Posterior Elements Research Articles

Biportal Endoscopic Lumbar Ponte Osteotomy for Kyphosis: A Technical Note

Biportal endoscopic lumbar Ponte osteotomy (BELPO) is an innovative technique for correcting kyphotic deformities. Unlike the original technique, which maintains an intact anterior column, BELPO involves the endoscopic release of the anterior elements in addition to the endoscopic resection of the posterior elements in interbody fusion. BELPO is performed using unilateral biportal endoscopy with the patient in a prone position. First, a small incision is made in the midline over the interspinous gap. Through this gap, a generous portion of the spinous processes and interspinous ligament is removed. Using this incision as both the viewing and working portal, complete facetectomy and partial laminectomy are performed. Posterior compression is then applied to achieve the desired lordosis. Pedicle screws are fixed with cement augmentation. A 71-year-old female patient presented with low back pain and positive sagittal imbalance. She had a rigid posttraumatic kyphosis at L2–3 due to an old compression fracture at L3. After BELPO, the kyphosis at L2–3 improved from 21º to 2º. BELPO is a promising novel method of minimally invasive deformity correction, offering particular advantages for frail, osteoporotic patients.

SPINEPS—automatic whole spine segmentation of T2-weighted MR images using a two-phase approach to multi-class semantic and instance segmentation

Abstract Objectives Introducing SPINEPS, a deep learning method for semantic and instance segmentation of 14 spinal structures (ten vertebra substructures, intervertebral discs, spinal cord, spinal canal, and sacrum) in whole-body sagittal T2-weighted turbo spin echo images. Material and methods This local ethics committee-approved study utilized a public dataset (train/test 179/39 subjects, 137 female), a German National Cohort (NAKO) subset (train/test 1412/65 subjects, mean age 53, 694 female), and an in-house dataset (test 10 subjects, mean age 70, 5 female). SPINEPS is a semantic segmentation model, followed by a sliding window approach utilizing a second model to create instance masks from the semantic ones. Segmentation evaluation metrics included the Dice score and average symmetrical surface distance (ASSD). Statistical significance was assessed using the Wilcoxon signed-rank test. Results On the public dataset, SPINEPS outperformed a nnUNet baseline on every structure and metric (e.g., an average over vertebra instances: dice 0.933 vs 0.911, p < 0.001, ASSD 0.21 vs 0.435, p < 0.001). SPINEPS trained on automated annotations of the NAKO achieves an average global Dice score of 0.918 on the combined NAKO and in-house test split. Adding the training data from the public dataset outperforms this (average instance-wise Dice score over the vertebra substructures 0.803 vs 0.778, average global Dice score 0.931 vs 0.918). Conclusion SPINEPS offers segmentation of 14 spinal structures in T2w sagittal images. It provides a semantic mask and an instance mask separating the vertebrae and intervertebral discs. This is the first publicly available algorithm to enable this segmentation. Key Points QuestionNo publicly available automatic approach can yield semantic and instance segmentation masks for the whole spine (including posterior elements) in T2-weighted sagittal TSE images. FindingsSegmenting semantically first and then instance-wise outperforms a baseline trained directly on instance segmentation. The developed model produces high-resolution MRI segmentations for the whole spine. Clinical relevanceThis study introduces an automatic approach to whole spine segmentation, including posterior elements, in arbitrary fields of view T2w sagittal MR images, enabling easy biomarker extraction, automatic localization of pathologies and degenerative diseases, and quantifying analyses as downstream research.

Differences in Cervical Spine Fractures in Patients Younger or Older Than 65 Years of Age: Implications for the Canadian C-Spine Rule.

There has been a distinction made in the 2001 Canadian C-Spine Rule regarding patients 65 and older and younger than 65 years of age as far as indications for cervical spine CT scanning. We sought to determine if there are differences in the symptoms, mechanisms of injury, fracture locations, and types that are still relevant in 2024. The institutional review board approved this retrospective study of cervical spine CT emergency department results from 2 hospitals in our health system after reviewing 5 years of data in patients experiencing trauma. In addition to the primary variable of age (younger than 65 years and 65 years and older), we looked at injury mechanism, fracture types, sites, symptoms, and operative or medical treatments. Because the demographics of our home site is different from most towns in the United States, we provide race/ethnicity data. Of 21,986 cervical spine CTs, 190/9455 (2.0%) participants 65 years of age and older and 199/12,531 (1.6%) participants younger than 65 years of age had fractures (total, 389/21,986, 1.8%). There were more cases of falls from standing (106, 55.8%) and falls from a height (46, 4.2%) in those 65 years and older and this mechanism was associated with a higher risk of C1 and C2 fractures (52, 27.4%; and 78, 41.1%, respectively). Among the C1 fractures, anterior and posterior arch fractures predominated (37, 19.5%). For C2 fractures, types 2 and 3 odontoid fractures (39, 20.5%; and 12, 6.3%) were more common in the older cohort. Motor vehicle collisions were more common in the younger cohort (89, 44.7%), and they were associated with more C5-C7 fractures (47, 23.6%; 60, 30.2%; and 66, 33.2%, respectively) including the facets (49, 24.6%), spinous processes (31, 15.6%), and transverse processes (52, 26.1%). Overall, the rates of instability, surgical intervention, and asymptomatic fractures were similar in the 2 age groups. Cervical spine fractures appear in about 1.8% of the CT scans performed in a busy emergency department environment. Fractures in the elderly occur more commonly due to falls, are located at C1 and C2, and may involve ligamentous injuries. Younger patients incur trauma more commonly due to motor vehicle collisions, and they are more likely to affect the posterior elements, especially C5-C7. The differences in trends for fractures in the 65 years of age and older and younger than 65 years of age groups have persisted since the Canadian C-Spine Rule 1996-1998 data were collected.

Posterior Column Release and Lengthening with a Magnetic Growing Rod Construct in Severe Congenital Thoracic Fusion: A Report of 2 Cases.

We describe treatment of severe multilevel congenital thoracic fusion in a 3-year-old girl with Apert Syndrome by posterior element excision, posterior column osteotomies, and gradual distraction with magnetically controlled growing rods (MCGR) with 3-year follow-up. We also describe short-term follow-up with similar management in an 8-year-old patient with a congenitally fused thoracic spine from Jarcho-Levin syndrome. Posterior element resection and targeted posterior column osteotomies combined with gradual distraction with MCGR offers a promising treatment course for children with severe thoracic insufficiency syndrome derived from congenital fusions.

Unstable C2-3 Posterior Ligamentous Injury in a Pediatric Patient with Successful Nonoperative Treatment: A Case Report.

The authors present a case of a 6-year-old boy who was treated nonoperatively for an unstable C2-3 hyperflexion injury with posterior cervical ligamentous disruption 8 years ago. The patient was managed with cervical collar immobilization for 2.5 years with long-term follow-up demonstrating complete healing of posterior element disruption, normal sagittal vertebral alignment on dynamic imaging, and full return to activities of daily living and sports. Pediatric spine injuries up to the C2-3 level with posterior ligamentous disruption alone without neurological deficit may be successfully treated nonoperatively with careful long-term immobilization and close follow-up.

Effect of two-level decompressive procedures on the biomechanics of the lumbo-sacral spine: an ex vivo study.

Hemilaminectomy and laminectomy are decompressive procedures commonly used in case of lumbar spinal stenosis, which involve the removal of the posterior elements of the spine. These procedures may compromise the stability of the spine segment and create critical strains in the intervertebral discs. Thus, this study aimed to investigate if decompressive procedures could alter the biomechanics of the lumbar spine. The focus was on the changes in the range of motion and strain distribution of the discs after two-level hemilaminectomy and laminectomy. Twelve L2-S1 cadaver specimens were prepared and mechanically tested in flexion, extension and both left and right lateral bending, in the intact condition, after a two-level hemilaminectomy on L4 and L5 vertebrae, and a full laminectomy. The range of motion (ROM) of the entire segment was assessed in all the conditions and loading configurations. In addition, Digital Image Correlation was used to measure the strain distribution on the surface of each specimen during the mechanical tests, focusing on the disc between the two decompressed vertebrae and in the two adjacent discs. Hemilaminectomy did not significantly affect the ROM, nor the strain on the discs. Laminectomy significantly increased the ROM in flexion, compared to the intact state. Laminectomy significantly increased the tensile strains on both L3-L4 and L4-L5 disc (p = 0.028 and p = 0.014) in ipsilateral bending, and the compressive strains on L4-L5 intervertebral disc, in both ipsilateral and contralateral bending (p = 0.014 and p = 0.0066), with respect to the intact condition. In conclusion, this study found out that hemilaminectomy did not significantly impact the biomechanics of the lumbar spine. Conversely, after the full laminectomy, flexion significantly increased the range of motion and lateral bending was the most critical configuration for largest principal strain.

The Truly Intermediate Subgroup Within the SINS “Potentially Unstable” Category: The Matryoshka Doll Phenomenon

A significant dilemma exists for the surgical plan of spinal metastases with a spinal instability neoplastic score (SINS) of 7-12. Our aim is to trim down this range of "potential instability" and find a virtual cut-off value for instrumentation. We performed a retrospective study on 60 patients who underwent surgical intervention for vertebral metastasis. They were segregated into 'instrumented' and "noninstrumented" groups. The primary endpoint of the study was to see whether surgical stabilization was done. Although univariate analysis showed the overall SINS score, involvement of posterior elements, and mechanical pain to be the factors that significantly affected our decision making in favor of stabilization, only the SINS score was found to be statistically significant on multivariate analysis. On plotting the proportion of patients undergoing stabilization at each SINS score we found the curves to crossover between SINS 8 and 9, ran almost parallel to each other at values 9 and 10 and then seemed to diverge from each other significantly at values above 10. Taking SINS 9 as the cut-off value above which instrumentation is advised, the receiver operating characteristic curve had a sensitivity of 67.57% (95% confidence interval 50.21% to 81.99%) and specificity of 73.91% (95% confidence interval 51.59% to 89.77%). The area under the curve was 0.79 (0.67-0.91). SINS 9-10 seems to be the actual ambiguous subset in the wider subgroup of the 'potentially unstable' category SINS 7-12, like a 'Matryoshka doll'. A SINS value of 9 can be seen as a cut-off value for instrumentation.

Spine Involvement and Vertebral Deformity in Patients Diagnosed with Chronic Recurrent Multifocal Osteomyelitis.

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory disorder of bone, typically arising adjacent to the physes of long bones but also seen throughout the skeleton. For patients with spinal involvement, CRMO lesions can cause compression deformities with a range of severity from minimal anterior wedging to circumferential height loss, known as vertebra plana. This study examines a large cohort of CRMO patients to determine the prevalence of spine involvement and vertebral deformity. This is a retrospective review of all patients with a diagnosis of CRMO seen at our institution between January 2003 and December 2020. These patients were identified through a prospectively maintained database of all CRMO patients seen at the institution. A retrospective review was undertaken to identify all patients with spinal involvement and determine the prevalence of CRMO in the spine and its effects on vertebral height and deformity. Of 170 patients included in this study, 48 (28.2%) were found to have spinal involvement. Among patients with spinal involvement, vertebral body lesions were identified in 27 (56.3%) patients. The remaining lesions were in the sacrum or posterior elements. Radiographic evidence of the vertebral body height loss was noted in 23 of these 27 patients. This cohort of CRMO patients demonstrates that 28% of patients have spinal involvement, and 48% of those patients have vertebral body height loss. While the ideal treatment for spinal CRMO has yet to be determined, imaging studies, including whole-body MRI and spine-specific MRI, are useful in identifying vertebral lesions and deformities. Identification and surveillance of these lesions are important as the disorder has a relapsing and remitting course, and patients can develop significant vertebral body height loss. Once deformity has developed, we have seen no evidence of reconstitution of the height of the collapsed vertebra. Bisphosphonates have been successful in preventing the progression of vertebral body height loss. Level II: Retrospective study investigating spinal involvement and prevalence of vertebral body deformity in patients diagnosed with CRMO.

Absence of the Posterior Element of C1 and C2 Along With Mild Wedge Shape in Body of C3: Case Report

Due to the wide variety of cervical vertebral congenital anomalies, knowledge of their types and related clinical conditions can prove to be helpful for physicians and surgeons in the diagnosis and treatment of patients. The aim of this study is to report on a rare case of unstable cervical vertebral congenital anomaly in which the patient had a defect in the body of the C3 vertebra in addition to defects in the posterior arch of C1 and posterior element of C2. This type of anomaly has not been reported so far in the literature. To reduce the patient’s related neurological disorders, our treatment choice for this patient was occipitocervical fusion (OCF) surgery. At the 3-year postoperative follow-up, all sensory and motor problems related to this anomaly affecting the patient's upper and lower limbs and causing shoulder and neck pain were eliminated. In this rare type of anomaly, OCF surgery seems to be an effective choice in relieving the patient's neurological symptoms.

Comparative Biomechanical Stability of the Fixation of Different Miniplates in Restorative Laminoplasty after Laminectomy: A Finite Element Study

A novel H-shaped miniplate (HSM) was specifically designed for restorative laminoplasties to restore patients’ posterior elements after laminectomies. A validated finite element (FE) model of L2/4 was utilized to create a laminectomy model, as well as three restorative laminoplasty models based on the fixation of different miniplates after a laminectomy (the RL-HSM model, the RL-LSM model, and the RL-THM model). The biomechanical effects of motion and displacement on a laminectomy and restorative laminoplasty with three different shapes for the fixation of miniplates were compared under the same mechanical conditions. This study aimed to validate the biomechanical stability, efficacy, and feasibility of a restorative laminoplasty with the fixation of miniplates post laminectomy. The laminectomy model demonstrated the greatest increase in motion and displacement, especially in axial rotation, followed by extension, flexion, and lateral bending. The restorative laminoplasty was exceptional in preserving the motion and displacement of surgical segments when compared to the intact state. This preservation was particularly evident in lateral bending and flexion/extension, with a slight maintenance efficacy observed in axial rotation. Compared to the laminectomy model, the restorative laminoplasties with the investigated miniplates demonstrated a motion-limiting effect for all directions and resulted in excellent stability levels under axial rotation and flexion/extension. The greatest reduction in motion and displacement was observed in the RL-HSM model, followed by the RL-LSM model and then the RL-THM model. When comparing the fixation of different miniplates in restorative laminoplasties, the HSMs were found to be superior to the LSMs and THMs in maintaining postoperative stability, particularly in axial rotation. The evidence suggests that a restorative laminoplasty with the fixation of miniplates is more effective than a conventional laminectomy due to the biomechanical effects of restoring posterior elements, which helps patients regain motion and limit load displacement responses in the spine after surgery, especially in axial rotation and flexion/extension. Additionally, our evaluation in this research study could benefit from further research and provide a methodological and modeling basis for the design and optimization of restorative laminoplasties.

3D CT modeling demonstrates the anatomic feasibility of S1AI screw trajectory for spinopelvic fixation in neuromuscular scoliosis.

In patients with neuromuscular scoliosis undergoing posterior spinal fusion, the S2 alar iliac (S2AI) screw trajectory is a safe and effective method of lumbopelvic fixation but can lead to implant prominence. Here we use 3D CT modeling to demonstrate the anatomic feasibility of the S1 alar iliac screw (S1AI) compared to the S2AI trajectory in patients with neuromuscular scoliosis. This retrospective study used CT scans of 14 patients withspinal deformity to create 3D spinal reconstructions and model the insertional anatomy, max length, screw diameter, and potential for implant prominence between 28 S2AI and 28 S1AI screw trajectories. Patients had a mean age of 14.42 (range 8-21), coronal cobb angle of 85° (range 54-141), and pelvic obliquity of 28° (range 4-51). The maximum length and diameter of both screw trajectories were similar. S1AI screws were, on average, 6.3 ± 5mm less prominent than S2AI screws relative to the iliac crests. S2AI screws were feasible in all patients, while in two patients, posterior elements of the lumbar spine would interfere with S1AI screw insertion. In this cohort of patients with neuromuscular scoliosis, we demonstrate that the S1AI trajectory offers comparable screw length and diameter to an S2AI screw with less implant prominence. An S1AI screw, however, may not be feasible in some patients due to interference from the posterior elements of the lumbar spine.

Feasibility of C2 Lamina Screw Placement in a New Zealand Cohort: Computed Tomography Analysis According to Ethnicity and Gender.

Previous analyses have suggested variations in cervical spine canal morphology according to ethnicity, possibly in part due to variations in the posterior elements. The potential for these variations to affect the placement of instrumentation is uncertain. The aim of this study was to report on the feasibility of C2 lamina screw insertion in a New Zealand cohort including analysis of Māori, the indigenous people of New Zealand. A trauma computed tomography database was accessed to identify suitable images. On axial images, where the isthmus was at its widest, the outer diameter (OD) and inner diameter (ID) of the lamina were measured. Screw length was measured from a proposed entry point to the contralateral junction of the lamina and lateral mass. The spinolaminar angle was measured as the angle subtended by the screw trajectory and midsagittal plane. A 5.5-mm OD was accepted as a threshold for the feasibility of lamina screw placement. One hundred eighty-seven images were assessed: 115 New Zealand European and 72 Māori. The mean age of the cohort was 41.9 years (SD 19.6), and most patients (64%) were men. For the entire cohort, mean OD was 6.6 and 6.8 mm on the right and left, respectively; the mean inner diameter was 3.5 and 3.8 mm; mean screw length was 31.5 and 31.5 mm; and mean spinolaminar angle was 46.0° and 46.1°. C2 lamina screw placement was feasible in a majority of patients. Considering only Māori patients, placement was feasible in 96% of right and 94% of left laminae in men but 72% of right and 72% of left laminae in women. In a majority of patients, C2 lamina screw placement is feasible. However, advanced imaging must be carefully assessed preoperatively because data suggest that Māori women may not necessarily have optimal anatomy.Clinical RelevanceCare needs to be taken when assessing and planning surgery inpatients of different ethnicities because variations may exist in the morphology of the posterior elements of C2, leading to variation in optimal fixation strategy.Level of Evidence3.

The Effect of C2 Muscular Exposure Technique on Radiographic and Clinical Outcomes After C2-T2 Posterior Cervical Fusion.

Retrospective cohort analysis. To determine whether the C2 exposure technique was a predictor of change in cervical alignment and patient-reported outcomes measures (PROMs) after posterior cervical decompression and fusion (PCDF) for degenerative indications. In PCDF handling of the C2 posterior paraspinal musculature during the operative approach varies by surgeon technique. To date, no studies have investigated whether maintenance of the upper cervical semispinalis cervicis attachments as compared with complete reflection of upper cervical paraspinal musculature from the posterior bony elements is associated with superior radiographic and clinical outcomes after PCDF. All adult patients who underwent C2-T2 PCDF for myelopathy or myeloradiculopathy at multi-institutional academic centers between 2013 and 2020 were retrospectively identified. Patients were dichotomized by the C2 exposure technique into semispinalis preservation or midline muscular reflection groups. Preoperative and short and long-term postoperative radiographic outcomes (upper cervical alignment, global alignment, and fusion status) and PROMs (Visual Analog Scale-Neck, Neck Disability Index, and Short Form-12) were collected. Univariate analysis compared patient factors, radiographic measures, and PROMs across C2 exposure groups. A total of 129 patients met the inclusion/exclusion criteria (73 muscle preservation and 56 muscle reflection). Patients in the muscular preservation group were on average younger (P= 0.005) and more likely to have bone morphogenic protein (P< 0.001) and C2 pars screws (P= 0.006) used during surgery. Preoperative to postoperative changes in C2 slope, C2 tilt, C2-C3 segmental lordosis, C2-C3 listhesis, C0-C2 Cobb angle, proximal junctional kyphosis, ADI, C1 lamina-occiput distance, C2 sagittal vertical axis, C2-C7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 exposure technique. Likewise, there were no significant differences in fusion status, C2-C3 pseudoarthrosis, C2 screw loosening, and complication and revision rates between C2 exposure groups. Preservation of C2 semispinalis attachments versus muscular reflection did not significantly impact cervical alignment, clinical outcomes, or proximal junction complications in long-segment PCDF. Level III.

Risk Factors for Residual Back Pain After Balloon Kyphoplasty for Osteoporotic Vertebral Fracture.

Balloon kyphoplasty (BKP) is a method for the management of osteoporotic vertebral body fracture (OVF). However, improvement in back pain (BP) is poor in some patients, also previous reports have not elucidated the exact incidence and risk factors for residual BP after BKP. We clarified the characteristics of residual BP after BKP in patients with OVF. In this study, we hypothesize that some risk factors may exist for residual BP 2years after the treatment of OVF with BKP. A multicenter cohort study was performed where patients who received BKP within 2months of OVF injury were followed-up for 2years. BP at 6months after surgery and final observation was evaluated by Visual Analog Scale (VAS) score. Patients with a score of 40mm or more were allocated to the residual BP group, and comparisons between the residual back pain group and the improved group were made for bone density, kyphosis, mobility of the fractured vertebral body, total spinal column alignment, and fracture type (fracture of the posterior element, pedicle fracture, presence or absence of posterior wall damage, etc.). Also, Short Form 36 (SF-36) for physical component summary (PCS) and mental component summary (MCS) at the final follow-up was evaluated in each radiological finding. Of 116 cases, 79 (68%) were followed-up for 2years. Two years after the BKP, 26 patients (33%) experienced residual BP. Neither age nor sex differed between the groups. In addition, there was no difference in bone mineral density, BKP intervention period (period from onset to BKP), and osteoporosis drug use. However, the preoperative height ratio of the vertebral body was significantly worse in the residual BP group (39.8% vs. 52.1%; p = 0.007). Two years after the operation, the vertebral body wedge angle was significantly greater in the residual BP group (15.7° vs. 11.9°; p = 0.042). In the multiple logistic regression model with a preoperative vertebral body height ratio of 50% or less [calculated by receiver operating characteristic (ROC) curve], the adjusted odds ratio for residual BP was 6.58 (95% confidence interval 1.64-26.30; p = 0.007); similarly, patients with vertebral body height ratio less than 50% had a lower score of SF-36 PCS 24.6 vs. 32.2 p = 0.08. The incidence of residual BP 2years after BKP was 33% in the current study. The risk factor for residual BP after BKP was a preoperative vertebral body height ratio of 50% or less, which should be attentively assessed for the selection of a proper treatment scheme and to provide adequate stabilization. III.

Navigating the Indeterminate Zone: Surgeons' Decision-Making Factors in Treating Vertebral Metastases with Spinal Instability Scores of 7–12

BackgroundThe Spinal Instability Neoplastic Score (SINS) classification system, is a validated and the most widely accepted instrument for defining instability in vertebral metastasis (VM), in which lesions scoring between 7 – 12 are defined as indeterminate and the treatment is controversial. This study aimed to determine which variables more frequently are considered by spine surgeons for choosing between the conservative and the surgical treatment of VMs among patients with an indeterminate SINS. Material and MethodsA single-round online survey was conducted in ten spine surgeons with expertise in the management of VMs from our AO Spine Region. In this survey, each surgeon independently reviewed demographic and cancer-related variables of 36 real-life cases of patients with vertebral metastases scored between 7 – 12 in the SINS. Bivariate and multivariate analyses were performed to identify significant SINS and non-SINS variables influencing the decision-making on surgical treatment. ResultsThe most commonly variables considered important, were the SINS element ‘mechanical pain’, rated important for 44.4% of the cases, ‘lesion type’ for 36.1%, ‘degree of vertebral collapse’ and the non-SINS factor ‘tumor histology’ rated for 13.9% of cases. By far the factor most commonly rated unimportant was ‘posterior element compromise’ (in 72.2% of cases). ConclusionsSurgeons relied on mechanical pain and type of metastatic lesion for treatment choices. Vertebral collapse, spinal malalignment, and mobility were less influential. Spinal mobility was a predictor of surgical versus non-surgical treatment. The only variables not identified either by surgeons themselves or as a predictor of surgery selection was the presence/degree of posterolateral/posterior element involvement.

Simulation of cancer progression in bone by a virtual thermal flux with a case study on lumbar vertebrae with multiple myeloma

BackgroundTwo main problems examining the mechanism of cancer progression in the tissues using the computational models are lack of enough knowledge on the effective factors for such events in vivo environments and lack of specific parameters in the available computational models to simulate such complicated reactions. MethodsIn this study, it was tried to simulate the progression of cancerous lesions in the bone tissues by an independent parameter from the anatomical and physiological characteristics of the tissues, so to degrade the orthotropic mechanical properties of the bone tissues, a virtual temperature was determined to be used by a well-known framework for simulation of damages in the composite materials. First, the reliability of the FE model to simulate hyperelastic response in the intervertebral discs (IVDs) and progressive failure in the bony components were verified by simulation of some In-Vitro tests, available in the literature. Then, the progression of the osteolytic damage was simulated in a clinical case with multiple myeloma in the lumbar vertebrae. ResultsThe FE model could simulate stress-shielding and diffusion of lesion in the posterior elements of the damaged vertebra which led to spinal stenosis. The load carrying shares associated with the anterior half and the posterior half of the examined vertebral body and the posterior elements were estimated equal to 41 %, 47 % and 12 %, respectively for the intact condition, that changed to 14 %, 16 % and 70 %, when lesion occupied one third of the vertebral body. ConclusionCorrelation of the FE results with the deformation shapes, observed in the MRIs for the clinical case study, indicated appropriateness of the procedure, proposed for simulation of the progressive osteolytic damage in the vertebral segments. The future studies may follow simulation of tumor growth for various metastatic tissues using the method, established here.

40 Gray in 5 Fractions for Salvage Reirradiation of Spine Lesions Previously Treated With Stereotactic Body Radiotherapy.

A retrospective single-center analysis of the safety and efficacy of reirradiation to 40 Gy in 5 fractions (reSBRT) in patients previously treated with stereotactic body radiotherapy to the spine was performed. We identified 102 consecutive patients treated with reSBRT for 105 lesions between 3/2013 and 8/2021. Sixty-three patients (61.8%) were treated to the same vertebral level, and 39 (38.2%) to overlapping immediately adjacent levels. Local control was defined as the absence of progression within the treated target volume. The probability of local progression was estimated using a cumulative incidence curve. Death without local progression was considered a competing risk. Most patients had extensive metastatic disease (54.9%) and were treated to the thoracic spine (53.8%). The most common regimen in the first course of stereotactic body radiotherapy was 27 Gy in 3 fractions, and the median time to reSBRT was 16.4 months. At the time of simulation, 44% of lesions had advanced epidural disease. Accordingly, 80% had myelogram simulations. Both the vertebral body and posterior elements were treated in 86% of lesions. At a median follow-up time of 13.2 months, local failure occurred in 10 lesions (9.5%). The 6- and 12-month cumulative incidences of local failure were 4.8% and 6%, respectively. Seven patients developed radiation-related neuropathy, and 1 patient developed myelopathy. The vertebral compression fracture rate was 16.7%. In patients with extensive disease involvement, reSBRT of spine metastases with 40 Gy in 5 fractions seems to be safe and effective. Prospective trials are needed to determine the optimal dose and fractionation in this clinical scenario.

Prevalence, Features, and Predictive Factors of Spontaneous Spinal Arthrodesis in Posttraumatic Thoracolumbar Kyphosis

ObjectiveSpontaneous spinal arthrodesis (SSA) is a phenomenon of spontaneous fusion, and SSA is not rare in post-traumatic thoracolumbar kyphosis (PTK). However, few reports have focused on SSA in patients with PTK. The objective of this study was to investigate the prevalence, features and predictive factors of SSA in PTK patients. MethodsIn this retrospective study, 70 patients with PTK were included. Data on the clinical and radiological parameters were obtained and evaluated. According to whether there was SSA or not, patients were divided into SSA group (n=45) or non-SSA group (n=25). A binary logistic regression analysis was used to identify the predictive factors for SSA. ResultsThe incidence of SSA in PTK was 64%. Among 45 PTK cases with SSA, SSA could be present as a solid bridging anterior osteophyte along the vertebral bodies in 11 cases, posterior contiguous bony growth through the facet joints bilaterally in 13 cases, bony formation in both anterior and posterior elements in 18 cases, and direct contiguous bony formation from injured vertebral body to adjacent one in 3 cases. Patients with longer disease duration, larger local Cobb angle and anterior wall height loss ratio (AWHL) of injured vertebral body, and less kyphosis flexibility index were significantly more likely to develop SSA. The parameter of AWHL remained significant in binary logistic regression analysis. ConclusionsSSA in PTK was common, and SSA sign could be present as various patterns, which might have implications for surgical decisions. AWHL was the independent predictor for SSA.

Subject-Specific Geometry of FE Lumbar Spine Models for the Replication of Fracture Locations Using Dynamic Drop Tests.

For traumatic lumbar spine injuries, the mechanisms and influence of anthropometrical variation are not yet fully understood under dynamic loading. Our objective was to evaluate whether geometrically subject-specific explicit finite element (FE) lumbar spine models based on state-of-the-art clinical CT data combined with general material properties from the literature could replicate the experimental responses and the fracture locations via a dynamic drop tower-test setup. The experimental CT datasets from a dynamic drop tower-test setup were used to create anatomical details of four lumbar spine models (T12 to L5). The soft tissues from THUMS v4.1 were integrated by morphing. Each model was simulated with the corresponding loading and boundary conditions from the dynamic lumbar spine tests that produced differing injuries and injury locations. The simulations resulted in force, moment, and kinematic responses that effectively matched the experimental data. The pressure distribution within the models was used to compare the fracture occurrence and location. The spinal levels that sustained vertebral body fracture in the experiment showed higher simulation pressure values in the anterior elements than those in the levels that did not fracture in the reference experiments. Similarly, the spinal levels that sustained posterior element fracture in the experiments showed higher simulation pressure values in the vertebral posterior structures compared to those in the levels that did not sustain fracture. Our study showed that the incorporation of the spinal geometry and orientation could be used to replicate the fracture type and location under dynamic loading. Our results provided an understanding of the lumbar injury mechanisms and knowledge on the load thresholds that could be used for injury prediction with explicit FE lumbar spine models.

Limited Intervention in Adult Scoliosis-A Systematic Review.

Adult scoliosis is traditionally treated with long-segment fusion, which provides strong radiographic correction and significant improvements in health-related quality of life but comes at a high morbidity cost. This systematic review seeks to examine the literature behind limited interventions in adult scoliosis patients and examine the best approaches to treatment. This is a MEDLINE- and PubMed-based literature search that ultimately included 49 articles with a total of 21,836 subjects. Our search found that long-segment interventions had strong radiographic corrections but also resulted in high perioperative morbidity. Limited interventions were best suited to patients with compensated deformity, with decompression best for neurologic symptoms and fusion needed to treat neurological symptoms secondary to up-down stenosis and to provide stability across unstable segments. Decompression can consist of discectomy, laminotomy, and/or foraminotomy, all of which are shown to provide symptomatic relief of neurologic pain. Short-segment fusion has been shown to provide improvements in patient outcomes, albeit with higher rates of adjacent segment disease and concerns for correctional loss. Interbody devices can provide decompression without posterior element manipulation. Future directions include short-segment fusion in uncompensated deformity and dynamic stabilization constructs. Limited interventions can provide symptomatic relief to adult spine deformity patients, with indications mostly in patients with balanced deformities and neurological pain.