How do C2 tilt and C2 slope correlate with patient reported outcomes in patients after anterior cervical discectomy and fusion?

Impact of Frailty and Cervical Radiographic Parameters on Postoperative Dysphagia Following Anterior Cervical Spine Surgery

STUDY DESIGN

Retrospective review of a prospectively collected registry.

OBJECTIVE

The purpose of the present study was to investigate the impact of frailty and radiographical parameters on postoperative dysphagia after anterior cervical spine surgery (ACSS).

SUMMARY OF BACKGROUND DATA

There is a growing body of literature indicating an association between frailty and increased postoperative complications following various surgeries. However, few studies have investigated the relationship between frailty and postoperative dysphagia after anterior cervical spine surgery.

MATERIALS AND METHODS

Patients who underwent anterior cervical spine surgery for the treatment of degenerative cervical pathology were included. Frailty and dysphagia were assessed by the modified Frailty Index-11 (mFI-11) and Eat Assessment Tool 10 (EAT-10), respectively. We also collected clinical demographics and cervical alignment parameters previously reported as risk factors for postoperative dysphagia. Multivariable logistic regression was performed to identify the odds ratio (OR) of postoperative dysphagia at early (2-6 weeks) and late postoperative time points (1-2 years).

RESULTS

Ninety-five patients who underwent ACSS were included in the study. Postoperative dysphagia occurred in 31 patients (32.6%) at the early postoperative time point. Multivariable logistic regression identified higher mFI-11 score (OR, 4.03; 95% CI: 1.24-13.16; P =0.021), overcorrection of TS-CL after surgery (TS-CL, T1 slope minus C2-C7 lordosis; OR, 0.86; 95% CI: 0.79-0.95; P =0.003), and surgery at C3/C4 (OR, 12.38; 95% CI: 1.41-108.92; P =0.023) as factors associated with postoperative dysphagia.

CONCLUSIONS

Frailty, as assessed by the mFI-11, was significantly associated with postoperative dysphagia after ACSS. Additional factors associated with postoperative dysphagia were overcorrection of TS-CL and surgery at C3/C4. These findings emphasize the importance of assessing frailty and cervical alignment in the decision-making process preceding ACSS.

The Significance of Odontoid Incidence in Patients With Cervical Spondylotic Myelopathy

STUDY DESIGN

Observational study.

OBJECTIVE

To analyze the cervical sagittal parameters for standing Digital radiography (DR) and supine Magnetic resonance imaging (MRI), and to further clarify the relationship between odontoid incidence (OI) and cervical spondylotic myelopathy (CSM).

METHODS

52 CSM patients aged 54.46 ± 2.89 years underwent both standing DR and supine MRI scans of cervical spine between November 2021 and November 2022. OI, odontoid tilt (OT), C2 slope (C2S), T1 slope (T1S), C0-2 angle, C2-7 angle (cervical lordosis [CL]), and T1S-CL were measured in both DR and MRI images using Surgimap (Version 2.3.2.1). Pearson correlation and linear regression were used to compare these parameters between the two modalities.

RESULTS

Cervical sagittal parameters, including OI, OT, C2S, C0-2 angle, T1S, C2-7 angle (CL) and T1S-CL, showed no significant differences in the measurements between the two modalities. Based on the DR images, OI was related to OT (r = .386, P < .01), C2S (r = .505, P < .01), CL (r = -.412, P < .01), and T1S-CL (r = .320, P < .05), and OI was matched with CL (r2 = .170) and T1S-CL (r2 = .102). Based on MRI images, OI was related to OT (r = .433, P < .01), C2S (r = .516, P < .01), CL (r = -.355, P < .01), and T1S-CL (r = .271, P < .05), and OI matched with C2-7 (r2 = .126) and T1S-CL (r2 = .073).

CONCLUSION

OI is an independent parameter related to cervical anatomy and its measurement is unaffected by external factors. In patients with CSM, odontoid parameters may effectively describe the sagittal alignment of the cervical spine on DR and MRI images.

Patients with radiculopathy have worse baseline disability and greater improvements following anterior cervical discectomy and fusion compared to patients with myelopathy

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is commonly performed in patients with radiculopathy and myelopathy. Although the goal of surgery in patients with radiculopathy is to improve function and reduce pain, patients with myelopathy undergo surgery to halt disease progression. Although the expectations between these preoperative diagnoses are generally understood to be disparate by spine surgeons, there is limited literature demonstrating their discordant outcomes.

PURPOSE

To compare improvements in patient reported outcome measures (PROMs) for patients undergoing ACDF for myelopathy or radiculopathy. Secondarily, we analyzed the proportion of patients who attain the minimum clinically important difference (MCID) postoperatively using thresholds derived from radiculopathy, myelopathy, and mixed cohort studies.

STUDY DESIGN/SETTING

Single institution retrospective cohort study PATIENT SAMPLE: Patients undergoing primary, elective ACDF with a preoperative diagnosis of radiculopathy or myelopathy and a complete set of preoperative and one-year postoperative PROMs.

OUTCOME MEASURES

Outcome measures included the following PROMs: Short-Form 12 Physical Component (PCS-12) and Mental Component (MCS-12) scores, the Visual Analog Scale (VAS) Arm score, and the Neck Disability Index (NDI). Hospital readmissions and revision surgery were also collected and evaluated.

METHODS

Patients undergoing an ACDF from 2014 to 2020 were identified and grouped based on preoperative diagnosis (radiculopathy or myelopathy). We utilized "general MCID" thresholds from a cohort of patients with degenerative spine conditions, and "specific MCID" thresholds generated from cohorts of patients with myelopathy or radiculopathy, respectively. Multivariate linear regressions were performed for delta (∆) PROMs and multivariate logistic regressions were performed for both general and specific MCID improvements.

RESULTS

A total of 798 patients met inclusion criteria. Patients with myelopathy had better baseline function and arm pain (MCS-12: 49.6 vs 47.6, p=.018; VAS Arm: 3.94 vs 6.02, p<.001; and NDI: 34.1 vs 41.9, p<.001), were older (p<.001), had more comorbidities (p=.014), more levels fused (p<.001), and had decreased improvement in PROMs following surgery compared to patients with radiculopathy (∆PCS-12: 4.76 vs 7.21, p=.006; ∆VAS Arm: -1.69 vs -3.70, p<.001; and ∆NDI: -11.94 vs -18.61, p<.001). On multivariate analysis, radiculopathy was an independent predictor of increased improvement in PCS-12 (β=2.10, p=.019), ∆NDI (β=-5.36, p<.001), and ∆VAS Arm (β=-1.93, p<.001). Radiculopathy patients were more likely to achieve general MCID improvements following surgery (NDI: Odds ratio (OR): 1.42, p=.035 and VAS Arm: OR: 2.98, p<.001), but there was no difference between patients with radiculopathy or myelopathy when using radiculopathy and myelopathy specific MCID thresholds (MCS-12: p=.113, PCS-12: p=.675, NDI: p=.108, and VAS Arm: p=.314).

CONCLUSIONS

Patients undergoing ACDF with myelopathy or radiculopathy represent two distinct patient populations with differing treatment indications and clinical outcomes. Compared to radiculopathy, patients with myelopathy have better baseline function, decreased improvement in PROMs, and are less likely to reach MCID using general threshold values, but there is no difference in the proportion reaching MCID when using specific threshold values.

LEVEL OF EVIDENCE

IRB.

Clinical significance of the C2 slope after multilevel cervical spine fusion

OBJECTIVE

The C2 slope (C2S) is one of the parameters that can determine cervical sagittal alignment, but its clinical significance is relatively unexplored. This study aimed to evaluate the clinical significance of the C2S after multilevel cervical spine fusion.

METHODS

A total of 111 patients who underwent multilevel cervical spine fusion were included in this study. The C2S, cervical sagittal vertical axis (cSVA), C2-7 lordosis, and T1 slope (T1S) were measured in standing lateral cervical spine radiographs preoperatively and 2 years after the surgery. Clinical outcome measures were visual analog scale (VAS) neck and arm pain scores, Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) scale score, and patient-reported subjective improvement rate (IR) percentage. Statistical analysis was performed using a paired-samples t-test and Pearson's correlation, and a receiver operating characteristic (ROC) curve to determine the cutoff values of C2S.

RESULTS

C2S demonstrated a significant correlation with the cSVA, C2-7 lordosis, T1S, and T1S minus cervical lordosis. C2S revealed a significant correlation with the JOA, neck pain VAS, and NDI scores at 2 years after surgery. Change in the C2S correlated with postoperative neck pain and NDI scores. ROC curves demonstrated the cutoff values of C2S as 18.8°, 22.25°, and 25.35°, according to a cSVA of 40 mm, severe disability expressed by NDI, and severe myelopathy, respectively.

CONCLUSIONS

C2S can be an additional cervical sagittal alignment parameter that can be a useful prognostic factor after multilevel cervical spine fusion.

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

OBJECTIVE

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).

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Radiographic Parameters in Cervical Myelopathy: Review of Current Literature

STUDY DESIGN

This was a narrative review.

OBJECTIVES

Provide a comprehensive review of radiographic alignment parameters and their effect on procedure selection, surgical decision-making, and clinical outcomes for the treatment of cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

The use of radiographic parameters to predict prognosis and surgical outcomes in patients with CSM is an evolving field given the complex presentation of patients with this condition.

METHODS

A literature search was conducted using PubMed for surgical treatment of CSM, with an emphasis on cervical radiographic parameters and clinical outcomes.

RESULTS

The principal goals of spine surgery can be broken down into decompression, stabilization, and restoration of alignment. The principle of restoring balance takes careful preoperative planning and attention to radiographic parameters including cervical lordosis, C2-C7 sagittal vertical axis, neck tilt, thoracic inlet angle, T1 slope, K-line, and modified K-line. Surgical interventions for CSM include anterior cervical discectomy and fusion, posterior cervical fusion, or laminoplasty and careful consideration of radiographic measures guide surgical decision-making is essential to ensure optimal outcomes.

CONCLUSION

Utilization of key radiographic parameters in surgical planning and decision-making allows surgeons to optimize clinical outcomes for CSM.

LEVEL OF EVIDENCE

Level V.

Sagittal alignment differences on the operating room table compared to preoperative and postoperative imaging in anterior cervical discectomy and fusion

Study Design

The study design used was a retrospective cohort.

Objective

The objective of this study is to determine if intraoperative improvements in sagittal alignment on the operating table persisted on postoperative standing radiographs.

Summary of Background Data

Cervical sagittal alignment may be correlated to postoperative outcomes. Since anterior cervical discectomy and fusions (ACDFs) can restore some cervical lordosis through intervertebral grafts/cages, it is important to understand if intraoperative radiographic measurements correlate with persistent postoperative radiographic changes.

Materials and Methods

Patients undergoing elective primary ACDF were screened for the presence of lateral cervical radiographs preoperatively, intraoperatively, and postoperatively. Patients were excluded if their first postoperative radiograph was more than 3 months following the procedure or if cervical lordosis was not able to be measured at each time point. Paired t-tests were utilized to compare differences in measurements between time points. Statistical significance was set at P < 0.05.

Results

Of 46 included patients, 26 (56.5%) were female, and the mean age was 55.2 ± 11.6 years. C0-C2 lordosis significantly increased from the preoperative to intraoperative time point (delta [Δ] = 4.49, P = 0.029) and significantly decreased from the intraoperative to postoperative time period (Δ = -6.57, P < 0.001), but this resulted in no significant preoperative to postoperative change (Δ = -2.08, P = 0.096). C2 slope decreased from the preoperative to the intraoperative time point (Δ = -3.84, P = 0.043) and significantly increased from the intraoperative to the postoperative time point (Δ = 3.68, P = 0.047), which also resulted in no net change in alignment between the preoperative and postoperative periods (Δ = -0.16, P = 0.848). There was no significant difference in the C2-C7 SVA from the preoperative to intraoperative (Δ = 0.85, P = 0.724) or intraoperative to postoperative periods (Δ = 2.04, P = 0.401); however, the C2-C7 SVA significantly increased from the preoperative to postoperative period (Δ = 2.88, P = 0.006).

Conclusions

Intraoperative positioning predominantly affects the mobile upper cervical spine, particularly C0-C2 lordosis and C2 slope, but these changes do not persist postoperatively.

Do the newly proposed realignment targets for C2 and T1 slope bridge the gap between radiographic and clinical success in corrective surgery for adult cervical deformity?

OBJECTIVE

Surgical correction of cervical deformity (CD) has been associated with superior alignment and functional outcomes. It has not yet been determined whether baseline or postoperative T1 slope (T1S) and C2 slope (C2S) correlate with health-related quality-of-life (HRQoL) metrics and radiographic complications, such as distal junctional kyphosis (DJK) and distal junctional failure (DJF). The objective of this study was to determine the impact of T1S and C2S deformity severity on HRQoL metrics and DJF development in patients with CD who underwent a cervical fusion procedure.

METHODS

All operative CD patients with upper instrumented vertebra above C7 and preoperative (baseline) and up to 2-year postoperative radiographic and HRQoL data were included. CD was defined as meeting at least one of the following radiographic parameters: C2-7 lordosis < -15°, TS1-cervical lordosis mismatch > 35°, segmental cervical kyphosis > 15° across any 3 vertebrae between C2 and T1, C2-7 sagittal vertical axis > 4 cm, McGregor's slope > 20°, or chin-brow vertical angle > 25°. Spearman's rank-order correlation and linear regression analysis assessed the impact of T1S and C2S on HRQoL metrics (Neck Disability Index [NDI], modified Japanese Orthopaedic Association [mJOA] scale, EuroQOL 5-Dimension Questionnaire [EQ-5D] visual analog scale [VAS] score, and numeric rating scale [NRS]-neck) and complications (DJK, DJF, reoperation). Logistic regression and a conditional inference tree (CIT) were used to determine radiographic thresholds for achieving optimal clinical outcome, defined as meeting good clinical outcome criteria (≥ 2 of the following: NDI < 20 or meeting minimal clinically important difference, mild myelopathy [mJOA score ≥ 14], and NRS-neck ≤ 5 or improved by ≥ 2 points), not undergoing reoperation, or developing DJF or mechanical complication by 2 years.

RESULTS

One hundred five patients with CD met inclusion criteria. By surgical approach, 14.7% underwent an anterior-only approach, 46.1% a posterior-only approach, and 39.2% combined anterior and posterior approaches. The mean baseline radiographic parameters were T1S 28.3° ± 14.5° and C2S 25.9° ± 17.5°. Significant associations were found between 3-month C2S and mJOA score (r = -0.248, p = 0.034), NDI (r = 0.399, p = 0.001), EQ-5D VAS (r = -0.532, p < 0.001), NRS-neck (r = 0.239, p = 0.040), and NRS-back (r = 0.264, p = 0.021), while significant correlation was also found between 3-month T1S and mJOA score (r = -0.314, p = 0.026), NDI (r = 0.445, p = 0.001), EQ-5D VAS (r = -0.347, p = 0.018), and NRS-neck (r = 0.269, p = 0.049). A significant correlation was also found between development of DJF and 3-month C2S (odds ratio [OR] 1.1, 95% confidence interval [CI] 1.01-1.1, p = 0.015) as well as for T1S (OR 1.1, 95% CI 1.01-1.1, p = 0.023). Logistic regression with CIT identified thresholds for optimal outcome by 2 years: optimal 3-month T1S < 26° (OR 5.6) and C2S < 10° (OR 10.4), severe 3-month T1S < 45.5° (OR 0.2) and C2S < 38.0° (no patient above this threshold achieved optimal outcome; all p < 0.05). Patients below both optimal thresholds achieved rates of 0% for DJK and DJF, and 100% met optimal outcome.

CONCLUSIONS

The severity of CD, defined by T1S and C2S at baseline and especially at 3 months, can be predictive of postoperative functional improvement and occurrence of worrisome complications in patients with CD, necessitating the use of thresholds in surgical planning to achieve optimal outcomes.

Odontoid Incidence: A Novel Cervical Parameter Influencing Cervical Alignment From Top to Bottom

Objective

By using angulation of the axis itself, this study aims to define and analyze odontoid incidence (OI) and odontoid tilt (OT) as novel cervical alignment parameters and investigate their correlations with cervical alignment.

Methods

Novel and existing parameters were measured with whole-spine lateral plain radiographs and EOS images of 42 adults without cervical symptoms. The correlations of OI, OT, C2 slope (C2S), and T1 slope (T1S) were calculated.

Results

The OI, OT, and C2S showed significant correlations with C2–7 angle (r = 0.43, r = -0.42, r = 0.62, respectively) and C0–2 angle (r = -0.33, r = 0.48, r = -0.61, respectively). OI, OT, T1S were independent predictors of the C2–7 angle in univariate regression analysis (adjusted-R² = 0.17, R² = 0.15, R² = 0.28, respectively). OI, OT, and T1S were independent predictors in the multivariable regression analysis with estimated standardized coefficients of 0.36, -0.67, -0.69, respectively (adjusted- R² = 0.80, p < 0.001). Regarding the C0–2 angle, OI and OT were independent predictors in the univariate regression analysis (adjusted-R² = 0.08, R² = 0.21, respectively).

Conclusion

OI, OT, and C2S had significant correlations with cervical alignment. As the pelvic incidence, the OI is the only anatomical and constant parameter that could be used as a reference point related to the cervical spine from the rostral end. The study results may serve as baseline data for further studies on the alignment and balance of the cervical spine.

The Effect of Anterior Cervical Discectomy and Fusion Procedure Duration on Patient-Reported Outcome Measures

OBJECTIVE

To determine whether operative duration of anterior cervical discectomy and fusion (ACDF) significantly affects patient-reported outcome measures (PROMs) 90 days after surgery and at 1-year follow-up.

METHODS

Patients who underwent primary 1-level to 4-level ACDF were retrospectively identified. Demographic data and PROMs were collected through chart review. Patients were split into short, medium, and long tertiles based on procedure duration. PROM surveys were administered preoperatively as baseline measurements, at initial follow-up (between 60 and 120 days postoperatively), and at 1 year postoperatively. Outcomes included Neck Disability Index, Short-Form 12 Physical Component Score (PCS-12), Short-Form 12 Mental Component Score, visual analog scale (VAS) neck score, and VAS arm score.

RESULTS

Significant short-term improvements were found across all groups for all PROMs. All groups showed long-term improvements in Short-Form 12 Mental Component Score, PCS-12, Neck Disability Index, VAS neck score, and VAS arm score, with the exception of the medium-duration group in PCS-12 (P = 0.093). On multivariate analysis, short-duration procedures predicted better improvement in VAS neck score (β = -1.01; P = 0.012) and VAS arm score (β = -1.38; P = 0.002) compared with long-duration procedures, whereas medium-duration procedures resulted in better improvement in VAS arm score (β = -1.00; P = 0.011). Further, short and medium duration was a predictor of decreased length of hospital stay (β = -0.67, P = 0.001 and β = -0.59, P = 0.001, respectively) compared with long-duration procedures.

CONCLUSIONS

All groups improved after ACDF regardless of surgical duration. Further, surgical duration was not a predictor of differing improvement in physical function or disability.