Comparison of the biomechanics of hydroxyapatite and polymethylmethacrylate vertebroplasty in a cadaveric spinal compression fracture model

2001 ◽  
Vol 95 (2) ◽  
pp. 215-220 ◽  
Author(s):  
Patrick W. Hitchon ◽  
Vijay Goel ◽  
John Drake ◽  
Derek Taggard ◽  
Matthew Brenton ◽  
...  
Keyword(s):  
Compression Fracture ◽  
Axial Rotation ◽  
Load Testing ◽  
Lateral Bending ◽  
Content Type ◽  
Significant Difference ◽  
Flexion Extension ◽  
Before And After ◽  
Weight Drop ◽  
Fine Print

Object. Polymethylmethacrylate (PMMA) has long been used in the stabilization and reconstruction of traumatic and pathological fractures of the spine. Recently, hydroxyapatite (HA), an osteoconductive, biocompatible cement, has been used as an alternative to PMMA. In this study the authors compare the stabilizing effects of the HA product, BoneSource, with PMMA in an experimental compression fracture of L-1. Methods. Twenty T9—L3 cadaveric spine specimens were mounted individually on a testing frame. Light-emitting diodes were placed on the neural arches as well as the base. Motion was tracked by two video cameras in response to applied loads of 0 to 6 Nm. The weight-drop technique was used to induce a reproducible compression fracture of T-11 after partially coring out the vertebra. Load testing was performed on the intact spine, postfracture, after unilateral transpedicular vertebroplasty with 7 to 10 ml of PMMA or HA, and after flexion—extension fatiguing to 5000 cycles at ± 3 Nm. No significant difference between the HA- and PMMA cemented—fixated spines was demonstrated in flexion, extension, left lateral bending, or right and left axial rotation. The only difference between the two cements was encountered before and after fatiguing in right lateral bending (p ≤ 0.05). Conclusions. The results of this study suggest that the same angular rigidity can be achieved using either HA or PMMA. This is of particular interest because HA is osteoconductive, undergoes remodeling, and is not exothermic.

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

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

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

Stabilizing effect of posterior lumbar interbody fusion cages before and after cyclic loading

2000 ◽  
Vol 92 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Annette Kettler ◽  
Hans-Joachim Wilke ◽  
Rupert Dietl ◽  
Matthias Krammer ◽  
Christianto Lumenta ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Interbody Fusion ◽  
Posterior Lumbar Interbody Fusion ◽  
Axial Rotation ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Content Type ◽  
Flexion Extension ◽  
Stabilizing Effect ◽  
Fine Print

Object. The function of interbody fusion cages is to stabilize spinal segments primarily by distracting them as well as by allowing bone ingrowth and fusion. An important condition for efficient formation of bone tissue is achieving adequate spinal stability. However, the initial stability may be reduced due to repeated movements of the spine during everyday activity. Therefore, in addition to immediate stability, stability after cyclic loading is of remarkable relevance; however, this has not yet been investigated. The object of this study was to investigate the immediate stabilizing effect of three different posterior lumbar interbody fusion cages and to clarify the effect of cyclic loading on the stabilization. Methods. Before and directly after implantation of a Zientek, Stryker, or Ray posterior lumbar interbody fusion cage, 24 lumbar spine segment specimens were each evaluated in a spine tester. Pure lateral bending, flexion—extension, and axial rotation moments (± 7.5 Nm) were applied continuously. The motion in each specimen was measured simultaneously. The specimens were then loaded cyclically (40,000 cycles, 5 Hz) with an axial compression force ranging from 200 to 1000 N. Finally, they were tested once again in the spine tester. Conclusions. In general, a decrease of movement in all loading directions was noted after insertion of the Zientek and Ray cages and an increase of movement after implantation of a Stryker cage. In all three cage groups greater stability was demonstrated in lateral bending and flexion than in extension and axial rotation. Reduced stability during cyclic loading was observed in all three cage groups; however, loss of stability was most pronounced when the Ray cage was used.

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

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

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

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

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

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

Biomechanical comparison of facet-sparing laminectomy and Christmas tree laminectomy

2003 ◽  
Vol 99 (2) ◽  
pp. 214-220 ◽  
Author(s):  
Paul W. Detwiler ◽  
Christina B. Spetzler ◽  
Sara B. Taylor ◽  
Neil R. Crawford ◽  
Randall W. Porter ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Shear Loading ◽  
Angular Motion ◽  
Christmas Tree ◽  
Lumbar Stenosis ◽  
Lateral Bending ◽  
Content Type ◽  
Objective Evidence ◽  
Flexion Extension ◽  
Fine Print

Object. The authors compared differences in biomechanical stability between two decompressive laminectomy techniques for treating lumbar stenosis. A Christmas tree laminectomy (CTL), in which bilateral facetectomies and foraminotomies are performed, was compared with facet-sparing laminectomy (FSL), in which the facets are undercut but not resected. Spinal instability was assessed immediately postoperatively and again after discectomy to model long-term degeneration. Methods. Sixteen motion segments obtained from five human cadaveric lumbar specimens were studied in vitro by conducting nondestructive flexibility tests. Specimens were tested intact, after FSL or CTL, and again after discectomy. Nonconstraining torques (≤ 5 Nm) were applied to induce flexion, extension, axial rotation, and lateral bending; strings and pulleys were used while vertebral angles were measured. Anteroposterior translation in response to shear loading (≤ 100 N) was also measured. Angular motion, shear motion, and sagittal-plane axes of rotation were compared to evaluate stability. Compared with the intact condition, CTL-treated specimens had significantly larger increases in angular motion during flexion, lateral bending, and axial rotation than their FSL-treated counterparts (p < 0.05, nonpaired Student t-tests). Subsequent discectomy caused greater increases in motion in the CTL group. Axes of rotation shifted less from their normal positions after FSL than after CTL. Conclusions. This study provides objective evidence that the treatment of lumbar stenosis with FSL induces less biomechanical instability and alters kinematics less than FSL. These findings support the use of the FSL in treating lumbar stenosis.

Spinal stability with anterior or posterior Ray threaded fusion cages

2000 ◽  
Vol 93 (1) ◽  
pp. 102-108 ◽  
Author(s):  
Patrick W. Hitchon ◽  
Vijay Goel ◽  
Thomas Rogge ◽  
Andrew Dooris ◽  
John Drake ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Posterior Instrumentation ◽  
Pedicle Screws ◽  
Posterior Lumbar Interbody Fusion ◽  
Base Plate ◽  
Axial Rotation ◽  
Load Testing ◽  
Content Type ◽  
Flexion Extension ◽  
Fine Print

Object. The authors conducted a study to determine if the rigidity supplied to the spine by posterior placement of the Ray threaded fusion cage (TFC) is further enhanced by the placement of pedicle screws and, additionally, if bilateral anteriorly placed TFCs render the spine more rigid than a single anteriorly placed TFC. Methods. Ten human cadaveric spinal specimens (L2—S1) were affixed within a testing frame. Loads of 1.5, 3, 4.5, and 6 Nm were applied to the spine in six degrees of freedom: flexion—extension, right and left lateral bending, and right and left axial rotation. Motion in an x, y, and z cartesian axis system was tracked using dual video cameras following light-emitting diodes attached to the spine and base plate. Load testing of the spines was performed in the intact mode, following which the spinal segments were randomized to receive anterior or posterior instrumentation. In five spine specimens we performed posterior discectomy, posterior lumbar interbody fusion (PLIF) with placment of femoral rings and pedicle screws, PLIF with bilateral TFCs, and bilateral TFCs with pedicle screws. Five other spines underwent anterior-approach discectomy, followed by implantation of a unilateral cage and bilateral cages. Load testing was performed after each step. Conclusion. Spines in which PLIF with pedicle screws and TFCs with pedicle screws were placed were more rigid than after discectomy in all directions of motion except flexion. Anterior discectomy provided significantly (p ≤ 0.05) less stability in left and right axial rotation than the intact spines and following posterior discectomy. Following anterior implantation of bilateral TFCs, spines were significantly more rigid than after discectomy in all directions except extension.

Evaluation of endorphin content in the CSF of patients with trigeminal neuralgia before and after Gasserian ganglion thermocoagulation

1981 ◽  
Vol 55 (6) ◽  
pp. 935-937 ◽  
Author(s):  
Giuseppe Salar ◽  
Salvatore Mingrino ◽  
Marco Trabucchi ◽  
Angelo Bosio ◽  
Carlo Semenza
Keyword(s):  
Cerebrospinal Fluid ◽  
Trigeminal Neuralgia ◽  
Control Group ◽  
Gasserian Ganglion ◽  
Content Type ◽  
Group Of Seven ◽  
Idiopathic Trigeminal Neuralgia ◽  
Significant Difference ◽  
Before And After ◽  
Fine Print

✓ The β-endorphin content in cerebrospinal fluid (CSF) was evaluated in 10 patients with idiopathic trigeminal neuralgia during medical treatment (with or without carbamazepine) and after selective thermocoagulation of the Gasserian ganglion. These values were compared with those obtained in a control group of seven patients without pain problems. No statistically significant difference was found between patients suffering from trigeminal neuralgia and those without pain. Furthermore, neither pharmacological treatment nor surgery changed CSF endorphin values. It is concluded that there is no pathogenetic relationship between trigeminal neuralgia and endorphins.

Biomechanical comparison of anterior and posterior stabilization methods in atlantoaxial instability

2004 ◽  
Vol 100 (3) ◽  
pp. 277-283 ◽  
Author(s):  
Sung-Min Kim ◽  
T. Jesse Lim ◽  
Josemaria Paterno ◽  
Tae-Jin Hwang ◽  
Kun-Woo Lee ◽  
...  
Keyword(s):  
The Other ◽  
Atlantoaxial Instability ◽  
Fixation Method ◽  
Posterior Fixation ◽  
Lateral Bending ◽  
Biomechanical Stability ◽  
Transarticular Screw ◽  
Content Type ◽  
Flexion Extension ◽  
Fine Print

Object. The authors compared the biomechanical stability of two anterior fixation procedures—anterior C1–2 Harms plate/screw (AHPS) fixation and the anterior C1–2 transarticular screw (ATS) fixation; and two posterior fixation procedures—the posterior C-1 lateral mass combined with C-2 pedicle screw/rod (PLM/APSR) fixation and the posterior C1–2 transarticular screw (PTS) fixation after destabilization. Methods. Sixteen human cervical spine specimens (Oc—C3) were tested in three-dimensional flexion—extension, axial rotation, and lateral bending motions after destabilization by using an atlantoaxial C1–2 instability model. In each loading mode, moments were applied to a maximum of 1.5 Nm, and the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ) were determined and values compared using the intact spine, the destabilized spine, and the postfixation spine. The AHPS method produced inferior biomechanical results in flexion—extension and lateral bending modes compared with the intact spine. The lateral bending NZ and ROM for this method differed significantly from the other three fixation techniques (p < 0.05), although statistically significant differences were not obtained for all other values of ROM and NZ for the other three procedures. The remaining three methods restored biomechanical stability and improved it over that of the intact spine. Conclusions. The PLM/APSR fixation method was found to have the highest biomechanical stiffness followed by PTS, ATS, and AHPS fixation. The PLM/APSR fixation and AATS methods can be considered good procedures for stabilizing the atlantoaxial joints, although specific fixation methods are determined by the proper clinical and radiological characteristics in each patient.

Craniovertebral junction fixation with transarticular screws: biomechanical analysis of a novel technique

2003 ◽  
Vol 98 (2) ◽  
pp. 202-209 ◽  
Author(s):  
L. Fernando Gonzalez ◽  
Neil R. Crawford ◽  
Robert H. Chamberlain ◽  
Luis E. Perez Garza ◽  
Mark C. Preul ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Axial Rotation ◽  
Craniovertebral Junction ◽  
Biomechanical Analysis ◽  
Lateral Bending ◽  
Content Type ◽  
Additional Stability ◽  
A New Technique ◽  
Flexion And Extension ◽  
Fine Print

Object. The authors compared the biomechanical stability resulting from the use of a new technique for occipitoatlantal motion segment fixation with an established method and assessed the additional stability provided by combining the two techniques. Methods. Specimens were loaded using nonconstraining pure moments while recording the three-dimensional angular movement at occiput (Oc)—C1 and C1–2. Specimens were tested intact and after destabilization and fixation as follows: 1) Oc—C1 transarticular screws plus C1–2 transarticular screws; 2) occipitocervical transarticular (OCTA) plate in which C1–2 transarticular screws attach to a loop from Oc to C-2; and (3) OCTA plate plus Oc—C1 transarticular screws. Occipitoatlantal transarticular screws reduced motion to well within the normal range. The OCTA loop and transarticular screws allowed a very small neutral zone, elastic zone, and range of motion during lateral bending and axial rotation. The transarticular screws, however, were less effective than the OCTA loop in resisting flexion and extension. Conclusions. Biomechanically, Oc—C1 transarticular screws performed well enough to be considered as an alternative for Oc—C1 fixation, especially when instability at C1–2 is minimal. Techniques for augmenting these screws posteriorly by using a wired bone graft buttress, as is currently undertaken with C1–2 transarticular screws, may be needed for optimal performance.

Intravertebral vacuum phenomenon in osteoporotic compression fracture: report of 67 cases with quantitative evaluation of intravertebral instability

2004 ◽  
Vol 100 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Dong-Yun Kim ◽  
Sang-Ho Lee ◽  
Jee Soo Jang ◽  
Sang Ki Chung ◽  
Ho-Yeon Lee
Keyword(s):  
Percutaneous Vertebroplasty ◽  
Compression Fracture ◽  
Control Group ◽  
Stable Group ◽  
Duration Of Symptoms ◽  
Content Type ◽  
Osteoporotic Compression Fracture ◽  
Vacuum Phenomenon ◽  
Flexion Extension ◽  
Fine Print

Object. The objectives of this study were to: 1) describe the incidence and clinical features of intravertebral vacuum phenomenon (IVVP) in a relatively large number of cases; 2) quantitatively evaluate intravertebral instability and determine the factors affecting instability; and 3) evaluate the efficacy of percutaneous vertebroplasty in the treatment of this phenomenon. Methods. A retrospective review was conducted of the records of 67 patients with IVVP among 652 consecutive cases of osteoporotic compression fracture. Comparisons between the IVVP group and a control group, a stable group, and an unstable group were conducted. Percutaneous vertebroplasty was performed in all patients. There were 67 patients (10.3%) in whom there were 70 vacuum phenomena of the intravertebral space. Intravertebral vacuum phenomena occurred predominantly in the thoracolumbar junction (81%) and in patients with a longer duration of symptoms (10.6 ± 9.8 months) compared with the control group. Of 59 vertebrae for which flexion—extension radiographs were available, 26 vertebrae were categorized as stable and 33 as unstable. Twenty-one vertebrae (64%) had undergone compression fracture in the unstable group compared with nine (35%) compression fractures in the stable group. There were 28 (85%) fractures of the wedged vertebrae in the unstable group compared with 16 (61%) fractures in wedged vertebrae in the stable group. Percutaneous vertebroplasty was performed with successful clinical outcome. Conclusions. Intravertebral vacuum phenomenon is more common than has been previously appreciated. The results of this study indicate that biomechanics, not ischemic or avascular theory, may play an important role in pathogenesis of this phenomenon. Percutaneous vertebroplasty was found to be a minimally invasive and effective procedure for the treatment of IVVP.

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