ROM, RS, and SS. METHODS Specimens were potted at L1 and the ilium. Specimens were equally divided into either an L5-S1 ALIF or TLIF group and underwent testing in the following conditions: (1) intact (2) L2-S1 pedicle screw rod fixation (PSR-S) (3) L2-ilium (PSR-I) (4) PSR-S+ALIF (ALIF-S) or TLIF (TLIF-S) (5) PSR-I + ALIF (ALIF-I) or TLIF (TLIF-I). Pure moment bending (7.5 Nm) in flexion, extension, lateral bending, axial rotation, and compressive loads (400N) were applied and ROM, SS, and RS were measured. Comparisons were performed using a one-way ANOVA (p<.05). RESULTS ALIF-S and TLIF-S provided similar decreases in ROM as TLIF-I (p>.05). Compared to PSR-S, PSR-I significantly decreased SS during bending in all directions (p<.02) but increased RS in flexion and extension (p≤.02). Anterior lumbar interbody fusion-S provided similar decreases in SS as TLIF-I in all directions (p>.40) but had significantly less RS than TLIF-I in flexion, extension, compression (p<.01). TLIF-S had more SS than TLIF-I in flexion, extension, axial rotation (p<.02), while TLIF-S had less RS only in flexion (p=.03). Compared to PSR-I, ALIF-I decreased the RS (p<.02) but TLIF-I did not (p>.67). CONCLUSIONS Iliac screws were protective of SS but increased RS at the lumbosacral junction. Constructs with ALIF and no iliac screws result in comparable SS as constructs with TLIF and iliac screws with significantly reduced RS. If iliac screws are utilized, ALIF but not TLIF reduces the iliac screw-induced RS. CLINICAL SIGNIFICANCE There is a relatively high incidence of lumbosacral instrumentation failure in adult spinal deformity. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. Iliac screws induce lumbosacral rod strain and may be responsible for instrumentation failure. Constructs with lumbosacral ALIF reduce iliac-screw induced rod strain and may obviate the need for fixation to the ilium.
Collapse
Affiliation(s)
- Randall J Hlubek
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Jakub Godzik
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Jennifer N Lehrman
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Bernardo de Andrada
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Michael A Bohl
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Samuel H Farber
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Brian P Kelly
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA
| | - Jay D Turner
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350W. Thomas Rd., Phoenix, AZ 85013, USA.
| |
Collapse
|
8
|
Godzik J, Lehrman JN, Newcomb AGUS, Menon RK, Whiting AC, Kelly BP, Snyder LA. Tailoring selection of transforaminal interbody spacers based on biomechanical characteristics and surgical goals: evaluation of an expandable spacer. J Neurosurg Spine 2019; 32:1-7. [PMID: 30978679 DOI: 10.3171/2019.1.spine181008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 01/18/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Transforaminal lumbar interbody fusion (TLIF) is commonly used for lumbar fusion, such as for foraminal decompression, stabilization, and improving segmental lordosis. Although many options exist, surgical success is contingent on matching design strengths with surgical goals. The goal in the present study was to investigate the effects of an expandable interbody spacer and 2 traditional static spacer designs in terms of stability, compressive stiffness, foraminal height, and segmental lordosis. METHODS Standard nondestructive flexibility tests (7.5 N⋅m) were performed on 8 cadaveric lumbar specimens (L3-S1) to assess intervertebral stability of 3 types of TLIF spacers at L4-5 with bilateral posterior screw-rod (PSR) fixation. Stability was determined as range of motion (ROM) in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Compressive stiffness was determined with axial compressive loading (300 N). Foraminal height, disc height, and segmental lordosis were evaluated using radiographic analysis after controlled PSR compression (170 N). Four conditions were tested in random order: 1) intact, 2) expandable interbody cage with PSR fixation (EC+PSR), 3) static ovoid cage with PSR fixation (SOC+PSR), and 4) static rectangular cage with PSR fixation (SRC+PSR). RESULTS All constructs demonstrated greater stability than the intact condition (p < 0.001). No significant differences existed among constructs in ROM (FE, AR, and LB) or compressive stiffness (p ≥ 0.66). The EC+PSR demonstrated significantly greater foraminal height at L4-5 than SRC+PSR (21.1 ± 2.6 mm vs 18.6 ± 1.7 mm, p = 0.009). EC+PSR demonstrated higher anterior disc height than SOC+PSR (14.9 ± 1.9 mm vs 13.6 ± 2.2 mm, p = 0.04) and higher posterior disc height than the intact condition (9.4 ± 1.5 mm vs 7.1 ± 1.0 mm, p = 0.002), SOC+PSR (6.5 ± 1.8 mm, p < 0.001), and SRC+PSR (7.2 ± 1.2 mm, p < 0.001). There were no significant differences in segmental lordosis among SOC+PSR (10.1° ± 2.2°), EC+PSR (8.1° ± 0.5°), and SRC+PSR (11.1° ± 3.0°) (p ≥ 0.06). CONCLUSIONS An expandable interbody spacer provided stability, stiffness, and segmental lordosis comparable to those of traditional nonexpandable spacers of different shapes, with increased foraminal height and greater disc height. These results may help inform decisions about which interbody implants will best achieve surgical goals.
Collapse
Affiliation(s)
| | - Jennifer N Lehrman
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Ram Kumar Menon
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | - Brian P Kelly
- 2Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | |
Collapse
|
9
|
Soriano-Baron H, Newcomb AGUS, Malhotra D, Martinez Del Campo E, Palma AE, Theodore N, Crawford NR, Kelly BP, Kaibara T. Biomechanical Effects of an Oblique Lumbar PEEK Cage and Posterior Augmentation. World Neurosurg 2019; 126:e975-e981. [PMID: 30876999 DOI: 10.1016/j.wneu.2019.02.200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Lumbar interbody spacers are widely used in lumbar spinal fusion. The goal of this study is to analyze the biomechanics of a lumbar interbody spacer (Clydesdale Spinal System, Medtronic Sofamor Danek, Memphis, Tennessee, USA) inserted via oblique lumbar interbody fusion (OLIF) or direct lateral interbody fusion (DLIF) approaches, with and without posterior cortical screw and rod (CSR) or pedicle screw and rod (PSR) instrumentation. METHODS Lumbar human cadaveric specimens (L2-L5) underwent nondestructive flexibility testing in intact and instrumented conditions at L3-L4, including OLIF or DLIF, with and without CSR or PSR. RESULTS OLIF alone significantly reduced range of motion (ROM) in flexion-extension (P = 0.005) but not during lateral bending or axial rotation (P ≥ 0.63). OLIF alone reduced laxity in the lax zone (LZ) during flexion-extension (P < 0.001) but did not affect the LZ during lateral bending or axial rotation (P ≥ 0.14). The stiff zone (SZ) was unaffected in all directions (P ≥ 0.88). OLIF plus posterior instrumentation (cortical, pedicle, or hybrid) reduced the mean ROM in all directions of loading but only significantly so with PSR during lateral bending (P = 0.004), without affecting the compressive stiffness (P > 0.20). The compressive stiffness with the OLIF device without any posterior instrumentation did not differ from that of the intact condition (P = 0.97). In terms of ROM, LZ, or SZ, there were no differences between OLIF and DLIF as standalone devices or OLIF and DLIF with posterior instrumentation (CSR or PSR) (P > 0.5). CONCLUSIONS OLIF alone significantly reduced mobility during flexion-extension while maintaining axial compressive stiffness compared with the intact condition. Adding posterior instrumentation to the interbody spacer increased the construct stability significantly, regardless of cage insertion trajectory or screw type.
Collapse
Affiliation(s)
- Hector Soriano-Baron
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Devika Malhotra
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Eduardo Martinez Del Campo
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Atilio E Palma
- Department of Neurosurgery, Wake Forest Baptist Hospital, Winston Salem, North Carolina, USA
| | - Nicholas Theodore
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | | | - Brian P Kelly
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Taro Kaibara
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
| |
Collapse
|
10
|
Godzik J, Dalton JF, Martinez-Del-Campo E, Newcomb AGUS, Dominguez F, Reyes PM, Theodore N, Kelly BP, Crawford NR. Biomechanical Evaluation of Cervicothoracic Junction Fusion Constructs. World Neurosurg 2018; 124:S1878-8750(18)32863-8. [PMID: 30579021 DOI: 10.1016/j.wneu.2018.12.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We studied the effect of different cervicothoracic construct design variables on biomechanical stability in vitro. METHODS Six fresh-frozen human cadaveric spines (C5-T4) were used. After intact analysis, each specimen was destabilized and reconstructed, with all groups having 4.0-mm pedicle screws placed at T1-T3. The 2 hook-rod constructs included interlaminar hooks at C6 and C7, with either 3.5-mm or 4.0-mm rods (C6-T3). The 2 screw-rod constructs tested included lateral mass screws at C6 and C7, with either 3.5-mm or 4.0-mm rods (C6-T3). The 2 screw-connector-rod constructs tested included lateral mass screws at C6 and C7, with either 3.5-mm or 4.0-mm rods; 1 rod spanned C6-C7 with a connector to a second rod of the same size spanning T1-T3. Global (C6-T3) and intervertebral (C6-C7, C7-T1, T1-T2, and T2-T3) ranges of motion were compared for each construct. RESULTS In terms of global (C6-T3) stability, 3.5-mm versus 4.0-mm rod constructs were not significantly different, regardless of whether the construct was hook-rod, screw-rod, or screw-connector-rod. The hook-rod constructs provided less stability compared with the screw-rod and screw-connector-rod constructs in lateral bending (P < 0.04) and axial rotation (P < 0.001). The screw-rod constructs demonstrated a similar range of motion to that of the screw-connector-rod constructs, except for significantly less axial rotation at the C6-C7 level with 3.5-mm rods (P = 0.04). CONCLUSIONS We found that the rod diameter of a construct does not appear to significantly influence the biomechanical stability of subaxial constructs. The screw-rod construct resulted in certain biomechanical advantages compared with the screw-connector-rod construct, and both were significantly superior to the hook-rod construct.
Collapse
Affiliation(s)
- Jakub Godzik
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | | | - Eduardo Martinez-Del-Campo
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Felix Dominguez
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Phillip M Reyes
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Nicholas Theodore
- Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland, USA
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
| | - Neil R Crawford
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| |
Collapse
|
11
|
Cross WW, Berven SH, Slater N, Lehrman JN, Newcomb AGUS, Kelly BP. In Vitro Biomechanical Evaluation of a Novel, Minimally Invasive, Sacroiliac Joint Fixation Device. Int J Spine Surg 2018; 12:587-594. [PMID: 30364882 DOI: 10.14444/5072] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Background Sacroiliac (SI) joint pathology may result in low-back pain, which causes substantial disability. Treatment failure with operative management of SI pain may be related to incomplete fusion of the joint and to fixation failure. The objective of this study was to evaluate the initial biomechanical stability of SI joint fixation with a novel implantable device in an in vitro human cadaveric model. Methods The right and left sides of 3 cadaveric L4-pelvis specimens were tested (1) intact, (2) destabilized, and (3) instrumented with an implantable SI joint fixation device using a simulated single-stance load condition. Right-leg and left-leg stance data were grouped together for a sample size of 6, and angular range of motion (ROM) was determined during application of flexion-extension, lateral bending, and axial rotation bending moments to a limit of 7.5 Nm. Results Following intact testing, destabilization by severing the posterior SI joint capsule and ligaments and the pubic symphysis reliably produced a significantly destabilized joint with the mean angular ROM more than doubling in flexion-extension and lateral bending and more than tripling in axial rotation (P ≤ .003) compared to the intact condition. Instrumentation with the SI screw fixation device significantly reduced mean joint ROM compared to the destabilized condition in all 3 anatomic planes tested (P < .001). When compared to the intact condition, the SI-instrumented condition significantly reduced lateral bending (P = .01) and had a similar ROM in flexion-extension (P = .14) and axial rotation (P = .85). Conclusions Instrumentation with the SI screw fixation device significantly reduced mean joint ROM compared to the destabilized condition, with similar ROM in flexion-extension and axial rotation, and it significantly reduced ROM in lateral bending compared to that for the intact joint. The ROM values observed with the instrumented condition were comparable to levels of mobility considered favorable for spinal fusion.
Collapse
Affiliation(s)
- William W Cross
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Sigurd H Berven
- Department of Orthopedic Surgery, University of California at San Francisco, San Francisco, California
| | | | - Jennifer N Lehrman
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
12
|
Godzik J, Hool N, Dalton JF, Whiting AC, Newcomb AGUS, Kelly BP, Crawford NR. Impact of Connector Placement and Design on Bending Stiffness of Spinal Constructs. World Neurosurg 2018; 121:e89-e95. [PMID: 30217782 DOI: 10.1016/j.wneu.2018.08.235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/29/2018] [Accepted: 08/31/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To evaluate the stability of multiple rod-connector construct designs using a mechanical 4-point bending testing frame. METHODS A mechanical study was used to evaluate the bending stiffness of 3 connectors across 12 different configurations of rod-connector-rod constructs. Stability was evaluated in flexion-extension and lateral bending. Combinations of rods having 1 of 3 diameters (4.0 mm, 5.5 mm, and 6.0 mm) connected by 1 of 3 connector types (parallel open, snap-on, and hinged) were compared. Configurations with single connectors and with double connectors with variable spacing were also compared to simulate revision surgery conditions. RESULTS Constructs consisting of 4.0-mm rods connected to 4.0-mm rods were significantly less stiff as the total number of connectors used in a series exceeded 2. When single-connector configurations were compared, parallel open rod connectors demonstrated greater stiffness in flexion-extension than hinged open connectors, whereas hinged open connectors demonstrated greater stiffness in lateral bending. Using double connectors increased stiffness of 4.0- to 4.0-mm rod configurations in flexion-extension and lateral bending, 4.0- to 6.0-mm rod configurations in flexion-extension, and 5.5- to 6.0-mm rod configurations in lateral bending. Spacing the double connectors significantly improved lateral bending stiffness of 4.0- to 4.0-mm and 5.5- to 6.0-mm rod configurations. CONCLUSIONS Our data indicate that the design, number, and placement of rod connectors have a significant impact on the bending stiffness of a surgical construct. Such mechanical data may influence construct design in primary and revision surgeries of the cervical spine and cervicothoracic junction.
Collapse
Affiliation(s)
- Jakub Godzik
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Nick Hool
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | - Alexander C Whiting
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona.
| | - Neil R Crawford
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
13
|
Dou N, Lehrman JN, Newcomb AGUS, Kelly BP. In Reply to the Letter to the Editor "C2 Spinous Process Screws". World Neurosurg 2018; 116:477. [PMID: 30049031 DOI: 10.1016/j.wneu.2018.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 05/02/2018] [Indexed: 11/28/2022]
Affiliation(s)
- NingNing Dou
- Department of Neurosurgery Research, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Jennifer N Lehrman
- Department of Neurosurgery Research, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Anna G U S Newcomb
- Department of Neurosurgery Research, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Brian P Kelly
- Department of Neurosurgery Research, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
| |
Collapse
|
14
|
Godzik J, Kalb S, Reis MT, Reyes PM, Singh V, Newcomb AGUS, Chang SW, Kelly BP, Crawford NR. Biomechanical evaluation of interbody fixation with secondary augmentation: lateral lumbar interbody fusion versus posterior lumbar interbody fusion. J Spine Surg 2018; 4:180-186. [PMID: 30069505 DOI: 10.21037/jss.2018.05.07] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Many approaches to the lumbar spine have been developed for interbody fusion. The biomechanical profile of each interbody fusion device is determined by the anatomical approach and the type of supplemental internal fixation. Lateral lumbar interbody fusion (LLIF) was developed as a minimally invasive technique for introducing hardware with higher profiles and wider widths, compared with that for the posterior lumbar interbody fusion (PLIF) approach. However, the biomechanics of the interbody fusion construct used in the LLIF approach have not been rigorously evaluated, especially in the presence of secondary augmentation. Methods Spinal stability of 21 cadaveric lumbar specimens was compared using standard nondestructive flexibility studies [mean range of motion (ROM), lax zone (LZ), stiff zone (SZ) in flexion-extension, lateral bending, and axial rotation]. Non-paired comparisons were made among four conditions: (I) intact; (II) with unilateral interbody + bilateral pedicle screws (BPS) using the LLIF approach (referred to as the LLIF construct); (III) with bilateral interbody + BPS using the PLIF approach (referred to as the PLIF construct); and (IV) with no lumbar interbody fusion (LIF) + BPS (referred to as the no-LIF construct). Results With bilateral pedicle screw-rod fixation, stability was equivalent between PLIF and LLIF constructs in lateral bending and flexion-extension. PLIF and LLIF constructs had similar biomechanical profiles, with a trend toward less ROM in axial rotation for the LLIF construct. Conclusions LLIF and PLIF constructs had similar stabilizing effects.
Collapse
Affiliation(s)
- Jakub Godzik
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Samuel Kalb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Marco T Reis
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Phillip M Reyes
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Steve W Chang
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Neil R Crawford
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
15
|
Dou N, Lehrman JN, Newcomb AGUS, Kelly BP. A Novel C2 Screw Trajectory: Preliminary Anatomic Feasibility and Biomechanical Comparison. World Neurosurg 2018; 113:e93-e100. [PMID: 29408275 DOI: 10.1016/j.wneu.2018.01.177] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/22/2018] [Accepted: 01/23/2018] [Indexed: 11/25/2022]
Abstract
BACKGROUND Pedicle screw and translaminar screw fixation in C2 may not be applicable in many patients with anatomic abnormalities or narrow laminar thickness and spinous process height. The aim of this study was to assess morphometric and mechanical feasibilities of a novel alternative screw trajectory that pierces the bifid base of C2. METHODS Anatomic measurements that determined the feasibility of spinous process bifid base (SPB) screw fixation were assessed in 14 cadaveric C2 vertebrae. Pullout tests to assess ultimate fixation strength for 3 screw trajectories (transpedicular, translaminar, and SPB) were performed in cadaveric vertebrae for comparison. RESULTS Anatomic measurements included mean spinous process height (10.4 ± 4.2 mm) and mean bilateral bifid base length (10.1 ± 2.2 mm) and thickness (left, 4.4 ± 1.0 mm; right, 4.3 ± 0.9 mm). In 64% (9/14) of specimens, bifid base length was ≥9 mm. Mean pullout strength for transpedicle, translaminar, and SPB screws in 9 viable specimens was 648 ± 305 N, 628 ± 417 N, and 755 ± 279 N. CONCLUSIONS SPB screw fixation may be viable anatomically and mechanically for C2 fixation. Feasibility of SPB screw fixation is determined by length, thickness, and mutual angle of the bilateral bifid bases. Patients with thin (<4 mm) and short (<9 mm) bifid bases are not likely to be suitable candidates. SPB screw fixation shows potential as an alternative approach or a salvage technique for patients with high-riding vertebral arteries or severely thin C2 lamina and warrants further investigation.
Collapse
Affiliation(s)
- NingNing Dou
- Department of Neurosurgery, XinHua Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jennifer N Lehrman
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
| |
Collapse
|
16
|
Grunert P, Reyes PM, Newcomb AGUS, Towne SB, Kelly BP, Theodore N, Härtl R. Biomechanical Evaluation of Lumbar Decompression Adjacent to Instrumented Segments. Neurosurgery 2017; 79:895-904. [PMID: 27580478 DOI: 10.1227/neu.0000000000001419] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Multilevel lumbar stenosis, in which 1 level requires stabilization due to spondylolisthesis, is routinely treated with multilevel open laminectomy and fusion. We hypothesized that a minimally invasive (MI) decompression is biomechanically superior to open laminectomy and may allow decompression of the level adjacent the spondylolisthesis without additional fusion. OBJECTIVE To study the mechanical effect of various decompression procedures adjacent to instrumented segments in cadaver lumbar spines. METHODS Conditions tested were (1) L4-L5 instrumentation, (2) L3-L4 MI decompression, (3) addition of partial facetectomy at L3-L4, and (4) addition of laminectomy at L3-L4. Flexibility tests were performed for range of motion (ROM) analysis by applying nonconstraining, pure moment loading during flexion-extension, lateral bending, and axial rotation. Compression flexion tests were performed for motion distribution analysis. RESULTS After instrumentation, MI decompression increased flexion-extension ROM at L3-L4 by 13% (P = .03) and axial rotation by 23% (P = .003). Partial facetectomy further increased axial rotation by 15% (P = .03). After laminectomy, flexion-extension ROM further increased by 12% (P = .05), a 38% increase from baseline, and axial rotation by 17% (P = .02), a 58% increase from baseline. MI decompression yielded no significant increase in segmental contribution of motion at L3-L4, in contrast to partial facetectomy and laminectomy (<.05). CONCLUSION MI tubular decompression is biomechanically superior to open laminectomy adjacent to instrumented segments. These results lend support to the concept that in patients in whom a multilevel MI decompression is performed, the fusion might be limited to the segments with actual instability. ABBREVIATION MI, minimally invasive.
Collapse
Affiliation(s)
- Peter Grunert
- *Weill Cornell Brain and Spine Center, Department of Neurological Surgery, Weill Cornell Medical College, New York, New York; ‡Spinal Biomechanics Research Laboratory, Barrow Neurological Institute, Phoenix, Arizona
| | | | | | | | | | | | | |
Collapse
|
17
|
Martinez-Del-Campo E, Turner JD, Soriano-Baron H, Newcomb AGUS, Kalb S, Theodore N. Pediatric occipitocervical fusion: long-term radiographic changes in curvature, growth, and alignment. J Neurosurg Pediatr 2016; 18:644-652. [PMID: 27472669 DOI: 10.3171/2016.4.peds15567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The authors assessed the rate of vertebral growth, curvature, and alignment for multilevel constructs in the cervical spine after occipitocervical fixation (OCF) in pediatric patients and compared these results with those in published reports of growth in normal children. METHODS The authors assessed cervical spine radiographs and CT images of 18 patients who underwent occipitocervical arthrodesis. Measurements were made using postoperative and follow-up images available for 16 patients to determine cervical alignment (cervical spine alignment [CSA], C1-7 sagittal vertical axis [SVA], and C2-7 SVA) and curvature (cervical spine curvature [CSC] and C2-7 lordosis angle). Seventeen patients had postoperative and follow-up images available with which to measure vertebral body height (VBH), vertebral body width (VBW), and vertical growth percentage (VG%-that is, percentage change from postoperative to follow-up). Results for cervical spine growth were compared with normal parameters of 456 patients previously reported on in 2 studies. RESULTS Ten patients were girls and 8 were boys; their mean age was 6.7 ± 3.2 years. Constructs spanned occiput (Oc)-C2 (n = 2), Oc-C3 (n = 7), and Oc-C4 (n = 9). The mean duration of follow-up was 44.4 months (range 24-101 months). Comparison of postoperative to follow-up measures showed that the mean CSA increased by 1.8 ± 2.9 mm (p < 0.01); the mean C2-7 SVA and C1-7 SVA increased by 2.3 mm and 2.7 mm, respectively (p = 0.3); the mean CSC changed by -8.7° (p < 0.01) and the mean C2-7 lordosis angle changed by 2.6° (p = 0.5); and the cumulative mean VG% of the instrumented levels (C2-4) provided 51.5% of the total cervical growth (C2-7). The annual vertical growth rate was 4.4 mm/year. The VBW growth from C2-4 ranged from 13.9% to 16.6% (p < 0.001). The VBW of C-2 in instrumented patients appeared to be of a smaller diameter than that of normal patients, especially among those aged 5 to < 10 years and 10-15 years, with an increased diameter at the immediately inferior vertebral bodies compensating for the decreased width. No cervical deformation, malalignment, or detrimental clinical status was evident in any patient. CONCLUSIONS The craniovertebral junction and the upper cervical spine continue to present normal growth, curvature, and alignment parameters in children with OCF constructs spanning a distance as long as Oc-C4.
Collapse
Affiliation(s)
- Eduardo Martinez-Del-Campo
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Jay D Turner
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Hector Soriano-Baron
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Samuel Kalb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Nicholas Theodore
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
18
|
Deniz FE, Reyes PM, Lazaro BCR, Dominguez FC, Newcomb AGUS, Sonntag VKH, Crawford NR. Contribution of Neural Elements to Thoracic Stability. Turk Neurosurg 2016; 27:631-635. [PMID: 27509454 DOI: 10.5137/1019-5149.jtn.16614-15.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AIM Studies of spinal biomechanics typically do not focus on the contributions to range of motion (ROM) of the primary components of the spinal canal, dura, arachnoid, pia, spinal cord, nerve roots, ligaments, and vessels. We sought to determine the stability offered by these soft tissues in vitro. MATERIAL AND METHODS Human cadaveric segments were tested intact, after osteoligamentous destabilization, and after transection of T8-9 spinal canal components. Specimens were induced into flexion, extension, axial rotation, and lateral bending using non-constraining, non-destructive pure moment while tracking motion response stereophotogrammetrically. The range of motion (ROM) was compared in each condition after adjusting for soft tissue creep. RESULTS After spinal canal element transection, ROM increased in all directions (mean 4.7%). This increase was most pronounced during lateral bending (p=0.055). The cumulative ROM from all directions of loading showed a statistically significant mean increase of 3.3% (p=0.040). CONCLUSION Sectioning of canal elements was found to cause a measurable increase in ROM. Although nonviable tissues were tested, living tissues are also likely to contribute to spinal stability.
Collapse
Affiliation(s)
- Fatih Ersay Deniz
- Gaziosmanpasa University, Faculty of Medicine, Department of Neurosurgery, Tokat, Turkey
| | | | | | | | | | | | | |
Collapse
|
19
|
Newcomb AGUS, Baek S, Kelly BP, Crawford NR. Effect of screw position on load transfer in lumbar pedicle screws: a non-idealized finite element analysis. Comput Methods Biomech Biomed Engin 2016; 20:182-192. [PMID: 27454197 DOI: 10.1080/10255842.2016.1209187] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Angled screw insertion has been advocated to enhance fixation strength during posterior spine fixation. Stresses on a pedicle screw and surrounding vertebral bone with different screw angles were studied by finite element analysis during simulated multidirectional loading. Correlations between screw-specific vertebral geometric parameters and stresses were studied. Angulations in both the sagittal and axial planes affected stresses on the cortical and cancellous bones and the screw. Pedicle screws pointing laterally (vs. straight or medially) in the axial plane during superior screw angulation may be advantageous in terms of reducing the risk of both screw loosening and screw breakage.
Collapse
Affiliation(s)
- Anna G U S Newcomb
- a Spinal Biomechanics Laboratory, Department of Neurosurgery Research , Barrow Neurological Institute, St. Joseph's Hospital and Medical Center , Phoenix , AZ , USA
| | - Seungwon Baek
- a Spinal Biomechanics Laboratory, Department of Neurosurgery Research , Barrow Neurological Institute, St. Joseph's Hospital and Medical Center , Phoenix , AZ , USA
| | - Brian P Kelly
- a Spinal Biomechanics Laboratory, Department of Neurosurgery Research , Barrow Neurological Institute, St. Joseph's Hospital and Medical Center , Phoenix , AZ , USA
| | - Neil R Crawford
- a Spinal Biomechanics Laboratory, Department of Neurosurgery Research , Barrow Neurological Institute, St. Joseph's Hospital and Medical Center , Phoenix , AZ , USA
| |
Collapse
|
20
|
Reis MT, Reyes PM, Bse, Altun I, Newcomb AGUS, Singh V, Chang SW, Kelly BP, Crawford NR. Biomechanical evaluation of lateral lumbar interbody fusion with secondary augmentation. J Neurosurg Spine 2016; 25:720-726. [PMID: 27391398 DOI: 10.3171/2016.4.spine151386] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Lateral lumbar interbody fusion (LLIF) has emerged as a popular method for lumbar fusion. In this study the authors aimed to quantify the biomechanical stability of an interbody implant inserted using the LLIF approach with and without various supplemental fixation methods, including an interspinous plate (IP). METHODS Seven human cadaveric L2-5 specimens were tested intact and in 6 instrumented conditions. The interbody implant was intended to be used with supplemental fixation. In this study, however, the interbody was also tested without supplemental fixation for a relative comparison of these conditions. The instrumented conditions were as follows: 1) interbody implant without supplemental fixation (LLIF construct); and interbody implant with supplemental fixation performed using 2) unilateral pedicle screws (UPS) and rod (LLIF + UPS construct); 3) bilateral pedicle screws (BPS) and rods (LLIF + BPS construct); 4) lateral screws and lateral plate (LP) (LLIF + LP construct); 5) interbody LP and IP (LLIF + LP + IP construct); and 6) IP (LLIF + IP construct). Nondestructive, nonconstraining torque (7.5 Nm maximum) induced flexion, extension, lateral bending, and axial rotation, whereas 3D specimen range of motion (ROM) was determined optoelectronically. RESULTS The LLIF construct reduced ROM by 67% in flexion, 52% in extension, 51% in lateral bending, and 44% in axial rotation relative to intact specimens (p < 0.001). Adding BPS to the LLIF construct caused ROM to decrease by 91% in flexion, 82% in extension and lateral bending, and 74% in axial rotation compared with intact specimens (p < 0.001), providing the greatest stability among the constructs. Adding UPS to the LLIF construct imparted approximately one-half the stability provided by LLIF + BPS constructs, demonstrating significantly smaller ROM than the LLIF construct in all directions (flexion, p = 0.037; extension, p < 0.001; lateral bending, p = 0.012) except axial rotation (p = 0.07). Compared with the LLIF construct, the LLIF + LP had a significant reduction in lateral bending (p = 0.012), a moderate reduction in axial rotation (p = 0.18), and almost no benefit to stability in flexion-extension (p = 0.86). The LLIF + LP + IP construct provided stability comparable to that of the LLIF + BPS. The LLIF + IP construct provided a significant decrease in ROM compared with that of the LLIF construct alone in flexion and extension (p = 0.002), but not in lateral bending (p = 0.80) and axial rotation (p = 0.24). No significant difference was seen in flexion, extension, or axial rotation between LLIF + BPS and LLIF + IP constructs. CONCLUSIONS The LLIF construct that was tested significantly decreased ROM in all directions of loading, which indicated a measure of inherent stability. The LP significantly improved the stability of the LLIF construct in lateral bending only. Adding an IP device to the LLIF construct significantly improves stability in sagittal plane rotation. The LLIF + LP + IP construct demonstrated stability comparable to that of the gold standard 360° fixation (LLIF + BPS).
Collapse
Affiliation(s)
- Marco T Reis
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center
| | | | - Bse
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center
| | - Idris Altun
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center
| | - Anna G U S Newcomb
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | | | - Steve W Chang
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center
| | - Brian P Kelly
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Neil R Crawford
- Spinal Biomechanics Laboratory, Department of Neurosurgery Research, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| |
Collapse
|
21
|
Perez-Orribo L, Kalb S, Snyder LA, Hsu F, Malhotra D, Lefevre RD, Elhadi AM, Newcomb AGUS, Theodore N, Crawford NR. Comparison of CT versus MRI measurements of transverse atlantal ligament integrity in craniovertebral junction injuries. Part 2: A new CT-based alternative for assessing transverse ligament integrity. J Neurosurg Spine 2016; 24:903-9. [DOI: 10.3171/2015.9.spine13807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE
The rule of Spence is inaccurate for assessing integrity of the transverse atlantal ligament (TAL). Because CT is quick and easy to perform at most trauma centers, the authors propose a novel sequence of obtaining 2 CT scans to improve the diagnosis of TAL impairment. The sensitivity of a new CT-based method for diagnosing a TAL injury in a cadaveric model was assessed.
METHODS
Ten human cadaveric occipitocervical specimens were mounted horizontally in a supine posture with wooden inserts attached to the back of the skull to maintain a neutral or flexed (10°) posture. Specimens were scanned in neutral and flexed postures in a total of 4 conditions (3 conditions in each specimen): 1) intact (n = 10); either 2A) after a simulated Jefferson fracture with an intact TAL (n = 5) or 2B) after a TAL disruption with no Jefferson fracture (n = 5); and 3) after TAL disruption and a simulated Jefferson fracture (n = 10). The atlantodental interval (ADI) and cross-sectional canal area were measured.
RESULTS
From the neutral to the flexed posture, ADI increased an average of 2.5% in intact spines, 6.25% after a Jefferson fracture without TAL disruption, 34% after a TAL disruption without fracture, and 25% after TAL disruption with fracture. The increase in ADI was significant with both TAL disruption and TAL disruption and fracture (p < 0.005) but not in the other 2 conditions (p > 0.6). Changes in spinal canal area were not significant (p > 0.70).
CONCLUSIONS
This novel method was more sensitive than the rule of Spence for evaluating the integrity of the TAL on CT and does not increase the risk of further neurological damage.
Collapse
Affiliation(s)
| | - Samuel Kalb
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Laura A. Snyder
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Forrest Hsu
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | | | - Ali M. Elhadi
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | - Nicholas Theodore
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | |
Collapse
|
22
|
Perez-Orribo L, Snyder LA, Kalb S, Elhadi AM, Hsu F, Newcomb AGUS, Malhotra D, Crawford NR, Theodore N. Comparison of CT versus MRI measurements of transverse atlantal ligament integrity in craniovertebral junction injuries. Part 1: A clinical study. J Neurosurg Spine 2016; 24:897-902. [DOI: 10.3171/2015.9.spine13808] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE
Craniovertebral junction (CVJ) injuries complicated by transverse atlantal ligament (TAL) disruption often require surgical stabilization. Measurements based on the atlantodental interval (ADI), atlas lateral diameter (ALD1), and axis lateral diameter (ALD2) may help clinicians identify TAL disruption. This study used CT scanning to evaluate the reliability of these measurements and other variants in the clinical setting.
METHODS
Patients with CVJ injuries treated at the authors' institution between 2004 and 2011 were evaluated retrospectively for demographics, mechanism and location of CVJ injury, classification of injury, treatment, and modified Japanese Orthopaedic Association score at the time of injury and follow-up. The integrity of the TAL was evaluated using MRI. The ADI, ALD1, and ALD2 were measured on CT to identify TAL disruption indirectly.
RESULTS
Among the 125 patients identified, 40 (32%) had atlas fractures, 59 (47.2%) odontoid fractures, 31 (24.8%) axis fractures, and 4 (3.2%) occipital condyle fractures. TAL disruption was documented on MRI in 11 cases (8.8%). The average ADI for TAL injury was 1.8 mm (range 0.9–3.9 mm). Nine (81.8%) of the 11 patients with TAL injury had an ADI of less than 3 mm. In 10 patients (90.9%) with TAL injury, overhang of the C-1 lateral masses on C-2 was less than 7 mm. ADI, ALD1, ALD2, ALD1 – ALD2, and ALD1/ALD2 did not correlate with the integrity of the TAL.
CONCLUSIONS
No current measurement method using CT, including the ADI, ALD1, and ALD2 or their differences or ratios, consistently indicates the integrity of the TAL. A more reliable CT-based criterion is needed to diagnose TAL disruption when MRI is unavailable.
Collapse
Affiliation(s)
| | - Laura A. Snyder
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Samuel Kalb
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Ali M. Elhadi
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Forrest Hsu
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | | | | | - Nicholas Theodore
- 2Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
23
|
Rodriguez-Martinez NG, Perez-Orribo L, Kalb S, Reyes PM, Newcomb AGUS, Hughes J, Theodore N, Crawford NR. The role of obesity in the biomechanics and radiological changes of the spine: an in vitro study. J Neurosurg Spine 2016; 24:615-23. [DOI: 10.3171/2015.7.spine141306] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
The effects of obesity on lumbar biomechanics are not fully understood. The aims of this study were to analyze the biomechanical differences between cadaveric L4–5 lumbar spine segments from a large group of nonobese (body mass index [BMI] < 30 kg/m2) and obese (BMI ≥ 30 kg/m2) donors and to determine if there were any radiological differences between spines from nonobese and obese donors using MR imaging.
METHODS
A total of 168 intact L4–5 spinal segments (87 males and 81 females) were tested using pure-moment loading, simulating flexion-extension, lateral bending, and axial rotation. Axial compression tests were performed on 38 of the specimens. Sex, age, and BMI were analyzed with biomechanical parameters using 1-way ANOVA, Pearson correlation, and multiple regression analyses. MR images were obtained in 12 specimens (8 from obese and 4 from nonobese donors) using a 3-T MR scanner.
RESULTS
The segments from the obese male group allowed significantly greater range of motion (ROM) than those from the nonobese male group during axial rotation (p = 0.018), while there was no difference between segments from obese and nonobese females (p = 0.687). There were no differences in ROM between spines from obese and nonobese donors during flexion-extension or lateral bending for either sex. In the nonobese population, the ROM during axial rotation was significantly greater for females than for males (p = 0.009). There was no significant difference between sexes in the obese population (p = 0.892). Axial compressive stiffness was significantly greater for the obese than the nonobese population for both the female-only group and the entire study group (p < 0.01); however, the difference was nonsignificant in the male population (p = 0.304). Correlation analysis confirmed a significant negative correlation between BMI and resistance to deformation during axial compression in the female group (R = −0.65, p = 0.004), with no relationship in the male group (R = 0.03, p = 0.9). There was also a significant negative correlation between ROM during flexion-extension and BMI for the female group (R = −0.38, p = 0.001), with no relationship for the male group (R = 0.06, p = 0.58). Qualitative analysis using MR imaging indicated greater facet degeneration and a greater incidence of disc herniations in the obese group than in the control group.
CONCLUSIONS
Based on flexibility and compression tests, lumbar spinal segments from obese versus nonobese donors seem to behave differently, biomechanically, during axial rotation and compression. The differences are more pronounced in women. MR imaging suggests that these differences may be due to greater facet degeneration and an increased amount of disc herniation in the spines from obese individuals.
Collapse
Affiliation(s)
| | | | | | | | | | - Jeremy Hughes
- 2Neuroradiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | | | | |
Collapse
|
24
|
Rodriguez-Martinez NG, Savardekar A, Nottmeier EW, Pirris S, Reyes PM, Newcomb AGUS, Mendes GAC, Kalb S, Theodore N, Crawford NR. Biomechanics of transvertebral screw fixation in the thoracic spine: an in vitro study. J Neurosurg Spine 2016; 25:187-92. [PMID: 27035506 DOI: 10.3171/2015.11.spine15562] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Transvertebral screws provide stability in thoracic spinal fixation surgeries, with their use mainly limited to patients who require a pedicle screw salvage technique. However, the biomechanical impact of transvertebral screws alone, when they are inserted across 2 vertebral bodies, has not been studied. In this study, the authors assessed the stability offered by a transvertebral screw construct for posterior instrumentation and compared its biomechanical performance to that of standard bilateral pedicle screw and rod (PSR) fixation. METHODS Fourteen fresh human cadaveric thoracic spine segments from T-6 to T-11 were divided into 2 groups with similar ages and bone quality. Group 1 received transvertebral screws across 2 levels without rods and subsequently with interconnecting bilateral rods at 3 levels (T8-10). Group 2 received bilateral PSR fixation and were sequentially tested with interconnecting rods at T7-8 and T9-10, at T8-9, and at T8-10. Flexibility tests were performed on intact and instrumented specimens in both groups. Presurgical and postsurgical O-arm 3D images were obtained to verify screw placement. RESULTS The mean range of motion (ROM) per motion segment with transvertebral screws spanning 2 levels compared with the intact condition was 66% of the mean intact ROM during flexion-extension (p = 0.013), 69% during lateral bending (p = 0.015), and 47% during axial rotation (p < 0.001). The mean ROM per motion segment with PSR spanning 2 levels compared with the intact condition was 38% of the mean intact ROM during flexion-extension (p < 0.001), 57% during lateral bending (p = 0.007), and 27% during axial rotation (p < 0.001). Adding bilateral rods to the 3 levels with transvertebral screws decreased the mean ROM per motion segment to 28% of intact ROM during flexion-extension (p < 0.001), 37% during lateral bending (p < 0.001), and 30% during axial rotation (p < 0.001). The mean ROM per motion segment for PSR spanning 3 levels was 21% of intact ROM during flexion-extension (p < 0.001), 33% during lateral bending (p < 0.001), and 22% during axial rotation (p < 0.001). CONCLUSIONS Biomechanically, fixation with a novel technique in the thoracic spine involving transvertebral screws showed restoration of stability to well within the stability provided by PSR fixation.
Collapse
Affiliation(s)
- Nestor G Rodriguez-Martinez
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Amey Savardekar
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Eric W Nottmeier
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Stephen Pirris
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Phillip M Reyes
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - George A C Mendes
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Samuel Kalb
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Nicholas Theodore
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Neil R Crawford
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
25
|
Abstract
OBJECTIVE Atlantooccipital fixation is an important technique in the treatment of upper cervical spine instability. Important considerations for implant devices are obtrusiveness and propagation of torque through the device caused by cervical rotation. The authors evaluated the feasibility of 3 regions of the occiput as sites for occipitocervical fixation by examining bone mineral density at these locations. METHODS Unembalmed occiputs of 9 male and 4 female cadavers were used (mean age at time of death was 61.6 years, range 36-68 years). Studies were undertaken using caliper measurements and dual-energy x-ray absorptiometry of the superior nuchal line (SNL), the external occipital protuberance (EOP), and the inferior nuchal line (INL). RESULTS Data indicate that the bone at the INL has a similar volumetric bone density as the bone at the SNL, despite having half the thickness. Also, the volumetric bone density increases laterally along the nuchal lines. CONCLUSIONS Most hardware fixation is centered on stabilization at the EOP and the SNL. On the basis of these radiological results, the INL shows promise as a potential alternative site for screw placement in occipitocervical fixation.
Collapse
Affiliation(s)
- Chandan Das
- Division of Neurological Surgery, University of Toledo Medical Center, Toledo, Ohio; and.,Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Anna G U S Newcomb
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Daniel P Gaudin
- Division of Neurological Surgery, University of Toledo Medical Center, Toledo, Ohio; and
| | - Neil R Crawford
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| |
Collapse
|
26
|
Rodriguez-Martinez NG, Safavi-Abbasi S, Perez-Orribo L, Newcomb AGUS, Reyes PM, Loughran G, Theodore N, Crawford NR. Biomechanics of a flexible sublaminar connector in long-segment thoracic fixation. J Neurosurg Spine 2015; 24:340-346. [PMID: 26460753 DOI: 10.3171/2015.4.spine14999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The Universal Clamp Spinal Fixation System (UC) is a novel sublaminar connection for the spine that is currently used in conjunction with pedicle screws at the thoracic levels for the correction of scoliosis. This device allows the surgeon to attach rods and incorporate a pedicle screw construction. The flexible composition of the UC should provide flexibility intermediate to the uninstrumented spine and an all-screw construct. This hypothesis was tested in vitro using nondestructive flexibility testing of human cadaveric spine segments. METHODS Six unembalmed human cadaveric thoracic spine segments from T-3 to T-11 were used. The specimens were tested under the following conditions: 1) intact; 2) after bilateral screws were placed at T4-T10 and interconnected with longitudinal rods; 3) after placement of a hybrid construction with screws at T-4, T-7, and T-10 with an interconnecting rod on one side and screws at T-4 and T-10 with the UC at T5-9 on the contralateral side; (4) after bilateral screws were placed at T-4 and T-10 and interconnected with rods and bilateral UC were placed at T5-9; and 5) after bilateral screws at T-4 and T-10 were placed and interconnected with rods and bilateral sublaminar cables were placed at T5-9. Pure moments of 6.0 Nm were applied while optoelectronically recording 3D angular motion. RESULTS Bilateral UC placement and bilateral sublaminar cables both resulted in a significantly greater range of motion than bilateral pedicle screws during lateral bending and axial rotation, but not during flexion or extension. There were no differences in stability between bilateral UC and bilateral cables. The construct with limited screws on one side and UC contralaterally showed comparable stability to bilateral UC and bilateral cables. CONCLUSIONS These results support using the UC as a therapeutic option for spinal stabilization because it allows comparable stability to the sublaminar cables and provides flexibility intermediate to that of the uninstrumented spine and an all-screw construct. Equivalent stability of the hybrid, bilateral UC, and bilateral cable constructs indicates that 6-level UC provides stability comparable to that of a limited (3-point) pedicle screw-rod construct.
Collapse
Affiliation(s)
- Nestor G Rodriguez-Martinez
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Sam Safavi-Abbasi
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Luis Perez-Orribo
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Anna G U S Newcomb
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Phillip M Reyes
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | | | - Nicholas Theodore
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Neil R Crawford
- Spinal Biomechanics, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| |
Collapse
|
27
|
Soriano-Baron H, Newcomb AGUS, Malhotra D, de Tranaltes K, Martinez-Del-Campo E, Reyes PM, Crawford NR, Theodore N, Tumialán LM. Biomechanics of Nested Transforaminal Lumbar Interbody Cages. Neurosurgery 2015; 78:297-304. [PMID: 26348015 DOI: 10.1227/neu.0000000000001005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Arthrodesis is optimized when the structural graft occupies most of the surface area within a disc space. The transforaminal corridor inherently limits interbody size. OBJECTIVE To evaluate the biomechanical implications of nested interbody spacers (ie, a second curved cage placed behind a first) to increase disc space coverage in transforaminal approaches. METHODS Seven lumbar human cadaveric specimens (L3-S1) underwent nondestructive flexibility and axial compression testing intact and after transforaminal instrumentation at L4-L5. Specimens were tested in 5 conditions: (1) intact, (2) interbody, (3) interbody plus bilateral pedicle screws and rods (PSR), (4) 2 nested interbodies, and (5) 2 nested interbodies plus PSR. RESULTS Mean range of motion (ROM) with 1 interbody vs 2 nested interbodies, respectively, was: flexion, 101% vs 85%; extension, 97% vs 92%; lateral bending, 127% vs 132%; and axial rotation, 145% vs 154%. One interbody and 2 nested interbodies did not differ significantly by loading mode (P > .10). With PSR, ROM decreased significantly compared with intact, but not between interbody and interbody plus PSR or 2 interbodies plus PSR (P > .80). Mean vertical height during compressive loading (ie, axial compressive stiffness) was significantly different with 2 nested interbodies vs 1 interbody alone (P < .001) (compressive stiffness, 89% of intact vs 67% of intact, respectively). CONCLUSION Inserting a second interbody using a transforaminal approach is anatomically feasible and nearly doubles the disc space covered without affecting ROM. Compressive stiffness significantly increased with 2 nested interbodies, and foraminal height increased. Evaluation of the clinical safety and efficacy of nested interbodies is underway.
Collapse
Affiliation(s)
- Hector Soriano-Baron
- *Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; ‡Division of Neurological Surgery, Spine Group Arizona, HonorHealth Research Institute, Scottsdale, Arizona
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Brasiliense LBC, Lazaro BCR, Reyes PM, Newcomb AGUS, Turner JL, Crandall DG, Crawford NR. Characteristics of immediate and fatigue strength of a dual-threaded pedicle screw in cadaveric spines. Spine J 2013; 13:947-56. [PMID: 23602373 DOI: 10.1016/j.spinee.2013.03.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 10/13/2012] [Accepted: 03/07/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Novel dual-threaded screws are configured with overlapping (doubled) threads only in the proximal shaft to improve proximal cortical fixation. PURPOSE Tests were run to determine whether dual-threaded pedicle screws improve pullout resistance and increase fatigue endurance compared with standard pedicle screws. STUDY DESIGN/SETTING In vitro strength and fatigue tests were performed in human cadaveric vertebrae and in polyurethane foam test blocks. PATIENT SAMPLE Seventeen cadaveric lumbar vertebrae (14 pedicles) and 40 test sites in foam blocks were tested. OUTCOME MEASURES Measures for comparison between standard and dual-threaded screws were bone mineral density (BMD), screw insertion torque, ultimate pullout force, peak load at cyclic failure, and pedicular side of first cyclic failure. METHODS For each vertebral sample, dual-threaded screws were inserted in one pedicle and single-threaded screws were inserted in the opposite pedicle while recording insertion torque. In seven vertebrae, axial pullout tests were performed. In 10 vertebrae, orthogonal loads were cycled at increasing peak values until toggle exceeded threshold for failure. Insertion torque and pullout force were also recorded for screws placed in foam blocks representing healthy or osteoporotic bone porosity. RESULTS In bone, screw insertion torque was 183% greater with dual-threaded than with standard screws (p<.001). Standard screws pulled out at 93% of the force required to pull out dual-threaded screws (p=.42). Of 10 screws, five reached toggle failure first on the standard screw side, two screws failed first on the dual-threaded side, and three screws failed on both sides during the same round of cycling. In the high-porosity foam, screw insertion torque was 60% greater with the dual-threaded screw than with the standard screw (p=.005), but 14% less with the low-porosity foam (p=.07). Pullout force was 19% less with the dual-threaded screw than with the standard screw in the high-porosity foam (p=.115), but 6% greater with the dual-threaded screw in the low-porosity foam (p=.156). CONCLUSIONS Although dual-threaded screws required higher insertion torque than standard screws in bone and low density foam, dual-threaded and standard pedicle screws exhibited equivalent axial pullout and cyclic fatigue endurance. Unlike single-threaded screws, the mechanical performance of dual-threaded screws in bone was relatively independent of BMD. In foam, the mechanical performance of both types of screws was highly dependent on porosity.
Collapse
Affiliation(s)
- Leonardo B C Brasiliense
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd, Phoenix, AZ 85013, USA
| | | | | | | | | | | | | |
Collapse
|
29
|
Little AS, Perez-Orribo L, Rodriguez-Martinez NG, Reyes PM, Newcomb AGUS, Prevedello DM, Crawford NR. 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. J Neurosurg Spine 2013; 18:327-32. [PMID: 23414005 DOI: 10.3171/2013.1.spine12835] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
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.
Collapse
Affiliation(s)
- Andrew S Little
- Barrow Pituitary and Cranial Base Center, Division of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA.
| | | | | | | | | | | | | |
Collapse
|