Spinal Fixation Research Articles

A Virtual Response Surface Strategy to Predict the Effects of Contouring on the Static and Fatigue Mechanical Behavior of Spinal Rods.

Spinal fixation techniques based on contoured spinal rods are well established to restore an adequate sagittal alignment; however, they often break due to fatigue loading because residual stresses arise while deforming the material and they significantly reduce rod fatigue strength. The present paper aims at developing a novel strategy based on Response Surfaces (RS) as surrogate reduced order models to accurately predict the key biomechanical parameters involved both during static spinal rod contouring and subsequent fatigue loading. Finite element (FE) models of different contouring methods are performed on a wide range of spinal rods to reproduce typical clinical scenarios. RSs based on polynomial equations are initially used to fit the collected FE data and relate input parameters of the process to outputs mechanical variables. Then, the RS approach is assessed and validated by comparison with extensive experimental observations from a variety of fatigue tests. The RS provides an accurate prediction of the output parameters of interest (R2 = 0.88-1), with an average relative error up to 9% compared to computationally demanding FE models. Fatigue outputs are correctly predicted both for breakages and survivals of rods, despite an average overestimation on the equivalent stress of 11%. The RS approach proves credible and accurate in predicting the experimental fatigue strength of contoured spinal rods. The proposed method could serve in clinical practice as an intraoperative virtual tool to support the decision-making process.

Concept and Fabrication of Beta-Type Titanium Alloy Rod with Parts Possessing Different Young’s Moduli for Spinal Fixation

Concept and Fabrication of Beta-Type Titanium Alloy Rod with Parts Possessing Different Young’s Moduli for Spinal Fixation

Endovascular Management of Aortic Rupture Secondary to Thoracolumbar Spine Fracture From a Domestic Fall: A Case Report and Clinical Challenges.

Instances of aortic lesions combined with thoracolumbar spine fractures have been rarely described, primarily occurring in high-speed motor vehicle collisions and falls from heights. We present a unique case of a 71-year-old woman with a thoracic aortic rupture caused by a thoracolumbar spine fracture during an accidental domestic fall. She experienced an injury at the level of the celiac trunk on the posterior aspect of the aorta. Hemorrhagic shock and profound hemodynamic instability prompted the swift initiation of a percutaneous endovascular approach, involving the use of REBOA (Resuscitative Endovascular Balloon Occlusion of the Aorta) followed by the parallel graft technique in a sandwich configuration. Subsequently, thoracolumbar spinal fixation was carefully scheduled and performed 20 days after achieving clinical stabilization. This case underscores the importance of a multidisciplinary approach in managing complex aortic and spinal injuries. The combined use of REBOA and the sandwich graft technique can be life-saving in managing acute thoracic aortic injuries, allowing for the staged stabilization and repair of associated spinal fractures. This case highlights a novel approach to managing a rare thoracic aortic rupture caused by an accidental domestic fall. The application of REBOA for immediate hemodynamic stabilization, combined with the use of a sandwich graft configuration, underscores the adaptability of advanced endovascular techniques in complex, life-threatening situations. These interventions demonstrate the importance of tailoring treatment strategies to individual patient needs, especially in cases involving atypical mechanisms of injury. The findings emphasize the value of early multidisciplinary collaboration and dynamic procedural planning, paving the way for improved outcomes and the refinement of clinical protocols in the management of similar trauma cases.

Effects of self-expandable pedicle screws with shape memory alloy structures on spinal fixation strength: A finite element study.

In many spine surgeries, pedicle screws are commonly used to stabilize vertebrae, however, loosening can be a complication. Different designs have shown improvements in fixation strength, with self-expandable screws featuring shape memory alloy (SMA) structures being of particular interest. This study aimed to assess the fixation strength of self-expandable pedicle screws made with SMA (specifically Nickel-Titanium) sheets. Three types of screws were evaluated: self-expandable screws with a smooth SMA surface, self-expandable screws with a porous SMA surface, and standard design screws. Each screw underwent pullout tests for comparison. Following the tests, the self-expandable screw with a porous surface exhibited the highest pullout force (1141.83 N), compared to 1056.86 N for the smooth self-expandable screw and 1104.25 N for the standard screw. The dissipated plastic strain energy differed among the screws, with values of 0.073 J for the porous self-expandable screw, 0.065 J for the smooth self-expandable screw, and 0.089 J for the standard pedicle screw. Notably, the porous self-expandable screw showed reduced stress on the bone-screw interface. Improving the mechanical design of pedicle screws could significantly enhance screw-bone fixation strength. The utilization of self-expandable pedicle screws with porous surface SMA sheets demonstrates superior performance, potentially mitigating complications like loosening.

Comparison of three sacral screw internal fixation techniques in the treatment of L4-S1 lumbar degenerative disease with osteoporosis: a retrospective observational study.

Patients with L4-S1 lumbar degenerative disease (LDD) with osteoporosis are prone to sacral-screw loosening during spinal internal fixation. We aimed to compare the clinical efficacy and imaging results of sacral bicortical, tricortical, and polymethylmethacrylate (PMMA)-augmented pedicle-screw fixation in the treatment of L4-S1 LDD with osteoporosis. This is a retrospective study, 72 patients were enrolled and divided into three groups according to the S1-screw fixation method: PMMA-augmented pedicle-screw fixation (Group A, n = 26), bicortical fixation (Group B, n = 22), and tricortical fixation (Group C, n = 24). The visual analog scale (VAS) and Oswestry disability index (ODI) were recorded preoperatively and at the last follow-up, and the postoperative complications, screw-loosening rate, and fusion rate were compared between the three groups. Upon the last follow-up, the VAS and ODI scores of the three groups were significantly improved compared with those recorded preoperatively. The VAS and ODI scores of Group A were significantly smaller than those of Groups B and C (P < 0.05), with no significant difference between Groups B and C. Moreover, the screw-loosening rate of Group A was significantly lower than that of Groups B and C (P < 0.05), with no significant difference between Groups B and C. No significant difference was noted in postoperative complications, bone-cement leakage rates, and intervertebral fusion rates among the three groups. Furthermore, we found that osteoporosis and change of lumbar lordosis(LL) value were independent risk factors for sacral-screw loosening in patients with L4-S1 LDD with osteoporosis. When patients with L4-S1 LDD with osteoporosis undergo lumbosacral fusion and fixation, the use of S1 pedicle screws with PMMA augmentation has better stability and less screw loosening. Furthermore, we recommend this surgery for patients with osteoporosis, and the LL should be increased as much as possible during the operation to restore the matching of lumbar and pelvic parameters.

The correlation analysis between the pedicle screw placement palpation and torque

BackgroundThis study endeavored to investigate the influencing factors of pedicle screw torque measured during surgery and the correlation between manual palpation scores and screw torque. MethodsThis investigation was a prospective study designed to gather data from patients who underwent spinal internal fixation performed by the same surgical team at the Department of Orthopedics, affiliated with the First Hospital of Guangzhou University of Chinese Medicine, spanning from January 2020 to September 2023. The sample comprised 51 individuals (18 males and 33 females; mean age: 60.78±11.48 years). All participants underwent bone mineral density (BMD) and comprehensive radiological testing to evaluate the affected spinal segments. Intraoperatively, parameters such as the surgeon's tactile perception, a visual analogue scale for manual palpation, and peak screw torque values were documented. Patients were subsequently stratified into three categories based on the resistance encountered during screw placement. Demographic variables (age, height, weight) and BMD measurements of patients within each category were compared. Factors exhibiting significant differences were subjected to multivariate logistic regression analysis (MLRA). Concurrently, the relationship between manual palpation scores and torque values was examined. ResultsThe results of the univariate analysis indicated that age (P=0.042), height (P=0.047), BMD of the lumbar (P<0.01), BMD of the femoral neck (P=0.02), BMD of the hip (P=0.02), and P1NP (P=0.044) were statistically significant. The results of MLRA revealed that BMD of the lumbar was an independent influencing factor for torque (P=0.000<0.05). Additionally, the manual palpation score and torque value of group A were significantly lower than those of the other two groups (P<0.001). There was a significant positive correlation between the intraoperative screw placement palpation and torque. ConclusionsThe BMD of the lumbar is an independent factor that influences the measured torque applied to pedicle screws during surgery. A significant and robust positive correlation exists between the intraoperative screw placement tactile sensation and the torque experienced. It is advisable to reinforce the screw channel with bone cement when the tactile score is ≤2.5 and the torque is ≤ 1.3 N.m.

Meta-Analysis Investigating Optimal Timing of Chemoprophylaxis for Venous Thromboembolism in Operatively Managed Blunt Spinal Injuries.

Blunt spinal injuries (BSIs) are associated with substantial morbidity and mortality. Management typically involves stabilization of the spinal column and may include chemoprophylaxis for venous thromboembolism (VTE) prevention. The optimal timing of chemoprophylaxis initiation in operatively managed BSI patients remains debated. Analyze available literature on optimal chemoprophylaxis timing for the prevention of VTE in patients postinjury undergoing operative repair. Systematic review and meta-analysis. A systematic review and meta-analysis were conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed and MEDLINE were searched for studies assessing chemoprophylaxis timing in adult BSI patients. Inclusion criteria focused on operatively managed BSIs and anticoagulant usage assessment. Three studies involving 4345 patients were included. Early chemoprophylaxis initiation was associated with significantly lower deep vein thrombosis (DVT) and overall VTE incidence compared with late initiation. No significant differences were found in pulmonary embolism (PE) incidence or mortality. Early anticoagulant administration after spinal fixation for BSI reduces DVT and overall VTE risk without impacting PE incidence or mortality. Further research is recommended to solidify these findings and address existing gaps in the literature. Early chemoprophylaxis initiation in operatively managed BSI patients reduces DVT and overall VTE risk without affecting PE incidence or mortality LEVEL OF EVIDENCE: 2.

Case series study and finite element analysis of a new cervicothoracic fixation device

ObjectiveTo introduce a specialized device designed for the fixation of the cervical-thoracic spine and describe its surgical installation, finite element analysis, and clinical outcomes.MethodsA finite element model of the C6-T1 segment was developed and validated, and simulations of subtotal resection of anterior cervical vertebrae, artificial vertebrae placement, and titanium plate fixation were performed. The model was subjected to a 75 N load to simulate the weight of the head and a 1 N·m force to simulate flexion, lateral bending, and axial rotation. The analysis focused on range of motion, total stress, stress in the artificial vertebrae, and stress in the device. The clinical outcomes were evaluated in a retrospective case series of 140 patients with cervical spine fractures.ResultsUnder the same loading conditions, the maximum stresses on specialized anatomical and biomechanical devices for the fixation of the cervicothoracic segment of the spine during neutral, forwards flexion, backwards extension, left lateral bending, right lateral bending, left rotation, right rotation and other working conditions were 25.097 MPa, 149.480 MPa, 64.150 MPa, 67.804 MPa, 72.754 MPa, and 117.98 MPa, respectively. And, the maximum ROMs were 2.230 mm, 5.585 mm, 4.682 mm, 3.184 mm, 3.061 mm, 4.451 mm, and 4.645 mm. Compared with those in the preoperative period, the patients’ CL, OPCL, UCL, LCL, UROM, LROM, VAS score, NDI score, JOA score, intervertebral space height at the injured segment, cervical anterior kyphosis angle, Cobb angle, vertebral displacement, ASIA grade, fracture classification, and vertebral displacement improved (P < 0.05). Sixty-two patients had dysphagia, and 3 patients experienced leakage of cerebrospinal fluid.ConclusionThe design of the new cervicothoracic internal fixation device conforms to the anatomical structure of the cervicothoracic spine, which can provide immediate stability, better screw placement and adequate bone grafting, and reduce the risk of complications. Despite some disadvantages, it is a good device for segmental fixation of the cervical and thoracic spine.

Entry point and screw path study of second sacral alar-iliac screw trajectory in spinal pelvic fixation under O-arm navigation

Objective: To explore the feasibility of using the entry point and screw path parameters of sacroiliac (S2AI) screws inserted under O-arm 3D computer navigation as a reference for freehand screw insertion in patients with degenerative spinal deformities. Methods: A retrospective analysis was conducted on the clinical data of 66 patients with degenerative spinal deformities who received S2AI screw fixation assisted by the O-arm 3D computer navigation system at Nanjing Drum Tower Hospital Affiliated with Nanjing University Medical School from January 2017 to April 2022. The patients included 6 males and 60 females, with a mean age of (64.3±5.9) years. Preoperatively, the entry point was set as the intersection of 1 mm from the outer and lower edges of the S1 foramen, adjusted intraoperatively by navigation, and verified postoperatively by full spinal CT scans and 3D reconstructions. Using the S1 screw entry point as the origin, the position of the bilateral S2AI screw entry points, tailward angulation (SA), outward angulation (TA), and vertical distance from the entry point to the skin (SD) were measured on postoperative CT 3D images. The accuracy of S2AI screw placement and any intraoperative and postoperative complications were recorded. Differences in entry point coordinates and screw path parameters between the left and right sides were compared. The intraclass correlation coefficient (ICC) was used to assess intra-observer and inter-observer agreement. Results: The coordinates and screw path parameters for the S2AI screws placed using the O-arm navigation demonstrated good intra-observer and inter-observer consistency (ICC>0.75). The left entry point was located (8.08±1.39) mm laterally and (24.47±2.20) mm caudally from the S1 entry point, while the right entry point was (8.09±1.41) mm laterally and (24.40±2.54) mm caudally, with no significant difference between the left and right sides (both P>0.05). The left TA was 46.33°±3.44°, SA was 39.14°±6.12°, and SD was (60.38±13.37) mm; the right TA was 46.37°±3.41°, SA was 39.59°±5.89°, and SD was (60.30±12.24) mm, with no significant differences between the left and right parameters (all P>0.05). There was no significant neurovascular complications intraoperatively or two weeks postoperatively, with a screw insertion accuracy of 97.7% (129/132). Conclusions: In the fixation of the pelvis in degenerative spinal deformities, the use of O-arm navigation-assisted S2AI screw insertion has a high accuracy rate. It is recommended that for freehand screw insertion, the entry point should be located 24 mm caudally and 8 mm laterally from the outer and lower edges of the superior articular process of S1, with an TA of approximately 46° and a SA of approximately 39°.

Clinical Implications of Surgical Resection without Spinal Fixation in Lumbar Dumbbell Tumors: Evaluating Postoperative Lumbar Alignment and Patient Outcomes

This study examined radiographic changes in local and global spinal alignments and clinical outcomes following tumor resection without spinal fixation in patients with lumbar dumbbell tumors (LDTs). We included 28 patients with LDTs who were followed for at least 2 years after surgery. We analyzed variations in the outcome variables by measuring individual coronal and sagittal parameters from radiographs. Clinical outcomes were assessed using the modified McCormick scale, the Japanese Orthopedic Association score, and the visual analog scale. To evaluate the impact of tumor location on these outcomes, we categorized the patients into 3 groups based on tumor location: upper (T12-L1), middle (L2-3), or lower (L4-S1) group. The local and global spinal parameters (including Cobb angle, cervical lordosis, T1 slope, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis [global, upper, middle, lower], sacral slope, pelvic incidence, and pelvic tilt) did not show significant changes after surgery. Preoperatively, all patients experienced gait disturbances, but at the final follow-up, nearly all of them (27 cases, 96.4%) could walk without support. The Japanese Orthopedic Association score and visual analog scale demonstrated significant postoperative improvements. There were no statistically significant group differences in postoperative coronal and sagittal profiles or clinical outcomes among the upper, middle, and lower groups. Tumor resection without spinal fixation had no substantial impact on local and global spinal alignments and led to satisfactory clinical outcomes, suggesting that spinal fixation may not always be necessary when resecting LDTs.

How does thoracic scoliosis surgery affect thoracolumbar spinal flexibility and lumbar intradiscal pressure? An in vitro study confirming the importance of the rib cage.

To evaluate effects of spinal and rib osteotomies on the resulting spinal flexibility for surgical correction of thoracic scoliosis and to explore effects of posterior fixation on thoracolumbar segmental range of motion and lumbar intervertebral disc loading. Six fresh frozen human thoracolumbar spine and rib cage specimens (26-45 years, two female / four male) without clinically relevant deformity were loaded with pure moments of 5 Nm in flexion/extension, lateral bending, and axial rotation. Optical motion tracking of all segmental levels (C7-S) and intradiscal pressure measurements of the lumbar spine (L1-L5) were performed (1) in intact condition, (2) after Schwab grade 1, (3) Schwab grade 2, and (4) left rib osteotomies at T6-T10 levels, as well as (5) after posterior spinal fixation with pedicle screw-rod instrumentation at T4-L1 levels. Schwab grade 1 and 2 osteotomies did not significantly (p > 0.05) affect spinal flexibility, whereas left rib osteotomies significantly (p < 0.05) increased segmental ranges of motion at upper and lower levels in flexion/extension and at treated levels in lateral bending. Posterior fixation caused significantly (p < 0.05) increased range of motion at upper adjacent thoracic and mid-lumbar levels, as well as significantly (p < 0.05) increased intradiscal pressure at the lower adjacent level. Low effects of Schwab grade 1 and 2 osteotomies question the impact of isolated posterior spinal releases for surgical correction maneuvers in adolescent idiopathic scoliosis, in contrast to additional concave rib osteotomies. High effects of posterior fixation potentially explain frequently reported complications such as adjacent segment disease or proximal junctional kyphosis.

Universal non-circular cone beam CT orbits for metal artifact reduction imaging during image-guided procedures

Innovation in image-guided procedures has been driven by advances in robotic Cone Beam Computed Tomography (CBCT) systems. A fundamental challenge for CBCT imaging is metal artifacts arising from surgical tools and implanted hardware. Here, we outline how two universal non-circular imaging orbits, optimized for metal artifact reduction, can be implemented in real-time on clinical robotic CBCT systems. Demonstrating potential clinical utility, the universal orbits were implemented during a pedicle screw cervical spine fixation and hip arthroplasty performed on a porcine and ovine cadaver respectively. In both procedures, the universal non-circular orbits noticeably reduced the metal artifacts surrounding the implanted orthopedic hardware, revealing anatomy and soft tissue obscured in current conventional CBCT imaging. This work represents a key step in clinically translating universal orbits, unlocking high quality in-room procedural verification to increase broader use of robotic CBCT systems and reduce the occurrence of secondary corrective surgeries.

Impact of an In-Hospital postoperative imaging after uncomplicated elective posterior lumbar fixation: A case series

Purpose: Following spinal fixation, postoperative imaging is routinely performed. The value of routine postoperative imaging and its impact on the surgical decision remains uncertain, especially in degenerative cases. Moreover, routine postoperative imaging is not free and is an ionizing radiation. This study investigated the value of postoperative imaging after uneventful uncomplicated elective posterior lumbar fixation. Methods: This case series retrospectively reviewed the medical records of patients who underwent elective posterior lumbar fixation surgeries at our institution within two years. A series of 98 cases met our selection criteria. Their mean age was 51.2 years. We reviewed the decisions taken after performing the routine postoperative images. We searched for further diagnostic or imaging studies, revision surgery, or an extended hospital stay. Results: We found no particular decision was made after performing the postoperative imaging after uneventful uncomplicated elective posterior lumbar fixation surgeries. Moreover, there was no change in the hospital stay or the regular postoperative clinical management for all the included patients. No revision surgery was required based on the postoperative routine images. Conclusions: We found that routine postoperative imaging after posterior fixation of a degenerative lumbar spine is of limited value. A randomized, controlled study is helpful to confirm this finding.

Carbon Fiber Reinforced Hybrid Polyaryl–Ether–Ether–Ketone (PEEK) Spinal Fixation System: Technical Features and Preliminary Clinical Trial

Carbon Fiber Reinforced Hybrid Polyaryl–Ether–Ether–Ketone (PEEK) Spinal Fixation System: Technical Features and Preliminary Clinical Trial

Neurosurgical skills conference for medical students: A before and after study.

Undergraduate conferences may improve exposure to neurosurgery among medical students. Hence, this study aimed to evaluate the effect of a neurosurgical skills conference on medical students' comprehension and perceptions of the specialty. A before-and-after (BA) study design was employed to assess the effects of a conference that integrated presentations with hands-on sessions. Practical workshops covered craniotomy, spinal fixation, surface anatomy, intracranial pressure (ICP) monitoring, basic surgical skills, and microsurgical simulation. Pre-conference and post-conference surveys, utilizing Likert scales, gauged participants' attitudes, prior neurosurgical exposure, and understanding of neurosurgical skills. Statistical analysis was conducted on dichotomized responses. Thirty-one participants completed both surveys, with the majority being 1st and 2nd-year medical students. Among the participants, 58.1% were female, and 77.4% identified with BAME ethnicities. Following the conference, there was a notable increase in comprehension regarding neurosurgical careers (from 58.1% to 96.8%, P < 0.001) and training criteria (from 22.6% to 93.5%, P < 0.001). The conference enhanced knowledge of indications for craniotomy (P < 0.001), ICP monitoring (P < 0.001), and spinal fixation (P < 0.001). Participants reported improved understanding of the steps involved in craniotomy (P < 0.001), familiarity with basic cranial surgical surface anatomy (P < 0.001), and confidence in performing basic surgical instrument ties (P < 0.001). Although interest in pursuing a career in neurosurgery remained high (from 87.1% to 90.3%, P = 1.000), a majority of participants, both BA the conference, expressed concerns about the impact on personal life (from 58.1% to 64.5%, P = 0.774). This study underscores the role of undergraduate mixed-method conferences in augmenting understanding of neurosurgery and nurturing early interest.

Preliminary Application of Bilateral Submandibular Horizontal Incision in the Treatment of Upper Cervical Tumors.

The upper cervical spine has a complex anatomical structure, making anterior surgical approaches challenging and prone to complications. This study aims to explore the use of bilateral submandibular incisions to provide safer and more convenient exposure of the upper cervical spine and to assess the feasibility of this approach for anterior surgical treatment of complex upper cervical diseases. From November 2019 to August 2021, three patients with malignant tumors of the upper cervical spine were subjected to an anterior-posterior combined approach for cervical tumor resection. The cohort consisted of one male and two females, aged between 41 and 51 years. The anterior approach began with a submandibular incision, followed by blunt dissection through the prevertebral muscles to expose the diseased vertebra. Subsequently, the diseased vertebra was excised, and either a titanium cage or a pre-customized 3D-printed artificial vertebral body was implanted anteriorly. Then, posterior fixation of the cervical spine was performed using pedicle screws to provide additional stability. Follow-up ranged from 8 to 34 months. All patients experienced varying degrees of pain relief within 24 hours post-operation. Frankel grading showed improvement by at least one grade in all three cases. Regular X-ray and magnetic resonance imaging examinations revealed no tumor recurrence or involvement of adjacent vertebrae in the surgical area. The anterior bilateral submandibular horizontal incision approach offers comprehensive exposure of the anatomical structures of the upper cervical spine. This approach introduces a new option for the anterior treatment of upper cervical spine diseases.

Safety and efficacy of short percutaneous fixation in AO3 and AO4 lumbar fractures: a single-centre experience of 35 cases.

Spinal fractures with subsequent bone fragment dislocation are among the injuries most feared by patients and physicians. The surgical strategy is tailored to the individual patient's characteristics and often consists of pedicle instrumentation with rod-screw systems. Short instrumentation has been associated with worse spinal correction and increased complications. However, recent studies have suggested similar results in terms of kyphosis correction and the maintenance of sagittal alignment compared to longer instrumentation. This single-center retrospective study was conducted between January 2018 and April 2021. We included 35 single lumbar burst fractures AO Spine grade A3 or A4 with evidence of intra-canal fragments. Patients underwent minimally invasive percutaneous posterior lumbar instrumentation with pedicle screws. Patients received short segmental fixation involving only one level above and below the fractured vertebra. An immediate postoperative computed tomography (CT) scan demonstrated a significant reduction in vertebral kyphotic deformation (11.7° ± 1.6 vs 16.7° ± 5, p<0.001) and sagittal Cobb angle (9.8° ± 1.3 vs 11.7° ± 1.5, p < 0.001). The correction was slightly reduced but remained significant at 12 months for both kyphotic (12.3° ± 1.4, p = 0.03) and sagittal Cobb (10.3° ± 0.9, p = 0.04). Upper lumbar vertebrae showed even larger correction indices compared to lower lumbar segments. No implant failure or screws pullout was seen at the last follow-up. Short spinal fixation is a safe and effective treatment of complete and incomplete burst fractures with posterior bone fragment dislocation. All included patients fared well and achieved good kyphotic correction with no perioperative or long-term complications.

Bone density as a risk of early loss of correction after percutaneous posterior spinal fixation for traumatic thoracolumbar fracture: a study on the usefulness of Hounsfield unit values on computed tomography scan.

Vertebral Hounsfield unit values on computed tomography scan (CT values) have been found to be correlated with bone density measured using dual-energy X-ray absorptiometry. We hypothesized that low preoperative CT values are risk factors for early loss of correction after percutaneous posterior spinal fixation (PPSF). This study aimed to evaluate the usefulness of measuring preoperative CT values. In total, 104 patients underwent PPSF due to traumatic thoracolumbar fracture. Among them, 53 with a range of fixation that was within two vertebrae above and below the fractured vertebra were selected. CT values were measured preoperatively from the most cephalad vertebrae on the fixed vertebrae. Vertebral wedge angle (VWA) and local kyphosis angle (LKA) were measured before and after surgery. participants were classified into progression (P) and nonprogression (NP) groups. The P group comprised patients with LKA progressing > 10° from the immediate postoperative period to 3months postoperatively. Meanwhile, the NP group included patients without progression. Eight (15.1%) patients were included in the P group. The vertebral CT values were 102.2 ± 36.7 in the P group and 162.4 ± 59.7 in the NP group (p < 0.01). The pedicle CT values were 114.4 ± 45.9 in the P group and 170.8 ± 72.3 in the NP group (p < 0.05). At 2weeks postoperatively, VWA and LKA of the P group progressed to 9.8° ± 7.0° and 10.9° ± 7.6°, respectively. CT values can predict progressive loss of correction after PPSF.

Impact of instrumentation material on local recurrence: a case-matched series using carbon fiber-PEEK vs. titanium.

Spine metastases are a major burden of oncologic care, contributing to substantial morbidity. A well-established treatment paradigm for patients with metastatic epidural spinal cord compression includes separation surgery followed by stereotactic body radiotherapy (SBRT). Innovations in implant technology have brought about the incorporation of Carbon fiber-reinforced polyetheretherketone (CFR-PEEK) instrumentation for spinal fixation. We present our experience of CFR-PEEK instrumentation, comparing outcomes and complication profiles with a matched cohort of titanium instrumented cases for spine metastatic disease. Oncology patients who underwent spinal fusion for metastatic spine disease from 2012 to 2023 were retrospectively reviewed. Ninety-nine cases with CFR-PEEK fusions were case-control matched with 50 titanium controls (2:1 ratio) based upon primary tumor type and spinal instability neoplastic score (SINS) location. Demographic, clinical, radiographic and progression free survival (PFS) were analyzed. In the study years, 263 patients underwent spinal decompression and fusion, for which 148 patients met predetermined inclusion criteria. Of these, 49 had titanium instrumentation, and 99 had CFR-PEEK. Complication profiles, including hardware failure and infection were similar between the groups. There was no significant difference in PFS between all CFR-PEEK and titanium patients (143 days versus 214 days; p = 0.41). When comparing patients in which recurrence was noted, CFR-PEEK patients had recurrence detected two times earlier than titanium patients (94 days versus 189 days; p = 0.013). In this case matched cohort, CFR-PEEK demonstrated decreased overall PFS suggestive of earlier local recurrence identification. Long-term studies are warranted for better evaluation of the impact on survival and systemic disease progression.

The Role of Dynamic Magnetic Resonance Imaging in Improving the Accuracy of Diagnosis of Degenerative Diseases of the Lumbosacral Spine

Abstract Background Low back pain (LBP) is one of the most common musculoskeletal complaints, the life time prevalence of low back pain may be up to 80% in the industrialized countries and is one of the main causes of sick leave and disability pension with huge personal and socioeconomic consequences. Low back pain causes more disability than any other condition, and global point prevalence has been calculated at 9.4%. Aim of the Work To evaluate the role of dynamic MRI in assessment of degenerative diseases of lumbosacral spine compared to conventional MRI regarding assessment of spinal instability and evaluating the degenerative changes in flexion and extension in comparison to neutral position to determine best clinical management and outcome for the patients. Patients and Methods A prospective study conducted on patients who was referred to the Radiology Department –MRI unit at Ain Shams University Specialized Hospital presented with symptoms of degenerative lumbar spine disease. The study was conducted at Ain Shams Specialized University Hospital. Results upon follow up with the spine surgeon and surveying the patients’ level of pain, surgery with thecal sac decompression with/without spinal fixation on the suggested levels was done, 75% of the patients showed postoperative clinical improvement. We have also to point out that dynamic MRI is a helpful tool for preventing unnecessary surgical intervention by making the orthopedic surgeon more confident about choosing the conservative management for the patient, this is reinforced by confidently ruling out the presence of spinal instability, presence of exaggerated neural foraminal compromise or spinal canal stenosis in certain position. In our study each patient had conventional and dynamic MRI study and accordingly the management plan was determined by the orthopedic physician, 70.3% was advised for conservative management with marked improvement of the pain level of the patient after 3 months of compliance of conservative management (91.6%) of the patients showed improvement. In 24.3% of the patients the treatment plan was changed from conservative to surgical intervention after performing dynamic MRI with 75 % showing improvement after surgical intervention. The evaluation of the patient’s pain level and outcome after the management plan taken according to the dynamic MRI showed significant improvement (p value 0.01). Conclusion functional imaging tools; like dynamic MRI of the lumbar spine, allows better visualization of hidden pathologies in conventional MRI especially with patients with clinical/radiological mismatch therefore it gives the spine surgeon a helpful tool in order to understand and explain patients’ symptomatology. It also provides documented proof of neural compression and hence facilitates accurate preoperative planning regarding the procedure and the target level, and accordingly better postoperative outcome.