Spinal Motion Segment Research Articles

Моделювання варіантів транспедикулярної фіксації грудного відділу хребта при резекції одного-трьох хребців

Актуальність. Патологічні переломи хребців є найбільшим ускладненням пухлинного процесу. Застосування додаткової внутрішньої фіксації металевими імплантатами значно покращує результати лікування й скорочує строки реабілітації хворих. Використання транспедикулярних пристроїв забезпечує стабільну фіксацію й стабільність сегментів хребта навіть при максимальному ступені його нестабільності. Мета: визначення оптимального варіанта протяжності заднього спондилодезу при паліативному та радикальному хірургічному лікуванні пухлин хребта. Матеріали та методи. Для вивчення можливостей стабілізації за допомогою транспедикулярної фіксації при резекції одного-трьох хребців провели експериментальні випробування на препаратах хребта свині. Використовували препарати сегментів грудного відділу хребта від Th3 до Th12 хребців. Вивчали 3 групи моделей: з одним резектованим хребцем Th6, з двома — Th5-Th6 і з трьома — Th5-Th7. Результати. Виявлено, що при резекції одного хребця в грудному відділі хребта транс-педикулярна фіксація за схемами 111х111, 101х101 та 011х110 має однакову ефективність. При резекції двох хребців найкращі стабілізуючі можливості мала конструкція за схемою 111хх111, схеми 101хх101 та 011хх110 показали доволі непогану фіксуючу здатність. При резекції трьох хребців грудного відділу хребта найбільш стабільну фіксацію показала схема 111ххх111. Схема фіксації 001ххх100 виявилась нестабільною при всіх видах резекції хребців. Висновки. Експериментальні дослідження транспедикулярної фіксації при радикальному хірургічному лікуванні пухлин хребта, який включає резекцію одного-трьох хребців, показали, що конструкція відповідає вимогам фіксації, коли кріплення відбувається не менше ніж за два верхніх та два нижніх хребці (можна через один), при резекції трьох хребців найбільш стабільною є конструкція з кріпленням за три верхні та три нижні хребці (без пропусків). Система кріплення за один хребець виявилася неспроможною майже при всіх видах резекції.

Alteration of the Sitting and Standing Movement in Adult Spinal Deformity.

Adults with spinal deformity (ASD) are known to have spinal malalignment affecting their quality of life and daily life activities. While walking kinematics were shown to be altered in ASD, other functional activities are yet to be evaluated such as sitting and standing, which are essential for patients’ autonomy and quality of life perception. In this cross-sectional study, 93 ASD subjects (50 ± 20 years; 71 F) age and sex matched to 31 controls (45 ± 15 years; 18 F) underwent biplanar radiographic imaging with subsequent calculation of standing radiographic spinopelvic parameters. All subjects filled HRQOL questionnaires such as SF36 and ODI. ASD were further divided into 34 ASD-sag (with PT > 25° and/or SVA >5 cm and/or PI-LL >10°), 32 ASD-hyperTK (with only TK >60°), and 27 ASD-front (with only frontal malalignment: Cobb >20°). All subjects underwent 3D motion analysis during the sit-to-stand and stand-to-sit movements. The range of motion (ROM) and mean values of pelvis, lower limbs, thorax, head, and spinal segments were calculated on the kinematic waveforms. Kinematics were compared between groups and correlations to radiographic and HRQOL scores were computed. During sit-to-stand and stand-to-sit movements, ASD-sag had decreased pelvic anteversion (12.2 vs 15.2°), hip flexion (53.0 vs 62.2°), sagittal mobility in knees (87.1 vs 93.9°), and lumbar mobility (L1L3-L3L5: −9.1 vs −6.8°, all p < 0.05) compared with controls. ASD-hyperTK showed increased dynamic lordosis (L1L3–L3L5: −9.1 vs −6.8°), segmental thoracic kyphosis (T2T10–T10L1: 32.0 vs 17.2°, C7T2–T2T10: 30.4 vs 17.7°), and thoracolumbar extension (T10L1–L1L3: −12.4 vs −5.5°, all p < 0.05) compared with controls. They also had increased mobility at the thoracolumbar and upper-thoracic spine. Both ASD-sag and ASD-hyperTK maintained a flexed trunk, an extended head along with an increased trunk and head sagittal ROM. Kinematic alterations were correlated to radiographic parameters and HRQOL scores. Even after controlling for demographic factors, dynamic trunk flexion was determined by TK and PI-LL mismatch (adj. R 2 = 0.44). Lumbar sagittal ROM was determined by PI-LL mismatch (adj. R 2 = 0.13). In conclusion, the type of spinal deformity in ASD seems to determine the strategy used for sitting and standing. Future studies should evaluate whether surgical correction of the deformity could restore sitting and standing kinematics and ultimately improve quality of life.

СПОСОБ ДИАГНОСТИКИ НЕСТАБИЛЬНОСТИ ПОЗВОНОЧНО-ДВИГАТЕЛЬНОГО СЕГМЕНТА ПРИ ОСТЕОХОНДРОЗЕ ШЕЙНОГО ОТДЕЛА ПОЗВОНОЧНИКА

Introduction. Instability — dislocation of the vertebrae, one of the forms of the motor segment dysfunction, causes pain and subsequent neurological disorders. There is a direct relationship between the data of the instability indicator and the clinical picture: the higher it is, the more pronounced the clinical manifestations of vertebral displacementare. And vice versa, conversely, its zero value (there is a functional block) coincides with rare exacerbations of the pain syndrome and a relatively satisfactory condition of the patient. Various types of vertebrae dislocation are much more common than is determined by functional radiography of the spine. As a rule, cervical dislocations are diagnosed already at a later date, when conservative measures are difficult and ineffective, and high-tech surgical treatment is requiring with certain material costs. Aim. To study the effectiveness of the developed method of functional radiography with weights for diagnosing instability of the spinal motion segment in the cervical spine. Materials and methods. 50 patients were under observation, the average age was 50.6 ± 2.19 years. All patients were admitted to the neurosurgical department of the clinic of the Irkutsk Scientific Center for Surgery and Traumatology with a diagnosis of adult osteochondrosis of spine (ICD M 42.1). Results. A comparative analysis of the study results of the effectiveness of X-ray methods for diagnosing instability of the spinal motion segment in the cervical spine revealed that the method of weight-bearing spondylography, where the percentage of verification was 68 %, was the most sensitive one. We have developed a formula for determining instability in the spinal motion segment: z = a + b · x – c · l, where z — indicator of instability of determined spinal motion segments; x — patient’s age; l — length of the cervical spine — the distance from the condyle of the lower jaw to the upper contour of the spinous process of the first thoracic vertebra — ThI, a, b, c — coefficients of linear dependence, obtained by the method of least squares by experimental-calculation (software-computing complex Table Curve 3D v4.0.01). The cervical dislocation was measured when the patient's neck was bent 45° forward (flexion) and 15° backward (extention). The obtained data were grouped according to the sex of the patients, and displacement of the vertebrae. This relationship shows that the maximum normal strain of the intervertebral discs is manifested at a neck flexion of 45°, extension of 15°, and with a load of 500 g, mounted on the patient’s head. A correlation between the length of the cervical spine and the age of patients was established, the correlation coefficient was rix = 0.58. The correlation dependence of the index of the cervical vertebrae instability and the age of patients was checked, the correlation coefficient was rix = 0,58. Correlation coefficients show a fairly high correlation between the length of the cervical spine and age of patients, the index of instability of the cervical vertebrae and age of patients, the index of instability of the cervical vertebrae and length of the neck of patients. The values of the coefficients used in the proposed formula are a = 11.13; b = 0.11; c = 0.45 were obtained by the least squares method experimentally and calculated based on a mathematical analysis of the results of studies of 50 patients. Conclusion. The method of functional weight-bearing spondylography makes it possible to reliably detect instability of the spinal motion segment, while the percentage of verification was 68%. The proposed formula of mathematical calculation helps to clarify the index of instability of the cervical spinal motion segment and can be used in practical work.

Development and Biomechanical Evaluation of a 3D Printed Analogue Lumbar Spine Motion Segment

Development and Biomechanical Evaluation of a 3D Printed Analogue Lumbar Spine Motion Segment

A Clinico–radiological Correlation of Patients with Lumbar Spinal Instability

Background: A larger than normal range of motion in the spinal segment defines lumbar segmental instability, which is a sort of aberrant motion to physiologic stressors. Clinical complaints and signs such as low back ache or radiculopathy, as well as Kotilainen and Valtonen's three criteria for instability (painful catch, instability catch, and apprehension) will be correlated with an MRI investigation to determine lumbar spinal instability. Disc degeneration and facet degeneration along with soft tissues supporting spinal motion segment are important provocative factors for lumbar spine instability. The existence of lumbar instability must be identified since it can alter the treatment approach and patient prognosis.&#x0D; Objective: To evaluate clinical signs and symptoms in patients with Lumbar spinal instability, as well as to investigate radiological signs using X-rays and an MRI scan.&#x0D; Methods and Materials: In this study in which patients with history suggestive of Lumbar spinal instability will be evaluated clinically and radiologically. Patients of age group of 25-75 years will be included in this study. Clinical tests, static and dynamic Xrays and MRI scan will be studied.&#x0D; Expected Outcomes: By this study we can expect clinico–radiological co relation in patient with low back ache in lumbar spinal instability. Outcome data will be assessed on Clinico-radiological Criteria of Lumbar Instability and clinic-radiological correlation will be done.

Facet syndrome. Minimally invasive surgical treatment. Clinical case with a literature review

Background: Degenerative pathology of the facet joints of the lumbar spine remains a significant medical and social problem due to persistent pain syndrome, high incidence and disability rate.&#x0D; Clinical case description: A patient complaining of pain and discomfort in the lumbosacral spine on the right, arising in the upright position, intensifying with bending and flexion-extension of the trunk, and periodically spreading to the right gluteal region and along the posterior surface of the thigh, was admitted to the neurosurgical department of the Irkutsk Scientific Center of Surgery and Traumatology. A surgical treatment was performed in the form of dereception of the LIILIII, LIIILIV, LIVLV arch-process joints. In the postoperative period, the patient noted a decrease in the intensity of pain in the lumbosacral spine to 3 points by a visual analog scale and was discharged from the department on the 5th day after the surgery in a satisfactory condition.&#x0D; Conclusion: Facet joint pathologies represent a most common nosological form of the degenerative-dystrophic process (spondyloarthrosis) and a potential source of pain with the formation of instability of the spinal motion segment and chronic pain syndrome. The complex anatomical and topographic relationships between the facet joints, intervertebral discs, and radicular nerves force clinicians to pay attention to the pathology of facet syndrome. Understanding the morphological, clinical, and radiological features of the course of the facet joint degeneration makes it possible to increase the diagnostic capabilities for detecting facet syndrome of the lumbar spine and effectively apply transcutaneous surgical technologies for the treatment of chronic pain syndromes.

Three-Dimensional-Printed Flexible Scaffolds Have Tunable Biomimetic Mechanical Properties for Intervertebral Disc Tissue Engineering.

The intervertebral disc (IVD) exhibits complex structure and biomechanical function, which supports the weight of the body and permits motion. Surgical treatments for IVD degeneration (e.g., lumbar fusion, disc replacement) often disrupt the mechanical environment of the spine which lead to adjacent segment disease. Alternatively, disc tissue engineering strategies, where cell-seeded hydrogels or fibrous biomaterials are cultured in vitro to promote matrix deposition, do not recapitulate the complex IVD mechanical properties. In this study, we use 3D printing of flexible polylactic acid (FPLA) to fabricate a viscoelastic scaffold with tunable biomimetic mechanics for whole spine motion segment applications. We optimized the mechanical properties of the scaffolds for equilibrium and dynamic moduli in compression and tension by varying fiber spacing or porosity, generating scaffolds with de novo mechanical properties within the physiological range of spine motion segments. The biodegradation analysis of the 3D printed scaffolds showed that FPLA exhibits lower degradation rate and thus has longer mechanical stability than standard PLA. FPLA scaffolds were biocompatible, supporting viability of nucleus pulposus (NP) cells in 2D and in FPLA+hydrogel composites. Composite scaffolds cultured with NP cells maintained baseline physiological mechanical properties and promoted matrix deposition up to 8 weeks in culture. Mesenchymal stromal cells (MSCs) cultured on FPLA adhered to the scaffold and exhibited fibrocartilaginous differentiation. These results demonstrate for the first time that 3D printed FPLA scaffolds have de novo viscoelastic mechanical properties that match the native IVD motion segment in both tension and compression and have the potential to be used as a mechanically stable and biocompatible biomaterial for engineered disc replacement.

Оптимізація хірургічної корекції сагітального контуру хребетно-рухового сегмента при виконанні вентрального субаксіального цервікоспондилодезу

Актуальність. Найбільш поширеною системою стабілізації при виконанні вентральних декомпресивно­стабілізуючих втручань на субаксіальному рівні шийного відділу хребта є комбінація вертикального циліндричного сітчастого імпланту та вентральної пластини. Незважаючи на значний клінічний досвід застосування, на сьогодні відсутня єдина думка щодо оптимальної корекції висоти оперованого хребетно­рухового сегмента і формування певного сегментарного профілю в зоні хірургічного втручання. Мета: поліпшити показники стану сагітального кіфозу оперованого сегмента у віддаленому післяопераційному періоді в пацієнтів, які перенесли вентральний субаксіальний цервікоспондилодез. Матеріали та методи. Виконано ретроспективну оцінку і спондилограмметричний аналіз стану сагітального кіфозу в 151 пацієнта, які перенесли вентральний бісегментарний субаксіальний цервікоспондилодез у зв’язку з травматичним пошкодженням. Проведено статистичний аналіз і визначено залежність фінальних результатів від ступеня інтраопераційної корекції. Верифіковано діапазони інтраопераційних значень сагітального кіфозу оперованого хребетно­рухового сегмента, що формують різні біомеханічні відповіді шийного відділу хребта у віддаленому післяопераційному періоді. Результати. Методом нелінійного регресійного аналізу визначено залежність фінальних від вихідних показників стану сегментарного кіфозу оперованого сегмента. Кластерний аналіз виявив такі діапазони інтраопераційних значень сегментарного кіфозу: &lt; –6,15°; –6,15°…–3,10°; &gt; –3,10°, що визначають різну динаміку післяопераційних змін. Висновки. Інтраопераційна корекція з формуванням кіфозу в діапазоні –6,15°…–3,10° є оптимальною для збереження фізіологічної кривизни оперованого сегмента в віддаленому післяопераційному періоді.

3D visualization and morphometric analysis of spinal motion segments and vascular networks: A synchrotron radiation-based micro-CT study in mice.

The structure of spinal motion segments and spinal vasculature is complicated. Visualizing the three-dimensional (3D) structure of the spine may provide guidance for spine surgery. However, conventional imaging techniques fail to simultaneously obtain 3D images of soft and hard tissues, and achieving such coimaging states of the spine and its vascular networks remains a challenge. Synchrotron radiation micro-CT (SRμCT) provides a relatively effective and novel method of acquiring detailed 3D information. In this study, specimens of the thoracic spine were obtained from six mice. SRμCT was employed to acquire 3D images of the structure, and histologic staining was performed for comparisons with the SRμCT images. The whole spinal motion segments and the spinal vascular network were simultaneously explored at high resolution. The mean thickness of the cartilaginous end plates (CEPs) and the volume of the intervertebral discs (IVDs) were calculated. The surface of the CEPs and the facet joint cartilage (FJC) were presented as heat maps, which allowed for direct visualization of the thickness distribution. Regional division revealed heterogeneity among the ventral, central, and dorsal parts of the CEPs and between the superior and inferior parts of the facet processes. Moreover, the connections and spatial morphology of the spinal vascular network were visualized. Our study indicates that SRμCT imaging is an ideal method for high-resolution visualization and 3D morphometric analysis of the whole spinal motion segments and spinal vascular network.

Morphometric measurements can improve prediction of progressive vertebral deformity following vertebral damage.

A damaged vertebral body can exhibit accelerated 'creep' under constant load, leading to progressive vertebral deformity. However, the risk of this happening is not easy to predict in clinical practice. The present cadaveric study aimed to identify morphometric measurements in a damaged vertebral body that can predict a susceptibility to accelerated creep. A total of 27 vertebral trabeculae samples cored from five cadaveric spines (3 male, 2 female, aged 36 to 73 (mean 57) years) were mechanically tested to establish the relationship between bone damage and residual strain. Compression testing of 28 human spinal motion segments (three vertebrae and intervening soft tissues) dissected from 14 cadaveric spines (10 male, 4 female, aged 67 to 92 (mean 80) years) showed how the rate of creep of a damaged vertebral body increases with increasing "damage intensity" in its trabecular bone. Damage intensity was calculated from vertebral body residual strain following initial compressive overload using the relationship established in the compression test of trabecular bone samples. Calculations from trabecular bone samples showed a strong nonlinear relationship between residual strain and trabecular bone damage intensity (R2 = 0.78, P < 0.001). In damaged vertebral bodies, damage intensity was then related to vertebral creep rate (R2 = 0.39, P = 0.001). This procedure enabled accelerated vertebral body creep to be predicted from morphological changes (residual strains) in the damaged vertebra. These findings suggest that morphometric measurements obtained from fractured vertebrae can be used to quantify vertebral damage and hence to predict progressive vertebral deformity.

Minimally Invasive Reconstruction of Vertebral Arch in Spondylolisthesis in Children and Adolescents.

The aim of the study was to assess the effectiveness of the minimally invasive technique used to reconstruct the vertebral arch with a pedicle screw hook system in grade I isthmic spondylolisthesis in comparison with the traditional technique of segment stabilization with interbody fusion.Materials and MethodsThe study included 26 patients aged from 11 to 17 years. The follow-up period lasted from 1 to 7 years. Two groups were formed: in group 1 (n=6), segments L5–S1 were stabilized using the traditional technique; in group 2 (n=20), the arch of the L5 vertebra was reconstructed by means of minimally invasive surgery. The pain syndrome was assessed in each study group using the visual analogue scale and Macnab criteria before and after surgery; blood loss, duration of surgery in minutes, and hospitalization in days were also measured.ResultsAccording to the Macnab scale, the two presented techniques did not show any statistically significant differences; however, when the arch synthesis technique was employed the spinal motion segment remained intact. Furthermore, in group 2, the volume of blood loss was smaller (44.0±19.6 compared to 300.0±130.4 ml, p<0.0001), the duration of the operation was 176.0±41.6 compared to 349.2±93.2 min, p<0.0001, and hospital stay was 6.9±1.6 compared to 10.0±2.1 days, p=0.0025 in the control group.ConclusionThe technique of vertebral arch reconstruction by a minimally invasive access gives the possibility to stabilize the spinal motion segment and to preserve biomechanics and movements in the spine. This technique allows for shorter inpatient stays for patients as well as earlier recovery and rehabilitation due to reduced surgery time and blood loss.

Comparative analysis of the results using direct lateral interbody spondilodesis and transforaminal lumbar interbody spondilodesis in patients with degenerative diseases of the lumbar spine

Introduction Various spondylodesis techniques are used in patients with degenerative diseases of the lumbar spine, but the benefits of these techniques have not been proven.Objective of the study was to assess the effect of the type of fusion on the incidence of implant instability and related revision surgeries.Material and Methods This monocentric prospective study included 133 patients with degenerative stenosis of the lumbar spine and confirmed instability of spinal motion segments. Patients underwent transforaminal lumbar interbody fusion (TLIF) with a single cage or direct lateral interbody fusion (DLIF) using standard-sized cages. The conventional open technique was used to supplement TLIF with pedicle screws while percutaneous screw placement was applied in patients treated with DLIF. The duration of follow-up was 18 months. Fisher's exact test was used to assess differences in the incidence of fixator instability based on MSCT and revision interventions. Logistic regression was used to assess the association between potential risk factors and complication rates.Results The use of DLIF detected by MSCT (32.9 vs 3.6%, p &lt; 0.0001) resulted in a significant reduction in the incidence of screw instability and associated revision interventions (11.8 vs 0%, p = 0.0122). The results of logistic regression, taking into account factors such as bone density and the number of levels at which spondylodesis was performed, confirm the relationship between the reduced incidence of complications and the use of DLIF technology. Conclusion Using DLIF instead of TLIF in patients with degenerative stenosis at the lumbar spine level can lead to a significant reduction in the frequency of screw instability and associated revision surgeries.

Effect of overload on changes in mechanical and structural properties of the annulus fibrosus of the intervertebral disc

The research focussed on analysing structural and mechanical properties in the intervertebral disc (IVD), caused by long-term cyclic loading. Spinal motion segments were divided into two groups: the control (C), and the group in which it was analysed the impact of posterior column in the load-bearing system of the spine—specimens with intact posterior column (IPC) and without posterior column (WPC). To evaluate the structural and mechanical changes, the specimens were tested with simulation of 100,000 compression-flexion load cycles after which it was performed macroscopic analysis. Mechanical properties of the annulus fibrosis (AF) from the anterior and posterior regions of the IVD were tested at the uniaxial tension test. The stiffness coefficient values were statistically 32% higher in the WPC group (110 N/mm) than in the IPC (79 N/mm). The dynamics of increase in this parameter does not correspond with the course of decrease in height loss. WPC segments revealed clear structural changes that mainly involve the posterior regions of the IVD (bulging and delamination with the effect of separation of collagen fibre bundles). Pathological changes also caused decreases in the value of stress in the AF. The greatest changes in the stress value about group C (7.43 ± 4.49 MPa) were observed in the front part of the fibrous ring, where this value was for IPC 4.49 ± 4.78 MPa and WPC 2.56 ± 1.01 MPa. The research indicates that the applied load model allows simulating damage that occurs in pathological IVD. And the posterior column’s presence affects this change’s dynamics, structural and mechanical properties of AF.

Surgical treatment of facet syndrome in segmental instability of the lumbar spine

A clinical example shows a rare case of surgical treatment of facet syndrome, which is formed against the background of instability of the spinal motion segment of the spine at the L IV -L V level using the method of laser vaporization and denervation of the facet joints. The aim of the work is to consider the clinical and diagnostic indicators of facet syndrome and to assess the role of imaging research methods in the diagnosis of this syndrome. At the outpatient stage, with long-term persistent pain syndrome in the lumbar spine, non-stop conservative methods of treatment, the patient underwent survey radiography and MRI examination of this area in order to exclude a specific process (oncopathology, pathological fracture against the background of osteoporosis, spondylitis, etc.) Chronic pain syndrome with its ineffective conservative treatment leads to maladjustment of the psychoemotional and professional-labor state of the patient. Determining the source of pain impulses in the lumbar spine can be difficult, since pain can cause degenerative and pathological changes in various anatomical structures of the spine (intervertebral disc, facet joints, ligaments, muscles, etc.), which can form a clinical picture of pain syndrome with its various manifestations and symptoms, which do not always clearly determine the level and structure of the affected spine. In this connection, for the timely and correct determination of the diagnosis of all patients with chronic pain syndrome in the lumbar spine, it is necessary to be sent to specialized neurosurgical institutions, in which patients undergo a set of necessary medical and diagnostic procedures to determine the further management tactics and treatment algorithm for this category of patients.

Prediction of the natural frequencies of different degrees of degenerated human lumbar segments L2-L3 using dynamic finite element analysis

Background and ObjectiveChronic exposure to resonant environment may cause more serious injuries to human lumbar spine than other vibrations. On the condition that the natural frequency of human lumbar spine is known, excitation frequency from an external vibration source can be optimized to keep away from the natural frequency and thus avoid lumbar resonance. Therefore, this study aimed to present an approach to predict the natural frequency of the human lumbar spine. MethodsFour poroelastic finite element models of human L2–L3 spinal motion segments with different degrees of degeneration were established. Dynamic finite element analyses of these models during 1 h of vibration were then conducted. The mechanical parameters of these models under vibrations at different excitation frequencies were predicted. The excitation frequencies that resulted in the greatest changes in the lumbar mechanical parameters were identified as the natural frequencies of the established L2–L3 spinal motion segments. ResultsSimulation results showed that the natural frequencies of the healthy and mildly degenerated L2–L3 spinal motion segments, moderately degenerated L2–L3 spinal motion segments, and seriously degenerated L2–L3 spinal motion segments were in the range of 5–7, 3–5, and 1–3 Hz, respectively. ConclusionsThe predicted results indicated that the natural frequencies of the human L2–L3 spinal motion segments gradually decreased with the severity of degeneration. These phenomena may be related to changes in the lumbar structures and materials because of degeneration. This study provided a feasible method to predict the lumbar natural frequencies for different populations, which may be helpful in optimizing external vibration sources to avoid lumbar resonance.

168. Minimally invasive hydrogel nucleoplasty in a goat model of moderate severity disc degeneration

<h3>BACKGROUND CONTEXT</h3> Intervertebral disc (IVD) degeneration (IVDD) is implicated as a cause of low back pain. The earliest degenerative changes typically occur in the central nucleus pulposus (NP), where progressive loss of proteoglycans and associated hydration compromise tissue mechanical function. <h3>PURPOSE</h3> We developed a noncrosslinked injectable hydrogel for NP replacement and augmentation together with its percutaneous delivery method and instrument assembly. We then evaluated the short- and long-term performance of this hydrogel in a goat model of moderate IVDD. <h3>Methods</h3> Six goats underwent two percutaneous procedures: one to induce degeneration in 3 lumbar IVDs via injection of 1U C-ABC and, 2 weeks later, a second procedure for the delivery of hydrogel at 2 levels with the third remaining untreated. Animals were euthanized at 6 weeks (n=2) and 12 weeks (n=1); three animals are currently enrolled for long-term survival. Disc height index (DHI) was measured from monthly lateral radiographs in the standing animal. Postmortem, motion segments were imaged using microcomputed tomography (µCT) to assess hydrogel distribution and bone volume fraction values (BV/TV) for cranial and caudal endplates. Volumetric analysis and compression testing were performed on explanted gels. Samples were dried to determine polymer and water content. Explant characteristics were compared to nonimplanted gels. Histology was performed to assess glycosaminoglycans and collagen content, cellularity, and disc morphology. Significant changes in DHI were established using Wilcoxon matched-pairs signed ranks tests and differences in histological grades were established using Kruskal-Wallis test with post-hoc Dunn's tests (p<0.05). <h3>Results</h3> Animals recovered uneventfully from surgical procedures. Extrusion of hydrogel into the spinal canal during delivery occurred in two animals without major clinical repercussions. At 2 weeks after C-ABC injection, DHI was ∼80% of pre-C-ABC levels. For IVDs treated with hydrogel, DHI improved while untreated IVDs continued to degenerate. The hydrogel presents radiographically unremarkable for up to 2 years post nucleoplasty. µCT imaging demonstrated that the majority of hydrogel was localized to the central NP. BV/TV ratio of treated levels at 6-week and 12-week endpoint were similar to controls. Explant analyses showed higher elastic moduli and polymer content compared to nonimplanted gels. Treated IVDs exhibited an overall improved histological grade compared to positive controls. <h3>Conclusions</h3> The results of this work illustrate the practical utility of an injectable hydrogel being effective in normalizing the mechanical function of the degenerating IVD in a clinically relevant animal model. The implant showed successful retention without extrusion following delivery. A critical benchmark for the success of any injectable implant to treat IVDD is the normalization of mechanical properties. We demonstrate through long-term in vivo follow up studies that hydrogel injected into degenerating goat discs can preserve the spine motion segment. There is a critical need for new therapies for patients with symptomatic disc degeneration that preserve joint mobility. A minimally invasive injectable therapy mitigates anulus fibrosus trauma during nucleoplasty and may restore the biomechanics of the motion segment. Moreover, successful biomechanical restoration of the affected motion segment may slow or prevent further IVDD. Motion preservation therapies may also help mitigate adjacent level IVDD in these patient cohorts. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Anatomic Image-Based Classification of Lumbar Intervertebral Disc Pathologies.

IntroductionSeveral minimally invasive spine approaches and techniques have been developed in recent years. While the disease processes affecting the spinal motion segment have remained largely the same, the emerging technologies have changed treatment options radically and not necessarily in an organized fashion. The current diagnostic techniques, also evolving, have helped us appreciate the disease's pathoanatomy in minute details. A comprehensive classification method accounting for all anatomical variations in the disc disease, tailored to treatment options, is necessary. Such a classification will allow the surgeon to choose an appropriate surgical option in a consistent fashion. We feel that our classification system will help the spine surgeon make that important decision consistently, with minimal risk of leaving behind a significant lesion or disrupting an otherwise normal structure of the spinal motion segment. Furthermore, we feel such a comprehensive classification will help surgeons and other caregivers to standardize treatment approaches to the various presentations of disc disease, and apply the evolving technology in an organized fashion.PurposeTo develop a comprehensive, treatment-orientated classification of the lumbar disc disease.Materials and MethodsThe literature was reviewed for the classification of disc disease. The morphology of the disc disease, the topography of the disc lesion, and the symptom-complex produced by the disc lesion are identified and graded. The features so identified and graded are placed in a matrix. The combinations of the anatomical features and symptoms are then computed as shown in the matrix. The MRI database held in the office was studied to determine the most frequent combinations of the disc disease and symptom complex.ResultsA total of 494 combinations were identified, but most have no clinical relevance. The retrospective study of the clinical data and MRI studies of 93 patients (50 male and 43 female) revealed the most affected motion-segment was L5-S1 (male = 19.3%, and female = 23.8%). The most common patho-anatomy is a globally bulging disc (T3L1), representing 37.6% of the total. The second most common combination is a degenerated disc with central, intra-annular tear T4L1), representing 20.4% of the total. At 11.8%, globally bulging with severe axial pain and moderate radicular pain represented the most common patho-anatomic/clinical classification (T3L1B4R2). The most frequent top 10 patho-anatomic/clinical classifications represented 15.5% of the total.ConclusionIn light of the multiple surgical options for excision of the herniated lumbar disc, including the conventional and minimally invasive, and the fact that the imaging technology allows spine surgeons to see in great detail, the disease status of each of the components of the spinal motion segment, it is imperative to develop comprehensive classification systems which take account of the unique characteristics of the disease entity and guide treatment strategies. The classification system presented here is fairly complex, but the software technology will be utilized for the classification system along with the most appropriate treatment approach.

Early bone ingrowth and segmental stability of a trussed titanium cage versus a polyether ether ketone cage in an ovine lumbar interbody fusion model

BACKGROUND CONTEXTLumbar interbody fusion is an effective treatment for unstable spinal segments. However, the time needed to establish a solid bony interbody fusion between the two vertebrae may be longer than twelve months after surgery. During this time window, the instrumented spinal segment is assumed to be at increased risk for instability related complications such as cage migration or subsidence. It is hypothesized that the design of new interbody cages that enable direct osseointegration of the cage at the vertebral endplates, without requiring full bony fusion between the two vertebral endplates, might shorten the time window that the instrumented spinal segment is susceptible to failure. PURPOSETo quantify the bone ingrowth and resulting segmental stability during consolidation of lumbar interbody fusion using two different cage types. STUDY DESIGNPreclinical ovine model. METHODSSeven skeletally mature sheep underwent bi-segmental lumbar interbody fusion surgery with one conventional polyether ether ketone (PEEK) cage, and one newly developed trussed titanium (TT) cage. After a postoperative time period of 13 weeks, non–destructive range of motion testing, and histologic analysis was performed. Additionally, sample specific finite element (FE) analysis was performed to predict the stability of the interbody fusion region alone. RESULTSPhysiological movement of complete spinal motion segments did not reveal significant differences between the segments operated with PEEK and TT cages. The onset of creeping substitution within the cage seemed to be sooner for PEEK cages, which led to significantly higher bone volume over total volume (BV/TV) compared with the TT cages. TT cages showed significantly more direct bone to implant contact (BIC). Although the mean stability of the interbody fusion region alone was not statistically different between the PEEK and TT cages, the variation within the cage types illustrated an all-or-nothing response for the PEEK cages while a more gradual increase in stability was found for the TT cages. CONCLUSIONSSpinal segments operated with conventional PEEK cages were not different from those operated with newly developed TT cages in terms of segmental stability but did show a different mechanism of bone ingrowth and attachment. Based on the differences in development of bony fusion, we hypothesize that TT cages might facilitate increased early segmental stability by direct osseointegration of the cage at the vertebral endplates without requiring complete bony bridging through the cage. CLINICAL SIGNIFICANCEInterbody cage type affects the consolidation process of spinal interbody fusion. Whether different consolidation processes of spinal interbody fusion result in clinically significant differences requires further investigation.

Evaluation of dynamic MRI data in patients with herniated intervertebral discs after the complex treatment including osteopathic correction

Introduction. Pain in the lumbosacral region is one of the most common causes of disability and medical attention acquiring. Magnetic resonance imaging (MRI) of the spine in these patients quite often demonstrates multiple hernias. Despite the success of modern, including complex, methods of treating patients with herniated discs of lumbosacral spine, the problem of objective revealing of the applied therapy effect with modern instrumental examination methods is actual.The goal of research — study was to study the changes in the MRI picture in patients with herniated intervertebral discs during treatment with inclusion of osteopathic correction.Materials and methods. The study involved 15 patients with herniated intervertebral discs of lumbosacral spine. The patients received outpatient conservative treatment with inclusion of osteopathic correction. Participants underwent MRI of the lumbar spine at the beginning of the study and 3 months after treatment. The obtained data were processed by methods of nonparametric statistics.Results. After the complex treatment, such indicators of MRI as the hernia size, the lateral pocket width and the pelvis configuration significantly improved. These parameters are important indicators of pathomorphological changes in the spinal motion segment, affecting the discoradicular conflict. At the same time, there were no obtained convincing data about the therapy effect on the L5 vertebra rotation, on the presence of sequestration and changes in the Tchaikovsky index. Perhaps this is due to the small sample and short follow-up period for patients.Conclusion. After the course of treatment with inclusion of osteopathic correction, the statistically significant changes in MRI images were revealed in patients with herniated intervertebral discs, indicating a positive dynamics in the parameters of the hernia size, the width of the lateral pocket and the configuration of the pelvis.

Developing a novel functional disc emulator to investigate the nucleus pulposus replacement

We have developed a simple, inexpensive and innovative device for reproducing the global mechanical behavior of spinal motion segments and the local mechanical environment experienced by lumbar intervertebral discs. The device has several broad functions: (1) exploration of the basic mechanics underlying this complex skeletal system, (2) connecting changes in tissue characteristics with overall motion segment function, and (3) evaluation of strategies for repair and replacement of disc components. This “disc emulator” consists of three main parts: (1) an artificial annulus fibrosus (AAF), made out of silicone, with lumbar disc geometry and adjustable material properties, (2) a hydrogel nucleus pulposus (NP) also with lumbar disc geometry and adjustable material properties, and (3) simulated vertebral bodies 3D printed with trabecular bone simulated by a rigid polymer (Acrylonitrile Butadiene Styrene, ABS) and end plates crafted from a compliant polymer (Thermoplastic Polyurethane, TPU). Mechanical compression experiments have been conducted using the disc emulator under similar protocols to published studies of human cadaver samples. Bulging of the artificial annulus fibrosus was examined under axial compression loads using digital image correlation (DIC), and results show close agreement. We see this approach of using anatomical geometry and multiple adjustable components as a useful means of creating accurate local stress/strain environments for preliminary material evaluation, without the variability and difficulty inherent indirect testing of cadaveric materials.