ABSTRACT Background Delayed postoperative spinal epidural hematoma (DPSEH) is a rare but serious complication of cervical open‐door laminoplasty, which occurs more than 3 days after the procedure. Although multi‐level surgery, coagulopathy, and hypertension are known risk factors, suture‐related mechanisms have rarely been identified as the main cause. Case Presentation We present two cases of symptomatic DPSEH occurring on the seventh postoperative day following posterior cervical open‐door laminoplasty. Following initial recovery, both patients experienced acute neurological deterioration. An emergency MRI revealed hematomas within the paraspinal muscles compressing the spinal cord. Intraoperative exploration identified a huge hematoma within the posterior cervical muscles and active bleeding from muscle tissue, with no injury to the epidural venous plexus. Interestingly, absorbable barbed sutures were used for muscular and fascial closure in both procedures. The patients exhibited significant neurological recovery following emergency hematoma evacuation. Conclusion These cases suggest that suture‐related complications, specifically knot loosening, suture migration, or barb‐induced tissue cutting, may contribute to intramuscular bleeding and subsequent DPSEH. However, given the limited evidence from a two‐case report, this association should be interpreted as a clinical alert rather than definitive proof of causality. Surgeons should maintain a high index of suspicion for DPSEH in patients who experience sudden postoperative pain or neurological decline. They should also consider suture choice as a potentially modifiable risk factor.

ABSTRACT Purpose Cervical curvature loss is a frequent complication following 3‐level anterior cervical discectomy and fusion (ACDF) using a Zero‐Profile device. Consequently, the capacity of this device to maintain cervical sagittal alignment in 3‐level ACDF remains highly controversial. This study aimed to identify potential predictors for postoperative curvature loss (PCL) and evaluate its impact on clinical outcomes. Methods A total of 113 patients who underwent ACDF for 3‐level cervical degenerative disc disease (CDDD) between January 2021 and December 2023 were retrospectively reviewed. Demographic data, radiological parameters, and clinical outcomes were analyzed. Radiographic measures included cervical curvature, T1 slope, C2–7 sagittal vertical axis, and titanium plate and endplate (TPE) distance. Clinical outcomes were assessed using the Visual Analog Scale (VAS), Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores. Statistical analyses were performed using paired and independent t‐tests, as well as Pearson correlation coefficients. Results The average curvature loss was 6.82° from 1 week postoperatively to the final follow‐up (p < 0.001). However, the final curvature (11.65°) was maintained, representing a 4.33° improvement compared to preoperative values. Significant correlations were observed between PCL and preoperative curvature (r = −0.368, p = 0.013), preoperative T1 slope (r = −0.546, p < 0.001), ∆T1 slope (r = 0.443, p = 0.002), and ∆TPE distance (r = 0.417, p = 0.004). PCL did not correlate with Japanese Orthopaedic Association (JOA) scores or arm VAS scores at the final follow‐up. Nevertheless, patients with a PCL ≥ 6° exhibited significantly higher neck VAS (p = 0.028) and NDI scores (p = 0.041). Conclusion Although contiguous 3‐level ACDF with a Zero‐Profile device may result in PCL, it preserves an improved cervical lordosis compared to the preoperative baseline. Low preoperative curvature and a low preoperative T1 slope are potentially predictive factors for PCL. Postoperative changes in TPE distance and T1 slope are significantly associated with PCL, suggesting a potential biomechanical link that requires direct validation. Furthermore, PCL may lead to higher neck VAS and NDI scores. Consequently, the Zero‐Profile device may require careful consideration in 3‐level CDDD patients presenting with low preoperative curvature and a low T1 slope. Importantly, the 6° PCL threshold identified is preliminary and requires prospective validation before clinical application.

Retrospective analysis. To identify the associations between preoperative paraspinal muscle parameters and postoperative outcomes following cervical disc arthroplasty (CDA), while screening for predictors. Paraspinal muscles play a critical role in maintaining cervical alignment, significantly contributing to cervical mobility and stability. To date, there is limited evidence regarding the impact of paraspinal muscles on CDA. This study included 185 patients who underwent single-level CDA. Preoperative paraspinal muscle parameters, including fatty infiltration (FI), cross-sectional area ratio (CSA r), and muscle asymmetry (ASY%), were assessed using MRI. Correlation analysis was employed for preliminary screening. Finally, structural equation modeling (SEM) was employed for comprehensive analysis. Paraspinal muscle degeneration was prevalent in this cohort, with a higher proportion of moderate to severe FI (Goutallier Grade > 2) from the cranial to caudal levels. According to the correlation analysis, at the final follow-up, cervical lordosis was most strongly correlated with CSA r at C4/5 ( P =0.010); SVA was most related to CSA r at C5/6 ( P =0.030); and the T1 slope was associated with CSA r at C4/5 ( P <0.001), C5/6 ( P <0.001), as well as at the surgical level ( P <0.001). Moreover, a positive correlation was observed between preoperative pain scores and FI ( P =0.035). However, no such correlation was identified in the postoperative period. Comparative analysis of SEMs across different muscle variables revealed variations in predictive factors for postoperative sagittal balance parameters, with CSA r emerging as the significant contributor ( P =0.019, estimate=0.176), rather than FI or ASY%. Compared with postoperative clinical outcomes, mobility, and prosthesis stability, preoperative muscle parameters were most correlated with sagittal balance after CDA. Specifically, CSA r outperformed in predicting postoperative sagittal balance. These findings suggest CDA may be associated with an elevated risk of sagittal imbalance when performed on patients with significant preoperative muscle degeneration. Level 3.

Due to the irregularity of cervical inferior endplate morphology among individuals and segments, a bone-implant interface (BII) gap is usually unavoidable between the prosthesis and endplate after cervical disc replacement (CDR). This study aimed to investigate the clinical and biomechanical effects of the BII gap after CDR. We retrospectively reviewed the clinical and radiological data of 180 patients who underwent 1-level or 2-level CDR. Cervical sagittal parameters, implant subsidence and migration, heterotopic ossification (HO) were evaluated through lateral radiographs. Endplate morphology was classified into three types according to the position of concavity apex: (I) posterior, (II) central, and (III) anterior. CDR finite element models with and without BII gap were developed based on type II endplate to analyze predictions of relative stress distributions, micromotions and associated risks for subsidence at BII. No statistical differences in clinical outcomes and the incidence of implant subsidence or migration between two groups were noted. The proportion of BII gaps after CDR was significantly larger in segments with type I endplate morphology (68.0

STUDY DESIGN:Retrospective analysis. OBJECTIVE:To identify the associations between preoperative paraspinal muscle parameters and postoperative outcomes following cervical disc arthroplasty (CDA), while screening for predictors. SUMMARY OF BACKGROUND DATA:Paraspinal muscles play a critical role in maintaining cervical alignment, significantly contributing to cervical mobility and stability. To date, there is limited evidence regarding the impact of paraspinal muscles on CDA. MATERIALS AND METHODS:This study included 185 patients who underwent single-level CDA. Preoperative paraspinal muscle parameters, including fatty infiltration (FI), cross-sectional area ratio (CSA r), and muscle asymmetry (ASY%), were assessed using MRI. Correlation analysis was employed for preliminary screening. Finally, structural equation modeling (SEM) was employed for comprehensive analysis. RESULTS:Paraspinal muscle degeneration was prevalent in this cohort, with a higher proportion of moderate to severe FI (Goutallier Grade > 2) from the cranial to caudal levels. According to the correlation analysis, at the final follow-up, cervical lordosis was most strongly correlated with CSA r at C4/5 ( P =0.010); SVA was most related to CSA r at C5/6 ( P =0.030); and the T1 slope was associated with CSA r at C4/5 ( P <0.001), C5/6 ( P <0.001), as well as at the surgical level ( P <0.001). Moreover, a positive correlation was observed between preoperative pain scores and FI ( P =0.035). However, no such correlation was identified in the postoperative period. Comparative analysis of SEMs across different muscle variables revealed variations in predictive factors for postoperative sagittal balance parameters, with CSA r emerging as the significant contributor ( P =0.019, estimate=0.176), rather than FI or ASY%. CONCLUSIONS:Compared with postoperative clinical outcomes, mobility, and prosthesis stability, preoperative muscle parameters were most correlated with sagittal balance after CDA. Specifically, CSA r outperformed in predicting postoperative sagittal balance. These findings suggest CDA may be associated with an elevated risk of sagittal imbalance when performed on patients with significant preoperative muscle degeneration. LEVEL OF EVIDENCE:Level 3.

Objective:To evaluate the safety and effectiveness of anterior cervical discectomy and fusion (ACDF) by using zero-profile anchored cage (ZAC) in treatment of consecutive three-level cervical spondylosis, by comparing with plate-cage construct (PCC). Methods:A clinical data of 65 patients with cervical spondylosis admitted between January 2020 and December 2022 and met the selection criteria was retrospectively analyzed. During consecutive three-level ACDF, 35 patients were fixed with ZAC (ZAC group) and 30 patients with PCC (PCC group). There was no significant difference in baseline data between the two groups ( P>0.05), including gender, age, body mass index, surgical segment, preoperative Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), visual analogue scale (VAS) score, prevertebral soft tissue thickness (PSTT), cervical lordosis, and surgical segmental angle. The operation time, intraoperative blood loss, hospital stay, clinical indicators (JOA score, NDI, VAS score), and radiological indicators (cervical lordosis, surgical segmental angle, implant subsidence, surgical segment fusion, and adjacent segment degeneration), and the postoperative complications [swelling of the neck (PSTT), dysphagia] were recorded and compared between the two groups. Results:Patients in both groups were followed up 24-39 months. There was no significant difference in follow-up duration between the two groups ( P>0.05). The operation time and intraoperative blood loss were lower in ZAC group than in PCC group, and the length of hospital stay was longer, but there was no significant difference ( P>0.05). At each time point after operation, both groups showed significant improvements in JOA score, VAS score, and NDI compared with preoperative scores ( P<0.05), but there was no significant difference between the two groups at each time point after operation ( P>0.05). Both groups showed an increase in PSTT at 3 days and 3, 6 months after operation compared to preoperative levels ( P<0.05), but returned to preoperative levels at last follow-up ( P>0.05). The PSTT at 3 days and 3 months after operation were significantly lower in ZAC group than in PCC group ( P<0.05), and there was no significant difference between the two groups at 6 months and at last follow-up ( P>0.05). The incidences of dysphagia at 3 days and 3 months were significantly lower in ZAC group than in PCC group ( P<0.05), while no significant difference was observed at 6 months and last follow-up between the two groups ( P>0.05). There was no postoperative complication in both groups including hoarseness, esophageal injury, cough, or hematoma. Both groups showed improvement in cervical lordosis and surgical segmental angle compared to preoperative levels, with a trend of loss during follow-up. The cervical lordosis loss and surgical segmental angle loss were significantly more in the ZAC group than in PCC group ( P<0.05). The incidence of implante subsidence was significantly higher in ZAC group than in PCC group ( P<0.05). There was no significant difference between the ZAC group and PCC group in the incidences of surgical segment fusion and adjacent segment degeneration ( P>0.05). Conclusion:In consecutive three-level ACDF, both ZAC and PCC can achieve satisfactory effectiveness. The former can reduce the incidence of postoperative dysphagia, while the latter can better maintain cervical curvature and reduce the incidence of implant subsidence.

Study DesignRandomized controlled trial (RCT).ObjectivesTo compare the clinical performance of anterior cervical X-shape-corpectomy and fusion (ACXF) and anterior cervical corpectomy and fusion (ACCF) in treating cervical spondylotic myelopathy (CSM).MethodsIn this single-center, prospective RCT, patients with CSM were enrolled between January 2023 and June 2024 and randomly assigned to undergo either ACXF or ACCF. Blinded coordinators collected clinical and imaging data at baseline, 3 months, 6 months, and 1 year postoperatively. The primary outcome was the composite success rate at 1 year postoperatively. Secondary outcomes included perioperative outcomes, patient-reported outcome measures (PROMs), and radiological outcomes.ResultsEighty-six patients were randomized equally to the ACXF or ACCF group, among whom 82 (95.3%) were eligible for the primary analysis. At 1 year postoperatively, the composite success rate was significantly higher in the ACXF group than in the ACCF group (57.5% vs 21.4%, P < 0.001), with lower incidences of general medical adverse events (15.0% vs 41.5%, P = 0.008), dysphagia (10.0% vs 27.5%, P = 0.045), and implant subsidence (25.0% vs 75.6%, P < 0.001). ACXF also resulted in lower drainage volume (P < 0.001) and shorter drainage duration (P < 0.001). Both groups showed improvements in PROMs and sagittal alignment, with no between-group differences. Fusion rates remained comparable between the ACXF and ACCF group throughout follow-up, while ΔFSU height and subsidence rate in the ACXF group was significantly lower than that in the ACCF group.ConclusionACXF achieved a higher composite success rate than conventional ACCF. It may represent a valuable surgical alternative for appropriately selected patients with CSM.

Anterior cervical corpectomy and fusion (ACCF) with Traditional Titanium Mesh Cages (TTMCs) can lead to complications such as cage subsidence, dysphagia, and implant-related issues. These complications suggest that the biomechanical stability of ACCF with TTMC may be insufficient. This study aims to evaluate whether a New Assembled Titanium Mesh Cage (NTMC) can improve the biomechanical performance after ACCF. ACCF procedures using both TTMC and NTMC models were constructed and compared. The range of motion (ROM) of the surgical segments and stress peaks in various regions including the endplate, bone-screw interface, facet joints, and adjacent intervertebral discs were analyzed. The use of NTMC significantly reduced the postoperative ROM of the surgical segments by 80.7

BACKGROUND CONTEXT: Hybrid surgery (HS), which involves both anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (ACDR), is increasingly used to treat multilevel cervical disc degenerative disease, yielding satisfactory clinical outcomes. Early fusion is critical after anterior cervical fusion surgeries, but there are no studies comparing the rate of early fusion of HS with that of ACDF. PURPOSE: The purpose of this study was to compare the rate of early fusion (3-6 months postoperatively) of two-level HS with that of two-level ACDF surgery. STUDY DESIGN: The fusion statuses of consecutive patients who underwent two-level ACDF were compared with those of consecutive patients who underwent HS, which involves both ACDF and ACDR. PATIENT SAMPLE: The study included 860 patients who underwent two-level ACDF or HS for CDDD. After the patients who did not meet the study criteria were excluded, 376 patients were included (165 males, 211 females). OUTCOME MEASURES: Radiographic measures included fusion rate of the ACDF level. Self-report measures included visual analog scale (VAS) neck, VAS arm, neck disability index (NDI), satisfaction with the surgery and other symptoms reported by patients during the follow-ups. METHODS: Eight hundred sixty patients who underwent two-level ACDF or HS for cervical disc degenerative disease between January 2015 and January 2023 at our hospital were screened. After excluding the patients who did not meet the study criteria, 376 patients were included (165 males, 211 females). The patients who underwent dual-segment ACDF were categorized into the ACDF-ACDF (FF) group (n=205), while those who underwent dual-segment HS were divided into the ACDF-ACDR (FR) group (n=82) and the ACDR-ACDF (RF) group (n=89) on the basis of the relative positions of the segments selected for ACDF and ACDR. The fusion rates of the segments subjected to ACDF and the clinical outcomes, including the neck VAS score, arm VAS score, NDI score, and other complications, were compared among the three groups at 3 months, 6 months, and 1 year postoperatively. Fusion was defined as the formation of a continuous bone bridge in the target fusion area, as observed on three-dimensional computed tomography (CT) images. RESULTS: The average age of the patients in the FF group was higher than that of the patients in the FR and RF groups (p<.001). At 3 months postoperatively, the fusion rate was 70.7% (58/82) in the FR group, 39.5% (162/410) in the FF group, and 42.7% (78/89) in the RF group (p<.001). At 6 months postoperatively, the fusion rate was 74.6% (306/410) in the FF group, 91.5% (75/82) in the FR group, and 87.6% (78/89) in the RF group (p<.001). At 1 year postoperatively, the fusion rate was 91.9% (377/410) in the FF group, 98.8% (81/82) in the FR group, and 100% (89/89) in the RF group (p=.002). At 3 months postoperatively, the fusion rate was higher in the FR group than in the FF group (70.7% vs 45.4%) (p<.001). At 6 months postoperatively, the fusion rate of the distal segment was higher in the RF group than in the FF group (87.6% vs 66.3%). In the FF group, the fusion rate in the proximal segment was higher than that in the distal segment at 3, 6, and 12 months postoperatively. One year after surgery, 15 segments-3 proximal and 12 distal-in the FF group developed pseudarthrosis. Compared with the other two groups, the FR group had lower neck VAS scores at 3 months postoperatively and a lower rate of dizziness complaints during the 1-year follow-up period. There were no statistically significant differences in the remaining clinical outcomes. CONCLUSIONS: The early fusion rate after two-level HS was higher than that after two-level ACDF. The early fusion rate of two-level HS was higher in the FR group than in the RF group. For two-level ACDF, the early fusion rate was higher in the proximal segment than in the distal segment. Additional biomechanical studies are needed to explore the biomechanical differences in fusion levels between HS and multilevel ACDF. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

OBJECTIVE:This study aimed to retrospectively evaluate the long-term clinical and radiological outcomes following cervical disc arthroplasty (CDA). METHODS:This study included 74 patients who underwent single- or two-level CDA between November 2004 and December 2013, with a minimum 10-year follow-up (22 in the Bryan disc group and 52 in the Prestige LP disc group). Patient-reported outcomes and radiological parameters were collected for comparisons. Additionally, the incidences of heterotopic ossification (HO), adjacent segment degeneration (ASD), prosthesis subsidence, and segmental kyphosis at the final follow-up were evaluated and analyzed. A 95% confidence interval (CI) for a mean difference or odds ratio (OR) was used for all general statistical calculations. RESULTS:After 10 years of follow-up, patients with CDA continued to show significant improvement from baseline in patient-reported outcomes (p < 0.001), with no significant differences between the two groups. However, the Bryan disc group had significantly higher global range of motion (ROM; 95% CI 4.8°-19.2°, p = 0.001) and segmental ROM (95% CI 1.3°-5.9°, p = 0.003) compared to the Prestige LP disc group. At 10 years postoperatively, the incidence of HO was 69.2%, including 29.7% ROM-limiting HO. The incidence of ASD was 55.4%. Segmental kyphosis was observed in 10 patients, with a 20.8% incidence in the Bryan disc group and an 8.1% incidence in the Prestige LP disc group (p = 0.072). In the univariate subgroup analysis, the age of the ASD group was significantly higher (95% CI 0.3-6.8, p = 0.034). However, no statistically significant parameters were identified between the HO and non-HO groups. CONCLUSIONS:Through at least 10 years of follow-up, CDA can achieve satisfactory clinical outcomes while effectively preserving segmental mobility.

ABSTRACT Objective There is a lack of research on modic change (MC) in the cervical spine, especially regarding its impact on patients following anterior cervical discectomy and fusion (ACDF). Some researchers strongly believe that MC may affect the prognosis after anterior cervical surgery. Thus, this study aimed to assess MC in patients who underwent ACDF, investigating its incidence, risk factors, and correlation with fusion success and subsidence rate. Methods We retrospectively reviewed 154 patients who underwent single‐level ACDF from January 2010 to December 2020, with a minimum follow‐up of 12 months. Preoperative and postoperative clinical and radiological parameters were recorded at pre‐operation, 1 week, 3 months after operation, and the last follow‐up. The primary outcomes were the fusion rate and cage subsidence. Radiological measurements, including overall (Cobb C) and segmental cervical angle (Cobb S), anterior disc height (ADH), and posterior disc height (PDH) were also recorded. The independent t‐test or Mann‐Whiteny U test was used to compare continuous data, and categorical variables were assessed using the Pearson's chi‐square test of Fisher's exact test. Logistic regression analysis was also adopted to distinguish corresponding factors related with the progress of MC. Results Of the 154 patients, the incidence of MC was 44.2% (68/154). The group with MC showed a larger proportion of males and osteoporosis. The fusion rate of those with MC was 88.2% (60/68) while that in the non‐MC group was 97.7% (84/86, p = 0.02). The MC group presented a subsidence rate of 27.9%, which was substantially higher than in the non‐MC group (9.3%, p < 0.01). NDI and VAS neck was significantly higher in the MC group than in the non‐MC group (p = 0.014; p = 0.039). Sex and osteoporosis were distinguished as independent factors related to MC by regression analysis (p = 0.006; p = 0.026). Conclusion Preoperative MC could adversely hinder the fusion process and may increase the incidence of subsidence, affecting clinical outcomes of those underwent ACDF. Patients with MC, especially type 1 MC, are more easily suffered from neck pain than those without MC. Male sex and osteoporosis were risk factors for MC. In order to achieve a better bony fusion and avoid cage subsidence in those with MC, we encourage patients to prolong their immobilization duration with a cervical collar and precisely manage osteoporosis during the peri‐operative period.

STUDY DESIGN:Retrospective case-control study. OBJECTIVES:This study aimed to develop and preliminarily validate a machine learning (ML) model for predicting the likelihood of early fusion (EF) after anterior cervical discectomy and fusion (ACDF) and to explore the influential factors. SUMMARY OF BACKGROUND DATA:ACDF is a commonly performed procedure, where EF plays an important role in achieving favorable outcomes. However, EF varies substantially among patients, and reliable predictive approaches remain limited. METHODS:We retrospectively analyzed 1039 surgical segments from 840 patients who underwent ACDF between 2013 and 2020. EF, defined as radiographic fusion within three months, was assessed using standard imaging criteria. Basic information, laboratory indicators, perioperative data, and radiologic parameters were collected. After multiple imputation and dimensionality reduction, nine ML algorithms were trained, evaluated, and compared. SHapley Additive exPlanations (SHAP) were applied for model interpretation. RESULTS:Among the nine algorithms, stochastic gradient boosting (SGB) exhibited the highest predictive ability, with an AUC of 0.884 in the training set and 0.830 in the testing set. SHAP analysis indicated that preoperative functional spinal unit (FSU) range of motion (ROM), ΔFSU height, fasting plasma glucose (FPG), calcium (Ca), low-density lipoprotein cholesterol (LDL-C), surgical type, age, and femoral bone mineral density (BMD) were the most influential factors. Higher preoperative FSU ROM, FPG, LDL-C, age, and two-level surgery were associated with a lower probability of EF, whereas optimal ΔFSU height and higher Ca and femoral BMD were favored EF. CONCLUSIONS:This exploratory study established an ML-based approach for predicting EF after ACDF, with the SGB algorithm showing relatively strong predictive performance. The identified influential factors may provide preliminary insights for individualized clinical assessment and perioperative management, warranting further validation in multicenter settings.

Abstract Objective To investigate (1) lateral atlantoaxial articulation (LAA) morphology in patients with basilar invagination (BI) with atlantoaxial dislocation (AAD) and healthy individuals and its relationship with the severity of dislocation and (2) the effect of the LAA morphology on reduction degree (RD) after surgery. Methods In this retrospective propensity score matching case-control study, imaging and baseline data of 62 patients with BI and AAD from 2011 to 2022 were collected. Six hundred thirteen participants without occipitocervical junctional deformity served as controls. Logistic regression and receiver operating characteristic (ROC) curve were used for analysis. Results The age, BMI and sex did not differ significantly between the two groups after propensity score matching. Sagittal slope angle (SSA) and coronal slope angle (CSA) was lower and greater, respectively, in the patient group than in the control group. A negative SSA value usually indicates anteverted LAA. Regression analysis revealed a significant negative correlation between SSA and severity of dislocation. However, no relationship was found between CSA and the severity of dislocation. The multivariate logistic regression analysis revealed that minimum-SSA emerged as an independent predictor of satisfactory reduction (RD ≥ 90%). The ROC curve demonstrated an area under the curve of 0.844, with a cut-off value set at -40.2. Conclusion SSA in patients group was significantly smaller and more asymmetric than that in the control group. Dislocation severity was related to SSA but not to CSA. Minimum-SSA can be used as a predictor of horizontal RD after surgery.

Background:Anterior bone loss (ABL) is a common phenomenon after cervical disc replacement (CDR), which can also be observed after anterior cervical discectomy and fusion (ACDF). This study aimed to investigate the incidence and severity of ABL in single-level CDR and ACDF and explore the association of cervical sagittal alignment with ABL. Methods:This is a single-center retrospective cohort study. A total of 113 patients treated with CDR and 99 patients treated with ACDF were retrospectively reviewed from January 2014 to December 2018 in West China Hospital. Radiological data were collected at pre-operation, 1 week, 3 months postoperatively, and the last follow-up. The incidence and severity of ABL after both CDR and ACDF were evaluated. Cervical sagittal alignment parameters, including C0-C2 angle, cervical lordosis (CL), C2-C7 sagittal vertical axis (cSVA), T1 slope, functional spinal unit angle, disc angle, and surgical level slope, were evaluated. Results:ABL was identified in 75 (66.4%) patients in the CDR group and 57 (57.6%) patients in the ACDF group. There were no significant differences in the incidence, severity, and location of ABL between the ACDF and CDR groups. For patients who underwent ACDF, the proportion of females was significantly higher in the ABL group (64.9% vs. 33.3%, P=0.002), whereas the body mass index (BMI) was significantly lower in the ABL group compared to the non-ABL group (22.72±3.09 vs. 24.60±3.04, P=0.002). No effect of ABL on the short-term clinical outcomes of ACDF and CDR was observed. In the ACDF group, patients with ABL had significantly smaller postoperative CL (11.83°±8.24° vs. 15.25°±8.32°, P=0.04) and cSVA (17.77±10.08 vs. 23.35±9.86 mm, P=0.007). In the CDR group, no significant differences were found in the cervical sagittal parameters between patients with and without ABL (CL: 12.58±8.70 vs. 15.46±8.50, P=0.10; cSVA: 20.95±8.54 vs. 19.40±9.43, P=0.38). Conclusions:ABL is common after both CDR and ACDF with comparable incidence and severity. Cervical sagittal alignment was closely related to ABL after ACDF yet had less influence on ABL after CDR.

PurposeThree‐level hybrid surgery (HS) consisting of cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) has been partly used for the treatment of multi‐level cervical degenerative disc disease (CDDD). The complications related to the implants and the collapse of the surgical vertebral bodies had been reported in multi‐level anterior cervical spine surgery. Thus, this study aimed to explore the biomechanical effects on the prostheses and vertebrae in three‐level HS.MethodsA FE model of cervical spine (C0‐T1) was constructed. Five surgical models were developed. They were FAF model (ACDF‐CDA‐ACDF), AFA model (CDA‐ACDF‐CDA), FFF model (three‐level ACDF), SF model (single‐level ACDF), and SA model (single‐level CDA). A 75‐N follower load and 1.0‐N·m moment was applied to produce flexion, extension, lateral bending, and axial rotation.ResultsCompared with the intact model, the range of motion (ROM) of total cervical spine in FAF model decreased by 34.54%, 54.48%, 31.76%, and 27.14%, respectively, in flexion, extension, lateral bending, and axial rotation, which were lower than those in FFF model and higher than those in AFA model. The ROMs of CDA segments in FAF and AFA models were similar to the intact model and SA model. Compared with the intact model, the ROMs at C3/4 segment in FFF model increased from 5.71% to 7.85%, and increased from 5.31% to 6.81% at C7/T1 segment, following by FAF model, then the FAF model. The maximum interface pressures of the Prestige‐LP in FAF model were similar to SA model, however the corresponding values were increased in AFA model. The maximum interface pressures of the Zero‐P were increased in FAF and AFA model compared with those in SF and FFF models. The stress was mainly distributed on the screws. In AFA model, the maximum pressures of the ball and trough articulation in superior and inferior Prestige‐LP were all increased compared with those in SA and FAF model. In FFF model, the maximum pressures of the vertebrae were higher than those in other models. The stress was mainly distributed on the anterior area of the vertebral bodies.ConclusionsHS seemed to be more suitable than ACDF for the surgical treatment of three‐level CDDD in consideration of the biomechanical effects, especially for the two‐level CDA and one‐level ACDF construct. But a more appropriate CDA prosthesis should be explored in the future.

Objective Cable‐dragged reduction and cantilever beam internal fixation can provide promising results in the treatment of atlantoaxial dislocation or instability. However, bilateral atlantoaxial joints bone autografting has not been conducted in this technique. We aim to evaluate the safety and effectiveness of bilateral atlantoaxial joints bone autografting in posterior cable‐dragged reduction and cantilever‐beam internal fixation. Methods In this retrospective study, we included 14 patients with a minimum 24‐month follow‐up from December 2019 to September 2020. The granular bone harvested from the iliac crest was packed into the bilateral atlantoaxial joints of 14 patients in posterior cable‐dragged reduction and cantilever‐beam internal fixation. X‐ray imaging and cervical computed tomography (CT) were performed during follow‐up. The time required for bone fusion was recorded. The clinical outcomes were evaluated using the JOA scores, NDI, and VAS scores. Mann–Whitney U test, the chi‐squared test, or the Fisher exact test were used to compare the two groups regarding patient characteristics, clinical outcomes, bone fusion rates, and cervical sagittal alignment. Results The operations were successfully performed in all patients without any intraoperative complications. The mean operation time was (169.64 ± 20.91) minutes, and the intraoperative blood loss was (130.71 ± 33.62) mL. All patients received satisfactory reductions and firm bony fusion at the final follow‐up. The fusion rates were 64.29% in the atlantoaxial joints and 21.43% in post bone graft area at 3 months postoperatively, and a significant difference was observed ( p = 0.022). Besides, the cervical sagittal alignment in all patients was well maintained in the last follow‐up compared to preoperatively. Importantly, a complete bony fusion in the atlantoaxial joints was observed in all patients. Moreover, the JOA, NDI, and VAS scores had improved significantly at the last follow‐up. Conclusion Bone autografting of the bilateral atlantoaxial joints is a safe and effective technique to increase bone fusion rates, shorten bone fusion time, and reduce complication rates when the cable‐dragged reduction and cantilever beam internal fixation approach is used. Therefore, it is a cost‐effective surgical procedure for treating patients with atlantoaxial dislocation or instability.

BACKGROUND:Anterior cervical corpectomy and fusion (ACCF) is a standard surgical procedure for cervical spondylosis with spinal cord compression (CSWSCC), especially in patients with intensity on T2-weighted imaging high signal (T2WIHS). The titanium mesh cage (TMC) utilized in this procedure is essential in stabilizing the spine; however, the optimal slotting width of the TMC remains unclear. OBJECTIVE:This study aimed to investigate the impact of TMC slotting width on the clinical and radiological outcomes of ACCF in patients with spinal cord compression type cervical spondylosis with intensity on T2WIHS (CST2WIHS). METHODS:We retrospectively analyzed 69 patients who underwent single-level ACCF between December 2010 and October 2021. The patients were divided into narrower (< 2 mm) and wider (> 2 mm) groups based on the slotting width of the TMC. The Neck Disability Index (NDI) and Japanese Orthopedic Association (JOA) scores were used to assess clinical outcomes. Radiological outcomes included cervical lordosis (CL), functional spinal unit (FSU) height, transverse decompression range (TDR), spinal canal area (SCA), TMC alignment, and subsidence and fusion rates. RESULTS:Patients in both groups exhibited significant postoperative improvement in NDI and JOA scores (P < 0.05). Radiologically, patients in the wider slotting group exhibited better decompression, evidenced by a larger TDR (P < 0.01) and smaller postoperative SCA (P < 0.01) than the narrow group. Regarding CL, FSU height, TMC alignment, subsidence, or fusion rates, the groups did not differ significantly. Although statistically non-significant, patients in the wider group exhibited a trend towards improvement in spinal cord signal intensity than those in the narrower group. CONCLUSION:The study demonstrated that a wider TMC slotting width offers superior decompression and may improve postoperative spinal cord signal; it does not compromise spinal stability or fusion outcomes. These findings indicate that slotting width should be carefully considered in ACCF procedures to optimize decompression and spinal cord recovery.

ObjectiveModic change (MC) is defined as abnormalities observed in the intervertebral disc subchondral and adjacent vertebral endplate subchondral bone changes. Most studies on MC were reported in the lumbar spine and associated with lower back pain. However, MC has been rarely reported in the cervical spine, let alone in those who underwent cervical disc replacement (CDR). This study aimed to focus on MC in the cervical spine and reveal clinical and radiological parameters, especially heterotopic ossification (HO), for patients who underwent CDR. Furthermore, we illustrated the association between MC and HO.MethodsWe retrospectively reviewed patients who underwent CDA from January 2008 to December 2019. The Japanese Orthopaedic Association (JOA), Neck Disability Index (NDI), and Visual Analog Scale (VAS) scores were used to evaluate the clinical outcomes. Radiological evaluations were used to conclude the cervical alignment (CL) and range of motion (ROM) of C2‐7, functional spinal unit angle (FSUA), shell angle (SA), FSU height, and HO. Univariate and multivariate logistic regressions were performed to identify the risk factors for HO. The Kaplan–Meier (K‐M) method was used to analyze potential risk factors, and multivariate Cox regression was used to identify independent risk factors.ResultsA total of 139 patients were evaluated, with a mean follow‐up time of 46.53 ± 26.60 months. Forty‐nine patients were assigned to the MC group and 90 to the non‐MC group. The incidence of MC was 35.3%, with type 2 being the most common. Clinical outcomes (JOA, NDI, VAS) showed no significant difference between the two groups. The differences in C2‐7 ROM between the two groups were not significant, while the differences in SA ROM and FSUA ROM were significantly higher in the non‐MC than in the MC group (p < 0.05). Besides, FSU height in MC group was significantly lower than that in non‐MC group. Parameters concerning CL, including C2‐7, FSUA, SA, were not significantly different between the two groups. The incidence of HO and high‐grade HO, respectively, in the MC group was 83.7% and 30.6%, while that in the non‐MC group was 53.3% and 2.2%, and such differences were significant (p < 0.05). Multivariate logistic regression analyses and Cox regression showed that MC and involved level were significantly associated with HO occurrence (p < 0.05). No implant migration and secondary surgery were observed.ConclusionMC mainly affected the incidence of HO. Preoperative MC was significantly associated with HO formation after CDR and should be identified as a potential risk factor for HO. Rigorous criteria for MC should be taken into consideration when selecting appropriate candidates for CDR.

Objective:To investigate the influence of preoperative symptom duration on effectiveness of cervical disc arthroplasty (CDA) in cervical spondylotic radiculopathy (CSR) patients. Methods:The clinical data of 90 CSR patients who underwent single-segment CDA between January 2008 and March 2020 and met the selection criteria were retrospectively analyzed. Based on preoperative symptom duration, patients were divided into an early intervention group (preoperative symptom duration <24 months) and a late intervention group (preoperative symptom duration ≥24 months). There was no significant difference in baseline data between the two groups ( P>0.05), including age, gender, body mass index, smoking status, surgical segment, preoperative neck disability index (NDI), visual analogue scale (VAS) score, cervical lordosis (CL), C 2-C 7 range of motion (ROM), disc angle (DA), disc ROM (DROM), and disc intervertebral height (DIH). The early intervention group had a slightly higher preoperative Japan Orthopedic Association (JOA) score than the late intervention group ( P<0.05). Perioperative indicators such as operation time, intraoperative blood loss, and postoperative hospital stay were recorded. The changes of JOA score, NDI, and VAS score at last follow-up compared with those before operation were used to evaluate the clinical efficacy, and the imaging evaluation of CL, C 2-C 7 ROM, DA, DROM, and DIH was performed before operation, immediately after operation, and at last follow-up. The incidence of prosthesis-related complications, including heterotopic ossification (HO), anterior bone loss (ABL), and prosthesis subsidence, was also assessed at last follow-up. Results:Patients in both groups were followed up 24-120 months, with an average of 53.4 months. There was no significant difference in operation time, intraoperative blood loss, or follow-up duration between the groups ( P>0.05). However, the late intervention group had significantly longer postoperative hospital stay compared to the early intervention group ( P<0.05). At last follow-up, there was no significant difference in the changes of JOA score, NDI, and VAS score between the two groups before and after operation ( P>0.05). During the follow-up, there was no surgical revision in the two groups, and there was no significant difference in the incidence of HO, ABL, and prosthesis subsidence between the two groups at last follow-up ( P>0.05). Imaging evaluation showed that there was no significant difference in CL, C 2-C 7 ROM, DA, DROM, and DIH between the two groups at each time point before and after operation ( P>0.05). The intra-group comparison showed that the early intervention group could maintain the immediate postoperative CL at last follow-up, while the late intervention group had recovered to the preoperative level. Additionally, the C 2-C 7 ROM, DROM, and DA had all recovered to preoperative levels at last follow-up in both groups; meanwhile, the DIH significantly increased immediately after operation and sustained until the last follow-up. Conclusion:Preoperative symptom duration significantly affects the effectiveness of CDA in CSR patients. Patients with preoperative symptom duration ≥24 months have longer postoperative hospital stays and potentially poorer ability to maintain CL compared with patients with preoperative symptom duration <24 months.

Cervical disc arthroplasty (CDA) is widely employed for patients diagnosed with cervical degenerative disc disease (CDDD). Postoperative bone loss (BL) represents a radiological alteration that is a relatively novel consideration in the realm of CDA. This study endeavors to examine the risk factors associated with BL following CDA, aiming to elucidate the underlying mechanisms and the impact of BL on surgical outcomes. A retrospective study was undertaken, encompassing consecutive patients subjected to one-level CDA, two-level CDA, or two-level hybrid surgery (HS) for the treatment of CDDD at our institution. Patient demographic and perioperative data were systematically recorded. Radiological images obtained preoperatively, at 1-week post-operation, and during the last follow-up were collected and evaluated, following with statistical analyses. A total of 295 patients and 351 arthroplasty segments were involved in this study. Univariate logistic regressions indicated that age ≥ 45 years and two-level HS was associated with lower risk of BL; and a greater ΔDA (change of disc angle before and after surgery) was correlated with an increased risk of BL. Multivariate logistic regression determined that two-level HS and greater ΔDA were independent preventative and risk factors for BL, respectively. Further analysis revealed that severe BL significantly elevated the risk of implant subsidence compared to non-BL and mild BL. This study posited bone remodeling and micromotion as potential underlying mechanisms of BL. Subsequent research endeavors should delve into the divergent mechanisms and progression observed between lower- and higher-grade BL, aiming to prevent potential adverse outcomes associated with severe BL.