Introduction: In the concept of sagittal balance, the cervical spine has long received insufficient attention from researchers, but this trend is now changing. The study of cervical sagittal balance in children with Down syndrome may help to approach the prerequisites for the development of atlantoaxial instability. Materials and methods: We retrospectively analyzed radiographs of the cervical spine in the neutral position in lateral projection, as well as postural radiographs of 110 pediatric patients. The patients were divided into 2 groups. Group 1 (normal)— 60 children aged 4 to 17 years without spinal pathology. Group 2 (Down syndrome) — 50 children aged 4 to 17 years with Down syndrome. The parameters of cervical sagittal balance were calculated (Oc-C2, Oc-C7, C1-C2, C2-C7, C2-C7H, C7S, Th1S, TIA, NT) and criteria for atlantoaxial instability (Nakamura angle, ADI, SAC-C1, SAC-C1/SAC-C4) and statistical analysis of the data was performed. Results: Statistically significant differences in C7S, Th1S, and TIA parameters were found in the direction of their increase in children with Down syndrome. These parameters are responsible for the formation of cervical lordosis, but there were no statistically significant differences in the angular parameters of cervical lordosis; therefore, the cervical spine is subcompensated during flexion in children with Down syndrome. Statistically significant differences in atlantoaxial instability criteria ADI, SAC-C1, SAC-C1/SAC-C4 were also found in the direction of their decreasing in children with Down syndrome. The obtained abnormalities can be considered as congenital determinants of predisposition to atlantoaxial instability in children with Down syndrome.

Objective: This study aims to compare the clinical and radiological outcomes of Titanium Mesh Cage (TMC), Nano-Hydroxyapatite/Polyamide (n-HA/PA66 cage), and 3D-printed vertebral bodies in anterior cervical corpectomy and fusion (ACCF) patients. Methods: This was a prospective non-randomized controlled study. We enrolled 60 patients undergoing ACCF using TMCs, n-HA/PA66 cages, or 3D-printed vertebral bodies from January 2020 to November 2021. For each group, there were 20 patients. Follow-up was conducted for minimum two years. Clinical outcomes, including JOA, NDI and VAS scores were collected pre-operatively and at each follow-up. Radiographic outcomes were collected at each visit, including FSU height, fusion rate, and cervical alignment. A loss of FSU height equal or greater than 3 mm was deemed implant subsidence. Results: Postoperative FSU height loss at 2 years differed significantly among the TMC, n-HA/PA66, and 3D-printed vertebral body groups, measuring 3.07±1.25mm, 2.11±0.73mm, and 1.46±0.71mm, respectively (P < 0.001). The rates of implant subsidence were 45%, 20%, and 10%, respectively. Regarding the clinical data, only the JOA score at 3 months postoperatively showed a statistically significant difference (P = 0.004). All patients obtained solid fusion at 2-year follow-up. Conclusion: At two-year follow-up after ACCF, the n-HA/PA66 cage group and the 3D-printed vertebral body group exhibited less FSU height loss and lower rates of implant subsidence compared to the TMC group. There appeared to be no significant differences in clinical outcomes among the three groups.

Objective: Increased signal intensity (ISI) is usually recognized at the disc level of the responsible lesion in the patients with cervical myelopathy. However, it is occasionally seen at the vertebral body level, below the level of compression. We aimed to investigate the clinical significance and the radiographic characteristics of ISI at the vertebral body level.
Methods: This retrospective study included 135 patients with cervical spondylotic myelopathy who underwent surgery and with local ISI. We measured the local and C2-7 angle at flexion, neutral, and extension. We also evaluated the local range of motion (ROM) and C2-7 ROM. The patients were classified into group D (ISI at disc level) and group B (ISI at vertebral body level).
Results: The prevalence was 80.7% (109/135) and 19.3% (26/135) for groups D and B, respectively. Local angle at flexion and neutral were more kyphotic in group B than in group D. The local ROM was larger in group B than in group D. Moreover, C2-7 angle at flexion, neutral and extension were more kyphotic in group B than in group D. There was no significant difference of clinical outcomes 2 years postoperatively between both groups.
Conclusions: Group B was associated with the kyphotic alignment and local greater ROM, compared to group D. As the spinal cord is withdrawn in flexion, the ISI lesion at vertebral body might be displaced towards the disc level, which impacted by the anterior components of the vertebrae. This should be different from the conventionally held pincer-mechanism concept.

Background: Biomechanical factors including endplate coverage and intervertebral disc height change may be related to heterotopic ossification (HO) formation after cervical disc replacement (CDR). However, there is a dearth of quantitative analysis for endplate coverage, intervertebral height change and their combined effects on HO. Methods: Patients who underwent single-level or two-level CDR were retrospectively reviewed. Radiological data, including the prosthesis-endplate depth ratio, intervertebral height change, posterior heterotopic ossification (PHO) and angular parameters, were collected. Logistic regression analysis was used to identify the potential risk factors. Receiver operating characteristic curves were plotted and the cutoff values of each potential factors were calculated. Results: A total of 138 patients with 174 surgical segments were evaluated. Both the prosthesis-endplate depth ratio (P<0.001) and postoperative disc height change (P<0.001) were predictive factors for PHO formation. The area under the curve (AUC) of the prosthesis-endplate depth ratio, disc height change and their combined effects represented by the combined parameter (CP) were 0.728, 0.712 and 0.793, respectively. The risk of PHO significantly increased when the prosthesis-endplate depth ratio < 93.77% (P<0.001, OR=6.909, 95% CI 3.521-13.557), the intervertebral height change ≥ 1.8 mm (P<0.001, OR=5.303, 95% CI 2.592-10.849), or the CP representing the combined effect < 84.88 (P<0.001, OR=10.879, 95% CI 5.142-23.019). Conclusions: Inadequate endplate coverage and excessive change of intervertebral height are both potential risk factors for the PHO after CDR. The combination of these two factors may exacerbate the non-uniform distribution of stress in the bone-implant interface and promote HO development.

Background: According to the different numbers and relative locations of cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF), three-level hybrid surgery (HS) has many constructs. Objective: The purpose of this retrospective study was to compare the sagittal alignment parameters of HS and ACDF for cervical degenerative disc disease (CDDD) and the association of the respective parameters. Methods: This study involved patients with three-level CDDD who underwent ACDF or HS. This follow-up included one-level CDR and two-level ACDF (type I group), two-level CDR and one-level ACDF (type II group) and three-level ACDF. Cervical sagittal alignment parameters included cervical lordosis (CL), segment alignment (SA), T1 slope (T1S), C2-C7 sagittal vertical axis (SVA), T1S-CL, C2 slope (C2S), occipital to C2 angle (O-C2A) and segment range of motion (ROM). Results: The three groups with a total of 106 patients were better matched in terms of demographics. Patients who underwent HS had significantly higher CL than those who underwent ACDF at 1 week, 6 months, 12 months and the final follow-up after surgery, as well as significantly better SA at 12 months and the final follow-up. Conclusion: Most improvements in cervical sagittal alignment were observed in all three groups postoperatively. HS was more advantageous than ACDF in the maintenance of postoperative CL and SA. Thus, three-level HS may be better for maintaining cervical curvature.

Background: There is very few literature on the treatment of symptomatic cervical hemangioma (SCH). Objective: The study aims to evaluate the safety and effectiveness of anterior vertebroplasty for patients with SCH. Methods: Clinical data of patients with SCH who underwent anterior vertebroplasty from January 2018 to January 2022 were retrospectively analyzed. A total of 20 patients were included in this study, including 12 males and 8 females, with an average age of 48.2±5.3 years. In all patients, an open anterior cervical biopsy and vertebroplasty at the diseased vertebrae was performed under general anesthesia. The VAS scores and NDI index of patients were compared before and 24 hours after surgery, 3 months, 6 months, 12 months after surgery and at the last follow-up. The injection amount of bone cement, diffusion and leakage of bone cement were also recorded. Results: All of the 20 patients underwent surgery successfully, including 4 cases of C3, 6 cases of C4, 7 cases of C5 and 3 cases of C6. The pathology of the tissues taken during the operation were hemangioma. The average injection volume of bone cement was 2.8±0.6ml, and the average follow-up was 42.5±5.6 months. The VAS score and NDI index were significantly improved after surgery and follow-up period compared with that before surgery (P<0.05). Bone cement spread to both sides of the diseased vertebra and no bone cement leakage occurred during surgery. No case recurred at the last follow-up. Conclusion: Anterior vertebroplasty is a safe and effective surgical method for patients with SCH.

Background: Traditional titanium mesh cages (TTMCs) are widely used in Anterior Cervical Corpectomy and Fusion (ACCF), but they often lead to complications like cage subsidence and adjacent segment degeneration (ASD). This study aimed to evaluate if a novel anatomic titanium mesh cage (NTMC) could enhance postoperative biomechanics.

Methods: NTMC, tailored to match patients' cervical anatomy, was compared to TTMC using preoperative CT data. Range of motion (ROM) and stress peaks in C6 endplates, titanium mesh cage (TMC), screw-bone interface, anterior titanium plate, and adjacent intervertebral discs were analyzed.

Results: NTMC significantly reduced segmental ROMs by 89.4% post-surgery. The C6 superior endplate stress peaks were higher in the TTMC (4.473-23.890 MPa), followed by the NTMC (1.923-5.035 MPa). The stress peaks on the TMC were higher in the TTMC (47.896-349.525 MPa), and the stress peaks on the TMC were lower in the NTMC (17.907-92.799 MPa). TTMC induced higher stress peaks in the screw-bone interface (40.0-153.2 MPa), followed by the NTMC (14.8-67.8 MPa). About the stress peaks on the anterior titanium plate, the stress of TTMC is from 16.499 to 58.432 MPa, and the NTMC is from 12.456 to 34.607 MPa. Besides, TTMC induced higher stress peaks in the C3/4 and C6/7 intervertebral disc (0.201-6.691 MPa and 0.248-4.735 MPa, respectively), followed by the NTMC (0.227-3.690 MPa and 0.174-3.521 MPa, respectively).

Conclusions: NTMC application effectively reduces TMC subsidence risk and lowers stresses at critical interfaces, decreasing instrument-related complications. Moreover, NTMC lowers the risk of ASD by minimizing stress on adjacent intervertebral discs.

Objective: In degenerative cervical disc, nucleus pulposus prolapse generally causes severe compression of the spinal cord, making decompression procedures a favored option. However, for cases in which the prolapse lies directly posterior to the vertebral body, even considering trumpet-shaped decompression, the anterior cervical discectomy and fusion (ACDF) procedure still poses the risk of inadequate coverage. Procedures such as anterior cervical corpectomy and fusion (ACCF) allow for adequate exposure of the compression, but with increased risk of cage subsidence and vertebral body collapse. Therefore, a surgical approach with adequate decompression coverage while preserving anterior vertebral body integrity is needed. Our aim was to describe a new anterior cervical procedure, anterior cervical V-shaped osteotomy and fusion (ACVF), for the treatment of cervical myelopathy with nucleus pulposus prolapse behind vertebral body. Methods: ACVF was performed in two patients with cervical myelopathy with post-vertebra nucleus pulposus prolapse and spinal cord compression. Main surgical procedures included responsible level discectomy, V-shaped osteotomy of posterior margins of involved vertebra, and interbody fusion device placement. Postoperative follow-up was performed for one year and three months, respectively. Results: Postoperative CT and MRI demonstrated adequate decompression of the spinal cord. Follow-up confirmed improvement in neurological function. The heights of the involved vertebrae were maintained without significant collapse. No complications related to this technique were recognized. Conclusion: ACVF may be safe and effective for spinal cord decompression in the case of nucleus pulposus prolapse posterior to vertebral body, by the potential to serve as a substitute for procedures such as ACCF.

Objective: Anterior bone loss (ABL) was considered as a non-progressive process secondary only to motion-preserving implant and has been noticed recently in cervical disc replacement (CDR) let alone patients with anterior cervical discectomy and fusion (ACDF). Our purpose is to reveal this unnoticed phenomenon in ACDF and further explore its clinical and radiological outcomes.
Methods: 77 patients underwent ACDF with a minimum follow-up of at least one-year were retrospectively reviewed. The average follow-up time was 22.51±16.31 months. There were 50 patients in group A with ABL while there were 27 patients in group B without ABL. ABL was measured and classified into 4 grades according to Kieser’s methods. Clinical evaluation, radiological parameters and fusion rate were recorded.

Results: The incidence of bone ABL was 64.9% of Zero-P and 55.2% of endplates. The incidence of upper and lower endplates was 61% and 49% respectively and such difference was not significant. Mild ABL occurred in 22%, moderate ABL in 38% and severe ABL of 40% patients underwent ACDF with ABL. ABL won’t affect both clinical outcomes and fusion rate. However, ABL would result in a higher incidence of subsidence.

Conclusion: ABL should be considered as a common phenomenon that both CDR and ACDF owned and was a none progressive process which confined in one year. ABL would result in a higher incidence of subsidence. Luckily, this phenomenon does not have an effect on postoperative clinical and fusion rate.

Introduction: Anterior bone loss (ABL) after cervical disc arthroplasty (CDA) is not well recognized. Especially, data on ABL after CDA with different prosthesis designs is limited. This study aims to investigate ABL occurrence after Prestige-LP CDA and its effects on clinical and radiological outcomes. Methods: We retrospectively reviewed patients who underwent Prestige-LP CDA at our institution. Clinical outcomes were assessed using JOA, VAS, and NDI scores. Radiographic parameters, including cervical lordosis, disc angle, ROM, HO, and ABL, were collected. Results: This study involving 396 patients, and ABL occurred in 56.6% of patients. Most ABL cases (88.2%) occurred within the first 3 months, but no progressive ABL was observed after 12 months. Patients with ABL were three years younger. ABL occurrence was associated with the surgical techniques, with 2-level CDA having the highest incidence (76.7%). JOA, VAS, NDI scores significantly improved postoperatively. The ROM of the arthroplasty level in ABL group was relatively well maintained compared to non-ABL group. HO occurred in 57.9% of CDA segments in non-ABL group versus 38.8% in ABL group, and 19.9% of CDA segments in non-ABL group developed high-grade HO. Conclusion: This study found ABL to be common but self-limited after early postoperative CDA. It occurred 3 to 6 months postoperatively, more in younger patients, especially those with 2-level CDA. Despite its occurrence, ABL did not affect clinical outcomes. Interestingly, patients with BL had a larger ROM at the arthroplasty level, likely due to a lower incidence and lower grade of HO.

Introduction: Diffusion tensor imaging (DTI), a magnetic resonance technique that is sensitive to the diffusion of water molecules, can diagnose derangement of spinal cord function which cannot be demonstrated on conventional MRI examinations. Useful DTI parameters include the apparent diffusion coefficient (ADC) and fractional anisotropy (FA). Decreased FA values reflect a loss of anisotropic diffusion of water molecules, indicating damage to tract fibers at the site of compression, whereas ADC values increase in compressed lesions of the spinal cord. DTI has been known to be more sensitive for detecting subtle white matter change than T2-weighted imaging. Abnormal FA values in the spinal cord may also predict severity and prognosis. DTI is a relatively novel investigation and more studies are required to assess the utility of the investigation in compressive myelopathies. In our study we will be evaluating the ability of the test to diagnose compressive cervical myelopathy in its earlier stages, aiding in timely diagnosis and intervention. Methods: A prospective observational study of patients with symptoms suggestive of myelopathy was done and DTI picture due to compressive causes was compared with the DTI picture in unaffected controls. Results: DTI showed a sensitivity of 85.7% and an NPV of 95% as compared to the sensitivity of MRI to detect changes which is <50% of the time. Conclusion: DTI is a highly sensitive tool to detect compressive myelopathic changes which may otherwise be missed on conventional T2-WI of MRI, and thus can guide timely intervention before irreversible changes of myelopathy set in.

Introduction: Harm’s technique of atlantoaxial fusion via C1 lateral mass and C2 pedicle screws is popular due to good initial stability and fusion rates. However, loss of fixation may occur, leading to implant impingement. Case report: A 79-year-old male with known atlantoaxial subluxation and retro-odontoid pseudotumor presented with worsening lower limb numbness and weakness. A magnetic resonance imaging (MRI) scan demonstrated cord compression and myelomalacia at C1-C2. Computer tomography (CT) revealed widened atlanto-dens interval (ADI) (7mm). Reduction of atlantoaxial subluxation and fusion of C1-3 with modified Harm’s technique was performed. Immediate postoperative radiographs demonstrated a reduced ADI (2mm) and satisfactory implant positioning. The patient experienced an initial reduction in numbness followed by an acute decrease in lower limb power on post operative day (POD) 14 with an associated persistent neckache. Repeat MRI and CT scans demonstrated a loss of reduction of C1-C2 with cord compression and occipital erosion from both spinal rods. The patient underwent revision occipital-C3 fusion, decompression laminectomy C1 and C2. Intraoperatively, the left rod was noted to be eroding into the occiput with a paper-thin layer separating it from perforating into the cranial vault. Post-revision surgery, the patient recovered motor function and had resolution of neck pain. Four months postoperatively, radiographs demonstrated implant stability with satisfactory alignment. Conclusion: Loss of C1–C2 reduction results in relative occipital extension, reducing the distance between the occiput and cranial end of rod beyond the C1 tulip head. This may result in occipital erosion and impending cranial perforation.

Introduction: Hybrid surgery (HS) is a promising approach for treating multilevel cervical degenerative disc disease. However, it is associated with several adverse outcomes, such as anterior bone loss (ABL). ABL is non-progressive early peri-prosthetic vertebral bone loss occurring within 6 months after surgery at the arthroplasty level. However, no study have discussed the occurrence of ABL in HS. This study examined whether the ABL in contiguous 2-level HS was affected by adjacent fusion compared with CDA alone. Methods: 180 patients undergoing either a 1-level CDA or contiguous 2-level HS were retrospectively reviewed. The clinical and radiographical outcomes were collected preoperatively and at a intervals of 1 week, 3, 6, and 12 months post-operation and at the last follow-up. ABL incidence and severity were compared using initial and postoperative radiographs. Results: ABL appeared in 68.7% of CDA cases (37.9% mild, 34.8% moderate, 27.3% severe) and 44.0% of HS cases (54.1% mild, 27.0% moderate, 18.9% severe). Factors like age, postoperative alignment, and range of movement at the arthroplasty segment showed no correlation with ABL incidence. Logistic regression highlighted surgery type and body mass index as significant ABL correlates. There was no significant difference in the ABL incidence and severity with or without an adjacent fusion level. Postoperative clinical outcomes improved significantly in both HS and CDA groups. Conclusion: ABL is common in CDA and HS. Despite that HS had a lower incidence rate and degree than CDA, the fusion location in HS did not affect the ABL of adjacent CDA.