Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 2: Treatment with threaded interbody cages/dowels and pedicle screws (original) (raw)
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Biomechanical evaluation of human lumbar spine in spondylolisthesis
Journal of Applied Biomedicine
One of the least known conditions of the lumbar spine in terms of biomechanics is spondylolisthesis which causes many serious consequences for the patient. This research aimed to perform a mechanical analysis of the origins of spondylolisthesis and its impact on the biomechanics of the lumbar section of the spine. Within the framework of this study, a physiologically model of the lumbar spine was created in the MADYMO software. In the next stage a slip of vertebra L4 was simulated by means of a controlled forward displacement of the vertebral body of vertebra L4. 10 variants of spondylolisthesis (W1-W10) of different degrees were subjected to a biomechanical evaluation. In maximum bending of the physiological spine at an angle of 27 the value of the shear force amounted to 1.9 kN, while for the spine affected by spondylolisthesis with slip grade W9 at the maximum bending of 34 the shear force amounted to 5.5 kN. It was observed that the lumbar spine with the simulated spondylolisthesis had greater mobility in comparison with the physiological spine, which was shown by maximum bending angles (physiological 27 , W9 34).
Spine, 2014
In vitro cadaveric biomechanical study of lateral interbody cages and supplemental fixation in a degenerative spondylolisthesis (DS) model. To investigate changes in shear and flexion-extension stability of lateral interbody fusion constructs. Instability associated with DS may increase postoperative treatment complications. Several groups have investigated DS in cadaveric spines. Extreme lateral interbody fusion (XLIF) cages with supplemental fixation have not previously been examined using a DS model. Seven human cadaveric L4-L5 motion segments were evaluated using flexion-extension moments to ±7.5 N·m and anterior-posterior (A-P) shear loading of 150 N with a static axial compressive load of 300 N. Conditions were: (1) intact segment, (2) DS simulation with facet resection and lateral discectomy, (3) standalone XLIF cage, (4) XLIF cage with (1) lateral plate, (2) lateral plate and unilateral pedicle screws contralateral to the plate (PS), (3) unilateral PS, (4) bilateral PS, (5) ...
Functional and radiological analysis of posterior lumbar interbody fusion in spondylolisthesis
Background: Spondylolisthesis is present in 5% of the adult population with clinical evidence of low back pain. These patients are treated initially by conservative measures, failing of which surgical intervention is mandatory. Majority of patients with varying degree of slip and disability ultimately require surgical intervention. In this study we are trying to analyse the functional outcome following posterior lumbar interbody fusion in spondylolisthesis. Methods: Posterior lumbar interbody fusion using pedicle screw and rods with cage was performed on 25 patients. 6 months follow-up was completed in 25 patients who were then reviewed at regular intervals. Out of the 25 patients, 17(68%) were females and 8(32%) were males. The mean age of the patients was 40.64 years. Out of 25 patients, 14 patients had listhesis at L4 -L5 level and another 11 at L5 -S1 level. 21(84%) were Isthmic variant and 4 (16%) were Degenerative spondylolisthesis. Results: The mean follow up period in this study of 25 patients is 19 months. Out of 25 patients, there was mean improvement of 18.96 in the Oswestry scoring index. The Visual analogue scale score showed a mean improvement of 6.48. Radiologically, the percentage of slip was decreased by a mean of 8.40%. One patient had a cage extrusion with no neurological deficit. Conclusions: The pedicle screw with rod and cage system is easy to use and provides the anatomic restoration of the isthmus in isthmic spondylolisthesis or restoring the stability after laminectomy/discectomy in degenerative spondylolisthesis. From our study, we strongly believe that this technique is very useful in low grade degenerative and isthmic spondylolisthesis.
The Biomechanical Effects Of Spondylolysis and Its Treatment
Spine, 2003
Study Design. Biomechanical analysis of the level above pars defects was performed using calf lumbar spines. Objectives. To evaluate whether complete spondylolysis contributes to the pathology of the upper adjacent motion segment to the pars defect. Summary of Background Data. It is well recognized that patients with spondylolysis show a higher incidence of spondylolisthesis or degenerative disc changes at the level of the pars defects. However, some authors have referred to the fact that disc damage may occur at the level above the defect and give rise to symptoms. However, no previous studies have been directed to the kinematic influence on the upper adjacent segment to pars defects. Methods. Nine fresh-frozen calf lumbar spines were used for this study. The bony defects were created on the L4 pars articularis bilaterally. Three linear extensometers and one specially designed angular extensometer were mounted across the L3-L4 and L4-L5 motion units. Nondestructive static loads, including axial compression, flexion-extension, and axial rotation, were applied on the specimens in four different conditions as follows: 1) intact spine; 2) bilateral pars defects on the L4 laminae; 3) pars defect repair with Buck technique; and 4) pedicle screwrod fixation at L4-L5 after removal of the interarticular screws. Testing was performed on a material testing machine (MTS 858 Bionix test system, Minneapolis, MN), and load-displacement curves were recorded with the extensometers. Each test was performed for over five full sinusoidal loading cycles, and data from the fifth cycle were collected and analyzed. Results. After creating the pars interarticularis defects at L4, mobility at both the L3-L4 and L4-L5 motion units were increased in all loading conditions. The normalized range of motion (% ROM) as compared with the intact specimens showed that the pars defects increased the mobility at the upper adjacent level (L3-L4) to 106.4% in flexion-extension and to 120.1% in axial rotation; the differences were significant (P Ͻ 0.01). Consequently, the increased mobility was stabilized by applying Buck screws through the defects on both sides; however, the
Numerical analysis of spinal stabiliser in spondylolisthesis treatment with pedicle screws
MATEC Web of Conferences
The aim of the research on experimental parts was to analyse the influence of the lumbar stabilisation on the strength aspects of the lumbar part of human spine and stabiliser in case of spondylolisthesis treatment. The models were built with the use of pre-surgical CT diagnostics, routinely used in medical practice. MIMICS software was used to process the results of the neuroimaging research and to create a 3D model. Two models were built: one with and the other without a stabilizer. Afterwards, a static load analysis for the load coming from the upper part of the body was done. Analysis was performed using the finite element method (FEA). The performed simulations enabled to determine the stress in particular discs for both models, with and without transpedicular stabiliser.
Degenerative lumbar spondylolisthesis: Anatomy, biomechanics and risk factors
Journal of Back and Musculoskeletal Rehabilitation, 2008
Degenerative spondylolisthesis (DS) is a major cause of spinal stenosis and is often related to low back and leg pain. We reviewed the anatomical and biomechanical predisposition of lumbar DS and discuss possible predictors and risk factors for this condition. Spinal segment L4-L5 is most vulnerable because of the great forces in this region and the increased mobility of this segment due to the specific anatomy of quadratus lumborum muscle and iliolumbar ligament. A high pelvic incidence and lumbar lordosis increase the forces on the low spinal segments and probably raise the risk for DS. Individuals with relatively more sagittal orientation of the lumbar facets have a higher probability of developing DS because such joints have less ability to resist the shearing forces. Disc degeneration is not an important predisposing factor for DS. Reduced disc space caused by disc degeneration increases the facet joint articulation overlap and together with osteophyte formation and ossification of spinal ligaments, can be seen as a part of the restabilization process. Deep abdominal and paraspinal muscles, most likely, play an important role in dynamic lumbar stability. Factors found to be associated with lumbar DS include age > 50, female gender, pregnancy, African American race, and generalized joint laxity.
Biomedical Engineering: Applications, Basis and Communications, 2008
This study investigates and compares the mechanical response of interbody and posterolateral fusion along with the transpedicular screw fixation for the degenerative spondylolisthesis under different load conditions using finite element (FE) analysis. Image processing, computer aided design (CAD), and computer aided engineering techniques were applied to build a three-dimensional model of a functional spinal unit (L4–L5) with transpedicular screw fixation for the posterolateral fusion FE model. Additionally, the intervertebral disc was replaced by two cages to represent the interbody fusion FE model. A unit moment of 1 Nm was applied on the top of L4 in different directions to simulate the flexion, extension, lateral bending, and axial rotation, respectively. The lower of L5 was fixed in all directions for constraint. The simulated results revealed that using cages obviously decreased (13%–58%) the stress imposed upon the instrumentations. The stress concentration occurred at the lo...
Arquivos de Neuro-Psiquiatria, 2007
The purpose of this study was to compare patients with lumbar spondylolisthesis submitted to two different surgical approaches, and evaluate the results and outcomes in both groups. In a two-year period, 60 adult patients with lumbar spondylolisthesis, both isthmic and degenerative, were submitted to surgery at the Biocor Institute, Brazil. All patients were operated on by the same surgeon (FLRD) in a single institution, and the results were analyzed prospectively. Group I comprised the first 30 consecutive patients that were submitted to a posterior lumbar spinal fusion with pedicle screws (PLF). Group II comprised the last 30 consecutive patients submitted to a posterior lumbar interbody fusion procedure (PLIF) with pedicle screws. All patients underwent foraminotomy for nerve root decompression. Clinical evaluation was carried out using the Prolo Economic and Functional Scale and the Rolland-Morris and the Oswestry questionnaire. Mean age was 52.4 for Group I (PLF), and 47.6 for Group II (PLIF). The mean follow-up was 3.2 years. Both surgical procedures were effective. The PLIF with pedicle screws group presented better clinical outcomes. Group I presented more complications when compared with Group II. Group II presented better results as indicated in the Prolo Economic and Functional Scale.
Trials
Background: Spinal fusion with pedicle screw fixation represents the gold standard for lumbar degenerative disc disease with instability. Although it is an established technique, it is nevertheless an invasive intervention with high complication rates. Therefore, minimally invasive approaches have been developed, the medialized bilateral screw pedicel fixation (mPACT) being one of them. The study objective is to evaluate prospectively the efficacy and safety of the mPACT technique compared with the traditional trajectory for degenerative lumbar spondylolisthesis. Methods/design: This is a single-center, randomized, controlled, parallel group, superiority trial. A total of 154 adult patients are allocated in a ratio of 1:1. Sample size and power calculation were performed to detect the minimal clinically important difference of 10%, with an expected standard deviation of 20% in the primary outcome parameter, the Oswestry Disability Index, with power of 80%, based on an assumed maximal dropout rate of 20%. Secondary outcome parameters include the EuroQoL 5-Dimension questionnaire, the Beck Depression Inventory, the painDETECT questionnaire and the "timed up and go" test. Furthermore, radiological and health economic outcomes will be evaluated. Follow up is performed until 5 years after surgery. Major inclusion criteria are lumbar degenerative spondylolisthesis with Meyerding grade I or II, which qualifies for decompression and fusion by medialised posterior screw placement with cortical trajectory (mPACT) or by a traditional trajectory for lumbar pedicle screw placement. Discussion: This trial will contribute to the understanding of the short-term and long-term clinical and radiological postoperative course in patients with lumbar degenerative disc disease, in which the mPACT technique is used.