Multilevel Posterior Cervical Fusion Research Articles

Is the Ossification of the Posterior Longitudinal Ligament a Positive Factor for the Fusion after Posterior Cervical Fusion and Decompression?

Objective: Multilevel posterior cervical fusion (PCF) and decompression surgery is a viable treatment option for multilevel ossification of posterior longitudinal ligament (OPLL) and spondylotic myelopathy. Since OPLL is known to affect bone formation, this study aimed to examine the effect of OPLL on the incidence of pseudarthrosis following PCF in a cohort study. Methods: We conducted a retrospective cohort study of patients with PCF and laminectomy at our institution. This study included patients who underwent C3 to C6 posterior fusion surgery involving lateral mass screw fixation without anterior surgery for OPLL or spondylotic myelopathy. Fusion status was evaluated 1 year postoperatively with computed tomography. Bone mineral density (BMD) and sagittal parameters were also evaluated as potential contributing factors to the fusion rate.Results: Eighty patients were included. Pseudarthrosis was observed in 22.5% (n=18) of patients. Pseudarthrosis incidence was lower in patients with OPLL (spondylosis vs. OPLL, 33.3% vs. 12.2%; p=0.003), and a higher BMD T-score (pseudarthrosis vs. fusion, -1.9 ± 0.7 vs. -0.6 ± 1.3; p<0.01), a larger preoperative range of motion (ROM) (26.7 ± 13.3 vs. 17.6 ± 10.9; p=0.01), and a greater preoperative-to-postoperative decrease in cervical lordosis (-8.1 ± 7.9 vs. -2.7 ± 7.9; p<0.01). Pseudarthrosis was associated with worsening neck pain after surgery. Conclusion: The absence of OPLL, lower BMD, larger preoperative ROM, and a greater decrease in postoperative cervical lordosis were identified as risk factors for pseudarthrosis after multiple PCF.

Crossing the Cervicothoracic Junction: A Biomechanical Investigation of C7 vs T1 Caudal Selection's Effect on Adjacent Segment Motion in Posterior Cervical Fusion.

Biomechanical Study. This study aims to evaluate the biomechanical adjacent segment effects of multi-level posterior cervical fusion constructs that terminate at C7 compared to those that terminate at T1 in cadaveric specimens. The cervicothoracic junction poses unique challenges for spine surgeons. Deciding to terminate multi-level posterior cervical fusion constructs at C7 or extend them across the cervicothoracic junction remains a controversial issue. Six cadaveric specimens underwent biomechanical testing in the intact state and after instrumentation with constructs from C3 and terminating at either C7 or T1. Range of motion (ROM) was assessed in flexion-extension, lateral bending, and axial rotation globally and at cranial and caudal adjacent segments. There was a significant decrease in overall flexion/extension by both C7 (-35.5°, P=0.002) and T1 (-39.8°, P=0.002) instrumentation compared to the intact spine. T1 instrumentation had significantly lower (-4.3°, P=0.008) flexion/extension ROM compared to C7 instrumentation. There were significant decreases in axial rotation by both C7 (-31.4°, P=0.009) and T1 (-36.8°, P=0.009) instrumentation compared to the intact spine, but no significant differences were observed between the two. There were also significant decreases in lateral bending by both C7 (-27.9°, P=0.022) and T1 (-33.7°, P=0.022) instrumentation compared to the intact spine, but no significant differences were observed between the two. No significant differences were observed in ROM at cranial or caudal adjacent segments between constructs terminating at C7 and those extending to T1. This biomechanical investigation demonstrates that constructs that cross the cervicothoracic junction experience less overall spinal motion in flexion-extension compared to those that terminate at C7. However, contrary to prior studies there is no difference in cranial and caudal adjacent segment motion. Surgeons should make clinical decisions regarding the caudal extent of fusion in multi-level posterior cervical fusions without major concerns about adjacent segment motion.

Cervical orthosis does not improve postoperative pain following posterior cervical fusion: a randomized controlled trial.

To determine whether postoperative neck pain in the first 4 weeks following multi-level posterior cervical fusion (PCF) with orthosis is equivalent to multi-level PCF without orthosis. Patients were randomly assigned in a 1:1 ratio to postoperative orthosis (CO) for 6 weeks or no orthosis (NO). Randomization was stratified by indication (traumatic vs. degenerative), and preoperative opioid use. A model of longitudinal regression for repeated measures was used. The two-sided 95% confidence interval (CI) was used to test equivalence. If the CI lay between the pre-determined margin of equivalence (-2.0 to + 2.0 pain score) the two groups were considered equivalent. A multiple imputation procedure was used to replace missing data. Thirty-one patients were enrolled in each group. At baseline, the CO group had more neck pain (5.3 vs. 3.2, p = 0.013). The Four week post-operative neck pain intensity score was 4.6 ± 0.3 for the CO group vs. 4.9 ± 0.3 for the NO group. The 95% confidence interval (-1.2 to 0.6) was within the pre-determined equivalence margin. Neck Disability Index, quality-of-life scores, and arm pain were similar. Eleven patients in the CO group and 12 patients in the NO group had an adverse event. The CO group had reduced range of motion at 6 weeks. Pain scores over the first 4 weeks after surgery were equivalent for patients undergoing multi-level PCF treated with or without a cervical orthosis. Our findings do not support the routine use of a postoperative cervical orthosis for postoperative pain control. Clinical Trials Registration Number NCT04308122, April 22, 2020.

P182. Age as a criterion in multilevel posterior cervical fusion surgery: a propensity scored analysis

P182. Age as a criterion in multilevel posterior cervical fusion surgery: a propensity scored analysis

Selecting the lowest instrumented vertebra in a multilevel posterior cervical fusion across the cervicothoracic junction: a biomechanical investigation.

Posterior cervical fusion is a common surgical treatment for patients with myeloradiculopathy or regional deformity. Several studies have found increased stresses at the cervicothoracic junction (CTJ) and significantly higher revision surgery rates in multilevel cervical constructs that terminate at C7. The purpose of this study was to investigate the biomechanical effects of selecting C7 versus T1 versus T2 as the lowest instrumented vertebra (LIV) in multisegmental posterior cervicothoracic fusion procedures. Seven fresh-frozen cadaveric cervicothoracic spines (C2-L1) with ribs intact were tested. After analysis of the intact specimens, posterior rods and lateral mass screws were sequentially added to create the following constructs: C3-7 fixation, C3-T1 fixation, and C3-T2 fixation. In vitro flexibility tests were performed to determine the range of motion (ROM) of each group in flexion-extension (FE), lateral bending (LB), and axial rotation (AR), and to measure intradiscal pressure of the distal adjacent level (DAL). In FE, selecting C7 as the LIV instead of crossing the CTJ resulted in the greatest increase in ROM (2.54°) and pressure (29.57 pound-force per square inch [psi]) at the DAL in the construct relative to the intact specimen. In LB, selecting T1 as the LIV resulted in the greatest increase in motion (0.78°) and the lowest increase in pressure (3.51 psi) at the DAL relative to intact spines. In AR, selecting T2 as the LIV resulted in the greatest increase in motion (0.20°) at the DAL, while selecting T1 as the LIV resulted in the greatest increase in pressure (8.28 psi) in constructs relative to intact specimens. Although these trends did not reach statistical significance, the observed differences were most apparent in FE, where crossing the CTJ resulted in less motion and lower intradiscal pressures at the DAL. The present biomechanical cadaveric study demonstrated that a cervical posterior fixation construct with its LIV crossing the CTJ produces less stress in its distal adjacent discs compared with constructs with C7 as the LIV. Future clinical testing is necessary to determine the impact of this finding on patient outcomes.

Crossing the cervicothoracic junction: an evaluation of radiographic alignment, functional outcomes, and patient-reported outcomes.

There is currently no consensus regarding the appropriate lower instrumented vertebra (LIV) for multilevel posterior cervical fusion (PCF) constructs between C7 and crossing the cervicothoracic junction (CTJ). The goal of the present study was to compare postoperative sagittal alignment and functional outcomes among adult patients presenting with cervical myelopathy undergoing multilevel PCF terminating at C7 versus spanning the CTJ. A single-institution retrospective analysis (January 2017-December 2018) was performed of patients undergoing multilevel PCF for cervical myelopathy that involved the C6-7 vertebrae. Pre- and postoperative cervical spine radiographs were analyzed for cervical lordosis, cervical sagittal vertical axis (cSVA), and first thoracic (T1) vertebral slope (T1S) in two randomized independent trials. Modified Japanese Orthopaedic Association (mJOA) and Patient-Reported Outcomes Measurement Information System (PROMIS) scores were used to compare functional and patient-reported outcomes at the 12-month postoperative follow-up. Sixty-six consecutive patients undergoing PCF and 53 age-matched controls were included in the study. There were 36 patients in the C7 LIV cohort and 30 patients in the LIV spanning the CTJ cohort. Despite significant correction, patients undergoing fusion remained less lordotic than asymptomatic controls, with a C2-7 Cobb angle of 17.7° versus 25.5° (p < 0.001) and a T1S of 25.6° versus 36.3° (p < 0.001). The CTJ cohort had superior alignment corrections in all radiographic parameters at the 12-month postoperative follow-up compared with the C7 cohort: increase in T1S (ΔT1S 14.1° vs 2.0°, p < 0.001), increase in C2-7 lordosis (ΔC2-7 lordosis 11.7° vs 1.5°, p < 0.001), and decrease in cSVA (ΔcSVA 8.9 vs 5.0 mm, p < 0.001). There were no differences in the mJOA motor and sensory scores between cohorts pre- and postoperatively. The C7 cohort reported significantly better PROMIS scores at 6 months (22.0 ± 3.2 vs 11.5 ± 0.5, p = 0.04) and 12 months (27.0 ± 5.2 vs 13.5 ± 0.9, p = 0.01) postoperatively. Crossing the CTJ may provide a greater cervical sagittal alignment correction in multilevel PCF surgeries. However, the improved alignment may not be associated with improved functional outcomes as measured by the mJOA scale. A new finding is that crossing the CTJ may be associated with worse patient-reported outcomes at 6 and 12 months of postoperative follow-up as measured by the PROMIS, which should be considered in surgical decision-making. Future prospective studies evaluating long-term radiographic, patient-reported, and functional outcomes are warranted.

Biomechanical Analysis of Multilevel Posterior Cervical Spinal Fusion Constructs.

Controlled Laboratory Study. To compare multilevel posterior cervical fusion (PCF) constructs stopping at C7, T1, and T2 under cyclic load to determine the range of motion (ROM) between the lowest instrumented level and lowest instrumented-adjacent level (LIV-1). PCF is a mainstay of treatment for various cervical spine conditions. The transition between the flexible cervical spine and rigid thoracic spine can lead to construct failure at the cervicothoracic junction. There is little evidence to determine the most appropriate level at which to stop a multilevel PCF. Fifteen human cadaveric cervicothoracic spines were randomly assigned to 1 of 3 treatment groups: PCF stopping at C7, T1, or T2. Specimens were tested in their native state, following a simulated PCF, and after cyclic loading. Specimens were loaded in flexion-extension), lateral bending, and axial rotation. Three-dimensional kinematics were recorded to evaluate ROM. The C7 group had greater flexion-extension motion than the T1 and T2 groups following instrumentation (10.17±0.83 degree vs. 2.77±1.66 degree and 1.06±0.55 degree, P <0.001), and after cyclic loading (10.42±2.30 degree vs. 2.47±0.64 degree and 1.99±1.23 degree, P <0.001). There was no significant difference between the T1 and T2 groups. The C7 group had greater lateral bending ROM than both thoracic groups after instrumentation (8.81±3.44 degree vs. 3.51±2.52 degree, P =0.013 and 1.99±1.99 degree, P =0.003) and after cyclic loading. The C7 group had greater axial rotation motion than the thoracic groups (4.46±2.27 degree vs. 1.26±0.69 degree, P =0.010; and 0.73±0.74 degree, P =0.003) following cyclic loading. Motion at the cervicothoracic junction is significantly greater when a multilevel PCF stops at C7 rather than T1 or T2. This is likely attributable to the transition from a flexible cervical spine to a rigid thoracic spine. Although this does not account for in vivo fusion, surgeons should consider extending multilevel PCF constructs to T1 when feasible. Not applicable.

Predictive risk factors for mechanical complications after multilevel posterior cervical instrumented fusion.

Mechanical complications should be considered following the correction of multilevel posterior cervical instrumented fusion. This study aimed to investigate clinical data on the patients' pre- and postoperative cervical alignment in terms of the incidence of mechanical complications after multilevel posterior cervical instrumented fusion. Between January 2008 and December 2018, 156 consecutive patients who underwent posterior cervical laminectomy and instrumented fusion surgery of 4 or more levels and were followed up for more than 2 years were included in this study. Age, sex, bone mineral density (BMD), BMI, mechanical complications, and pre- and postoperative radiographic factors were analyzed using multivariate logistic regression analysis to investigate the factors related to mechanical complications. Of the 156 patients, 114 were men and 42 were women; the mean age was 60.38 years (range 25-83 years), and the mean follow-up duration of follow-up was 37.56 months (range 24-128 months). Thirty-seven patients (23.7%) experienced mechanical complications, and 6 of them underwent revision surgery. The significant risk factors for mechanical complications were low BMD T-score (-1.36 vs -0.58, p = 0.001), a large number of fused vertebrae (5.08 vs 4.54, p = 0.003), a large preoperative C2-7 sagittal vertical axis (SVA; 32.28 vs 23.24 mm, p = 0.002), and low preoperative C2-7 lordosis (1.85° vs 8.83°, p = 0.001). The clinical outcomes demonstrated overall improvement in both groups; however, the neck visual analog scale, Neck Disability Index, and Japanese Orthopaedic Association scores after surgery were significantly worse in the mechanical complication group compared with the group without mechanical complications. Low BMD, a large number of fused vertebrae, a large preoperative C2-7 SVA, and low C2-7 lordosis were significant risk factors for mechanical complications after posterior cervical fusion surgery. The results of this study could be valuable for preoperative counseling, medical treatment, or surgical planning when multilevel posterior cervical instrumented fusion surgery is performed.

Is It Meaningful and Necessary to Avoid the Seventh Cervical Vertebra in Long Level Cervical Fusion?

To compare the clinical and radiological results of patients who underwent multilevel posterior cervical fusion (PCF) with different end levels (C6 or C7). We collected radiographs and clinical results of all subjects who underwent 3 level or more PCF for degenerative disease from May 2012 to December 2020. Based on the location of the end of fusion during surgery, patients were divided into C6 (group 1) and C7 patients (group 2). The clinical and radiological results of both groups were compared over two years. A total of 52 patients met the inclusion criteria of this study (21 in group 1 and 31 in group 2). The clinical results demonstrated a statistically significant difference with respect to a lower neck visual analog scale score in group 1 than in group 2 at the last follow-up (p=0.03). With regard to the radiological results, the C2-C7 sagittal vertical axis showed significantly greater values in group 2 than in group 1 at the final follow-up (p=0.02). For thoracic kyphosis (TK), group 2 had lower TK values than group 1 (p=0.03), and the T9 spinopelvic inclination was significantly greater in group 2 than in group 1 (p=0.01). In this study, aggravation of cervical kyphosis and neck pain was observed when C7 was included in multilevel PCF surgery. The inclusion of C7 also affected the thoracolumbar parameters and global spine alignment.

Clinical Impact and Correlations of Odontoid Parameters Following Multilevel Posterior Cervical Fusion Surgery.

C2 slope (C2S), a cervical parameter mathematically approximated as T1 slope minus cervical lordosis (T1S-CL), predicts functional improvement in cervical deformity patients. Nonetheless, C2S is a positional parameter based only on the horizontal axis. The current study aims to introduce novel odontoid parameters and establish their relationships with patient-reported health-related quality of life (HRQoL). Lateral plain radiographs of 32 adults who underwent multilevel posterior cervical fusion were analyzed. The odontoid parameters included odontoid incidence (OI), C2S, odontoid tilt (OT), and gravity line-C2 distance (GL-C2), while the cervical parameters were the Cobb angle at C0-1, C1-2, C0-2, C2-7, C2-7 sagittal vertical axis (cSVA), T1 slope, and T1S-CL. The range of motion (ROM) of the occipito-atlantoaxial complex was measured in flexion and extension plain radiographs. Scores on the Neck Disability Index (NDI) and visual analogue scale (VAS) for axial neck (VASn) and arm pain were measured. Compared to asymptomatic subjects, patients had larger C2S, cSVA, and T1S-CL, and smaller OT. Preoperatively, OI was significantly correlated with the ROM of C1-2 (r = 0.37, p < 0.05) and C0-2 (r = 0.46, p < 0.01). OT and C2S had significant correlations with the C0-1, C1-2, and C0-2 angles, GL-C2, and T1S-CL. Postoperative NDI scores were significantly correlated with OI (r = -0.40, p < 0.05) and OT (ρ = -0.37, p < 0.05). VASn was significantly correlated with GL-C2 (r = -0.35, p < 0.05). The odontoid parameters were significantly correlated with established cervical parameters and HRQoL measures. OI is a constant parameter representing the individual's compensatory reservoir at the upper cervical spine.

C7 distal fixation anchor and its influence on sagittal profile in posterior cervical fusion; a retrospective analysis of 44 cases

Study designRetrospective. PurposeIn multilevel posterior cervical fusion, whether to stop distal fixation at C7 or T1, remains a matter of debate. We aimed to assess clinical feasibility of C7 as distal fixation point and sought to compare complication rates and radiological outcome between lateral mass screws and pedicle screws at C7. Overview of literatureCurrent literature remains inconclusive regarding need for thoracic extension of instrumentation in multilevel posterior cervical fusion. MethodsWe did a retrospective review of 44 consecutive patients who underwent posterior instrumented cervical decompression and fusion for degenerative cervical myelopathy with C7 as distal fixation point, and a minimum follow-up period of two years. We had two groups of patients based on C7 instrumentation. Group 1Lateral mass screw fixation. Group 2Pedicle screw fixation. Primary outcomePost-operative clinico-radiological evaluation of whole study population Secondary outcome: Comparison of complication rates and radiological outcome between groups 1 and 2. ResultsMean age was 58.06 ± 14.4 years with average follow-up duration of 35.4 ± 4.5 months. There were 18 patients in Group 1 and 26 patients in Group 2. Mean pre-operative mJOA score was 10.51 and post-operative mJOA score was 15.74 with mean recovery rate (RR) 69.82%, of which 30 patients (70.23%) had good recovery and 14 patients (29.77%) had fair recovery at final follow up. The two groups didn't show any significant difference in complication rates and outcome. ConclusionC7 as distal fixation anchor is safe and effective in maintaining cervical sagittal balance following multilevel posterior cervical fusion. C7 lateral mass screws are found to be equally efficacious as pedicle screws in preventing worsening of sagittal profile.

Does extending a posterior cervical fusion construct into the upper thoracic spine impact patient-reported outcomes as long as 2 years after surgery in patients with degenerative cervical myelopathy?

In multilevel posterior cervical instrumented fusion, extension of fusion across the cervicothoracic junction (CTJ) at T1 or T2 has been associated with decreased rates of reoperation and pseudarthrosis but with longer surgical time and increased blood loss. The impact on patient-reported outcomes (PROs) remains unclear. The primary objective was to determine whether extension of fusion through the CTJ influenced PROs at 3, 12, and 24 months after surgery. The secondary objective was to compare the number of patients who reached the minimal clinically important differences (MCIDs) for the PROs, modified Japanese Orthopaedic Association (mJOA) score, operative time, intraoperative blood loss, length of stay, discharge disposition, adverse events (AEs), reoperation within 24 months of surgery, and patient satisfaction. This was a retrospective observational cohort study of prospectively collected multicenter data of patients with degenerative cervical myelopathy. Patients who underwent posterior instrumented fusion of 4 levels or greater (between C2 and T2) between January 2015 and October 2020 and received 24 months of follow-up were included. PROs (scores on the Neck Disability Index [NDI], EQ-5D, physical component summary and mental component summary of SF-12, and numeric rating scale for arm and neck pain) and mJOA scores were compared using ANCOVA and adjusted for baseline differences. Patient demographic characteristics, comorbidities, and surgical details were abstracted. The proportions of patients who reached the MCIDs for these outcomes were compared with the chi-square test. Operative duration, intraoperative blood loss, AEs, reoperation, discharge disposition, length of stay, and satisfaction was compared by using the chi-square test for categorical variables and the independent-samples t-test for continuous variables. A total of 198 patients were included in this study (101 patients with fusion not crossing the CTJ and 97 with fusion crossing the CTJ). Patients with a construct extending through the CTJ were more likely to be female and have worse baseline NDI scores (p > 0.05). When adjusted for baseline differences, there were no statistically significant differences between the two groups in terms of the PROs and mJOA scores at 3, 12, and 24 months. Surgical duration was longer (p < 0.001) and intraoperative blood loss was greater in the group with fusion extending to the upper thoracic spine (p = 0.013). There were no significant differences between groups in terms of AEs (p > 0.05). Fusion with a construct crossing the CTJ was associated with reoperation (p = 0.04). Satisfaction with surgery was not significantly different between groups. The proportions of patients who reached the MCIDs for the PROs were not statistically different at any time point. There were no statistically significant differences in PROs between patients with a posterior construct extending to the upper thoracic spine and those without such extension for as long as 24 months after surgery. The AE profiles were not significantly different, but longer surgical time and increased blood loss were associated with constructs extending across the CTJ.

Clinical and radiographic benefits of skipping C7 instrumentation in posterior cervicothoracic fusion: a retrospective analysis.

BackgroundC7 instrumentation during posterior cervicothoracic fusion can be challenging because it requires additional work of either placing side connectors to a single rod or placing two rods. Our clinical observations suggested that skipping instrumentation at C7 in a multi-level posterior cervicothoracic fusion will result in minimal intraoperative complications and decreased blood-loss while still maintaining sagittal balance parameters of cervical fusion. The objective of this study is to determine the clinical and radiographic outcomes of skipping C7 instrumentation compared to instrumenting the C7 vertebra in posterior cervicothoracic fusion.MethodsThis is a retrospective chart review of 314 consecutive patients who underwent multilevel posterior cervical fusion (PCF) at our institution. Out of 314 patients, 19 were instrumented at C7 serving as the control group, while the remaining 295 patients were not. Evaluation of efficacy was based on intraoperative complications, operative time, estimated blood loss (EBL), significant long-term complications, and radiographic evidence of fusion.ResultsSkipping the C7 level resulted in a significant reduction in EBL (488±576 vs. 822±1,137; P=0.007); however, operative time was similar between groups (174±95 vs. 184±86 minutes; P=0.844). Complications were minimal in both groups and not statistically significant. Radiographic analysis revealed C7 bridge patients had a significantly increased postoperative sagittal vertical axis (SVA) (29.3±13.1 vs. 20.2±3.1 mm; P=0.008); however, there was no significant difference between groups in SVA correction (−0.3±16.2 vs. −16.1±16.0 mm; P=0.867), T1 slope correction (3.4°±9.9° vs. 3.2°±5.5°; P=0.127), or cervical cobb angle correction (−5.7°±14.2° vs. −7.0°±12.2°; P=0.519). There were no significant long-term complications in either group.ConclusionsSkipping instrumentation at C7 in a multilevel posterior cervicothoracic fusion is associated with significantly reduced operative blood loss without loss of radiographic correction. This study demonstrates the clinical benefits of skipping C7 instrumentation in posterior cervicothoracic fusion with maintenance of radiographic correction parameters.

Change in the Alignment and Distal Junctional Kyphosis Development after Posterior Cervical Spinal Fusion Surgery for Cervical Spondylotic Myelopathy - Risk Factor Analysis.

ObjectiveThis study analyzed the risk factors in patients who developed distal junctional kyphosis (DJK) after posterior cervical fusion. MethodsWe retrospectively analyzed the clinical and radiographic outcomes of 64 patients, aged ≥18 years (51 and 13 male and female patients, respectively), who underwent single-staged multilevel (3–6 levels) posterior cervical fusion surgery due to multiple cervical spondylotic myelopathy. The surgeries were performed by a single spinal surgeon between January 2012 and December 2017. Demographic data, clinical outcomes, and radiological results were collected. We divided the patients into a DJK group and a non-DJK group according to the presence of DJK and investigated the risk factors by comparing the differences between the two groups. ResultsOf the 64 patients, 13 developed DJK. No significant differences in clinical results were observed between the two groups before and immediately after the surgery. At the final follow-up, a higher visual analog score for neck pain was observed in the DJK group compared to the non-DJK group (p<0.01). The DJK group had a significantly lower T1 slope and a significantly higher C2-7 sagittal vertical axis (SVA) before surgery compared to the non-DJK group (p=0.03 and p<0.01, respectively). Immediately after surgery, the difference between the two groups decreased and no significant difference was observed. However, at the last followup, a significantly higher C2-7 SVA was observed in the DJK group (p<0.01). At the last follow up, there is no discrepancy in T1S-CL. In multiple logistic regression analysis, preoperative higher C2-7 SVA and preoperative lower T1 slope were identified as independent risk factors (p=0.03 and p<0.01, respectively). As a result, it was confirmed that DJK occurred along the process of returning to preoperative values. ConclusionDJK can be considered to be caused by cervical misalignment due to excessive change in the surgical site in patients with low T1 slope and high C2-7 SVA before surgery. This also affects the clinical outcome after surgery. It is recommended to refrain from excessive segmental lordosis changes during multilevel cervical post fusion surgery, especially in patients with a small preoperative T1 slope and a large SVA value.

Bridging the Cervicothoracic Junction During Multi-Level Posterior Cervical Decompression and Fusion: A Systematic Review and Meta-Analysis.

Systematic review and Meta-analysis. This systematic review seeks to compare fusion, reoperation and complication rates, estimated blood loss (EBL), and surgical time between multi-level instrumented fusions with LIVs (lowest instrumented vertebra) in the cervical spine and those that extend into the thoracic spine. Several studies address the question of whether to extend a long-segment, posterior cervical fusions, performed for degenerative disease, into the upper thoracic spine. Recommendations for appropriate LIV continue to vary. A comprehensive computerized literature search through multiple electronic databases without date limits up until April 3rd, 2020 using combinations of key search terms and sets of inclusion/exclusion criteria was performed. Our comprehensive literature search yielded 3852 studies. Of these, 8 articles consisting of 1162 patients were included in the meta-analysis. In 61.2% of the patients, the fusion did not cross the cervicothoracic junction (CTJ) (cervical LIV, CLV). In the remaining 38.8%, the fusion extended into the upper thoracic spine (thoracic LIV, TLV). Overall, mean patient age was 62.5years (range: 58.8-66.1years). Our direct analysis showed that odds of fusion were not statistically different between the CLV and TLV groups (OR: .648, 95% CI: .336-1.252, P = .197). Similarly, odds of reoperation (OR: 0.726, 95% CI: 0.493-1.068, P = .104) and complication rates were similar between the 2 groups (OR: 1.214, 95% CI: 0.0.750-1.965, P = .430). Standardized mean difference (SMD) for the blood loss (SMD: .728, 95% CI: 0.554-.901, P = .000) and operative (SMD: 0.653, 95% CI: .479-.826, P = .000) differed significantly between the 2 groups. The indirect analysis showed similar fusion (Effect Size (ES)TLV: .892, 95% CI: .840-.928 vs ESCLV:0.894, 95% CI:0.849-.926); reoperation rate (ESTLV:0.112, 95% CI: 0.075-.164 vs ESCLV: .125, 95% CI: .071-.211) and complication rates (ESTLV: .108, 95% CI: .074-.154 vs ESCLV:0.081, 95% CI: .040-.156). Our meta-analysis showed that fusion, complication, and reoperation rates did not differ significantly between patients in whom multi-level posterior fusions ended in the cervical spine vs those of which was extended into the thoracic spine. The mean blood loss, operative time and length of stay were significantly lower in patients with CLV at C6 or C7, compared to their counterparts. These data suggest that, absent focal, C7-T1 pathology, extension of long, posterior cervical fusions into the thoracic spine may not be necessary.

Instrumentation Across the Cervicothoracic Junction Does Not Improve Patient-reported Outcomes in Multilevel Posterior Cervical Decompression and Fusion.

This was a retrospective cohort. The objective of this study was to determine if instrumentation across the cervicothoracic junction (CTJ) in elective multilevel posterior cervical decompression and fusion (PCF) is associated with improved patient-reported outcome measures (PROMs). Fusion across the CTJ may result in lower revision rates at the expense of prolonged operative duration. However, it is unclear whether constructs crossing the CTJ affect PROMs. Standard Query Language (SQL) identified patients with PROMs who underwent elective multilevel PCF (≥3 levels) at our institution. Patients were grouped based on anatomic construct: crossing the CTJ (crossed) versus not crossing the CTJ (noncrossed). Subgroup analysis compared constructs stopping at C7 or T1. Independent t tests and χ 2 tests were utilized for continuous and categorical data, respectively. Regression analysis controlled for baseline demographics. The α was set at 0.05. Of the 160 patients included, the crossed group (92, 57.5%) had significantly more levels fused (5.27 vs. 3.71, P &lt;0.001), longer operative duration (196 vs. 161 min, P =0.003), greater estimated blood loss (242 vs. 160 mL, P =0.021), and a decreased revision rate (1.09% vs. 10.3%, P =0.011). Neither crossing the CTJ (vs. noncrossed) nor constructs spanning C3-T1 (vs. C3-C7) were independent predictors of ∆PROMs (change in preoperative minus postoperative patient-reported outcomes) on regression analysis. However, C3-C7 constructs had a greater revision rate than C3-T1 constructs (15.6% vs. 1.96%, P =0.030). Crossing the CTJ in patients undergoing elective multilevel PCF was not an independent predictor of improvement in PROMs at 1 year, but they experienced lower revision rates. Level III.

32. DJK and revision rates in multilevel posterior cervical fusions terminating at the cervicothoracic junction

<h3>BACKGROUND CONTEXT</h3> Despite the consensus that posterior cervical fusion can be used to treat multiple cervical pathologies, questions remain as to if crossing the cervicothoracic junction (CTJ) influences the rate of revision and how radiographic outcomes may differ. Even less is known about how crossing the CTJ may predict the development of adjacent segment disease. A retrospective review of 91 posterior cervical fusion patients was performed comparing long constructs (≥3 levels) terminating at C7 vs T1-3. Revision and DJK rates were compared between the two groups. Mean change in cervical lordosis, T1 slope, cervical SVA, and T1 slope-cervical lordosis mismatch (T1S-CL) were also compared. Distal segment kyphosis at final follow up was significantly greater in the thoracic group, but no other statistically significant differences were identified. <h3>PURPOSE</h3> Compare revision rates and radiographic outcomes in patients receiving posterior cervical fusion of ≥3 levels that terminate at C7 vs T1, 2 or 3. Our hypothesis is patients with multilevel posterior cervical fusion constructs terminating at C7 will have similar rates of revision, DJK and cervicothoracic radiographic outcomes compared to patients whose constructs crossed the CTJ to T1, T2, or T3. <h3>STUDY DESIGN/SETTING</h3> Single center retrospective analysis. <h3>PATIENT SAMPLE</h3> Consecutive posterior cervical fusion patients with greater than or equal to 3 levels fused from January 2010 until December 31, 2019 at a single institution. <h3>OUTCOME MEASURES</h3> Primary outcome: 1. Need for revision. Secondary outcomes: 2. Distal junctional kyphosis; 3. Mean change in cervical lordosis (CL); 4. Mean change in T1 slope (T1S); 5. T1S - CL mismatch; 6. cervical SVA. <h3>METHODS</h3> A retrospective review of medical records identified posterior cervical fusion cases with at least one year of radiographic follow-up and fusion greater than or equal to 3 segments. Identified cases were divided into 2 groups based on location of lowest instrumented vertebra. Group 1 included fusions terminating at C7 and group 2 included fusions terminating at T1, 2, or 3. At multiple intervals, cervical lordosis (CL), T1 slope, cervical sagittal vertical axis (cSVA), distal segment kyphosis, and T1 slope-cervical lordosis mismatch (T1S-CL) were measured. Any need for revision surgery was also documented. <h3>RESULTS</h3> A total of 91 patients were included, 53 in Group 1 (mean age 58.9 years, 56.6% women) and 38 in Group 2 (mean age 64.4 yrs, 55% women). Revision rate did not reveal statistical difference between the two groups (Group 1: 9.4% vs Group 2: 2.6% P=0.39). There was no statistical difference in patients meeting criteria for DJK at final follow up (Group 1: 5.6% vs Group 2: 5.2% P=0.9). However, within each group, a statistically significant increase in mean distal segment kyphosis at final follow-up was identified in Group 2 (Group 1: 0.82°, P=0.31 vs Group 2: 2.5°, P=0.0001). Mean change in CL, T1 Slope, cSVA and T1S-CL mismatch were not statistically different between the groups at final follow up. <h3>CONCLUSIONS</h3> Our study demonstrated that revision rates, cervicothoracic radiographic parameters, and DJK were not significantly different when comparing multilevel posterior cervical fusions terminating at C7 vs the upper thoracic spine. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P109. Bridging the cervicothoracic junction during multi-level posterior cervical decompression and fusion -A systematic review and meta-analysis

<h3>BACKGROUND CONTEXT</h3> Several studies address the question of whether to extend a long-segment, posterior cervical fusions into the upper thoracic spine. Recommendations for appropriate caudal "end level" continue to vary. <h3>PURPOSE</h3> This systematic review seeks to compare fusion, reoperation and complication rates, estimated blood loss (EBL) and surgical time between multilevel instrumented fusions ending in the cervical spine and those that extend into the thoracic spine. <h3>STUDY DESIGN/SETTING</h3> Systematic review and Meta-analysis. <h3>OUTCOME MEASURES</h3> Fusion, reoperation and complication rates, EBL and surgical time. <h3>METHODS</h3> A comprehensive computerized literature search through multiple electronic databases without date limits up until April Week 3 2020 using combinations of key search terms and inclusion/exclusion criteria was performed. <h3>RESULTS</h3> Our comprehensive literature search yielded 3,852 studies. Of these, 8 articles consisting of 1,162 patients were included in the meta-analysis. In 61.2% of the patients the fusion did not cross the CTJ (the cervical end level CEL). In the remaining 38.8%, fusion extended into the upper thoracic spine (thoracic end level, TEL). Mean age of CEL group ranged from 57 to 67.8 years, and for TEL group, it was 55 to 65.3 years. Our direct analysis showed that odds of fusion were not statistically different between CEL and TEL groups (OR: 0.648, 95% CI: 0.336-1.252, p=0.197). Similarly, odds of reoperation (OR:0.726, 95% CI:0.493-1.068, p=0.104) and complication rates were similar between the two groups (OR:1.299, 95% CI:0.536-3.149, p=0.563). Standardized mean difference (SMD) for the blood loss (SMD: 0.728, 95% CI:0.554-0.901, p=0.000) and operative (SMD:0.653, 95% CI: 0.479-0.826, p=0.000) differed significantly between the two groups. The indirect analysis showed similar fusion (Effect Size (ES)crossing: 0.892, 95% CI: 0.840-0.928 vs ES not crossing:0.894, 95% CI:0.849-0.926); reoperation rate (EScrossing:0.112, 95% CI:0.075-0.164 vs ES not crossing: 0.125, 95% CI: 0.071-0.211) and complication rates (EScrossing: 0.108, 95% CI: 0.074-0.154 vs ES not crossing:0.081, 95% CI: 0.040-0.156). <h3>CONCLUSIONS</h3> Our meta-analysis showed that fusion, complication and reoperation rates did not differ significantly between patients in whom multi-level posterior fusions ended in the cervical spine versus those of which was extended into the thoracic spine. The mean blood loss, operative time and length of stay were significantly lower in patients with caudal level as C7 or below, compared to their counterparts. These data suggest that, absent focal C7-T1 pathology, extension of long posterior cervical fusions into the thoracic spine may not be necessary. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Relative Risks and Benefits of Crossing the Cervicothoracic Junction During Multilevel Posterior Cervical Fusion: A Multicenter Cohort

To compare the clinical and radiographic outcomes and complications in patients undergoing multilevel posterior cervical fusion surgery, ending at C7 or crossing the cervicothoracic junction (CTJ). A total of 96 patients undergoing multilevel posterior cervical fusion surgery ending at C7, T1, or T2 were screened. The patients who fulfilled the inclusion criteria were divided into 2 groups based on the lower instrumented vertebra (LIV) level: group C7 (ending at C7) and group T1-T2 (crossing the CTJ). The radiographic and clinical outcomes were compared between the 2 groups, and the risk factors for instrument failure at LIV were investigated. In total, 73 patients (76%) completed at least 1 year follow-up and divided into group C7 (n= 43) and group T1-T2 (n= 30). Preoperative and postoperative radiographic parameters, the Japanese Orthopaedic Association score, and patient-reported outcomes were not significantly different between the 2 groups. Significantly longer surgical time, increased blood loss, and higher incidence rates of perioperative or postoperative complications were noted in group T1-T2. On the other hand, the incidence of instrument failures at LIV was significantly higher in group C7. Multivariate analysis showed that ending at C7, skipping screw insertion at the proximal vertebra adjacent to LIV, and a large postoperative cervical sagittal vertical axis (>40 mm) were risk factors for instrument failure at LIV. Crossing the CTJ during multilevel posterior cervical fusion surgery reduced instrument failures at LIV, but increased the surgical invasiveness and perioperative and postoperative complications.

Multilevel, Percutaneous Posterior Cervical Interfacet Distraction and Fusion for Cervical Spondylotic Radiculopathy: Clinical and Radiographic Outcomes.

Retrospective review of patients who underwent multilevel posterior cervical interfacet distraction and fusion (PCIDF) using cages for cervical spondylotic radiculopathy (CSR). To determine clinical and radiographic outcomes following multilevel PCIDF. Anterior cervical discectomy and fusion has long been the standard of treatment for CSR. Advancements in surgery have employed minimally invasive techniques such as endoscopic discectomy, foraminotomy, and PCIDF. Studies on single-level PCIDF have reported good clinical outcomes, short hospital stays, and rare complications, but its application in multilevel disease is still evolving. Patients with CSR and confirmed radiologic evidence of multilevel foraminal stenosis without central canal stenosis were reviewed. Two-year outcomes of multilevel PCIDF included Neck Disability Index, neck and arm Visual Analogue Scale (VAS), radiographic cervical alignment parameters, evidence of fusion, and incidence of adjacent segment degeneration were compared at different time points. Thirty patients (mean age 54.6 ± 8.3) were included in the study with an average of 3.4 ± 0.8 levels treated. Mean surgical duration and intraoperative blood loss was 143.2 ± 69.7 minutes and 27.7 ± 28.7 mL, respectively, with an average length of stay at 1.8 ± 1.5 days. Neck Disability Index, VAS-neck, and VAS-arm all significantly improved at 2 weeks (P < 0.001) and was maintained until 2 years postoperatively. A significant decrease in segmental and C2-C7 lordosis, with a corresponding increase in sagittal vertical axis, was observed at 3 months postoperatively (P < 0.001) but did not deteriorate further on subsequent visits. Successful fusion was achieved in 90% of patients after 2 years. There was a 13.3% incidence of adjacent segment degeneration in the study cohort and one perioperative complication (3.3%). Our study suggests that multilevel PCIDF is safe and effective for CSR caused by foraminal stenosis. However, its potential to cause kyphosis and clinical impact on global sagittal alignment requires further scrutiny and long-term evaluation.Level of Evidence: 4.