Intervertebral fusion sites in patients with ankylosing spondylitis: A computed tomography study.

OBJECTIVES: To examine intervertebral fusion sites along the whole spine of patients with ankylosing spondylitis using computed tomography. METHODS: This retrospective study examined intervertebral fusion of five sites (anterior/posterior vertebrae, left/right zygapophyseal joints, and spinous process) on 23 vertebrae in the cervical, thoracic, and lumbar regions of the spine in 40 patients diagnosed with ankylosing spondylitis at our institute between January 2004 and December 2022. RESULTS: Mean age [± standard deviation (SD)] was 40.5 (± 17) years, and mean disease duration (± SD) was 11.4 (± 10.5) years at computed tomography evaluation; 55.9% were human leukocyte antigen B-27-positive. Fifteen (37.5%) patients showed intervertebral fusion in the thoracic and/or cervical regions, but not in the lumbar region. Fusion of posterior vertebrae was observed most frequently in the thoracic region, compared to the cervical and lumbar regions. In particular, more than half of the patients showed fusion of posterior vertebrae Th4-Th5 to Th7-Th8. CONCLUSIONS: In 37.5% of patients, intervertebral fusion was evident in the thoracic and/or cervical regions but not in the lumbar region. The most common site and region of intervertebral fusion were the posterior vertebrae of the middle thoracic region.

Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine.

OBJECTIVE: This study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system. METHODS: A total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior-posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results. RESULTS: The screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92-6.08 mm) and female (2.32-5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73-66.76°), lower screw (48.05-65.35°); female group upper screw (49.15-65.66°) and lower screw (49.42-63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06-39.56°), lower screw (29.12-36.95°); female group upper screw (30.97-38.92°) and lower screw (27.29-37.20°). The anterior-posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). CONCLUSIONS: Through the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

A more than 20-year follow-up of pain and disability after anterior cervical decompression and fusion surgery for degenerative disc disease and comparisons between two surgical techniques.

BACKGROUND: Follow-ups more than 20 years after neck surgery are extremely rare. No previous randomized studies have investigated differences in pain and disability more than 20 years after ACDF surgery using different techniques. The purpose of this study was to describe pain and functioning more than 20 years after anterior cervical decompression and fusion surgery, and to compare outcomes between the Cloward Procedure and the carbon fiber fusion cage (CIFC). METHODS: This study is a 20 to 24-year follow-up of a randomized controlled trial. Questionnaires were sent to 64 individuals, at least 20 years after ACDF due to cervical radiculopathy. Fifty individuals (mean age 69, 60% women, 55% CIFC) completed questionnaires. Mean time since surgery was 22.4 years (range 20,5-24). Primary outcomes were neck pain and neck disability index (NDI). Secondary outcomes were frequency and intensity of neck and arm pain, headache, dizziness, self-efficacy, health related quality of life or global outcome. Clinically relevant improvements were defined as 30 mm decrease in pain and a decrease in disability of 20 percentage units. Between-group differences over time were analyzed with mixed design ANOVA and relationships between main outcomes and psychosocial factors were analyzed by Spearman´s rho. RESULTS: Neck pain and NDI score significantly improved over time (p < .001), with no group differences in primary or secondary outcomes. Eighty-eight per cent of participants experienced improvements or full recovery, 71% (pain) and 41% (NDI) had clinically relevant improvements. Pain and NDI were correlated with lower self-efficacy and quality of life. CONCLUSION: The results from this study do not support the idea that fusion technique affects long-term outcome of ACDF. Pain and disability improved substantially over time, irrespective of surgical technique. However, the majority of participants reported residual disability not to a negligible extent. Pain and disability were correlated to lower self-efficacy and quality of life.

Analysis of risk factors for contralateral symptomatic foraminal stenosis after unilateral transforaminal lumbar interbody fusion.

PURPOSE: To analyze the risk factors of contralateral symptomatic foraminal stenosis (FS) after unilateral transforaminal lumbar interbody fusion (TLIF) and to guide and standardize the operation process of unilateral TLIF to reduce the occurrence of contralateral symptomatic FS. METHODS: A retrospective study was undertaken on 487 patients with lumbar degeneration who underwent unilateral TLIF in the Department of Spinal Surgery of Ningbo Sixth Hospital between January 2017 and January 2021, comprising 269 males and 218 females, with a mean age of 57.1 years (range, 48-77 years). Cases of intraoperative improper operations, such as screw deviation, postoperative hematoma, and contralateral disc herniation, were excluded, and cases of nerve root symptoms caused by contralateral FS were analyzed. Post-surgery, 23 patients with nerve root symptoms caused by contralateral FS were categorized as group A, and 60 patients without nerve root symptoms were randomly selected as group B during the same period. The general data (gender, age, body mass index (BMI), bone mineral density (BMD), and diagnosis) and imaging parameters before and after operation (including contralateral foramen area (CFA), lumbar lordosis angle (LL), segmental lordosis angle (SL), disc height (DH), foramen height (FH), foramen width (FW), fusion cage position, and the difference between postoperative and preoperative) were compared between the two groups. Univariate analysis was performed, and multivariate analysis was undertaken through logistics analysis to determine the independent risk factors. Additionally, the clinical outcomes of the two groups were compared immediately before surgery and one year after surgery, using the visual analogue scale (VAS) score and the Japanese Orthopaedic Association (JOA) score for evaluation. RESULTS: The patients in this study were followed up for a period of 19-25 (22.8atien months. Among them, 23 cases (4.72% incidence) were diagnosed with contralaterally symptomatic FS after the surgery. Univariate analysis indicated significant differences between the two groups in CFA, SL, FW, and cage coronal position. Logistic regression analysis identified preoperative contralateral foramen area (OR = 1.176, 95% CI (1.012, 1.367)), small segmental lordosis angle (OR = 2.225, 95% CI (1.124, 4.406)), small intervertebral foramen width (OR = 2.706, 95% CI (1.028, 7.118)), and cage coronal position not crossing the midline (OR = 1.567, 95% CI (1.142, 2.149)) as independent risk factors for contralateral symptomatic FS after unilateral TLIF. However, there was no statistically significant difference in the pain VAS score between the two groups one year after the operation. In contrast, there was a significant difference in the JOA score between the two groups. CONCLUSION: The identified risk factors for contralateral symptomatic FS after TLIF include preoperative contralateral intervertebral foramen stenosis, a small segmental lordosis angle, a small intervertebral foramen width, and the coronal position of the cage not crossing the midline. For patients with these risk factors, it is recommended to carefully lock the screw rod during the recovery of lumbar lordosis and ensure that the coronal position of the fusion cage is implanted beyond the midline. If necessary, preventive decompression should also be considered. However, this study did not quantify the imaging data for each risk factor, and further research is needed to improve our understanding of the topic.

Comparison among perfect-C®, zero-P®, and plates with a cage in single-level cervical degenerative disc disease.

BACKGROUND: We intended to analyze the efficacy of a new integrated cage and plate device called Perfect-C for anterior cervical discectomy and fusion (ACDF) to cure single-level cervical degenerative disc disease. METHODS: We enrolled 148 patients who were subjected to single-level ACDF with one of the following three surgical devices: a Perfect-C implant (41 patients), a Zero-P implant (36 patients), or a titanium plate with a polyetheretherketone (PEEK) cage (71 patients). We conducted a retrospective study to compare the clinical and radiological results among the three groups. RESULTS: The length of the operation, intraoperative blood loss, and duration of hospitalization were significantly lower in the Perfect-C group than in the Zero-P and plate-with-cage groups (P < 0.05). At the last follow-up visit, heterotopic ossification (HO) was not observed in any cases (0%) in the Perfect-C and Zero-P groups but was noted in 21 cases (30%) in the plate-with-cage group. The cephalad and caudal plate-to-disc distance (PDD) and the cephalad and caudal PDD/anterior body height (ABH) were significantly greater in the Perfect-C and Zero-P groups than in the plate-with-cage group (P < 0.05). Subsidence occurred in five cases (14%) in the Perfect-C group, in nine cases (25%) in the Zero-P group, and in 15 cases (21%) in the plate-with-cage group. Fusion occurred in 37 cases (90%) in the Perfect-C group, in 31 cases (86%) in the Zero-P group, and in 68 cases (95%) in the plate-with-cage group. CONCLUSIONS: The Perfect-C, Zero-P, and plate-with-cage devices are effective for treating single-level cervical degenerative disc disease. However, the Perfect-C implant has many advantages over both the Zero-P implant and conventional plate-cage treatments. The Perfect-C implant was associated with shorter operation times and hospitalization durations, less blood loss, and lower subsidence rates compared with the Zero-P implant or the titanium plate with a PEEK cage.

Minimally invasive resection of extradural dumbbell tumors of thoracic spine: surgical techniques and literature review.

PURPOSE: Dumbbell-shaped thoracic tumors represent a distinct type of tumor and involve in both the spinal canal and the posterior thoracic cavity. Successful treatment for the tumors depends on gross total resection (GTR) via an open laminectomy and facetectomy or transthoracic transpleural approach. In this case series, we report our experiments with minimally invasive method for the removal of extradural dumbbell thoracic tumor and present related literature review. METHODS: We retrospectively reviewed two patients with dumbbell-shaped thoracic tumors who underwent minimally invasive resection and unilateral transforaminal thoracic intervertebral fusion (TTIF) through unilateral paraspinal muscle approachwith a spotlight expandable tubular retractor. Clinical data, tumor characteristics, and outcomes were analyzed. RESULTS: Two patients underwent successful minimally invasive treatment of their spinal neoplasms. There were no procedure-related complications. The efficacy in terms of neurological recovery, pain improvement and operative variables (length of incision, operative duration, blood loss, and hospital stay) was better when compared with prior published studies. Postoperative CT image demonstrated complete resection of dumbbell tumor in the patients. The solid fusion was obtained after 3 months follow-up and there was no failure of internal fixation. CONCLUSION: If the medial border of intracanal component of extradural dumbbell tumor is near the midline of canal and the pedicles of adjacent vertebrae to tumor are intact, minimally invasive resection of tumor through unilateral paraspinal muscle approach combined with unilateral TTIF is good choice.

The Effect of Topical Vancomycin Powder Application on the Rate of Intervertebral Fusion Following Lumbar Fusion: A Retrospective Study.

PURPOSE: The occurrence of surgical site infection (SSI) after lumbar spinal fusion is a serious complication. Therefore, an increasing number of clinicians are applying vancomycin powder topically in the surgical field to reduce the incidence of SSI. However, there is concern that topical vancomycin powder application may affect intervertebral fusion. The purpose of this study was to analyse the effect of clinically relevant topical vancomycin doses on the rate of intervertebral fusion after lumbar fusion and to further investigate the effect of vancomycin powder on the prevention of SSI. METHODS: The clinical data of 192 patients with degenerative lumbar spine disease admitted from January 2019 to June 2022, all of whom underwent posterior lumbar fusion, were retrospectively analysed. According to the infection prevention protocol, they were divided into a vancomycin group and a control group (no vancomycin), and the vancomycin group was sub-divided into 0.5 g, 1.0 g, and 1.5 g vancomycin groups. General information and surgical evaluation indexes were compared between the control and vancomycin groups and intervertebral fusion was compared between the vancomycin groups at 6 months and 12 months, postoperatively. RESULTS: The rate of SSI in the vancomycin group was 0.0%, which was significantly lower than that in the control group (5.3%, P < 0.05), and intervertebral fusion was good in all 3 vancomycin groups at 6 months and 12 months postoperatively, with no statistically-significant differences (P > 0.05). CONCLUSIONS: Topical application of 0.5 g, 1.0 g, or 1.5 g vancomycin powder did not affect the rates of intervertebral fusion after lumbar fusion. In addition, topical application of vancomycin powder significantly reduced the rates of SSI.

Biomimetic Porous Ti6Al4V Implants: A Novel Interbody Fusion Cage via Gel-Casting Technique to Promote Spine Fusion.

An interbody fusion cage (Cage) is crucial in spinal decompression and fusion procedures for restoring normal vertebral curvature and rebuilding spinal stability. Currently, these Cages suffer from issues related to mismatched elastic modulus and insufficient bone integration capability. Therefore, a gel-casting technique is utilized to fabricate a biomimetic porous titanium alloy material from Ti6Al4V powder. The biomimetic porous Ti6Al4V is compared with polyetheretherketone (PEEK) and 3D-printed Ti6Al4V materials and their respective Cages. Systematic validation is performed through mechanical testing, in vitro cell, in vivo rabbit bone defect implantation, and ovine anterior cervical discectomy and fusion experiments to evaluate the mechanical and biological performance of the materials. Although all three materials demonstrate good biocompatibility and osseointegration properties, the biomimetic porous Ti6Al4V, with its excellent mechanical properties and a structure closely resembling bone trabecular tissue, exhibited superior bone ingrowth and osseointegration performance. Compared to the PEEK and 3D-printed Ti6Al4V Cages, the biomimetic porous Ti6Al4V Cage outperforms in terms of intervertebral fusion performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. This biomimetic porous Ti6Al4V Cage offers cost-effectiveness, presenting significant potential for clinical applications in spinal surgery.

[Analysis of the causes of cage subsidence after oblique lateral lumbar interbody fusion].

OBJECTIVE: To observe the cage subsidence after oblique lateral interbody fusion (OLIF) for lumbar spondylosis, summarize the characteristics of the cage subsidence, analyze causes, and propose preventive measures. METHODS: The data of 144 patients of lumbar spine lesions admitted to our hospital from October 2015 to December 2018 were retrospectively analyzed. There were 43 males and 101 females, and the age ranged from 20 to 81 years old, with an average of (60.90±10.06) years old. Disease types:17 patients of lumbar intervertebral disc degenerative disease, 12 patients of giant lumbar disc herniation, 5 patients of discogenic low back pain, 33 patients of lumbar spinal stenosis, 26 patients of lumbar degenerative spondylolisthesis, 28 patients of lumbar spondylolisthesis with spondylolisthesis, 11 patients of adjacent vertebral disease after lumbar internal fixation, 7 patients of primary spondylitis in the inflammatory outcome stage, and 5 patients of lumbar degenerative scoliosis. Preoperative dual-energy X-ray bone mineral density examination showed 57 patients of osteopenia or osteoporosis, and 87 patients of normal bone density. The number of fusion segments:124 patients of single-segment, 11 patients of two-segment, 8 patients of three-segment, four-segment 1 patient. There were 40 patients treated by stand-alone OLIF, and 104 patients by OLIF combined with posterior pedicle screw. Observed the occurrence of fusion cage settlement after operation, conducted monofactor analysis on possible risk factors, and observed the influence of fusion cage settlement on clinical results. RESULTS: All operations were successfully completed, the median operation time was 99 min, and the median intraoperative blood loss was 106 ml. Intraoperative endplate injury occurred in 30 patients and vertebral fracture occurred in 5 patients. The mean follow-up was (14.57±7.14) months from 6 to 30 months. During the follow-up, except for the patients of primary lumbar interstitial inflammation and some patients of lumbar spondylolisthesis with spondylolisthesis, the others all had different degrees of cage subsidence. Cage subsidence classification:119 patients were normal subsidence, and 25 patients were abnormal subsidence (23 patients were gradeⅠ, and 2 patients were gradeⅡ). There was no loosening or rupture of the pedicle screw system. The height of the intervertebral space recovered from the preoperative average (9.48±1.84) mm to the postoperative average (12.65±2.03) mm, and the average (10.51±1.81) mm at the last follow-up. There were statistical differences between postoperative and preoperative, and between the last follow-up and postoperative. The interbody fusion rate was 94.4%. The low back pain VAS decreased from the preoperative average (6.55±2.2 9) to the last follow-up (1.40±0.82), and there was statistically significant different. The leg pain VAS decreased from the preoperative average (4.72±1.49) to the final follow-up (0.60±0.03), and the difference was statistically significant (t=9.13, P<0.000 1). The ODI index recovered from the preoperative average (38.50±6.98)% to the latest follow-up (11.30±3.27)%, and there was statistically significant different. The complication rate was 31.3%(45/144), and the reoperation rate was 9.72%(14/144). Among them, 8 patients were reoperated due to fusion cage subsidence or displacement, accounting for 57.14%(8/14) of reoperation. The fusion cage subsidence in this group had obvious characteristics. The monofactor analysis showed that the number of abnormal subsidence patients in the osteopenia or osteoporosis group, Stand-alone OLIF group, 2 or more segments fusion group, and endplate injury group was higher than that in the normal bone mass group, OLIF combined with pedicle screw fixation group, single segment fusion group, and no endplate injury group, and the comparison had statistical differences. CONCLUSION: Cage subsidence is a common phenomenon after OLIF surgery. Preoperative osteopenia or osteoporosis, Stand-alone OLIF, 2 or more segments of fusion and intraoperative endplate injury may be important factors for postoperative fusion cage subsidence. Although there is no significant correlation between the degree of cage subsidence and clinical symptoms, there is a risk of cage migration, and prevention needs to be strengthened to reduce serious complications caused by fusion of cage subsidence, including reoperation.

Biomechanical study of anterior transpedicular root screw intervertebral fusion system of lower cervical spine: a finite element analysis.

Background: The cervical anterior transpedicular screw (ATPS) fixation technology can provide adequate stability for cervical three-column injuries. However, its high risk of screw insertion and technical complexity have restricted its widespread clinical application. As an improvement over the ATPS technology, the cervical anterior transpedicular root screw (ATPRS) technology has been introduced to reduce the risk associated with screw insertion. This study aims to use finite element analysis (FEA) to investigate the biomechanical characteristics of a cervical spine model after using the novel ATPRS intervertebral fusion system, providing insights into its application and potential refinement. Methods: A finite element (FE) model of the C3-C7 lower cervical spine was established and validated. After two-level (C4-C6) anterior cervical discectomy and fusion (ACDF) surgery, FE models were constructed for the anterior cervical locked-plate (ACLP) internal fixation, the ATPS internal fixation, and the novel ATPRS intervertebral fusion system. These models were subjected to 75N axial force and 1.0 Nm to induce various movements. The range of motion (ROM) of the surgical segments (C4-C6), maximum stress on the internal fixation systems, and maximum stress on the adjacent intervertebral discs were tested and recorded. Results: All three internal fixation methods effectively reduced the ROM of the surgical segments. The ATPRS model demonstrated the smallest ROM during flexion, extension, and rotation, but a slightly larger ROM during lateral bending. Additionally, the maximum bone-screw interface stresses for the ATPRS model during flexion, extension, lateral bending, and axial rotation were 32.69, 64.24, 44.07, 35.89 MPa, which were lower than those of the ACLP and ATPS models. Similarly, the maximum stresses on the adjacent intervertebral discs in the ATPRS model during flexion, extension, lateral bending, and axial rotation consistently remained lower than those in the ACLP and ATPS models. However, the maximum stresses on the cage and the upper endplate of the ATPRS model were generally higher. Conclusion: Although the novel ATPRS intervertebral fusion system generally had greater endplate stress than ACLP and ATPS, it can better stabilize cervical three-column injuries and might reduce the occurrence of adjacent segment degeneration (ASD). Furthermore, further studies and improvements are necessary for the ATPRS intervertebral fusion system.

Application of 3D­printed porous titanium interbody fusion cage vs. polyether ether ketone interbody fusion cage in anterior cervical discectomy and fusion: A systematic review and meta­analysis update.

The present study aimed to compare the differences between 3D-printed porous titanium and polyether ether ketone (PEEK) interbody fusion cages for anterior cervical discectomy and fusion (ACDF). Literature on the application of 3D-printed porous titanium and PEEK interbody fusion cages for ACDF was searched in the PubMed, Web of Science, Embase, China National Knowledge Infrastructure, Wanfang and VIP databases. A total of 1,181 articles were retrieved and 12 were finally included. The Cochrane bias risk assessment criteria and Newcastle-Ottawa scale were used for quality evaluation and Review Manager 5.4 was used for data analysis. The 3D cage group was superior to the PEEK cage group in terms of operative time [mean difference (MD): -7.68; 95% confidence interval (CI): -11.08, -4.29; P<0.00001], intraoperative blood loss (MD: -6.17; 95%CI: -10.56, -1.78; P=0.006), hospitalization time (MD: -0.57; 95%CI: -0.86, -0.28: P=0.0001), postoperative complications [odds ratio (OR): 0.35; 95%CI: 0.15, 0.80; P=0.01], C2-7 Cobb angle (MD: 2.85; 95%CI: 1.45, 4.24; P<0.0001), intervertebral space height (MD: 1.20; 95%CI: 0.54, 1.87; P=0.0004), Japanese Orthopaedic Association Assessment of Treatment (MD: 0.69; 95%CI: 0.24, 1.15; P=0.003) and visual analogue scale score (MD: -0.43; 95%CI: -0.78, -0.07; P=0.02). The difference was statistically significant, while there was no significant difference between the two groups in terms of fusion rate (OR: 1.74; 95%CI: 0.71, 4.27; P=0.23). The use of 3D-printed porous titanium interbody fusion cage in ACDF has the advantages of short operation time, less bleeding loss, shorter hospitalization time and fewer postoperative complications. It can better maintain the cervical curvature and intervertebral height, relieve pain and accelerate postoperative functional recovery.

Development of gelatin-methacryloyl composite carriers for bone morphogenetic Protein-2 delivery: A potential strategy for spinal fusion.

To reduce the risk of nonunion after spinal fusion surgery, the in situ transplantation of bone marrow mesenchymal stem cells (BMSCs) induced toward osteogenic differentiation by bone morphogenetic protein-2 (BMP2) has been proven effective. However, the current biological agents used for transplantation have limitations, such as a short half-life and low bioavailability. To address this, our study utilized a safe and effective gelatin-methacryloyl (GelMA) as a carrier for BMP2. In vitro, experiments were conducted to observe the ability of this composite vehicle to induce osteogenic differentiation of BMSCs. The results showed that the GelMA hydrogel, with its critical properties and controlled release performance of BMP2, exhibited a slow release of BMP2 over 30 days. Moreover, the GelMA hydrogel not only enhanced the proliferation activity of BMSCs but also significantly promoted their osteogenic differentiation ability, surpassing the BMP2 effects. To investigate the potential of the GelMA-BMP2 composite vehicle, a rabbit model was employed to explore its ability to induce in situ intervertebral fusion by BMSCs. Transplantation experiments in rabbits demonstrated the effective induction of intervertebral bone fusion by the GelMA-BMP2-BMSC composite vehicle. In conclusion, the GelMA-BMP2-BMSC composite vehicle shows promising prospects in preclinical translational therapy for spinal intervertebral fusion. It addresses the limitations of current biological agents and offers a controlled release of BMP2, enhancing the proliferation and osteogenic differentiation of BMSCs.

Porous titanium-6 aluminum-4 vanadium cage has better osseointegration and less micromotion than a poly-ether-ether-ketone cage in sheep vertebral fusion.

Interbody fusion cages made of poly-ether-ether-ketone (PEEK) have been widely used in clinics for spinal disorders treatment; however, they do not integrate well with surrounding bone tissue. Ti-6Al-4V (Ti) has demonstrated greater osteoconductivity than PEEK, but the traditional Ti cage is generally limited by its much greater elastic modulus (110 GPa) than natural bone (0.05-30 GPa). In this study, we developed a porous Ti cage using electron beam melting (EBM) technique to reduce its elastic modulus and compared its spinal fusion efficacy with a PEEK cage in a preclinical sheep anterior cervical fusion model. A porous Ti cage possesses a fully interconnected porous structure (porosity: 68 ± 5.3%; pore size: 710 ± 42 µm) and a similar Young's modulus as natural bone (2.5 ± 0.2 GPa). When implanted in vivo, the porous Ti cage promoted fast bone ingrowth, achieving similar bone volume fraction at 6 months as the PEEK cage without autograft transplantation. Moreover, it promoted better osteointegration with higher degree (2-10x) of bone-material binding, demonstrated by histomorphometrical analysis, and significantly higher mechanical stability (P < 0.01), shown by biomechanical testing. The porous Ti cage fabricated by EBM could achieve fast bone ingrowth. In addition, it had better osseointegration and superior mechanical stability than the conventional PEEK cage, demonstrating great potential for clinical application.

Targeted Protein Fate Modulating Functional Microunits Promotes Intervertebral Fusion.

Stable regulation of protein fate is a prerequisite for successful bone tissue repair. As a ubiquitin-specific protease (USP), USP26 can stabilize the protein fate of ß-catenin to promote the osteogenic activity of mesenchymal cells (BMSCs) and significantly increased bone regeneration in bone defects in aged mice. However, direct transfection of Usp26 in vivo is inefficient. Therefore, improving the efficient expression of USP26 in target cells is the key to promoting bone tissue repair. Herein, 3D printing combined with microfluidic technology is applied to construct a functional microunit (protein fate regulating functional microunit, denoted as PFFM), which includes GelMA microspheres loaded with BMSCs overexpressing Usp26 and seeded into PCL 3D printing scaffolds. The PFFM provides a microenvironment for BMSCs, significantly promotes adhesion, and ensures cell activity and Usp26 supplementation that stabilizes ß-catenin protein significantly facilitates BMSCs to express osteogenic phenotypes. In vivo experiments have shown that PFFM effectively accelerates intervertebral bone fusion. Therefore, PFFM can provide new ideas and alternatives for using USP26 for intervertebral fusion and other hard-to-repair bone defect diseases and is expected to provide clinical translational potential in future treatments.

Early fusion outcome after surgical treatment of single-level and multi-level pyogenic spondylodiscitis: experience at a level 1 center for spinal surgery-a single center cohort study.

STUDY DESIGN: Retrospective single center cohort study. PURPOSE: Spinal instrumentation in combination with antibiotic therapy is a treatment option for acute or chronic pyogenic spondylodiscitis (PSD). This study compares the early fusion outcome for multi-level and single-level PSD after urgent surgical treatment with interbody fusion in combination with fixation. METHODS: This is a retrospective cohort study. Over a 10 year period at a single institution, all surgically treated patients received surgical debridement, fusion und fixation of the spine to treat PSD. Multi-level cases were either adjacent to each other on the spine or distant. Fusion rates were assessed at 3 and 12 months after surgery. We analyzed demographic data, ASA status, duration of surgery, location and length of spine affected, Charlson comorbidity index (CCI), and early complications. RESULTS: A total of 172 patients were included. Of these, 114 patients suffered from single-level and 58 from multi-level PSD. The most frequent location was the lumbar spine (54.0%) followed by the thoracic spine (18.0%). The PSD was adjacent in 19.0% and distant in 81.0% of multi-level cases. Fusion rates at the 3 month follow-up did not differ among the multi-level group (p = 0.27 for both adjacent and distant sites). In the single-level group, sufficient fusion was achieved in 70.2% of cases. Pathogen identification was possible 58.5% of the time. CONCLUSIONS: Surgical treatment of multi-level PSD is a safe option. Our study demonstrates that there was no significant difference in early fusion outcomes between single-level and multi-level PSD, whether adjacent or distant.

Fusion's Location and Quality within the Fixated Segment Following Transforaminal Interbody Fusion (TLIF).

Transforaminal interbody fusion (TLIF) has gained increased popularity over recent decades and is being employed as an established surgical treatment for several lumbar spine pathologies, including degenerative spondylosis, spondylolisthesis, infection, tumor and some cases of recurrent disc herniation. Despite the seemingly acceptable fusion rates after TLIF (up to 94%), the literature is still limited regarding the specific location and quality of fusion inside the fixated segment. In this single-institution, retrospective population-based study, we evaluated all post-operative computed tomography (CT) of patients who underwent TLIF surgery at a medium-sized medical center between 2010 and 2020. All CT studies were performed at a minimum of 1 year following the surgery, with a median of 2 years. Each CT study was evaluated for post-operative fusion, specifically in the posterolateral and intervertebral body areas. The fusion's quality was determined and classified in each area according to Lee's criteria, as follows: (1) definitive fusion: definitive bony trabecular bridging across the graft host interface; (2) probable fusion: no definitive bony trabecular crossing but with no gap at the graft host interface; (3) possible arthrosis: no bony trabecular crossing with identifiable gap at the graft host interface; (4) definite pseudarthrosis: no traversing trabecular bone with definitive gap. A total of 48 patients were included in this study. The median age was 55.6 years (SD ± 15.4). The median time from surgery to post-operative CT was 2 years (range: 1-10). Full definitive fusion in both posterolateral and intervertebral areas was observed in 48% of patients, and 92% showed definitive fusion in at least one area (either posterolateral or intervertebral body area). When comparing the posterolateral and the intervertebral area fusion rates, a significantly higher definitive fusion rate was observed in the posterolateral area as compared to the intervertebral body area in the long term follow-up (92% vs. 52%, p < 0.001). In the multivariable analysis, accounting for several confounding factors, including the number of fixated segments and cage size, the results remained statistically significant (p = 0.048). In conclusion, a significantly higher definitive fusion rate at the posterolateral area compared to the intervertebral body area following TLIF surgery was found. Surgeons are encouraged to employ bone augmentation material in the posterolateral area (as the primary site of fusion) when performing TLIF surgery.

Analysis of injury and pain scores during fusion surgery for multisegmental lumbar spinal stenosis in elderly patients.

INTRODUCTION: Lumbar stenosis has become a common disease. Controversies exist regarding fusion surgery. MATERIAL AND METHODS: The patients were divided into groups per the method of fusion received: the posterolateral fusion group (group P) and the intervertebral fusion group (group I). The patients were further divided into groups based on the number of fusion segments: the 2-segment group (P2 and I2), the 3-segment group (P3 and I3), and the 4-segment group (P4 and I4). The operative time, intraoperative blood loss, blood transfusion volume, and postoperative drainage volume were summarized. In particular, wound healing appearance and management were observed. RESULTS: The operation time and blood transfusion volume of the P2 and P3 groups were significantly less than those of the I2 and I3 groups (p < 0.05). The postoperative drainage volume of group I4 was less than that of group P4 (p < 0.05). Postoperative numeric rating scale (NRS) scores of P2 and P3 groups were lower than those of I2 and I3 groups (p < 0.05), while the NRS scores of P4 group were higher than those of I4 group (p < 0.05). CONCLUSIONS: Posterolateral and intervertebral fusion techniques can be used in the surgical treatment of elderly patients with lumbar spinal stenosis. The posterolateral fusion method should be used when three or fewer segments require surgery. The intervertebral fusion method should be used when four segments require surgery.

Accuracy of post-operative recall by degenerative cervical myelopathy patients using the modified Japanese Orthopaedic Association scale.

Background and Aim: The modified Japanese Orthopaedic Association (mJOA) scale is one of the primary measures of neurological function used on patients with degenerative cervical myelopathy (DCM). Contrary to some reports, the mJOA is not based on patient-reported outcomes as it is an assessment conducted by physicians, allied health professionals, or trained staff. To date, the accuracy of post-operative recall by DCM patients of their pre-operative neurological function, as assessed by the mJOA scale, has not been examined. This study, therefore, aimed to evaluate recall accuracy in DCM patients using the mJOA scale. Methods: This study analyzed recall capacity of DCM patients who had undergone anterior cervical discectomy and fusion by a single surgeon at a large academic spine center between February 2012 and August 2017. Patient recall of neurological function pre-surgery was assessed at 3, 12, and 24 months post-surgery using the mJOA scale. Actual mJOA scores were also determined at each follow-up. Recall error (RE) was defined as the difference between recalled mJOA score at each post-operative visit and the actual baseline score. Age, gender, surgical segments, hospital length of stay, actual mJOA scores at follow-up, and actual rate of improvement in mJOA score were analyzed as predictors of recall accuracy. Descriptive statistics were collected to profile the characteristics of patients enrolled in the study cohort. All statistical computing and graphing were performed with R software and generalized estimating equation (GEE) model fitting was done using geepack package. Results: A total of 105 patients (56.2% of males and 43.8% of females) were enrolled in the study. The median ± SD (range) age at the pre-surgical baseline measurement was 50 ± 8 (25 - 78) years. The recalled mJOA scores at the three follow-up time points were lower than the actual mJOA scores. The recall accuracy gradually decreased over time. Estimated coefficients showed that all variables in the GEE model except for surgical fusion segments were significant (P < 0.05). The pre-operative actual baseline mJOA score was inversely associated with RE. An increasing actual mJOA score over time had a significant positive influence on RE. Greater RE was found in males compared to females. Unexpectedly, age was inversely associated with RE. Conclusions: The RE increases with the time interval between pre-surgical measurement and post-surgical follow-up and is more prominent in male DCMs patients following upper spine surgery. Relevance for Patients: It is necessary to select post-operative patients who need to pay attention according to the three factors of post-operative time, gender, and age, that is, patients with large RE should be given early or timely psychological counseling and treatment concerns, so as to reduce the occurrence of potential medical disputes and improve the level of medical safety.

[Comparison of short-term effectiveness of Prodisc-C Vivo artificial disc replacement and Zero-P fusion for treatment of single-segment cervical spondylosis].

Objective: To compare the short-term effectiveness and the impact on cervical segmental range of motion using Prodisc-C Vivo artificial disc replacement and Zero-P fusion for the treatment of single-segment cervical spondylosis. Methods: The clinical data of 56 patients with single-segment cervical spondylosis who met the selection criteria between January 2015 and December 2018 were retrospectively analyzed, and they were divided into study group (27 cases, using Prodisc-C Vivo artificial disc replacement) and control group (29 cases, using Zero-P fusion) according to different surgical methods. There was no significant difference between the two groups in terms of gender, age, type of cervical spondylosis, disease duration, involved segments and preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), surgical segments range of motion, upper and lower adjacent segments range of motion, overall cervical spine range of motion, and cervical curvature (P>0.05). The operation time, intraoperative blood loss, postoperative hospitalization stay, time of returning to work, clinical effectiveness indicators (VAS score, JOA score, NDI, and improvement rate of each score), and imaging indicators (surgical segments range of motion, upper and lower adjacent segments range of motion, overall cervical spine range of motion, and cervical curvature, prosthesis position, bone absorption, heterotopic ossification, etc.) were recorded and compared between the two groups. Results: There was no significant difference in operation time and intraoperative blood loss between the two groups (P>0.05); the postoperative hospitalization stay and time of returning to work in the study group were significantly shorter than those in the control group (P<0.05). Both groups were followed up 12-64 months, with an average of 26 months. There was no complication such as limb or organ damage, implant failure, and severe degeneration of adjacent segments requiring reoperation. The VAS score, JOA score, and NDI of the two groups at each time point after operation significantly improved when compared with those before operation (P<0.05); there was no significant difference in the above scores at each time point after operation between the two groups (P>0.05); there was no significant difference in the improvement rate of each score between the two groups at last follow-up (P>0.05). The surgical segments range of motion in the study group maintained to varying degrees after operation, while it in the control group basically disappeared after operation, showing significant differences between the two groups (P<0.05). At last follow-up, there was no significant difference in the upper and lower adjacent segments range of motion in the study group when compared with preoperative ones (P>0.05), while the upper adjacent segments range of motion in the control group increased significantly (P<0.05). The overall cervical spine range of motion and cervical curvature of the two groups decreased at 3 months after operation, and increased to varying degrees at last follow-up, but there was no significant difference between groups and within groups (P>0.05). At last follow-up, X-ray films and CT examinations showed that no prosthesis loosening, subsidence, or displacement was found in all patients; there were 2 cases (7.4%) of periprosthetic bone resorption and 3 cases (11.1%) of heterotopic ossification which did not affect the surgical segments range of motion. Conclusion: Both the Prodisc-C Vivo artificial disc replacement and Zero-P fusion have satisfactory short-term effectiveness in treatment of single-segment cervical spondylosis. Prodisc-C Vivo artificial disc replacement can also maintain the cervical spine range of motion to a certain extent, while reducing the occurrence of excessive motion of adjacent segments after fusion.

One step excision combined with unilateral transforaminal intervertebral fusion via minimally invasive technique in the surgical treatment of spinal dumbbell-shaped tumors: A retrospective study with a minimum of 5 years' follow-up.

Introduction: Spinal dumbbell-shaped tumors are rare, usually benign tumors with intraspinal and paravertebral components connected through intervertebral foramen. Complete excision is often performed through traditional open surgery (TOS). The efficacy and long-term outcomes of minimally invasive surgery (MIS) have not been reported to date in resection of dumbbell-shaped spinal tumors. Purpose: The purpose was to evaluate the efficacy and long-term outcomes of minimally invasive resection combined with unilateral transforaminal intervertebral fusion (TIF) through comparing with TOS in the treatment of spinal dumbbell-shaped tumors. Methods: Fifteen patients underwent MIS and 18 patients underwent TOS. Thoracic dumbbell-shaped tumors were directly exposed after removal of costotransverse joints, adjacent rib components, unilateral hemilamina, and facet joints. Lumbar dumbbell-shaped tumors were completely exposed after removal of transverse processes, unilateral hemilamina, and facet joints. Whether for minimally invasive resection or traditional open removal, dumbbell-shaped tumors were completely excised and unilateral TIF was performed to guarantee spinal stability. All patients were followed up for 5 years at least. Results: The mean length of surgical incision for two groups was 3.47 ± 0.37 vs. 6.49 ± 0.39 cm (p < 0.05). The average duration of the operation was 131.67 ± 26.90 vs. 144.17 ± 23.59 min (p > 0.05). The mean blood loss was 172.00 ± 48.79 vs. 285.83 ± 99.31 ml (p < 0.05). No blood transfusions were required in the two groups. The median length of hospitalization was 6 vs. 10 days (range: 5-8 vs. 7-14 days). The patients of two groups were monitored for an average of 65.93 ± 3.88 vs. 65.78 ± 3.56 months. At 5-year follow-up, all patients presented with normal neurological function (American Spinal Injury Association scale E). The Oswestry Disability Index in the MIS group decreased significantly more than the TOS group. No spondylolisthesis or spinal instability were found in the follow-up period. There was no recurrence of any spinal tumor 5 years after surgery. Conclusions: Spinal dumbbell-shaped tumors can be safely and effectively treated with minimally invasive resection combined with unilateral TIF. Compared with TOS, MIS offers a reduced length of surgical incision, blood loss, hospital stay, and postoperative pain. This surgical protocol might provide an alternative for the treatment of spinal dumbbell-shaped tumors.