Cervical spine MRI phenotypes and prediction of pain, disability and adjacent segment degeneration/disease after ACDF

Development and validation of a predictive model for the risk of symptomatic adjacent segmental degeneration after anterior cervical discectomy and fusion

Background

To investigate the risk factors for symptomatic adjacent segment degeneration (ASD) 5 years after anterior cervical discectomy and fusion (ACDF) and develop and evaluate predictive models.

Methods

A total of 655 patients who underwent ACDF were randomly assigned to the training set (n = 393) or validation set (n = 262) at a ratio of 6:4. Independent predictors of ASD were selected by LASSO regression and logistic regression analysis. A calibration curve, ROC curve and DCA curve were used to evaluate the model performance.

Results

LASSO regression combined with logistic regression analysis revealed that age, cervical canal stenosis, smaller T1S and smaller cervical lordosis (CL) were risk factors for ASD 5 years after surgery. Nomographic analysis using appeal factors was used to predict the risk of ASD. The area under the ROC curve was 0.711 (95% CI: 0.643-0.780) in the training set and 0.701 (95% CI: 0.618-0.785) in the validation set. The calibration curve showed no significant bias in either set. The DCA indicated that using the nomogram to predict the risk of ASD would be more accurate when the risk threshold probability was 12-53% in the training set and 6-43% in the validation set.

Conclusion

Age, cervical spinal stenosis, a smaller T1S, and a smaller CL are independent risk factors for ASD 5 years after ACDF surgery. Based on these four indicators, we constructed a new clinical prediction model that has a certain predictive effect and is conducive to clinical decision-making and treatment planning.

The Association of Modic Changes and Disc-Endplate-Bone Marrow Complex Classification in Patients With Cervical Degenerative Disc Disease

STUDY DESIGN

Observational cohort study.

OBJECTIVE

To assess the association of Modic changes and DEBC classification in patients with cervical degenerative disc disease.

METHODS

The study includes 2 groups, neck pain patients presenting to the out-patient services (neck pain group) (n = 301) and polytrauma patients without cervical spine injury or a history of neck pain, who underwent whole spine MRI (control group) (n = 200). Degenerative changes in the MRI were classified according to the Modic changes (MC) and DEBC classification. Modifiers including End-Plate (EP) erosion and herniation (H+) presence were documented.

RESULTS

3612 EPs of 301 patients with neck pain and 2400 EPs of 200 controls were assessed. The incidence of MC and DEBC in the neck pain group was 20.93% and in the control group, it was 12%, (P < 0.05). In the neck pain group with DEBC changes, the distribution was Type A-6.51%; Type B-20.71%; Type C-71.6%; and Type D - 1.18%, while in the controls the distribution was Type A-10.29%, Type B-29.41%, Type C-54.41%, and Type D - 5.88%, The co-occurrence of H+ with DEBC in cases and controls was 13.95% vs 5.5% (P < 0.005). The odds ratio for the need for surgery was highest (OR: 6.8) when H+ and DEBC change co-occurred.

CONCLUSION

Our study highlights that patients with DEBC changes and disc herniation were more likely to experience neck pain and require surgical intervention, indicating the reliability and clinical significance of the DEBC classification in degenerative cervical spine patients.

A Strong Association Between Modic Changes Type 2 and Endplate Defects at Nonfused Segments After Anterior Cervical Decompression and Fusion

BACKGROUND

To determine the association between Modic changes (MCs) with other magnetic resonance imaging parameters and clinical symptoms of cervical degenerative disc disease.

METHODS

A retrospective analysis of data on patients with cervical degenerative disc disease who underwent single-level anterior cervical discectomy and fusion. Preoperative demographic data (age, sex, surgical data) were collected, cervical magnetic resonance imaging parameters (disc degeneration grade, MCs, and endplate defects, each determined at each cervical level), and clinical data (numerical pain rating scale [NPRS] neck and arm, the Neck Disability Index) were compared to preoperative data.

RESULTS

The study included 121 patients at Visit 1 and 83 patients at Visit 2. The median follow-up duration was 26.5 [18.9; 33.1] months. Patients with MC had more intense NPRS-based neck pain before surgery compared to patients without MC (P = 0.001). There were significant changes in MC rate at the C5-C6 levels due to a significant number of new MC type 1 and MC type 2 (P = 0.002 and P < 0.001, respectively). MC type 2 was associated with disc degeneration, endplate defects, patients' age, and clinical scales (Neck Disability Index, NPRS) (P < 0.05). The endplate defects score threshold for predicting MC type 2 at the C3-C7 cervical levels was 5.

CONCLUSIONS

The factor predicting MC type 2 at the C3-C7 cervical levels is submaximal damage to the endplate. The MC rate is increased due to MC type 1 and MC type 2. MC types at the cervical levels may not represent consecutive stages of the same process.

Detection and Characterization of Endplate Structural Defects on CT: A Diagnostic Accuracy Study

STUDY DESIGN

Diagnostic test study.

OBJECTIVE

To determine the reliability and validity or diagnostic accuracy of two previously described endplate structural defect (EPSD) assessment methods.

SUMMARY OF BACKGROUND DATA

Studies of EPSD may further the understanding of pathoanatomic mechanisms underlying back pain. However, clinical imaging methods used to document EPSD have not been validated, leaving uncertainty about what the observations represent.

MATERIALS AND METHODS

Using an evaluation manual, 418 endplates on CT sagittal slices obtained from 19 embalmed cadavers (9 men and 10 women, aged 62-91 yr) were independently assessed by two experienced radiologists and a novice for EPSD using the two methods. The corresponding micro-CT (µCT) from the harvested T7-S1 spines were assessed by another independent rater with excellent intra-rater reliability (k=0.96).

RESULTS

Inter-rater reliability was good for the presence (k=0.60-0.69) and fair for specific phenotypes (k=0.43-0.58) of EPSD. Erosion, for which the Brayda-Bruno classification lacked a category, was mainly (82.8%) classified as wavy/irregular, while many notched defects (n=15, 46.9%) and Schmorl's nodes (n=45, 79%) were recorded as focal defects using Feng's classification. When compared to µCT, endplate fractures (n=53) and corner defects (n=28) were routinely missed on CT. Endplates classified as wavy/irregular on CT corresponded to erosion (n=29, 21.2%), jagged defects (n=21, 15.3%), calcification (n=19, 13.9%), and other phenotypes on µCT. Some focal defects on CT represented endplate fractures (n=21, 27.6%) on µCT. Overall, with respect to the presence of an EPSD, there was a sensitivity of 70.9% and a specificity of 79.1% using Feng's method, and 79.5% and 57.5% using Brayda-Bruno's method. Poor to fair inter-rater reliability (k=0.26-0.47) was observed for defect dimensions.

CONCLUSION

There was good inter-rater reliability and evidence of criterion validity supporting assessments of EPSD presence using both methods. However, neither method contained all needed EPSD phenotypes for optimal sensitivity, and specific phenotypes were often misclassified.

Prevalence, risk factors, natural history, and prognostic significance of Modic changes in the cervical spine: a comprehensive systematic review and meta-analysis of 12,754 participants

OBJECTIVE

Modic changes (MCs) in the cervical spine are common, but remain an under-researched phenomenon, particularly regarding their prevalence, natural history, risk factors, and implications for surgical outcomes. This systematic review and meta-analysis endeavors to elucidate the multifactorial dimensions and clinical significance of cervical MCs.

METHODS

Following PRISMA guidelines, a comprehensive systematic search was performed using Medline (via PubMed), EMBASE, Scopus, and Web of Science databases from their dates of inceptions to September 4, 2023. All identified articles were meticulously screened based on their relevance to our investigative criteria. Bias was assessed using quality assessments tools, including Quality in Prognosis Studies (QUIPS) and Newcastle-Ottawa Scale (NOS). Diverse datasets encompassing MCs prevalence, demographic influences, risk factors, cervical sagittal parameters, and surgical outcomes were extracted. Meta-analysis using both random and common effects model was used to synthesis the metadata.

RESULTS

From a total of 867 studies, 38 met inclusion criteria and underwent full-text assessment. The overall prevalence of cervical MCs was 26.0% (95% CI: 19.0%, 34.0%), with a predominance of type 2 MCs (15% ; 95% CI: 0.10%, 0.23%). There was no significant difference between MCs and non-MCs in terms of neck pain (OR:3.09; 95% CI: 0.81, 11.88) and radicular pain (OR: 1.44; 95% CI: 0.64, 3.25). The results indicated a significantly higher mean age in the MC group (MD: 1.69 years; 95% CI: 0.29 years, 3.08 years). Additionally, smokers had 1.21 times the odds (95% CI: 1.01, 1.45) of a higher risk of developing MCs compared to non-smokers. While most cervical sagittal parameters remained unaffected, the presence of MCs indicated no substantial variation in pain intensity. However, a significant finding was the lower Japanese Orthopaedic Association (JOA) scores observed in MC patients at the 3-month (MD: -0.34, 95% CI: -0.62, -0.07) and 6-month (MD: -0.40, 95% CI: -0.80, 0.00) postoperative periods, indicating a prolonged recovery phase.

CONCLUSION

This study found a predominant of type 2 MCs in the cervical spine. However, there was no significant mean difference between MCs and non-MC groups regarding neck pain and radicular pain. The results underscore the necessity for expansive, longitudinal research to elucidate the complexity of cervical MCs, particularly in surgical and postoperative contexts.

Quantitative analysis and stochastic modeling of osteophyte formation and growth process on human vertebrae based on radiographs: a follow-up study

Osteophytes are frequently observed in elderly people and most commonly appear at the anterior edge of the cervical and lumbar vertebrae body. The anterior osteophytes keep developing and will lead to neck/back pain over time. In clinical practice, the accurate measurement of the anterior osteophyte length and the understanding of the temporal progression of anterior osteophyte growth are of vital importance to clinicians for effective treatment planning. This study proposes a new measuring method using the osteophyte ratio index to quantify anterior osteophyte length based on lateral radiographs. Moreover, we develop a continuous stochastic degradation model with time-related functions to characterize the anterior osteophyte formation and growth process on cervical and lumbar vertebrae over time. Follow-up data of anterior osteophytes up to 9 years are obtained for measurement and model validation. The agreement test indicates excellent reproducibility for our measuring method. The proposed model accurately fits the osteophyte growth paths. The model predicts the mean time to onset of pain and obtained survival function of the degenerative vertebrae. This research opens the door to future quantification and mathematical modeling of the anterior osteophyte growth on human cervical and lumbar vertebrae. The measured follow-up data is shared for future studies.

Determining Differences in Perioperative Functional Mobility Patterns in Lumbar Decompression Versus Fusion Patients Using Smartphone Activity Data

BACKGROUND AND OBJECTIVES

Smartphone activity data recorded through high-fidelity accelerometry can provide accurate postoperative assessments of patient mobility. The "big data" available through smartphones allows for advanced analyses, yielding insight into patient well-being. This study compared rate of change in functional activity data between lumbar fusion (LF) and lumbar decompression (LD) patients to determine preoperative and postoperative course differences.

METHODS

Twenty-three LF and 18 LD patients were retrospectively included. Activity data (steps per day) recorded in Apple Health, encompassing over 70 000 perioperative data points, was classified into 6 temporal epochs representing distinct functional states, including acute preoperative decline, immediate postoperative recovery, and postoperative decline. The daily rate of change of each patient's step counts was calculated for each perioperative epoch.

RESULTS

Patients undergoing LF demonstrated steeper preoperative declines than LD patients based on the first derivative of step count data (P = .045). In the surgical recovery phase, LF patients had slower recoveries (P = .041), and LF patients experienced steeper postoperative secondary declines than LD patients did (P = .010). The rate of change of steps per day demonstrated varying perioperative trajectories that were not explained by differences in age, comorbidities, or levels operated.

CONCLUSION

Patients undergoing LF and LD have distinct perioperative activity profiles characterized by the rate of change in the patient daily steps. Daily steps and their rate of change is thus a valuable metric in phenotyping patients and understanding their postsurgical outcomes. Prospective studies are needed to expand upon these data and establish causal links between preoperative patient mobility, patient characteristics, and postoperative functional outcomes.

Deep phenotyping the cervical spine: automatic characterization of cervical degenerative phenotypes based on T2-weighted MRI

PURPOSE

Radiological degenerative phenotypes provide insight into a patient's overall extent of disease and can be predictive for future pathological developments as well as surgical outcomes and complications. The objective of this study was to develop a reliable method for automatically classifying sagittal MRI image stacks of cervical spinal segments with respect to these degenerative phenotypes.

METHODS

We manually evaluated sagittal image data of the cervical spine of 873 patients (5182 motion segments) with respect to 5 radiological phenotypes. We then used this data set as ground truth for training a range of multi-class multi-label deep learning-based models to classify each motion segment automatically, on which we then performed hyper-parameter optimization.

RESULTS

The ground truth evaluations turned out to be relatively balanced for the labels disc displacement posterior, osteophyte anterior superior, osteophyte posterior superior, and osteophyte posterior inferior. Although we could not identify a single model that worked equally well across all the labels, the 3D-convolutional approach turned out to be preferable for classifying all labels.

CONCLUSIONS

Class imbalance in the training data and label noise made it difficult to achieve high predictive power for underrepresented classes. This shortcoming will be mitigated in the future versions by extending the training data set accordingly. Nevertheless, the classification performance rivals and in some cases surpasses that of human raters, while speeding up the evaluation process to only require a few seconds.

Biomechanical analysis of the novel S-type dynamic cage by implementation of teaching learning based optimization algorithm - An experimental and finite element study

Anterior Cervical Discectomy and Fusion (ACDF) is the most popular and effective procedure for patients with intervertebral disc degeneration, where the degenerated disc is replaced with an interbody implant (widely known as cage). The design of the cage plays a vital role since it has to provide stability for the anterior cervical column without any side-effects. We designed a novel S-type dynamic cage for C4-C5 level, using Polyetheretherketone (PEEK) material considering four different shapes namely: square, circle, rectangle and elliptical, for the central window to occupy bone graft. The major design constrain for a successful cage is minimized cage stress, in order to avoid subsidence. Finite Element (FE) analysis results revealed that the cage stress values obtained during the physiological motion varied depending upon the shape of the central window provided for bone graft. The objective of this study is to optimize the central window shape using the Teaching Learning Based Optimization (TLBO) algorithm. It was found that square and elliptical shape bone graft cavity resulted in better outcomes. Additional experimental study was also conducted with a six-axis spine simulator. Based on the optimization results, we manufactured two PEEK cage models with square and elliptical shaped central window using additive manufacturing. A prototype model of the C4-C5 level made of Polyvinylchloride (PVC) was used for experiment due to the existing constraints for using a cadaveric model. The experimental results were cross-verified using FE analysis. Thus, we would like to conclude that square and elliptical shape of the central window were the better design factor for our novel dynamic cage.

Endplate abnormalities, Modic changes and their relationship to alignment parameters and surgical outcomes in the cervical spine

Modic changes (MC) and endplate abnormalities (EA) have been shown to impact preoperative symptoms and outcomes following spinal surgery. However, little is known about how these phenotypes impact cervical alignment. This study aimed to evaluate the impact that these phenotypes have on preoperative, postoperative, and changes in cervical alignment in patients undergoing anterior cervical discectomy and fusion (ACDF). We performed a retrospective study of prospectively collected data of ACDF patients at a single institution. Preoperative magnetic resonance imagings (MRIs) were used to assess for the MC and EA. Patients were subdivided into four groups: MC-only, EA-only, the combined Modic-Endplate-Complex (MEC), and patients without either phenotype. Pre and postoperative MRIs were used to assess alignment parameters. Associations with imaging phenotypes and alignment parameters were assessed, and statistical significance was set at p < 0.5. A total of 512 patients were included, with 84 MC-only patients, 166 EA-only patients, and 71 patients with MEC. Preoperative MC (p = 0.031) and the MEC (p = 0.039) had significantly lower preoperative T1 slope compared to controls. Lower preoperative T1 slope was a risk factor for MC (p = 0.020) and MEC (p = 0.029) and presence of MC (Type II) and the MEC (Type III) was predictive of lower preoperative T1 slope. There were no differences in postoperative alignment measures or patient reported outcome measures. MC and endplate pathologies such as the MEC appear to be associated with worse cervical alignment at baseline relative to patients without these phenotypes. Poor alignment may be an adaptive response to these degenerative findings or may be a risk factor for their development.

Artificial intelligence in predicting early-onset adjacent segment degeneration following anterior cervical discectomy and fusion

PURPOSE

Anterior cervical discectomy and fusion (ACDF) is a common surgical treatment for degenerative disease in the cervical spine. However, resultant biomechanical alterations may predispose to early-onset adjacent segment degeneration (EO-ASD), which may become symptomatic and require reoperation. This study aimed to develop and validate a machine learning (ML) model to predict EO-ASD following ACDF.

METHODS

Retrospective review of prospectively collected data of patients undergoing ACDF at a quaternary referral medical center was performed. Patients > 18 years of age with > 6 months of follow-up and complete pre- and postoperative X-ray and MRI imaging were included. An ML-based algorithm was developed to predict EO-ASD based on preoperative demographic, clinical, and radiographic parameters, and model performance was evaluated according to discrimination and overall performance.

RESULTS

In total, 366 ACDF patients were included (50.8% male, mean age 51.4 ± 11.1 years). Over 18.7 ± 20.9 months of follow-up, 97 (26.5%) patients developed EO-ASD. The model demonstrated good discrimination and overall performance according to precision (EO-ASD: 0.70, non-ASD: 0.88), recall (EO-ASD: 0.73, non-ASD: 0.87), accuracy (0.82), F1-score (0.79), Brier score (0.203), and AUC (0.794), with C4/C5 posterior disc bulge, C4/C5 anterior disc bulge, C6 posterior superior osteophyte, presence of osteophytes, and C6/C7 anterior disc bulge identified as the most important predictive features.

CONCLUSIONS

Through an ML approach, the model identified risk factors and predicted development of EO-ASD following ACDF with good discrimination and overall performance. By addressing the shortcomings of traditional statistics, ML techniques can support discovery, clinical decision-making, and precision-based spine care.

Biomechanical Analysis of the Reasonable Cervical Range of Motion to Prevent Non-Fusion Segmental Degeneration After Single-Level ACDF

The compensatory increase in intervertebral range of motion (ROM) after cervical fusion can increase facet joint force (FJF) and intradiscal pressure (IDP) in non-fusion segments. Guiding the post-ACDF patient cervical exercise within a specific ROM (defined as reasonable ROM) to offset the increase in FJF and IDP may help prevent segmental degeneration. This study aimed to determine the reasonable total C0–C7 ROM without an increase in FJF and IDP in non-fusion segments after anterior cervical discectomy and fusion (ACDF). A three-dimensional intact finite element model of C0–C7 generated healthy cervical conditions. This was modified to the ACDF model by simulating the actual surgery at C5–C6. A 1.0 Nm moment and 73.6 N follower load were applied to the intact model to determine the ROMs. A displacement load was applied to the ACDF model under the same follower load, resulting in a total C0–C7 ROM similar to that of the intact model. The reasonable ROMs in the ACDF model were calculated using the fitting function. The results indicated that the intervertebral ROM of all non-fusion levels was increased in the ACDF model in all motion directions. The compensatory increase in ROM in adjacent segments (C4/5 and C6/7) was more significant than that in non-adjacent segments, except for C3/4 during lateral bending. The intervertebral FJF and IDP of C0–C7 increased with increasing ROM. The reasonable ROMs in the ACDF model were 42.4°, 52.6°, 28.4°, and 42.25° in flexion, extension, lateral bending, and axial rotation, respectively, with a decreased ROM of 4.4–7.2%. The postoperative increase in FJF and IDP in non-fusion segments can be canceled out by reducing the intervertebral ROM within reasonable ROMs. This study provided a new method to estimate the reasonable ROMs after ACDF from a biomechanical perspective, and further in vitro and clinical studies are needed to confirm this.

The Modic-endplate-complex phenotype in cervical spine patients: Association with symptoms and outcomes

This study describes a novel, combined Modic changes (MC) and structural endplate abnormality phenotype of the cervical spine, which we have termed the Modic-Endplate-Complex (MEC), and its association with preoperative symptoms and outcomes in anterior cervical discectomy and fusion (ACDF) patients. This was a retrospective study of prospectively collected data at a single institution. Preoperative cervical magnetic resonance imagings were used to assess the presence of MC and endplate abnormalities. Patients were divided into four groups: MC-only, endplate abnormality-only, the MEC and controls. The MEC was defined as the presence of both a MC and endplate abnormality in the cervical spine. Phenotypes were further stratified by location and compared to controls. Associations with patient-reported outcome measures were assessed using regression controlling for baseline characteristics. A total of 628 patients were included, with 84 MC-only, 166 endplate abnormality-only, and 187 MEC patients. Both MC (p < 0.001) and endplate abnormalities (p < 0.001) were independently associated with one another. MC at the adjacent level (p = 0.018), endplate abnormalities (regardless of location) (p = 0.001), and the MEC within the fusion segment (p = 0.027) were all associated with higher Neck Disability Index scores. Both MC within the fusion segment (p = 0.008) and endplate abnormalities within the fusion segment (p = 0.017) associated with lower Veteran's Rand 12-item scores. MC and structural endplate abnormalities commonly manifest concomitantly in patients indicated for ACDF for degenerative pathology. Patients with the endplate pathology, including the MEC phenotype, reported significantly higher levels of postoperative disability following ACDF. These findings add valuable data to the prognostic assessment of degenerative cervical spine patients.

The impact of age, sex, disc height loss and T1 slope on the upper and lower cervical lordosis: a large-scale radiologic study

PURPOSE

To clarify the relative influence of age, sex, disc height loss and T1 slope on upper (Occiput-C2) and lower cervical lordosis (C2-C7).

METHODS

Standing lateral cervical radiographs of 865 adult subjects were evaluated. The presence and severity of disc height loss from C2/C3 to C6/C7 (a total of 4325 discs) were assessed using a validated grading system. The total disc height loss score for each subject was calculated as the sum of the score of each disc space. Sagittal radiographic parameters included: occipital slope, occiput-C2 (Oc-C2) lordosis, C2-C7 lordosis and T1 slope. Multivariable regression analyses were performed to examine the relative influence of the multiple factors on upper and lower cervical lordosis.

RESULTS

This study included 360 males and 505 females, with a mean age of 40.2 ± 16.0 years (range, 20-95 years). Linear multivariate regression analyses showed that greater age, male sex, greater T1 slope were each found to be significantly and independently associated with greater C2-C7 lordosis, whereas total disc height loss score was negatively associated with C2-C7 lordosis. T1 slope had the most independent influence on C2-C7 lordosis among these factors. Age, sex and disc height loss were not independently associated with Oc-C2 lordosis.

CONCLUSIONS

Results from our large-scale radiologic analysis may enhance the understanding of the factors that affect cervical lordosis, indicating that age, sex, disc height loss and T1 slope were each independently associated with C2-C7 lordosis. However, age, sex and disc height loss were not independently associated with upper cervical lordosis.

Radiographic cervical spine degenerative findings: a study on a large population from age 18 to 97 years

Purpose

The aims of this study were (1) to determine the prevalence of radiographic cervical disc degeneration in a large population of patients aged from 18 to 97 years; (2) to investigate individually the prevalence and distribution of height loss, osteophyte formation, endplate sclerosis and spondylolisthesis; and (3) to describe the patterns of cervical disc degeneration.

Methods

A retrospective study was performed. Standard lateral cervical spine radiographs in standing, neutral position of 1581 consecutive patients (723 males, 858 females) with an average age of 41.2 ± 18.2 years were evaluated. Cervical disc degeneration was graded from C2/C3 to C6/C7 based on a validated quantitative grading system. The prevalence and distribution of radiographic findings were evaluated and associations with age were investigated.

Results

53.9% of individuals had radiographic disc degeneration and the most affected level was C5/C6. The presence and severity of disc degeneration were found to be significantly associated with age both in male and female subjects. The most frequent and severe occurrences of height loss, osteophyte formation, and endplate sclerosis were at C5/C6, whereas spondylolisthesis was most observed at C4/C5. Age was significantly correlated with radiographic degenerative findings. Contiguous levels degeneration pattern was more likely found than skipped level degeneration. The number of degenerated levels was also associated with age.

Conclusions

The presence and severity of radiographic disc degeneration increased with aging in the cervical spine. Older age was associated with greater number of degenerated disc levels. Furthermore, the correlations between age and the degree of degenerative findings were stronger at C5/C6 and C6/C7 than at other cervical spinal levels.