Search Results (212)

Background/Objectives: Pathological vertebral fragility (path-VF) increases the risk of osteoporotic fractures and pedicle screw loosening (PSL) after posterior instrumented spinal fusion (PISF). While WHO body mass index (BMI) categories broadly identify risks related to underweight and obesity, fixed thresholds may inadequately reflect vertebral fragility risks among elderly patients, especially within the normal-weight range. This study investigates whether current BMI classifications sufficiently capture the risk of path-VF in older adults. Methods: This retrospective study included 225 patients who underwent kyphoplasty or PISF (2022–2023). Path-VF was defined by non-tumorous fractures, screw reinforcement, or PSL within six months without prior reinforcement. Patients were grouped into the path-VF (n = 94) and control (n = 131) groups. HU and BMI values, BMI-related ORs, and age trends were analysed, and a logistic regression was performed. Results: Mean HU values were significantly lower in the path-VF group (71.37 ± 30.50) than in controls (130.35 ± 52.53, p < 0.001). Path-VF females (26.26 ± 5.38) had a lower BMI than the control females (29.33 ± 5.98, p = 0.002); no difference was found in males. Normal-weight females showed a borderline risk for path-VF (OR 2.03, p = 0.0495). Obesity (OR_male 0.31/OR_female 0.37) and being male and overweight (OR 0.21) were protective (all p < 0.05). BMI declined with age in path-VF males (p = 0.001) but increased in the controls (p = 0.023). A logistic regression identified a BMI < 22.5 kg/m² and age > 67.5 years as significant risk thresholds. Notably, 20.2% of path-VF patients over 67.5 had a normal weight, suggesting a potentially overlooked subgroup. Conclusions: The current WHO lower limit for normal BMI (18.5 kg/m²) may underestimate the risk of path-VF in patients older than 67.5 years, potentially overlooking 24.7% of cases. The results offer a new approach for clinicians to interpret BMI values at the lower end of the normal range (<22.5 kg/m²) with caution in elderly patients undergoing spinal surgery. Full article

Pedicle screw fixation is a critical technique for stabilizing lumbar fractures in canines, yet the biomechanical implications of insertion angles remain underexplored. This study aims to identify optimal screw trajectories by analyzing stress distribution and deformation patterns in beagle lumbar segments (L6-L7) using finite element analysis (FEA). A 3D finite element model was reconstructed from CT scans of a healthy beagle, incorporating cortical/cancellous bone, intervertebral disks, and cartilage. Pedicle screws (2.4 mm diameter, 22 mm length) were virtually implanted at angles ranging from 45° to 65°. A 10 N vertical load simulated standing conditions. Equivalent stress and total deformation were evaluated under static loading. The equivalent stress occurred at screw–rod junctions, with maxima at 50° (11.73 MPa) and minima at 58° (3.25 MPa). Total deformation ranged from 0.0033 to 0.0064 mm, with the highest at 55° and the lowest at 54°. The 58° insertion angle demonstrated optimal biomechanical stability with minimal stress concentration, with 56–60° as a biomechanically favorable range for pedicle screw fixation in canine lumbar fractures, balancing stress distribution and deformation control. Future studies should validate these findings in multi-level models and clinical settings. Full article

Background: Traumatic fractures of the cervical spine pose significant challenges in management, particularly in young patients, where preserving mobility is crucial. Patient Characteristics: A 30-year-old woman presented with a C3 lateral mass and pedicle fracture following a motor vehicle collision. Initial conservative management with a rigid cervical collar for three months failed to reduce the diastasis, and the debilitating neck pain worsened. Preoperative imaging confirmed fracture instability without spinal cord compression. Intervention and Outcome: Preoperative screw trajectory planning was conducted with the My Spine MC system (Medacta), and fine-tuning was achieved on a 3D-printed model of the vertebra. A posterior midline approach was employed to expose the C3 vertebra, and a Herbert screw was inserted under fluoroscopic guidance. Imaging at three months demonstrated significant fracture reduction and early bone fusion. The patient achieved substantial improvement in functional mobility without complications. Conclusion: Herbert screw fixation holds potential as a less-invasive alternative to conventional posterior stabilization for selected cervical fractures. This technical note provides the reader with the required information to support surgical planning and execution. Full article

Pedicle screw fixation is a common spinal surgery technique, but concerns remain about stability when screws are malpositioned. Traditional in vitro pull-out tests assess anchorage but lack physiological accuracy. This study examined the stability of correctly placed and intentionally malpositioned pedicle screws on forty vertebrae from five cadavers. Optimal screw paths were planned via CT scans and applied using 3D-printed guides. Four malposition types—medial, lateral, superior, and superior-lateral—were created by shifting the original trajectory. A custom setup applied three consecutive cycles of tensile and compressive load from 50 N to 200 N. Screw inclination under load was measured with a 3D optical system. The results showed increasing screw inclination with higher forces, reaching about 1° at 50 N and 2° at 100 N, similar in both load directions. Significant differences in inclination were only found at 100 N tensile load, where malpositioned screws showed a lower inclination. Overall, malpositioning had no major effect on screw loosening. These findings suggest that minor deviations in screw placement do not significantly compromise mechanical stability. Clinically, the main concern with malpositioning lies in the potential for injury to nearby structures rather than reduced screw fixation strength. Full article

Background/Objectives: One of the surgical interventions applied in the cervical region is the pedicle screw method. The cervical pedicle screw is stronger than any other screw method; however, use of the cervical pedicle screw is limited due to the variability in the anatomy of the cervical vertebrae and the risks to the neurological and vascular structures in this region. This study aimed to determine the morphological features of subaxial cervical vertebrae of the adult Turkish population and to provide guidance for the pedicle screwing method. Methods: In our study, pedicle analyses were examined in the subaxial neck vertebrae of a total of 60 patients, 30 male and 30 female, using computed tomography images. In subaxial vertebrae (C3–C7), bilateral pedicle width, pedicle axis length, pedicle transverse angle, sagittal and transverse diameter of vertebral foramen, and the distance between two pedicles were measured. Results: Pedicle widths that did not fit the commonly used 3.5 mm pedicle screw were detected in both male and female patients. The mean bilateral pedicle width in male patients was found to be greater than in female patients. When the parameter results were compared according to the levels, it was found that the pedicle width, pedicle axis length, transverse diameter, and the distance between the two pedicles increased statistically significantly. Conclusions: We think that the data obtained from the study will help determine the appropriate screwing (screw selection) in subaxial vertebra pedicle surgery and increase the success of the surgical procedure. Full article

Background: The aim of this study was to assess pedicle screw (PS) accuracy and identify perforation patterns using computed tomography (CT) navigation in adolescent idiopathic scoliosis (AIS) surgery. Methods: A total of 107 AIS patients were retrospectively reviewed. Preoperative CT navigation was used in 48 patients (853 screws), and intraoperative CT with a second 3D scan was used in 59 patients (1059 screws). Postoperative CT images were analyzed using the Rampersaud grading system. Results: Overall PS accuracy (grade A + B) was significantly higher in the intraoperative CT group than the preoperative group (97% vs. 95%, p = 0.008). In Lenke type 1 cases, accuracy was also higher in the intraoperative group (97.8% vs. 95.1%, p = 0.014). Grade D perforations were most frequent on the concave side of the proximal thoracic (PT) zone in both groups. Ten screws were re-inserted during surgery in the intraoperative group based on findings from the second 3D scan. Conclusions: The concave PT zone is a common site for PS misplacement. Intraoperative CT navigation with a second 3D scan enhances PS accuracy compared with preoperative CT navigation. Full article

Background/Objectives: Previous studies have reported satisfactory outcomes and low rates of instrumentation-related complications (IRCs) following nonfusion posterior fixation in patients with metastatic spinal tumors (MSTs). However, to adequately assess the longevity and durability of nonfusion instrumentation in patients with longer life expectancy, an extended follow-up period is essential. This study aims to evaluate the incidence of and risk factors for IRCs in patients with MSTs who underwent nonfusion posterior fixation and had radiographic follow-up data available for at least one year postoperatively. Methods: Consecutive data were collected from patients who underwent pedicle screw-based posterior fixation without fusion for MSTs in the thoracic and/or lumbar region from 2005 to 2018. The IRCs included screw loosening, screw pull-out, and metal breakage. The IRC-free survival and related factors were analyzed by Kaplan–Meier survivorship analysis with the log-rank test within a minimum follow-up period of one year. A multivariate analysis was performed using a Cox proportional-hazards regression model. Results: In total, 61 patients were included. The mean follow-up period was 28.3 months (range: 12.0–102.6 months). There were 27 cases (44.2%) of IRCs, including 22 cases of screw loosening, four cases of screw pull-out, and one case of rod breakage, at an average of 9.6 months (range: 1.0–38.1 months). The median IRC-free survival was 38.1 months (range: 1.0–102.6 months). Only three patients experienced pain aggravation with IRCs. No revision surgery was performed. A multivariate analysis identified that fixation length was a risk factor for IRCs (odds ratio: 0.358, 95% confidence interval: 0.114–0.888; p = 0.027). Conclusions: IRCs are frequent but mostly asymptomatic after nonfusion posterior fixation in patients with MSTs followed up for at least one year. Overall, the IRC-free survival was long enough considering the patient survival. Fixation length was a significant risk factor for IRCs regardless of MST location. Full article

Background/Objectives: Lateral lumbar interbody fusion (LLIF) has gained popularity as an effective technique for indirect decompression through ligamentotaxis. Despite the perceived importance of using appropriately sized cages for achieving optimal decompression, comprehensive reports on cage size and its impact on indirect decompression are limited. This study aimed to assess the ligamentotaxis effect by measuring the “backward bulging” length in pre- and postoperative MRIs and examining its correlation with cage size and subsidence. Methods: T2 images of 270 patients with lumbar herniated disc and/or lumbar spondylolisthesis (June 2022 to March 2025) were analyzed for 530 intervertebral spaces. Data on gender, age, length of hospital stay, preoperative and postoperative lumbar JOA scores, and the level of the disease were collected. Measurements included backward bulging length, intervertebral height, and cage subsidence. Statistical analysis was performed using StatMate. Surgical procedures involved oblique lateral interbody fusion (OLIF) to minimize impact on the iliopsoas and lumbar plexus. Trial cages starting from 8 mm were sequentially inserted, with confirmation through lateral fluoroscopy. Posterior fixation was performed using percutaneous pedicle screws. Results: Analysis of 530 intervertebral spaces revealed that 70% could accommodate a cage 3 mm or larger than the preoperative intervertebral height. Significant backward bulging shortening (3 mm or more) occurred in 339 spaces, predominantly with larger cages. Only 8.8% of cases (14/159) with a large backward bulging shortening had an intervertebral height extension of 3 mm or less. On the other hand, a large reduction in backward bulging was observed in 91.3% of cases (339/371) with an intervertebral height extension of 3 mm or more. Postoperative cage subsidence was observed in 9.2% (49/530) of all intervertebral spaces and 8.6% (32/371) in spaces where a cage larger than 3 mm was used. There was no statistically significant difference between these two groups. Conclusions: To achieve a sufficient ligamentotaxis effect, it is necessary to select a cage size that allows for an intervertebral height increase of at least 3 mm compared to the preoperative measurement. Full article

The accuracy of pedicle screw insertion in pediatric scoliosis correction surgery using augmented reality technology in combination with a conventional navigation system was evaluated, and its usefulness was verified. A retrospective study of patients who underwent mixed reality technology-assisted posterior scoliosis correction and fixation was conducted. In total, 361 pedicle screws inserted with a mixed reality technology-assisted navigation system were analyzed; 25 pedicle screws (6.9%) showed Rao Classification Grade 1 deviation, whereas 0.83% showed Rao Classification Grade 2.3 deviation, which is a clinical deviation. In terms of the relationship between the rotation of the vertebral body and the deviation of the pedicle screw, the pedicle screw tended to deviate more easily when it was necessary to insert the pedicle screw in a more strongly oblique position due to the rotation of the vertebral body. The results suggest that the pedicle screw insertion accuracy with augmented reality technology may be superior to that with conventional navigation alone in scoliosis correction and fusion surgery for scoliosis in children. This system is expected to become a standard support tool for spine surgery and will contribute to improving the success rate of surgery and reducing the burden on the surgeon. Full article

Objective: The aim of this study is to present the initiation of robotic-guided (RG) spine surgery into routine clinical care at a single center with the use of intraoperative CT (iCT) automatic registration-based navigation. The workflow included iCT with automatic registration, fusion with preoperative imaging, verification of preplanned screw trajectories, RG introduction of K-wires, and the insertion of pedicle screws (PSs), followed by a control iCT scan. Methods: All patients who underwent RG implantation of pedicle screws using the Cirq^® robotic arm (BrainLab, Munich, Germany) in the thoracolumbar spine at our department were included in the study. The accuracy of the pedicles screws was assessed using the Gertzbein–Robbins scale (GRS). Results: In total, 108 patients (60 female, mean age 68.7 ± 11.4 years) in 109 surgeries underwent RG PS placement. Indications included degenerative spinal disorders (n = 30 patients), spondylodiscitis (n = 24), tumor (n = 33), and fracture (n = 22), with a mean follow-up period of 7.7 ± 9 months. Thirty-seven cases (33.9%) were performed percutaneously, and all others were performed openly. Thirty-three operations were performed on the thoracic spine, forty-four on the lumbar and lumbosacral spine, thirty on the thoracolumbar, one on the cervicothoracic spine, and one on the thoracolumbosacral spine. The screws were inserted using a fluoroscopic (first 12 operations) or navigated technique (latter operations). The mean operation time was 228.8 ± 106 min, and the mean robotic time was 31.5 ± 18.4 min. The mean time per K-wire was 5.35 ± 3.98 min. The operation time was lower in the percutaneous group, while the robot time did not differ between the two groups. Robot time and the time per K-wire improved over time. Out of 688 screws, 592 were GRS A screws (86.1%), 54 B (7.8%), 22 C (3.2%), 12 D (1.7%), and 8 E (1.2%). Seven screws were revised intraoperatively, and after revision, all were GRS A. E screws were either revised or removed. In the case of D screws, screws located at the end of the construct were revised, while so-called in-out-in screws in the middle of the construct were not revised. Conclusions: Brainlab’s Cirq^® Robotic Alignment Module feature enables placement of pedicle screws in the thoracolumbar spine with high accuracy. A learning curve is shown through improvements in robotic time and time per K-wire. Full article

The traditional bilateral pedicle screw system has been used for the treatment of various lumbar spine conditions including advanced degenerative disc disease. However, there is an ongoing need to develop more effective and less invasive techniques. The purpose of this study was to compare the traditional bilateral pedicle screw system (BPSS) with the novel reverse transdiscal screw system (RTSS) for lumbar disc degenerative disease. A 3D solid lumbar L1–L5 spine model was developed and validated based on a human CT scan. Fusions were simulated at L3–L4. The first scenario comprised a transforaminal lumbar interbody cage in combination with the bilateral pedicle screw-rod system (BPSS-TLIF). In the second scenario, the same TLIF cage was combined with reverse L3–L4 transdiscal screws (RTSS-TLIF). Testing parameters included range of motion (ROM) in three orthogonal axes, hardware (cage and screw) stress, and shear load resistance. The ROM of the surgical model was reduced by approximately 90% compared to the intact model at the fused level. The RTSS model demonstrated less ROM compared to the BPSS model at the fused level for all loading conditions. Overall, the RTSS model exhibited lower stress on both screws and cage compared with the BPSS model in all biomechanical testing conditions. The RTSS model also exhibited higher anterior and posterior shear load resistance than the BPSS model. In conclusion, the RTSS model proved superior to the BPSS model in all respects. These findings indicate that the RTSS could serve as a feasible option for patients undergoing lumbar fusion, especially for adjacent segment disease, potentially enhancing surgical outcomes for disc degeneration. Full article

This study aimed to develop a novel modular pedicle screw system incorporating an elliptical sleeve to conform the pedicle’s elliptical cross-section and enhance fixation strength with mechanical stability. The biomechanical evaluation was conducted based on fundamental mechanics principles, followed by a finite element (FE) analysis to assess stress distribution under compressive and torsional loads. Subsequently, mechanical testing was performed to evaluate static and fatigue bending performance and in vitro biomechanical fatigue in porcine vertebrae by pull-out testing after 5000 and 100,000 cycles to assess fixation stability. The FE analysis demonstrated that the elliptical sleeve design improved bending resistance by 1.21× and torsional resistance by 1.91× compared to conventional cylindrical screws. Mechanical testing revealed greater bending/torsion stiffness and fatigue resistance, with the elliptical sleeve screw withstanding 5 million cycles at 235.4 N, compared to 175.46 N for cylindrical screws. Biomechanical pull-out testing further confirmed significantly higher retention strength after 100,000 cycles (1229.75 N vs. 867.83 N, p = 0.0101), whereas cylindrical screws failed prematurely at 10,663 cycles due to excessive displacement (>2 mm). The elliptical sleeve pedicle screw system demonstrated enhanced fixation strength, reduced micromotion, and superior fatigue resistance, making it a promising alternative to conventional pedicle screws for improving long-term spinal fixation stability. Full article

Background: This study aimed at delivering first clinical results after the use of a screw-and-PEEK rod system. Emphasis was placed on the ability of the construct to prevent adjacent segment disease at an average of 5 years follow up. Methods: The cohort was made up of 33 patients who received decompressive surgery in one segment and instrumentation with a screw-and-PEEK rod-based construct for stenosis of the lumbar spinal canal and a control group of 20 who received fusion surgery. Results: At an average of 68 months follow up there were 19 patients where the symptoms had markedly improved or completely subsided. There were also nine patients where the symptoms initially subsided only to reoccur years later and five who had a subjective non-satisfactory result. Conclusions: The system showed no major disadvantage when compared to similar non-fusion pedicle-based techniques, nor was it able to consequently prevent ASD. Under a clinical point of view, there was, in our opinion, no marked benefit when compared against decompressive surgery and fusion as the accepted standard. Full article

Background/Objectives: Stand-alone lateral lumbar interbody fusion (LLIF) remains a debated approach in spinal surgery, with limited published evidence supporting its efficacy without supplemental fixation. This prospective study presents the institutional case series on single-level L3-L4 stand-alone LLIF, using next-generation 3D-printed titanium cages, as treatment for degenerative disc disease (DDD). Methods: A cohort of 49 patients with symptomatic DDD, unresponsive to conservative therapy, underwent stand-alone LLIF at L3-L4 (neither posterior pedicle screws nor lateral plating). Clinical outcomes (VAS and ODI) and radiological parameters (disc height, segmental/lumbar lordosis) were collected preoperatively and at 1, 6, and 12 months. Repeated-measures ANOVA with Bonferroni correction was adopted for statistical analysis. Results: Significant improvements were observed in pain and disability scores at all time points, with the mean VAS score decreasing from 6.53 to 0.29, and ODI from 27.6% to 3.84% at one year (p < 0.001). Radiographic analysis confirmed durable increases in disc height and segmental lordosis. Solid fusion was achieved in 97.9% of cases. No patient required posterior revision; transient neurological symptoms were mild and self-limiting. Conclusions: This study demonstrates that stand-alone LLIF at L3-L4 is safe and effective in achieving stable fusion and clinical–radiological improvement. These results challenge the necessity of supplemental fixation and support the broader adoption of a less invasive fusion paradigm. Full article

Background/Objectives: Early-onset scoliosis (EOS) frequently requires growth-friendly interventions, such as magnetically controlled growing rods (MCGRs), followed by definitive spinal fusion upon skeletal maturity. The optimal implant density (ID) for final posterior spinal fusion in these patients remains controversial. This study aimed to compare the radiographic, surgical, and economic outcomes associated with high-density (HD) versus low-density (LD) screw constructs in EOS patients previously treated with MCGRs undergoing definitive fusion. Methods: This retrospective study included 27 EOS patients who underwent definitive posterior spinal fusion between January 2017 and September 2022. Participants were categorized into two groups: HD (n = 13) and LD (n = 14). Primary outcomes included coronal and sagittal radiographic parameters assessed at early postoperative and final follow-up visits (minimum of 2 years). The secondary outcomes analyzed were major postoperative complications (grade ≥ IIIB according to Clavien–Dindo–Sink Classification [CDSC]), operative time, blood loss, hospital stay length, and total implant costs. Results: Baseline characteristics between the HD and LD groups were comparable. Early postoperative radiographic assessment demonstrated significantly greater thoracic kyphosis (16.3 ± 7.6° vs. 10.9 ± 14.4°, p = 0.021) and T1-S1 spinal height (43.3 ± 6.7 mm vs. 39.1 ± 4.3 mm, p = 0.039) in the HD group. At final follow-up, only T1-S1 spinal height remained significantly higher in the HD group (45.4 ± 7 mm vs. 39.7 ± 5.1 mm, p = 0.021). Implant costs were significantly higher in the HD group (EUR 6046.5 ± 1146.9 vs. EUR 4376.4 ± 999.4, p < 0.001), while operative time, blood loss, and hospital stay length showed no significant differences. HD constructs had three major complications requiring surgical revision, whereas LD constructs reported no perioperative complications but experienced three late-onset complications also necessitating revision surgery. Conclusions: LD constructs provided comparable long-term radiographic and clinical outcomes to HD constructs, with significantly lower implant-related costs. Despite initial superior kyphosis correction in HD constructs, this benefit diminished by the final follow-up. These findings support a selective, lower-density screw placement strategy to minimize costs and surgical complexity without compromising patient outcomes in EOS undergoing definitive spinal fusion. Full article