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Purpose To investigate the relationship between the preoperative paraspinal Goutalier grade of fatty infiltration and postoperative cervical sagittal alignment in patients undergoing anterior cervical discectomy and fusion (ACDF). Methods A total of 101 patients who underwent single-level ACDF with the Zero-profile implant system between March 2011 and April 2020 were included in this study. Cervical sagittal alignment parameters, including the C2-C7 Cobb angle, functional spinal unit (FSU) angle, cervical sagittal vertical axis (SVA), and T1 slope (T1S), were assessed. Preoperative magnetic resonance images were used to classify patients according to Goutalier grade. Clinical outcomes including Neck Disability Index (NDI) scores, Japanese Orthepaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores were collected and analyzed. Results According to the Goutalier grade, 33 patients were classified as Goutalier 0–1 (Group A), 44 were classified as Goutalier 1.5–2 (Group B), and 24 were classified as Goutalier 2.5–4.0 (Group C). The mean age among the three groups showed significant differences (P = 0.007). At the last follow-up, the C2-C7 Cobb angle, FSU angle, and T1S improved after the surgery among the groups. Although there were varying degrees of loss of curvature among the different groups during the follow-up period, the postoperative cervical sagittal alignment parameters demonstrated no statistical differences among the three groups (P > 0.05). In addition, patients in all groups experienced significant relief of their symptoms, and the clinical scores were comparable among the groups (P > 0.05). Conclusion The complex nature of anterior cervical surgery requires surgical attention both in decompression and sagittal alignment. Our study demonstrates satisfactory postoperative cervical sagittal alignment of patients despite different grades of fatty infiltration of the multifidus muscle following single-level ACDF. Based on our results, the improvement and maintenance of cervical sagittal alignment after ACDF remains a complex problem that spine surgeons should consider before surgery.

Study Design. Retrospective analysis. Objective. The aim of this study was to investigate the relationship between bony fusion after anterior cervical discectomy and fusion (ACDF) and heterotopic ossification (HO) after cervical disc arthroplasty (CDA) in hybrid surgery (HS). Summary of Background Data. The mechanism of postoperative bone formation still remains unknown. It is considered a risk factor in CDA but is essential for a solid union in ACDF. With HS, we could directly study the mechanism and relationship of different forms of postoperative bone formation. Methods. Clinical data of 91 patients who had undergone consecutive two-level HS between January 2011 and January 2018 and with a minimum of 2-year follow-up was analyzed. HO was assessed based on McAfee's classifications, whereas fusion success was evaluated according the Food and Drug Administration approved criteria. Clinical outcomes and radiographic parameters were collected and used for the relevant comparisons. Results. HO was identified in 48.4% of patients (44/91). The fusion rates of patients in the HO group and the non-HO group at 3, 6, and 12 months postoperatively, and the final follow-up were 81.8% and 19.1%, 95.4% and 74.5%, 95.4% and 85.1%, and 97.7% and 93.6%, respectively. The fusion rates were significantly higher at 3 and 6 months after operation in the HO group than in the non-HO group (P < 0.05). Patients in both groups had significant improvements across all clinical outcomes at final follow-up. Conclusion. There was a significant relationship between bony fusion and occurrence of HO after HS, suggesting that both bony fusion and HO are reflections of individual osteogenic capacity. However, a reliable predictor of postoperative bone formation is needed in the future to guarantee a solid bony fusion after ACDF and to further take full advantage of the motion-preserving from CDA. Level of Evidence: 3

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To compare the differences among constructs with one‐level cervical disc arthroplasty (CDA) and two‐level anterior cervical discectomy and fusion (ACDF). A retrospective study was conducted involving patients who underwent one‐level CDA and two‐level ACDF between June 2012 and July 2020. According to the different locations of CDA and ACDF, we divided the constructs into three types: type Ⅰa: CDA‐ACDF‐ACDF; type Ⅰb: ACDF‐CDA‐ACDF; type Ⅰc: ACDF‐ACDF‐CDA. The differences of clinical and radiological outcomes were evaluated. Fifty‐three patients were included with 29 in type Ⅰa group, 11 in type Ⅰb group, and 13 in type Ⅰc group. After surgery, all groups showed significant improvement in apanese Orthopedic Association, Neck Disability Index, and Visual Analog Scale scores (p < 0.001). Range of motion (ROM) of the total cervical spine in type Ⅰc group decreased significantly compared with those in type Ⅰa and type Ⅰb groups (p < 0.05). No significant differences in ROM of the arthroplasty segment and the variations in ROM of the superior adjacent segment were observed among the three groups. The fusion rates of the superior ACDF segments were significantly higher at 6 and 12 months postoperatively than those of the inferior ACDF segments (p < 0.05). The clinical outcomes were similar among constructs concerning different locations of CDA and ACDF in three‐level hybrid surgery. ROM of the cervical spine in type Ⅰc group decreased significantly compared with that in type Ⅰa and type Ⅰb groups. The fusion rates of superior ACDF segments were higher at early time points after surgery than those of inferior ACDF segments.