Modified K-line in magnetic resonance imaging predicts insufficient decompression of cervical laminoplasty

Evaluating the Predictive Value of K-Line Conversion in Surgical Outcomes for K-Line Negative Cervical Ossification of the Posterior Longitudinal Ligament (OPLL): Laminectomy with Fusion versus Laminoplasty

BACKGROUND CONTEXT

Laminectomy with fusion (LF) and laminoplasty are common treatments for K-line negative cervical ossification of the posterior longitudinal ligament (OPLL). However, the clinical significance of postoperative K-line conversion from negative to positive remains unclear.

PURPOSE

To determine whether converting a K-line from negative to positive improves surgical outcomes in patients with cervical OPLL by comparing LF and laminoplasty.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Patients with cervical myelopathy due to K-line negative OPLL who underwent LF or laminoplasty, with ≥1 year of follow-up.

OUTCOME MEASURES

Primary outcomes included neck and arm pain visual analog scale (VAS) scores, neck disability index (NDI), Japanese Orthopedic Association (JOA) score, JOA recovery rate, and radiographic parameters (C2-C7 lordosis, modified K-line interval).

METHODS

We compared radiographic and clinical outcomes between the two groups.

RESULTS

Among 85 patients with K-line-negative OPLL (39 LF, 46 laminoplasty), postoperative K-line conversion occurred significantly more frequently in the LF group (56.4% vs. 16.8%; p <0.001). Although laminoplasty better preserved cervical range of motion and reduced neck pain, LF provided superior neurologic outcomes, as indicated by higher final JOA scores and recovery rates. Patients who achieved K-line conversion had significantly higher rates of favorable clinical outcomes compared to those who did not (58.1% vs. 27.7%; p=0.019). Multivariate regression analyses further demonstrated that K-line conversion independently predicted favorable clinical outcomes (odds ratio [OR]: 3.900; p = 0.023), and LF was significantly associated with a higher likelihood of K-line conversion compared to laminoplasty (OR: 3.683; p = 0.033).

CONCLUSION

In patients with K-line-negative cervical OPLL, postoperative conversion to K-line-positive status is significantly associated with improved neurological outcomes. Although laminoplasty provides advantages regarding neck pain relief and motion preservation, LF more reliably facilitates K-line conversion and suppresses kyphosis, leading to superior clinical outcomes. Careful preoperative evaluation of cervical alignment, combined with surgical strategies aimed at promoting K-line conversion, may optimize surgical results.

LEVEL OF EVIDENCE

III.

Proposal of a new score system (Cervical Surgical Score) for management of degenerative cervical myelopathy

BACKGROUND

To date, no shared algorithms with the aim of guiding surgical strategy in complex cases of degenerative cervical myelopathy (DCM) exist. Our purpose is to present the Cervical Surgical Score (CSS) which could help in identifying complex DCM cases, suggesting a surgical strategy.

METHODS

We created the CSS based on multidisciplinary and literature-focused discussions, based on eight parameters including number of levels of cervical pathology and myelopathy, type and predominance of compression and grade of clinical myelopathy. We prospectively enrolled surgical DCM patients in a 15-months period, collecting clinical and radiological data. During outpatient clinic a specific surgical indication was offered to DCM patients. To validate the score, each outpatient clinic surgical indication was compared a posteriori to the one that resulted from multidisciplinary CSS scoring, focusing on patients for which both an anterior and posterior approach were considered suitable.

RESULTS

A total of 100 patients operated on for DCM at our Institution between December 2021 and February 2023 were prospectively enrolled. In 53% of patients the pathology was present at more than two levels. According to CSS calculation, 14% of patients resulted in the "grey zone", where both an anterior and posterior approach were deemed feasible. Among them, in 42.8% of cases the CSS allowed a modification of the originally planned surgery. Looking at outcome, an improvement of m-JOA score in 62% of patients was disclosed.

CONCLUSIONS

This preliminary study showed the reliability and usefulness of CSS in detecting complex DCM cases, requiring further analysis by expert spine surgeons, suggesting a surgical strategy.

Long-Term Outcomes of One-Stage Combined Posteroanterior Procedure and Laminoplasty-Alone for Multilevel Degenerative Cervical Myelopathy With Concomitant Anterior and Posterior Compression: A Propensity Score Matching Analysis of 8-year Follow-Up

Study DesignRetrospective cohort study.ObjectiveThis study aimed to investigate the long-term outcomes of laminoplasty-alone (LP) and combined procedure (CP), consisting of laminoplasty and single-level anterior cervical discectomy and fusion, in comparable patients who had multilevel degenerative cervical myelopathy (MDCM) with concomitant anterior and posterior compression (CAPC).MethodsConsecutive MDCM patients with CAPC underwent LP or CP between 2012 and 2015 from a same surgical group were enrolled and followed up for a minimum of 8 years. Preoperative demographic, radiological, and clinical variables were collected. Propensity score matching (PSM) analysis was performed to match patients with comparable conditions. The outcomes were evaluated by postoperative Japanese Orthopedic Association (JOA) score improvement, JOA recovery rate (JOARR) and complications.ResultsA total of 230 patients were included, of whom 146 underwent LP and 84 underwent CP. After PSM, 84 pairs of comparable patients were matched. The matched groups presented fair comparability in preoperative conditions. The CP group had significantly prolonged surgery time and greater blood loss. At the final follow-up, the postoperative JOA scores of LP and CP groups were 14.51 ± 1.79 and 15.47 ± 1.81 (P < 0.001) and the JOARR were 42.5% ± 53.3% and 68.5% ± 35.4%, respectively (P < 0.001). Three (3.6%) patients in the LP group underwent reoperations because of recurrent symptoms (P = 0.081).ConclusionBoth LP and CP demonstrated considerable long-term neurological recovery in patients with CAPC. The CP showed a significantly higher JOA improvement and JOARR. The combined decompression might be a safe and effective alternative in treating MDCM with CAPC in experienced hands.

Identifying Factors for Predicting Postoperative Segmental Motor Paralysis in Patients Undergoing Anterior Cervical Spine Surgery: A Multicenter Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the incidence of and risk factors for segmental motor paralysis after anterior cervical spine surgery.

SUMMARY OF BACKGROUND DATA

Segmental motor paralysis is a potential complication following both anterior and posterior cervical decompression procedures; however, previous studies investigating risk factors for segmental motor paralysis after anterior cervical spine surgery were limited by small sample sizes. Consequently, the exact pathogenesis and risk factors for this complication remain poorly understood, highlighting the need for larger-scale investigations focused exclusively on anterior cervical spine surgeries.

MATERIALS AND METHODS

We retrospectively reviewed the clinico-demographic and operative factors and postoperative outcomes of 1428 patients undergoing anterior cervical spine surgery at three spine centers in Japan. Postoperative segmental motor paralysis was defined as deterioration of upper extremity muscle strength by ≥1 grade; recovery was defined as a return to preoperative muscle strength levels. Univariate and multivariate analyses were performed to identify risk factors.

RESULTS

Ninety-nine patients (6.9%) developed segmental motor paralysis, mostly involving the C5 segment (81.8%), the incidence being highest in patients with ossification of the posterior longitudinal ligament (OPLL) and those undergoing anterior cervical corpectomy and fusion or hybrid fusion (discectomy + corpectomy). Older age, male sex, higher body mass index, OPLL, and cervical corpectomy were independent risk factors for paralysis, with these patients having significantly worse clinical outcomes at 1 year postoperatively. Most patients (74/99, 79.6%) regained preoperative muscle strength levels at a final follow-up.

CONCLUSION

This study identified important clinico-demographic and operative risk factors for segmental motor paralysis after anterior cervical spine surgery. Patients undergoing corpectomy, with or without OPLL, were found to be at particularly high risk. While most patients recover well, worse outcomes with segmental motor paralysis highlight the importance of preventing this complication, particularly for OPLL patients and corpectomy procedures.

LEVEL OF EVIDENCE

Level III.

Predicting Neck Dysfunction After Open-Door Cervical Laminoplasty - A Prospective Cohort Patient-Reported Outcome Measurement Study

OBJECTIVE

To analyze the predictive factors for neck pain and cervical spine function after laminoplasty for degenerative cervical myelopathy (DCM) using K-means for longitudinal data (KML).

METHODS

In this prospective cohort study, we collected clinical and radiographic data from patients with DCM who underwent cervical laminoplasty. A novel index of surgical outcome, "neck function," which comprises neck pain and cervical spine function according to the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire, was proposed. We treated surgical outcomes as longitudinal rather than cross-sectional data and used KML for analysis. Patients were categorized as having good or poor outcomes based on the KML graph of neck pain and cervical spine function.

RESULTS

From 2016 to 2020, 104 patients underwent laminoplasty for DCM; however, 35 patients were excluded because of loss to follow-up or incomplete data. The authors found that central canal stenosis (odds ratio [OR], 17.93; 95% confidence interval [CI], 1.26-254.73; p=0.03) and preoperative neck pain (OR per 1 point increase=1.49; 95% CI, 1.12-1.99; p=0.006) were 2 negative predictive factors and that a positive K-line during flexion was a positive predictive factor (OR, 0.11; 95% CI, 0.01-0.87; p=0.036) for neck function after laminoplasty.

CONCLUSION

Central canal stenosis, preoperative neck pain and a K-line during flexion were found to be predictive of postoperative neck pain and cervical spine function after laminoplasty. To achieve better surgical outcomes for neck function, the authors suggest the utilization of these determinants as a guiding framework for the selection of surgical approaches for DCM.

Accuracy of Realigned K-line for Predicting Surgical Outcomes After Laminoplasty in Patients With Degenerative Cervical Myelopathy

STUDY DESIGN

A prospective cohort study.

OBJECTIVES

To report a new index, the realigned K-line, for predicting surgical outcomes after laminoplasty in patients with degenerative cervical myelopathy (DCM).

METHODS

One hundred twenty-eight patients with DCM undergoing laminoplasty were enrolled from January 2018 to April 2021 in our department. A realigned K-line was defined as the line connecting the midpoints of the spinal cord between C2 and C7 on realigned T1-weighted magnetic resonance imaging. The minimum interval between the anterior compression factors of the spinal cord and the realigned K-line (INTrea), and the modified K-line (INTmod) were measured. A logistic regression analysis was performed to identify factors associated with unsatisfactory surgical outcomes. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) was applied to evaluate the reliability of the multivariate logistic regression model.

RESULTS

Univariate analysis showed that the score for the bladder function section of the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire, numeric rating scale scores for arm pain, and INTrea might be related to the Japanese Orthopaedic Association (JOA) recovery rate (RR) not achieving the minimal clinically important difference (MCID) (P < .05). Only INTrea (odds ratio = .744, P < .05) was an independent preoperative factor related to the JOA RR not achieving the MCID (area under the curve, .743). A cutoff of 5.0 mm for INTrea had an accuracy of 71.9% and specificity of 80.3% for predicting the JOA RR not achieving the MCID.

CONCLUSIONS

INTrea is an independent preoperative risk factor related to the JOA RR not achieving the MCID in patients with DCM. A cutoff point of 5.0 mm is most appropriate for alerting spine surgeons to a high likelihood of the JOA RR not achieving the MCID.

A Novel Posterior Compression Score System for Outcome Prediction in Laminoplasty Treated OPLL Patients: A Propensity-Matched Analysis

STUDY DESIGN

A retrospective observational study.

OBJECTIVE

To describe a novel outcome indication system, the posterior compression score (PCS), and investigate its clinical value in cervical ossification of the posterior longitudinal ligament (OPLL) patients treated with laminoplasty.

METHODS

A total of 282 OPLL patients who underwent laminoplasty from January 2013 to December 2018 were reviewed. The patients were divided into high-score (HS) or low-score (LS) groups based on whether the PCS was over 8. Propensity score matching analysis with a caliper of .1 was used to attenuate the potential selection bias. Clinical measurements, including the Japanese Orthopedic Association (JOA) score, visual analog scale (VAS), neck disability index (NDI), and radiological measurements, including C2-C7 lordotic angle and range of motion (ROM), were compared between the groups.

RESULTS

The mean follow-up period was 29.87 ± 9.17 months. There were no significant differences between the two groups regarding patients' baseline demographical and clinical characteristics after propensity score matching. No significant differences were found in the operative time, blood loss, postoperative VAS score for neck and arm pain, postoperative C2-C7 lordotic angle, or postoperative ROM (P > .05). However, the postoperative JOA score and recovery rate were significantly higher in the HS group than in the LS group, while the postoperative NDI was significantly lower in the HS group (P < .05).

CONCLUSION

OPLL patients with higher PCS scores displayed better clinical outcomes. The novel PCS system is suggested to be a reliable scoring system for surgical outcome evaluation in patients with cervical OPLL.

Finite Element Analysis for Degenerative Cervical Myelopathy: Scoping Review of the Current Findings and Design Approaches, Including Recommendations on the Choice of Material Properties

BACKGROUND

Degenerative cervical myelopathy (DCM) is a slow-motion spinal cord injury caused via chronic mechanical loading by spinal degenerative changes. A range of different degenerative changes can occur. Finite element analysis (FEA) can predict the distribution of mechanical stress and strain on the spinal cord to help understand the implications of any mechanical loading. One of the critical assumptions for FEA is the behavior of each anatomical element under loading (ie, its material properties).

OBJECTIVE

This scoping review aims to undertake a structured process to select the most appropriate material properties for use in DCM FEA. In doing so, it also provides an overview of existing modeling approaches in spinal cord disease and clinical insights into DCM.

METHODS

We conducted a scoping review using qualitative synthesis. Observational studies that discussed the use of FEA models involving the spinal cord in either health or disease (including DCM) were eligible for inclusion in the review. We followed the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines. The MEDLINE and Embase databases were searched to September 1, 2021. This was supplemented with citation searching to retrieve the literature used to define material properties. Duplicate title and abstract screening and data extraction were performed. The quality of evidence was appraised using the quality assessment tool we developed, adapted from the Newcastle-Ottawa Scale, and shortlisted with respect to DCM material properties, with a final recommendation provided. A qualitative synthesis of the literature is presented according to the Synthesis Without Meta-Analysis reporting guidelines.

RESULTS

A total of 60 papers were included: 41 (68%) "FEA articles" and 19 (32%) "source articles." Most FEA articles (33/41, 80%) modeled the gray matter and white matter separately, with models typically based on tabulated data or, less frequently, a hyperelastic Ogden variant or linear elastic function. Of the 19 source articles, 14 (74%) were identified as describing the material properties of the spinal cord, of which 3 (21%) were considered most relevant to DCM. Of the 41 FEA articles, 15 (37%) focused on DCM, of which 9 (60%) focused on ossification of the posterior longitudinal ligament. Our aggregated results of DCM FEA indicate that spinal cord loading is influenced by the pattern of degenerative changes, with decompression alone (eg, laminectomy) sufficient to address this as opposed to decompression combined with other procedures (eg, laminectomy and fusion).

CONCLUSIONS

FEA is a promising technique for exploring the pathobiology of DCM and informing clinical care. This review describes a structured approach to help future investigators deploy FEA for DCM. However, there are limitations to these recommendations and wider uncertainties. It is likely that these will need to be overcome to support the clinical translation of FEA to DCM.

Effects of Cervical Paravertebral Extensors in Patients with Cervical Ossification of the Posterior Longitudinal Ligament Grouped According to mK-Line

OBJECTIVES

The objective of this study was to quantify the morphology, composition, and asymmetry of the paravertebral extensor muscles (PSEMs) in patients with cervical ossification of the posterior longitudinal ligament (OPLL) who had different modified K-line (mK-line) and the minimum interval between the mK-line and OPLL (INTmin ) values and to investigate the relationship between PSEMs and symptoms and outcomes following laminoplasty. These original findings elucidated that the atrophy of PSEMs could predict decompression outcomes and provided a theoretical basis for paraspinal muscle rehabilitation.

METHODS

A total of 94 consecutive patients who underwent laminoplasty for OPLL between January 2020 and January 2022 were enrolled in this retrospective study. The relative cross-sectional areas (rCSA), functional cross-sectional areas (rFCSA), and FCSA/CSA ratio of the multifidus (MF), semispinalis cervicalis (SSCe), semispinalis capitis (SSCa), and splenius capitis (SpCa) were measured at the C3-C7 segments on cervical magnetic resonance imaging (MRI). This study compared the differences between the mK-line (+) group and the mK-line (-) group, as well as between the INTmin  <4 mm group and the INTmin  ≥4 mm group, using the independent t-test or Mann-Whitney test for continuous variables and the χ2 -test for categorical variables. The correlations between the PSEMs and symptoms were analyzed using either the Pearson or Spearman correlation coefficient.

RESULTS

The relative total CSA (rTCSA) of the PSEMs, especially the MF, was significantly smaller in the mK-line (-) group. However, the FCSA/CSA of the right deep extensor muscle (DEM) was larger. The asymmetry of the MF TFCSA/TCSA showed a significant difference between the mK-line groups. In the INTmin  <4 mm group, the PSEMs rCSA and rFCSA were significantly smaller, while the bilateral MF TFCSA/TCSA and right SSCe TFCSA/TCSA were larger. The asymmetry of the superficial extensor muscle rCSA was significantly lower in the group with INTmin  <4 mm. The postoperative modified Japanese Orthopedic Association score (mJOA) and mJOA recovery rate were positively correlated with the INTmin and DEM rCSA and negatively correlated with the asymmetry of MF FCSA/CSA.

CONCLUSIONS

In patients with mK-line (-) or INTmin  <4 mm, the PSEMs were smaller, and the DEM atrophy and composition changes were predominant. The MF asymmetry was higher in patients with mK-lines (-), whereas the SEM atrophy and asymmetry were more prevalent in patients with INTmin  <4 mm. The DEM was related to the preoperative and postoperative mJOA scores. DEM-preserving surgery or DEM-specific rehabilitation exercises can improve the recovery of patients with OPLL during the perioperative period. In addition, attention should be paid to the evaluation of the SEM, especially the SpCa at the C3 and C5 levels.

MRI-based measurements of spondylolisthesis and kyphosis in degenerative cervical myelopathy

BACKGROUND

To provide normative data and to determine accuracy and reliability of preoperative measurements of spondylolisthesis and kyphosis on supine static magnetic resonance imaging (MRI) of patients with degenerative cervical myelopathy.

METHODS

T2-weighted midsagittal images of the cervical spine were in 100 cases reviewed twice by one junior observer, with an interval of 3 months, and once by a senior observer. The spondylolisthesis slip (SSlip, mm) and the modified K-line interval (mK-line INT, mm) were assessed for accuracy with the standard error of measurement (SEm) and the minimum detectable change (MDC). Intraobserver and interobserver reliability levels were determined using the intraclass correlation coefficient (ICC).

RESULTS

The SEm was 0.5 mm (95% CI 0.4-0.6) for spondylolisthesis and 0.6 mm (95% CI 0.5-0.7) for kyphosis. The MDC, i.e., the smallest difference between two examinations that can be detected with statistical certainty, was 1.5 mm (95% CI 1.2-1.8) for spondylolisthesis and 1.6 mm (95% CI 1.3-1.8) for kyphosis. The highest reliability levels were seen between the second observation of the junior examiner and the senior observer (ICC = 0.80 [95% CI 0.70-0.87] and ICC = 0.96 [95% CI 0.94-0.98] for SSlip and mK-line INT, respectively).

CONCLUSIONS

This study provides normative values of alignment measurements of spondylolisthesis and kyphosis in DCM patients. It further shows the importance of taking measurement errors into account when defining cut-off values for cervical deformity parameters and their potential clinical application in surgical decision-making.

The Deterioration of Cervical Kyphosis During Neck Flexion after Laminoplasty Affects the Surgical Outcome of Cervical Spondylotic Myelopathy

STUDY DESIGN

A retrospective single-center study.

OBJECTIVE

The present study investigated whether postoperative cervical alignment changes, in addition to preoperative patient backgrounds, imaging parameters, and disease severity, affect outcomes 1 year after laminoplasty.

METHODS

One hundred and three cervical spondylotic myelopathy (CSM) patients who underwent laminoplasty were enrolled. Preoperative and postoperative (1-year) Japanese Orthopedic Association (JOA) scores, cervical alignment, and balance on X-rays were assessed. Patients were classified into 2 groups for a univariate analysis according to the status of the recovery rate (RR) of the JOA score ≥50%. A multiple logistic regression analysis was performed to identify factors associated with good surgical outcomes a.

RESULTS

The mean RR of the JOA score was 47.5% and the loss of cervical lordosis in the neutral position was 5.5°. The univariate analysis revealed slight differences in age, sex, and the duration of disease. Preoperative C2-7 angles were not significantly different. The C2-7 angle during flexion after surgery was significantly smaller in Group F. In the multiple logistic regression analysis, significant factors associated with the status of RR≥50% were a younger age (OR: .75, 95%CI: .59-.96), shorter duration of disease (OR: .94, 95%CI: .89-.99), and a lordotic C2-7 angle during neck flexion after surgery (OR: 1.47, 95%CI: 1.1-1.95).

CONCLUSION

We retrospectively assessed the surgical outcomes of laminoplasty in 103 CSM cases. In addition to an older age and longer duration of disease, postoperative deteriorations in cervical kyphosis during neck flexion had a negative impact on outcomes.

Evaluating Changes to the Modified K-Line Using Kinematic MRIs

STUDY DESIGN

Retrospective cross-sectional review of a large database.

OBJECTIVE

Little is known regarding extension K-lines for treatment of cervical myelopathy. Therefore, this study seeks to examine differences between K-lines drawn in neutral and extension.

SUMMARY OF BACKGROUND DATA

The modified K-line is a radiological tool used in surgical planning of the cervical spine. As posterior cervical decompression and fusion often results in patients being fused in a more lordotic position than the preoperative neutral radiograph, a K-line measured in the extension position may offer better utility for these patients.

MATERIALS AND METHODS

Total of 97 patients were selected with T2-weighted, upright cervical magnetic resonance imaging taken in neutral and extension. For each patient, the K-line was drawn at the mid-sagittal position for both neutral and extension. The distance from the most posterior portion of each disk (between C2 and C7) to the K-line was measured in neutral and extension and the difference was calculated. Paired t test was used to assess significant differences.

RESULTS

Across all levels between C2 and C7 there was an increase in the distance between the dorsal aspect of the disk and K-line when comparing neutral and extension radiographs. The average change in difference (extension minus neutral) at each cervical spinal level was 0.9 mm (C2-C3), 2.5 mm (C3-C4), 2.6 mm (C4-C5), 2.0 mm (C5-C6), and 0.9 mm (C6-C7). A paired t test showed that the K-line increase from neutral to extension was statistically significant across all disk levels ( P <0.001).

CONCLUSION

When positioned in extension, patients experience a significant increase in distance from the dorsal aspect of a disk to the K-line compared to when positioned in neutral, especially between C3 and C6. This is clinically relevant for surgeons considering a posterior cervical decompression and fusion in patients with a negative modified K-line on preoperative magnetic resonance imaging, as these patients may have enough cervical cord drift back when fused in an extended position, maximizing likelihood of improving postoperative DSM functional outcomes.

Comparison of Midline Splitting versus Unilateral Open Door Laminoplasty and Its Impact on Patient Outcomes

Background

Laminoplasty is a common and effective surgery for decompression of the spinal cord in multilevel cervical myelopathy. The midline splitting technique (MST) and the unilateral open door technique (UODT) are the two most commonly performed laminoplasty techniques with continuous debate on which is preferable. This study aimed to add light to the matter by comparing and exploring the possible causes of different outcomes.

Methods

A total of 101 patients who underwent laminoplasty for degenerative cervical myelopathy were included in this study. Radiographic measurements including C2-7 Cobb angle, C2-7 range of motion (ROM), Pavlov ratio of the most compressed level, and canal area with diameter were compared. Modified Japanese Orthopedic Association (mJOA) score and complications including C5 palsy, axial neck pain, hinge fractures, and spacer displacement were also compared. Statistical analysis was performed using independent samples t-test, chi-square test, Fisher's exact test, and linear mixed model.

Results

C2-7 ROM, canal diameter, Pavlov ratio, and mJOA score did not demonstrate differences between the two techniques. The UODT group had greater postoperative canal expansion but had more loss of C2-7 lordosis than did the MST group. Of the complications, hinge fractures were more common in the UODT group, with more loss of C2-7 lordosis in patients with hinge fractures. On the other hand, spacer displacement occurred only in the MST group, with lesser canal expansion in patients with spacer displacement.

Conclusions

The two laminoplasty techniques both demonstrated effectiveness in treating patients with multilevel cervical myelopathy. However, care should be given to avoid hinge fractures and spacer displacement since both can possibly lead to unfavorable outcomes.

Comparison of Surgical Outcomes Between Anterior and Posterior Cervical Fusions Stratified by Levels Decompressed

STUDY DESIGN

Retrospective database study.

OBJECTIVE

To compare outcomes between 1-, 2-, 3-, and 4- level anterior cervical discectomy and fusions (ACDF) and posterior cervical fusions (PCF) procedures using a national database.

SUMMARY OF BACKGROUND DATA

Surgical outcomes involving 3- or 4-level ACDF and PCF cases are not well-described. As there are situations where both ACDF and PCF can be employed, it is important to compare the risks and benefits of both procedures.

MATERIALS AND METHODS

Patients who underwent ACDF or PCF between 2010 and 2020 were identified in PearlDiver using current procedural terminology codes. Surgeries done for infectious, traumatic, or neoplastic etiologies were excluded. 2-year reoperations and 90-day readmissions were queried. Surgical complications and transfusions were compiled using ICD-9/10 billing codes. ACDF and PCF procedures were then matched by age, sex, Charlson Comorbidity Index, and a number of levels fused, and the above outcomes were compared.

RESULTS

In all, 31,301 PCFs and 110,526 ACDFs were identified. After matching for age, sex, and Charlson Comorbidity Index, a total of 30,353 ACDF and PCF procedures were compared. Three-level and 4-level PCFs had higher rates of 90-day postoperative surgical complications compared with ACDF (OR=2.4 and 2.87, respectively; P <0.001). In addition, higher rates of 90-day readmissions were noted in 3-level PCF compared with 3-level ACDF (OR=1.24, P <0.001). Ninety-day postoperative transfusions were higher in both 3- and 4-level PCFs (OR=2.44 and 18.27, respectively; P <0.001). Two-year reoperations rates were higher for 3-level PCF procedures than 3-level ACDF (OR=1.22; P =0.01).

CONCLUSIONS

Patients who underwent 3-4-level ACDF had lower rates of readmission, blood transfusions, and postoperative complications compared with 3-4-level PCF. This data suggests that in cases of 3-4-level pathology with clinical equipoise regarding approach, ACDF may be associated with less short-term morbidity, however, data on fusion rates and adjacent level disease are needed.

Degenerative cervical myelopathy: Where have we been? Where are we now? Where are we going?

Degenerative cervical myelopathy (DCM), a recently coined term, encompasses a group of age-related and genetically associated pathologies that affect the cervical spine, including cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament (OPLL). Given the significant contribution of DCM to global disease and disability, there are worldwide efforts to promote research and innovation in this area. An AO Spine effort termed 'RECODE-DCM' was initiated to create an international multistakeholder consensus group, involving patients, caregivers, physicians and researchers, to focus on launching actionable discourse on DCM. In order to improve the management, treatment and results for DCM, the RECODE-DCM consensus group recently identified ten priority areas for translational research. The current article summarizes recent advancements in the field of DCM. We first discuss the comprehensive definition recently refined by the RECODE-DCM group, including steps taken to arrive at this definition and the supporting rationale. We then provide an overview of the recent advancements in our understanding of the pathophysiology of DCM and modalities to clinically assess and diagnose DCM. A focus will be set on advanced imaging techniques that may offer the opportunity to improve characterization and diagnosis of DCM. A summary of treatment modalities, including surgical and nonoperative options, is then provided along with future neuroprotective and neuroregenerative strategies. This review concludes with final remarks pertaining to the genetics involved in DCM and the opportunity to leverage this knowledge toward a personalized medicine approach.

Predicting surgical outcome and sagittal alignment change in patients with cervical spondylosis and degenerative kyphosis after anterior cervical discectomy and fusion

The aim of this study was to forecast the risk factors of poor outcomes and postoperative loss of lordosis or recurrence of kyphosis. In this retrospective study, 101 patients with cervical spondylosis and preoperative kyphosis who underwent anterior cervical discectomy and fusion (ACDF) were enrolled, between June 2015 and June 2019. Patients were grouped according to the recovery rate of Japanese Orthopaedic Association (JOA) score whether more than 50%, and the change of postoperative cervical Cobb angle. There were 22 cases with less than 50% of recovery rate and 35 cases with the worsening of postoperative sagittal alignment (WPSA). Multivariate linear-regression analysis was conducted with the data. Advanced age (p = 0.019), longer duration of symptoms (p = 0.003) and loss of local Cobb angle (LCA) after surgery (p = 0.031) was significantly associated with a poor clinical outcome. A whole kyphosis (p = 0.009), aggravated neck pain after surgery (p = 0.012), preoperative lower thoracic 1 (T1) (p < 0.001), bigger change of C2-7 sagittal vertical axis (SVA) (p = 0.008) and adjacent segment degeneration (ASD) (p = 0.024) was significantly associated with the WPSA. Preoperative health education, nutritional support and early postoperative rehabilitation intervention, in perioperative period, were recommended for patients with advance age, longer duration of symptoms, whole cervical kyphosis and lower T1. Postoperative sagittal malalignment was related to neck pain and ASD after surgery.

Laminoplasty is relevant for degenerative cervical spondylolisthesis when there is little risk of postoperative excessive kyphosis during neck flexion

BACKGROUND

Elderly patients with degenerative cervical myelopathy frequently have severe symptoms due to spondylolisthesis. The effectiveness of laminoplasty for degenerative cervical spondylolisthesis (DCS) is an important question.

OBJECTIVE

The aim of this study is to elucidate factors associated with the outcome of laminoplasty for DCS.

METHOD

Eighty-nine patients with cervical spondylotic myelopathy (CSM) who underwent laminoplasty without instrumented posterior fusion were enrolled. Positive spondylolisthesis was defined as more than 2 mm during neck flexion or extension, from this, 46 DCS cases and 43 non-DCS cases were classified. Radiological parameters, including cervical alignment, balance, range of motion, and slippage along with the Japanese Orthopedic Association (JOA) score, were obtained before and 1 year after surgery. Factors associated with good surgical outcomes for DCS were analyzed using multivariate logistic analysis.

RESULTS

There were no significant differences in background and preoperative JOA score, but the DCS group recovery rate was significantly less (42% vs 53%). Multivariate logistic analysis revealed only the postoperative C2-7 angle during neck flexion was associated with a favorable outcome for DCS (P = 0.0039, Odds ratio: 1.49, 95% CI: 1.14-1.94). Multivariate regression analysis positively correlated the preoperative C2-7 angle in neutral and during flexion with the postoperative C2-7 angle during flexion.

CONCLUSION

The major factor related to poor outcome was the magnitude of postoperative kyphotic C2-7 angle during neck flexion. Slippage was not directly related to outcome and postoperative cervical alignment. Caution is recommended for surgeons performing laminoplasty on patients with risk factors for postoperative excessive kyphotic C2-7 angle during flexion.

Improvement rates, adverse events and predictors of clinical outcome following surgery for degenerative cervical myelopathy

PURPOSE

To investigate improvement rates, adverse events and predictors of clinical outcome after laminectomy alone (LAM) or laminectomy with instrumented fusion (LAM + F) for degenerative cervical myelopathy (DCM).

METHODS

This is a post hoc analysis of a previously published DCM cohort. Improvement rates for European myelopathy score (EMS) and Neck Disability Index (NDI) at 2- and 5-year follow-ups and adverse events are presented descriptively for available cases. Predictor endpoints were EMS and NDI scores at follow-ups, surgeon- and patient-reported complications, and reoperation-free interval. For predictors, univariate and multivariable models were fitted to imputed data.

RESULTS

Mean age of patients (LAM n = 412; LAM + F n = 305) was 68 years, and 37.4% were women. LAM + F patients had more severe spondylolisthesis and less severe kyphosis at baseline, more surgeon-reported complications, more patient-reported complications, and more reoperations (p ≤ 0.05). After imputation, the overall EMS improvement rate was 43.8% at 2 years and 36.3% at 5 years. At follow-ups, worse EMS scores were independent predictors of worse EMS outcomes and older age and worse NDI scores were independent predictors of worse NDI outcomes. LAM + F was associated with more surgeon-reported complications (ratio 1.81; 95% CI 1.17-2.80; p = 0.008). More operated levels were associated with more patient-reported complications (ratio 1.12; 95% CI 1.02-1.22; p = 0.012) and a shorter reoperation-free interval (hazard ratio 1.30; 95% CI 1.08-1.58; p = 0.046).

CONCLUSIONS

These findings suggest that surgical intervention at an earlier myelopathy stage might be beneficial and that less invasive procedures are preferable in this patient population.

Evaluating a paradigm shift from anterior decompression and fusion to muscle-preserving selective laminectomy: a single-center study of degenerative cervical myelopathy

OBJECTIVE

Muscle-preserving selective laminectomy (SL) is an alternative to conventional decompression surgery in patients with degenerative cervical myelopathy (DCM). It is less invasive, preserves the extensor musculature, and maintains the range of motion of the cervical spine. Therefore, the preferred treatment for DCM at the authors' institution has changed from anterior decompression and fusion (ADF), including anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF), toward SL. The aim of this study was to evaluate surgical outcomes before and after this paradigm shift with patient-reported outcome measures (PROMs), complications, reoperations, and cost-effectiveness.

METHODS

This study was a retrospective register-based cohort study. All patients with DCM who underwent ADF or SL at the authors' institution from 2008 to 2019 were reviewed. Using ANCOVA, changes in PROMs from baseline to the 2-year follow-up were compared between the two groups, adjusting for clinicodemographic parameters, baseline PROMs, number of decompressed levels, and MRI measurements (C2-7 Cobb angle, C2-7 sagittal vertical axis [SVA], and modified K-line interval [mK-line INT]). The PROMs, including the European Myelopathy Score (EMS), the Neck Disability Index (NDI), and the EQ-5D, were collected from the national Swedish Spine Register. Complications, reoperations, and in-hospital treatment costs were also compared between the two groups.

RESULTS

Ninety patients (mean age 60.7 years, 51 men [57%]) were included in the ADF group and 63 patients (mean age 68.8 years, 41 men [65%]) in the SL group. The ADF and SL groups had similar PROMs at baseline. The preoperative MR images showed similar C2-7 Cobb angles (10.7° [ADF] vs 14.1° [SL], p = 0.12) and mK-line INTs (4.08 vs 4.88 mm, p = 0.07), but different C2-7 SVA values (16.2 vs 19.3 mm, p = 0.04). The comparison of ANCOVA-adjusted mean changes in PROMs from baseline to the 2-year follow-up presented no significant differences between the groups (EMS, p = 0.901; NDI, p = 0.639; EQ-5D, p = 0.378; and EQ-5D health, p = 0.418). The overall complication rate was twice as high in the ADF group (22.2% vs 9.5%, p = 0.049), while the reoperation rate was comparable (16.7% vs 7.9%, p = 0.146). The average in-hospital treatment cost per patient was $6617 (USD) for SL, $7046 for ACDF, and $12,000 for ACCF.

CONCLUSIONS

SL provides similar PROMs after 2 years, a significantly lower complication rate, and better cost-effectiveness compared with ADF.

Cervical Laminoplasty Versus Posterior Laminectomy and Fusion: Trends in Utilization and Evaluation of Complication and Revision Surgery Rates

INTRODUCTION

Cervical laminoplasty (LP) and laminectomy with fusion (LF) are common operations used to treat cervical spondylotic myelopathy. Conflicting data exist regarding which operation provides superior patient outcomes while minimizing the risk of complications. This study evaluates the trends of LP compared with LF over the past decade in patients with cervical myelopathy and examines long-term revision rates and complications between the two procedures.

METHODS

Patients aged 18 years or older who underwent LP or LF for cervical myelopathy from 2010 to 2019 were identified in the PearlDiver Mariner Database. Patients were grouped independently (LP versus fusion) and assessed for association with common medical and surgical complications. The primary outcome was the incidence of LP versus LF for cervical myelopathy over time. Secondary outcomes were revision rates up to 5 years postoperatively and the development of complications attributable to either surgery.

RESULTS

In total, 1,420 patients underwent LP and 10,440 patients underwent LF. Rates of LP (10.5% to 13.7%) and LF (86.3% to 89.5%) remained stable, although the number of procedures nearly doubled from 865 in 2010 to 1,525 in 2019. On matched analysis, LP exhibited lower rates of wound complications, surgical site infections, spinal cord injury, dysphagia, cervical kyphosis, limb paralysis, incision and drainage/exploration, implant removal, respiratory failure, renal failure, and sepsis. Revision rates for both procedures at were not different at any time point.

CONCLUSION

From 2010 to 2019, rates of LP have not increased and represent less than 15% of posterior-based myelopathy operations. Up to 5 years of follow-up, there were no differences in revision rates for LP compared with LF; however, LP was associated with fewer postoperative complications than LF.

LEVEL OF EVIDENCE

Level III retrospective cohort study.

Different standing postures are the influencing factors for the efficacy of laminoplasty in the treatment of K-Line (-) patients with ossification of the posterior longitudinal ligament

OBJECTIVE

To investigate the relationship between different standing postures and surgical outcomes of K-Line (-) ossification of the posterior longitudinal ligament (OPLL) patients after laminoplasty with a titanium basket. There is a lack of data evaluating the relationship between the postoperative satisfaction of K-Line (-) patients and their standing postures.

METHODS

OPLL patients enrolled in the study were divided into a K-Line (+) group (Group A) and a K-Line (- group (Group B) in natural and relaxed standing positions. We compared the postoperative outcomes after cervical laminoplasty with titanium basket surgery using the Japanese Orthopaedic Association score (JOA), recovery rate and the degree of improvement in the six JOA score items. The degree of satisfaction with the outcome was assessed at the 1-year follow-up using a 7-point numerical rating scale.

RESULTS

A total of 34 K-Line (+) patients with OPLL (age 61.9 ± 2.9 years) in Group A and 40 K-Line (-)patients with OPLL (age 60.4 ± 3.5 years) in Group B in natural and relaxed standing positions were recruited. In Group A, the mean preoperative and postoperative JOA scores were 10.1 ± 1.4 and 13.1 ± 0.8 points, respectively, and in Group B, the mean preoperative and postoperative JOA scores were 9.7 ± 1.3 and 11.1 ± 0.9 points, respectively. A significant improvement in the JOA score was seen in both groups postoperatively, but the recovery rate of the patients' JOA scores was significantly lower in Group B. In Group A, significant improvements were seen in all JOA score items, but in Group B, improvements were seen only in upper- and lower-extremity sensory functions.

CONCLUSION

Different standing postures are risk factors in the treatment of K-Line (-) patients, and therefore, natural and relaxed standing positions should be given more attention before devising the surgical plan.

Significance of Vertebral Body Sliding Osteotomy as a Surgical Strategy for the Treatment of Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Vertebral body sliding osteotomy (VBSO) has previously been reported as a technique to decompress ossification of the posterior longitudinal ligament (OPLL) by translating the vertebral body anteriorly. This study aimed to evaluate the radiological and clinical efficacies of VBSO and clarify the surgical indications of VBSO for treating myelopathy caused by OPLL.

METHODS

Ninety-seven patients with symptomatic OPLL-induced cervical myelopathy treated with VBSO or laminoplasty who were followed up for more than 2 years were retrospectively reviewed. Cervical alignment, range of motion, fusion, modified K-line (mK-line) status, and minimum interval between ossified mass and mK-line (INT_(min)), and the Japanese Orthopaedic Association (JOA) score were assessed. Patients in the VBSO group were compared with those who underwent laminoplasty.

RESULTS

Cervical lordosis and INT_(min) significantly increased in the VBSO group. All patients in the VBSO group assessed as mK-line (-) preoperatively were assessed as mK-line (+) postoperatively. However, in the LMP group, the mK-line status changed from (+) preoperatively to (-) postoperatively in 3 patients. Final JOA score (p = 0.02) and JOA score improvement (p = 0.01) were significantly higher in the VBSO group. JOA recovery ratio (p = 0.03) and proportion of patients with a recovery rate ≥50% were significantly higher in the VBSO group (p < 0.01).

CONCLUSIONS

VBSO is an effective surgical option for OPLL-induced myelopathy, demonstrating favorable neurological recovery and lordosis restoration with low complication rates. It is best indicated for kyphotic alignment, OPLL with a high space-occupying ratio, and OPLL involving ≤3 segments.

Analysis of the risk factors for increasing cervical sagittal vertical axis after cervical laminoplasty for cervical spondylotic myelopathy

INTRODUCTION

The cervical sagittal vertical axis (cSVA) as another aspect of cervical alignment been recognized as one of the important factors affecting the pain and disability outcomes of cervical spine surgery. The purpose of the present study was to analyze the risk factors for increasing cSVA after cervical laminoplasty for cervical spondylotic myelopathy (CSM).

MATERIALS AND METHODS

This retrospective study included 110 consecutive patients (68 males and 42 females, average age 72.6 years) who underwent laminoplasty for CSM between January 2007 and June 2018. We recorded the operative time, blood loss, Japanese Orthopaedic Association (JOA) score and the recovery rate. Radiological measurements were performed to analyze the following parameters: pre- and 1-year postoperative McGregor's slope (McGS), occiput to C2 Cobb angle (O-C2 angle), C2-C7 Cobb angle (C2-7 angle), T1-slope (T1S), C2-7 SVA (cSVA) and calculated the change (Δ). Patients were divided into two groups according to whether ΔcSVA was positive or negative. We also used Spearman's correlation coefficient and multiple regression analysis.

RESULTS

ΔC2-7 angle, ΔT1S-preoperative C2-7 angle, ΔO-C2 angle were different between the two groups significantly. Correlation analysis between the ΔcSVA and the various sagittal parameters showed some independent explanatory factors including the ΔC2-7 angle (r = - 0.25, p = 0.010), T1S-preoperative C2-7 angle (r = - 0.28, p = 0.004), postoperative O-C2 angle (r = 0.26, p = 0.007), ΔO-C2 angle (r = 0.37, p = 0.001). Multiple regression analysis revealed that ΔcSVA was associated with the T1S-preoperative C2-7 angle (β = - 0.25, p = 0.034) and ΔO-C2 angle (β = 0.32, p = 0.001).

CONCLUSIONS

The imbalance between T1S and preoperative C2-7 angle influences the change of cSVA after cervical laminoplasty. If cSVA increases postoperatively, the O-C2 angle increases to compensate and maintain the horizontal gaze.

The Kappa Line as a Regional Modification of the K-line: A Predictor of Neurological Outcome and Indicator of the Adequate Level of Decompression in Selective Laminoplasty

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

The aim was to introduce Kappa line (modification of K-line) for the prediction of postoperative neurological recovery after selective cervical laminoplasty (LMP) and use in determining the decompression level.

SUMMARY OF BACKGROUND DATA

The K-line is a radiographic marker that can predict prognosis and aid in surgical planning for patients undergoing LMP through C3 to C7. However, its efficacy in LMP involving limited segments is unclear. Furthermore, no specific radiographic marker to predict the prognosis of selective LMP has been reported.

MATERIALS AND METHODS

Fifty-one consecutive patients with a minimum 2-year follow-up after selective LMP for cervical myelopathy caused by ossification of posterior longitudinal ligament were retrospectively reviewed. The Kappa line was defined as a straight line connecting the midpoints of the spinal canal made by remaining bony structure after decompression procedures on a plain lateral radiograph in the neutral position. Patients were classified as K-line (+) or (-) and Kappa line (+) or (-) based on whether the ossified mass crossed the indicator line.

RESULTS

The Kappa line (+) group demonstrated significantly higher Japanese Orthopaedic Association (JOA) recovery rate (P=0.01), final JOA score (P<0.01), and dural sac diameter (P<0.01) postoperatively than the Kappa line (-) group. Cord compression grade was significantly lesser in the Kappa line (+) group. However, the K-line-based classification did not demonstrate significant difference in JOA recovery rate, final JOA score, and cord compression grade between the (+) and (-) groups; the dural sac diameter was significantly higher in the K-line (+) group (P<0.01).

CONCLUSIONS

The Kappa line showed better correlation with ossification of posterior longitudinal ligament size and cervical alignment, providing better prediction of neurological recovery and remaining cord compression following selective LMP. Therefore, the Kappa line can aid in determining the level of decompression in selective LMP.

Imaging and Electrophysiology for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 9]

STUDY DESIGN

Narrative review.

OBJECTIVE

The current review aimed to describe the role of existing techniques and emerging methods of imaging and electrophysiology for the management of degenerative cervical myelopathy (DCM), a common and often progressive condition that causes spinal cord dysfunction and significant morbidity globally.

METHODS

A narrative review was conducted to summarize the existing literature and highlight future directions.

RESULTS

Anatomical magnetic resonance imaging (MRI) is well established in the literature as the key imaging tool to identify spinal cord compression, disc herniation/bulging, and inbuckling of the ligamentum flavum, thus facilitating surgical planning, while radiographs and computed tomography (CT) provide complimentary information. Electrophysiology techniques are primarily used to rule out competing diagnoses. However, signal change and measures of cord compression on conventional MRI have limited utility to characterize the degree of tissue injury, which may be helpful for diagnosis, prognostication, and repeated assessments to identify deterioration. Early translational studies of quantitative imaging and electrophysiology techniques show potential of these methods to more accurately reflect changes in spinal cord microstructure and function.

CONCLUSION

Currently, clinical management of DCM relies heavily on anatomical MRI, with additional contributions from radiographs, CT, and electrophysiology. Novel quantitative assessments of microstructure, perfusion, and function have the potential to transform clinical practice, but require robust validation, automation, and standardization prior to uptake.

Optimizing the Application of Surgery for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 10]

STUDY DESIGN

Literature Review (Narrative).

OBJECTIVE

To introduce the number 10 research priority for Degenerative Cervical Myelopathy: Individualizing Surgery.

METHODS

This article summarizes the current recommendations and indications for surgery, including how known prognostic factors such as injury time, age, disease severity, and associated comorbidities impact surgical outcome. It also considers key areas of uncertainty that should be the focus of future research.

RESULTS

While a small proportion of conservatively managed patients may remain stable, the majority will deteriorate over time. To date, surgical decompression is the mainstay of treatment, able to halt disease progression and improve neurologic function and quality of life for most patients. Whilst this recognition has led to recommendations on when to offer surgery, there remain many uncertainties including the type of surgery, or timing in milder and/or asymptomatic cases. Their clarification has the potential to transform outcomes, by ensuring surgery offers each individual its maximum benefit.

CONCLUSION

Developing the evidence to better guide surgical decision-making at the individual patient level is a research priority for Degenerative Cervical Myelopathy.

Surgical and Functional Outcomes of Expansive Open-Door Laminoplasty for Patients With Mild Kyphotic Cervical Alignment

Objective

To evaluate the cervical dynamics, neurological function, pain, and quality of life in patients with mild cervical kyphotic alignment who underwent expansive unilateral open-door laminoplasty (ELAP).

Methods

In this retrospective single-center study, we reviewed the surgical outcomes of 80 patients with cervical spondylotic myelopathy who were followed for at least 2 years. The patients were categorized into the preoperative kyphotic group (C2–7 angle < 0°) and nonkyphotic group (angle ≥ 0°). We compared clinical information, radiographic parameters, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) scores, and cervical Japanese Orthopaedic Association (JOA) scores between the groups.

Results

The kyphotic and nonkyphotic groups comprised 17 and 63 patients, respectively. The preoperative C2–7 angles were -3.7° in the kyphotic group and 15.4° in the nonkyphotic group (p<0.01). In the kyphotic group, kyphotic alignment improved to lordosis at the final follow-up (2.6°, p=0.01). The preoperative (16.4° vs. 24.1°, p<0.01) and final-follow-up (17.8° vs. 24.5°, p<0.01) C7 slopes were significantly smaller in the kyphotic group. ELAP reduced pain in the arms or hands (p=0.02) and improved the JOA scores (p<0.01) in the kyphotic group. Patient-reported outcomes assessed using the JOACMEQ showed comparable effective rates in both groups.

Conclusion

Patients with mild cervical kyphosis showed smaller C7 slopes as a compensatory mechanism. Kyphotic angles significantly improved to lordosis after ELAP, resulting in favorable clinical outcomes. ELAP is a useful surgical option for patients even if they present mild kyphotic cervical angles.

Radiological factors associated with the severity of corticospinal tract dysfunctions for cervical spondylotic myelopathy: An analysis of the central motor conduction time and kinematic CT myelography

Patients with cervical spondylotic myelopathy (CSM) often exhibit symptoms in clinical practice, particularly the elderly, whose lower extremity functions are more likely to deteriorate; however, the underlying mechanisms currently remain unclear. The present study aimed to elucidate the relationship between the neurological severity of CSM based on an electrophysiological examination and radiological findings. Eighty-six patients with CSM were examined using kinematic CT myelography. The cross-sectional area of the spinal cord and dynamic changes in the spinal cord were measured at the affected level. The central motor conduction time (CMCT) using transcranial magnetic stimulation was calculated as follows: motor evoked potential latency - (compound muscle action potential latency + F latency - 1)/2 (ms). A multiple logistic regression analysis was performed to identify the radiological parameters associated with severe lower limb dysfunction. CMCT in the upper limbs correlated with spinal cord compression during neck extension, while that in the lower limbs correlated with a larger C2-7 sagittal vertical axis, cervical lordosis, a small C2-7 range of motion (ROM), and spinal cord compression during neck flexion. In a multiple logistic regression analysis, significant risk factors specific for severe lower limb dysfunction were greater anterior spondylolisthesis during neck extension (P = 0.006, OR: 2.53, 95%CI: 1.13-2.07) and small C2-7 ROM in neutral to flexion (P = 0.035, OR: 0.67, 95%CI: 0.52-0.88). Imaging findings affect upper and lower extremity functions in specific manners. Cervical stiffness or anterior compression factors may be associated with the deterioration of lower limb function.

Laminectomy alone versus laminectomy with fusion for degenerative cervical myelopathy: a long-term study of a national cohort

PURPOSE

To compare patient-reported 5-year clinical outcomes between laminectomy alone versus laminectomy with instrumented fusion in patients with degenerative cervical myelopathy in a population-based cohort.

METHODS

All patients in the national Swedish Spine Register (Swespine) from January 2006 until March 2019, with degenerative cervical myelopathy, were assessed. Multiple imputation and propensity score matching based on clinicodemographic and radiographic parameters were used to compare patients treated with laminectomy alone with patients treated with laminectomy plus posterior-lateral instrumented fusion. The primary outcome measure was the European Myelopathy Score, a validated patient-reported outcome measure. The scale ranges from 5 to 18, with lower scores reflecting more severe myelopathy.

RESULTS

Among 967 eligible patients, 717 (74%) patients were included. Laminectomy alone was performed on 412 patients (mean age 68 years; 149 women [36%]), whereas instrumented fusion was added for 305 patients (mean age 68 years; 119 women [39%]). After imputation, the propensity for smoking, worse myelopathy scores, spondylolisthesis, and kyphosis was slightly higher in the fusion group. After imputation and propensity score matching, there were on average 212 pairs patients with a 5-year follow-up in each group. There were no important differences in patient-reported clinical outcomes between the methods after 5 years. Due to longer hospitalization times and implant-related costs, the mean cost increase per instrumented patient was approximately $4700 US.

CONCLUSIONS

Instrumented fusions generated higher costs and were not associated with superior long-term clinical outcomes. These findings are based on a national cohort and can thus be regarded as generalizable.

Kinematics after cervical laminoplasty: risk factors for cervical kyphotic deformity after laminoplasty

BACKGROUND CONTEXT

Laminoplasty of the cervical spine is widely used as an effective surgical method to treat compressive myelopathy of the cervical spine; however, there is an adverse effect of kyphosis after surgery. The risk factors or predictors of kyphosis have not been sufficiently evaluated.

PURPOSE

To assess the risk factors for kyphosis following laminoplasty.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients diagnosed with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) who underwent laminoplasty between May 2011 and October 2018 were enrolled.

OUTCOME MEASURES

Changes in lordosis and range of motion (ROM).

METHODS

Radiological imaging data were collected from simple neutral and flexion-extension radiographs at baseline and at 2-year follow-up. The ROM from the neutral position to complete flexion was defined as the flexion capacity, and the ROM from the neutral position to complete extension was defined as the extension capacity.

RESULTS

This study included 53 patients (mean age, 59.3 years). Multivariate linear regression analysis revealed that, the smaller the preoperative extension capacity, the greater was the decrease in lordosis (p=.025), while the larger the T1 slope, the greater was the decrease in lordosis following laminoplasty (p= .008). Correlation analysis revealed that C2-7 lordosis increased with increasing baseline T1 slope before surgery (p< .01). In patients with large preoperative C2-7 lordosis, the postoperative decrease in ROM tended to be greater (p= .028). However, the degree of lordosis and ROM reduction did not demonstrate a clear correlation with the clinical outcomes at 2 years after surgery.

CONCLUSIONS

Kyphotic changes in the cervical spine following laminoplasty were related to preoperative radiological parameters. The greater the preoperative extension capacity, the lower was the decrease in lordosis, and the greater the T1 slope, the greater was the decrease in lordosis.

Degenerative Cervical Myelopathy: Towards a Personalized Approach

Degenerative cervical myelopathy (DCM) is a recently coined term encompassing a variety of age-related and genetically associated pathologies, including cervical spondylotic myelopathy, degenerative disc disease, and ligamentous aberrations such as ossification of the posterior longitudinal ligament. All of these pathologies produce chronic compression of the spinal cord causing a clinical syndrome characterized by decreased hand dexterity, gait imbalance, and potential genitourinary or sensorimotor disturbances. Substantial variability in the underlying etiology of DCM and its natural history has generated heterogeneity in practice patterns. Ongoing debates in DCM management most commonly center around clinical decision-making, timing of intervention, and the ideal surgical approach. Pivotal basic science studies during the past two decades have deepened our understanding of the pathophysiologic mechanisms surrounding DCM. Growing knowledge of the key pathophysiologic processes will help us tailor personalized approaches in an increasingly heterogeneous patient population. This article focuses on summarizing the most exciting approaches in personalizing DCM patient treatments including biomarkers, factors affecting clinical decision-making, and choice of the optimal surgical approach. Throughout we provide a concise review on the conditions encompassing DCM and discuss the underlying pathophysiology of chronic spinal cord compression. We also provide an overview on clinical-radiologic diagnostic modalities as well as operative and nonoperative treatment strategies, thereby addressing knowledge gaps and controversies in the field of DCM.

Impact of focal apex angle on postoperative decompression status of the spinal cord and neurological recovery after cervical laminoplasty

OBJECTIVE

Although anterior compression factors and cervical alignment affect neural decompression, cervical laminoplasty may be used to achieve indirect posterior decompression. The focal apex (FA) angle of the anterior compression factor of the spine represents the degree of anterior prominence toward the spinal cord. The authors investigated the mechanism underlying the influence of FA angle and cervical alignment on spinal cord alignment (SCA) after laminoplasty, including how high-intensity signal cord change (HISCC) on preoperative T2-weighted MRI (T2-MRI) may affect neurological improvement.

METHODS

We performed a retrospective study of patients who underwent laminoplasty for CSM or OPLL at two hospitals (Kanto Rosai Hospital, Kawasaki City, and Yokohama Minami Kyousai Hospital, Yokohama City, Japan) between April 2004 and March 2015. In total, 109 patients (mean age 67.3 years) with cervical compression myelopathy were included. FA angle was defined as the preoperative angle between the lines from the top of the prominence to the upper and lower adjacent vertebrae. Preoperative cervical alignment was measured between the C2 and C7 vertebrae (C2-7 angle). MRI was used to classify SCA as lordosis (type-L SCA), straight (type-S), local kyphosis (type-LK), or kyphosis (type-K). Preoperative HISCC was investigated by using T2-MRI. Neurological status was evaluated by using the Japanese Orthopaedic Association score.

RESULTS

The mean preoperative FA and C2-7 angles were 32.1° and 12.4°, respectively. Preoperative SCA was type-L or type-S in 53 patients. The neurological recovery rate (NRR) was significantly higher for patients with preoperative type-L and type-S SCA (51.4% for those with type-L and 45.0% for those with type-S) than for patients with other types (35.3% for those with type-LK and 31.7% for those with type-K). Among patients with preoperative type-L or type-S SCA, 87.3% maintained SCA; however, 5/12 (41.7%) patients with a preoperative average C2-7 angle < 12.4° and an average FA angle > 32.1° had postoperative type-LK or type-K SCA. SCA changed to type-L or type-S in 13.0% of patients with preoperative type-LK or type-K SCA. Moreover, in these patients, FA angle was significantly smaller and NRR was significantly higher than in other patients in whom postoperative SCA remained type-LK or type-K. Preoperative T2-MRI showed 73 patients with HISCC (43 with type-L and type-S, and 30 with type-LK and type-K SCA) and 36 without HISCC (20 with type-L and type-S, and 16 with type-LK and type-K SCA); the NRRs of these patients were 42.6% and 41.2%, respectively. No significant differences in SCA or NRR were observed between patients with and without HISCC.

CONCLUSIONS

NRR depends on preoperative SCA type; however, it is possible to change the type of SCA after laminoplasty. Preoperative FA and C2-7 angles influence change in SCA; therefore, they are important parameters for successful decompression with cervical laminoplasty.

Laminar Closure in Double-door Laminoplasty for Cervical Spondylotic Myelopathy with Nonkyphotic Alignment

STUDY DESIGN

A retrospective case series.

OBJECTIVE

The aim of this study was to investigate the incidence and clinical features of laminar closure in patients with cervical spondylotic myelopathy (CSM) based on prospectively collected data.

SUMMARY OF BACKGROUND DATA

Laminar closure after single open-door laminoplasty (LAMP) has been reported to result in poor clinical outcomes. However, no studies to date have examined the underlying mechanisms and frequency of laminar closure after double-door LAMP.

METHODS

This study prospectively enrolled 128 consecutive patients with CSM scheduled for double-door LAMP without a laminar spacer at our hospital between 2008 and 2013. Sagittal parameters including C2-7 angle, T1 slope, and cervical sagittal vertical axis (C-SVA), which is defined as the distance between the anterior margin of the external auditory canal plumb line and the posterior-cranial corner of the C7 vertebral body on x-ray, were calculated before and after the operation. Laminar angle was also measured on magnetic resonance images preoperatively and at 1 week and 1 year postoperatively. Laminar closure was defined as > 20% decrease in laminar angle at 1 year compared with that at 1 week postoperatively. The Japanese Orthopedic Association score for cervical myelopathy and the recovery rate determined from the preoperative and postoperative scores were evaluated as clinical outcomes.

RESULTS

In total, 110 patients were completely followed up for at least 1 year (follow-up rate: 85.9%). Laminar closure was observed in six cases (5.5%) at the 1-year follow-up. The recovery rate in these six cases was significantly lower than in cases without laminar closure (16.6% vs. 45.1%, respectively). Logistic regression analysis revealed age and C-SVA as significant risk factors for postoperative laminar closure.

CONCLUSION

This study is the first to investigate the incidence of laminar closure after double-door LAMP without a laminar spacer. Laminar closure occurred exclusively in elderly patients with kyphotic deformity after LAMP.Level of Evidence: 4.

Impact of various MRI signal intensity changes on radiological parameters, the neurological status, and surgical outcomes in degenerative cervical myelopathy

STUDY DESIGN

A retrospective study of prospectively collected date.

PURPOSE

The present study aimed to identify patient characteristics, radiological factors, the neurological status, and postoperative outcomes associated with MRI signal intensity changes in degenerative cervical myelopathy (DCM).

MATERIAL AND METHOD

One hundred and fourteen DCM patients who underwent posterior decompression surgeries were enrolled. Pre- and postoperative (12 months) Japanese Orthopedic Association (JOA) scores, cervical alignment and balance on X rays, the cross-sectional area of the spinal cord (CSA) in kinematic CT myelography (CTM). The recovery rate (RR) of the total JOA score and those specific for the upper and lower limb items were evaluated. MRI included T1-weighted imaging (WI) and T2WI. Patients were classified into two groups for a univariate analysis according to the presence or absence of a high signal intensity (HIS) in the sagittal view on T2WI, a low signal intensity (LSI) in the sagittal view on T1WI, the distribution of HSI at a single or multiple levels, and the presence or absence of the snake eye appearance. A multiple logistic regression analysis (MLRA) was performed to identify factors associated with signal intensity changes on MRI.

RESULTS

Ninety-six patients (84.3%) were classified into HIS changes in the sagittal view on T2WI. The group with multilevel HSI showed significantly lower RR specific for the lower extremity JOA score (30.8% vs 47.7%; P = 0.016). The snake eye-positive group showed a significantly inferior RR specific for the upper extremity JOA score (40.1% vs 53.2%; P = 0.04). In MLRA, LSI changes on T1WI revealed small CSAF (P = 0.02, Odds ratio; 0.77, 95%CI:0.61-0.97), while HSI changes on T2WI revealed a small CSAF (P = 0.008, Odds ratio;1.36, 95%CI:1.08-1.72) and large C2-7 angle during extension (P = 0.009, Odds ratio;0.73, 95%CI:0.58-0.92). CSAF correlated with multilevel HSI changes (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93). The snake eye appearance correlated with CSAF (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93) and the duration of disease (P = 0.05, Odds ratio;1.01, 95%CI:1.0-1.03).

CONCLUSION

Severe and poorly compensated spinal cord compression during neck flexion may cause signal intensity changes. The snake eye appearance may be useful as a sign of the inferior postoperative recovery of upper limb function, and multilevel HSI as a sign of the inferior postoperative recovery of lower limb function.

Preoperative Radiological Parameters to Predict Clinical and Radiological Outcomes after Laminoplasty

Many studies have focused on pre-operative sagittal alignment parameters which could predict poor clinical or radiological outcomes after laminoplasty. However, the influx of too many new factors causes confusion. This study reviewed sagittal alignment parameters, predictive of clinical or radiological outcomes, in the literature. Preoperative kyphotic alignment was initially proposed as a predictor of clinical outcomes. The clinical significance of the K-line and K-line variants also has been studied. Sagittal vertical axis, T1 slope (T1s), T1s-cervical lordosis (CL), anterolisthesis, local kyphosis, the longitudinal distance index, and range of motion were proposed to have relationships with clinical outcomes. The relationship between loss of cervical lordosis (LCL) and T1s has been widely studied, but controversy remains. Extension function, the ratio of CL to T1s (CL/T1s), and Sharma classification were recently proposed as LCL predictors. In predicting postoperative kyphosis, T1s cannot predict postoperative kyphosis, but a low CL/T1s ratio was associated with postoperative kyphosis.

Modified K-line for Making Decisions Regarding the Surgical Approach in Patients with K-line (-) OPLL

Objective

To investigate whether the modified K‐line can be used to predict the clinical outcome and to determine the surgical approach for K‐line (−) patients with cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

A new modified K‐line was defined as the line connecting the midpoints of the spinal cord at C₄ and C₆ on the lateral cervical radiographs. A total of four consecutive patients (three men and one woman) with cervical myelopathy due to OPLL were included in this research. The patients were diagnosed with OPLL with K‐line (−) while they were also classified as modified K‐line (+). Preoperative modified K‐line was used to predict the surgical outcome in K‐line (−) patients with OPLL according to the original K‐line. And a modified laminoplasty with C₃ laminectomy and C_4‐6 bilateral open‐door laminoplasty was adopted to perform on all the patients. The Japanese Orthopaedic Association scores before surgery and at 1‐year follow‐up after surgery were evaluated and the recovery rate was calculated. The visual analogue scale (VAS) scores were also evaluated before surgery and after surgery. Furthermore, cervical plain radiographs in neutral position before surgery and after surgery were obtained to measure C₂–C₇ angles for assessing the cervical sagittal alignment.

Results

The results showed that good neurological improvement could be achieved in all K‐line (−) patients who underwent C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty. The Postoperative JOA scores improved from 13.5 to 16.5, from 11 to 16.5, from 13 to 16, and from 12.5 to 13, respectively. The mean recovery rate was 65.4% in the K‐line (−) patients. And the VAS scores dropped from 3 to 1, 5 to 2, 5 to 3, and 4 to 2, respectively. The JOA and VAS scores showed satisfaction in all patients at the 1‐year follow‐up. Relatively satisfactory and stable cervical sagittal alignment was observed on postoperative lateral radiography in all patients at the 3‐month follow‐up period. There were no postoperative complications associated with this technique found in all the patients.

Conclusions

Modified K‐line may predict the clinical outcome of this modified laminoplasty and offer guidance regarding the choice of surgical method for K‐line (−) patients with OPLL. Additionally, C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty should be recommended for the use in patients with K‐line (−) OPLL, who were also classified as modified K‐line (+). However, further studies with more cases will be required to reveal its generalizability and availability.

Effect of decompression range on decompression limit of cervical laminoplasty

Backgrounds

Cervical posterior decompression surgery is used to relieve ventral compression indirectly by incorporating a backward shift of the spinal cord, and this indirect decompression is bound to be limited. This study aimed to determine the decompression limit of posterior surgery and the effect of the decompression range.

Methods

We retrospectively reviewed the data of 129 patients who underwent cervical open-door laminoplasty through 2008 to 2012 and were grouped as follows: C4–C7 (n = 11), C3–C6 (n = 61), C3–C7 (n = 32), and C2–C7 (n = 25). According to the relative location of spinal levels within a decompression range, the type of decompression at a given level was categorized as external decompression (ED; achieved at the levels located immediately external to the decompression range margin), internal decompression (ID; achieved at the levels located immediately internal to the decompression range margin), and central decompression (CD; achieved at the levels located in the center, far from the decompression range margin). The vertebral–cord distance (VCD) was used to evaluate the decompression limit. The C2–C7 angle and VCD on post-operative magnetic resonance images were analyzed and compared between groups. The relationship between VCD and decompression type was analyzed. Moreover, the relationship between the magnitude of the ventral compressive factor and the probability of post-operative residual compression at each level for different decompression ranges was studied.

Results

There was no significant kyphosis in cervical curvature (> −5°), and there was no significant difference among the groups (F = 2.091, P = 0.105). The VCD of a specific level depended on the decompression type of the level and followed this pattern: ED < ID < CD (P < 0.05). The decompression type of a level was sometimes affected by the decompression range. For a given magnitude of the ventral compressive factor, the probability of residual compression was lower for the group with the larger VCD at this level.

Conclusions

Our study suggests that the decompression range affected the decompression limit by changing the decompression type of a particular level. For a given cervical spinal level, the decompression limit significantly varied with decompression type as follows: ED < ID < CD. CD provided maximal decompression limit for a given level. A reasonable range of decompression could be determined based on the relationship between the magnitude of the ventral compressive factor and the decompression limits achieved by different decompression ranges.

The Impact of Anterior Spondylolisthesis and Kyphotic Alignment on Dynamic Changes in Spinal Cord Compression and Neurological Status in Cervical Spondylotic Myelopathy: A Radiological Analysis Involving Kinematic CT Myelography and Multimodal Spinal Cord Evoked Potentials

STUDY DESIGN

A retrospective study of prospectively collected data.

OBJECTIVE

This study aimed to examine how radiological parameters affect dynamic changes in the cross-sectional area of the spinal cord (CSA) in cervical spondylotic myelopathy (CSM) patients and how they correlate with the severity of myelopathy, by evaluating multi-modal spinal cord evoked potentials (SCEPs).

SUMMARY OF BACKGROUND DATA

Appropriate assessments of dynamic factors should reveal hidden spinal cord compression and provide useful information for choosing surgical procedures.

METHODS

Seventy-nine CSM patients were enrolled. They were examined with kinematic CT myelography (CTM), and the spinal levels responsible for their CSM were determined via SCEP examinations. The C2-7 angle, C2-7 range of motion, and percentage of slip were measured on the midsagittal view during flexion and extension, and the CSA was measured on the axial view in each neck position using kinematic CTM. The patients who exhibited the smallest CSA values during extension and flexion were classified into Groups E and F, respectively.

RESULTS

Fifty-two (65.8%) and 27 (34.2%) cases were included in Groups E and F, respectively. The preoperative JOA score did not differ significantly between the groups; however, the preoperative lower-limb JOA score of Group F was significantly lower than that of Group E (2.24 ± 0.82 vs. 2.83 ± 1.09, P = 0.016). In the multiple logistic regression analysis, a small C2-7 angle during extension (β = 5°, odds ratio: 0.69, 95% confidence interval [CI]: 0.54-0.90) and the slip percentage during flexion (β = 5%, odds ratio: 1.42, 95% CI: 1.09-1.85) were identified as significant predictors of belonging to Group F.

CONCLUSION

Exhibiting more severe spinal cord compression during neck flexion was associated with a small C2-7 angle and anterior spondylolisthesis. The neurological status of the patients in Group F was characterized by severe lower limb dysfunction because of a disturbed blood supply to the anterior column.Level of Evidence: 4.

Fate of Ossification of Posterior Longitudinal Ligament Following Anterior Cervical Fusion: Progression of Cervical Ossification of Posterior Longitudinal Ligament After Vertebral Body Sliding Osteotomy or Laminoplasty

OBJECTIVE

In the treatment of ossification of posterior longitudinal ligament (OPLL)-induced cervical myelopathy, laminoplasty (LMP) is the most widely used surgical procedure. However, the progression of ossification masses is a well-known complication of LMP. This study aimed to investigate whether the novel anterior cervical decompression technique (vertebral body sliding osteotomy; VBSO) based on anterior column fusion suppresses the progression of OPLL compared with motion-preserving posterior decompression surgery (LMP).

METHODS

All 77 consecutive patients (VBSO group, n = 33; LMP group, n = 44) who underwent VBSO or LMP for cervical OPLL at our institute between January 2012 and November 2017 were included. A total of 62 and 86 cervical motion segments in the VBSO and LMP groups were investigated, respectively. The OPLL thickness was measured twice (immediate postoperative and final follow-up), and the change of OPLL thickness was compared between the 2 groups.

RESULTS

The increase in OPLL thickness in the VBSO group (-0.18 ± 0.24 mm) was significantly smaller than that in the LMP group (1.0 ± 0.9 mm, P < 0.001). Interestingly, in some patients, suppressed OPLL progression and decreased OPLL thickness were observed.

CONCLUSIONS

The solid fusion of the anterior column by VBSO is associated with the lower incidence of OPLL growth and potential for growth arrest.

Thin Cervical Spinal Cord Between Ossifications of the Ligamentum Flavum and the Posterior Longitudinal Ligament: Case Report and Literature Review

BACKGROUND

Cervical ossification of the ligamentum flavum (OLF) is a rare condition; however, the coexistence of OLF and ossification of the posterior longitudinal ligament (OPLL) is extremely uncommon. These can exist simultaneously and cause thinning of the cervical spinal cord. Sufficient decompression, dural ossification, semispinalis dissection, and postoperative kyphosis were evaluated. We report the successful treatment of coexisting cervical OLF and OPLL.

CASE DESCRIPTION

A 70-year-old man had been experiencing weakness in the left knee and clumsiness in the left hand for 6 months. Hemiparesis was considered; however, magnetic resonance imaging revealed a cervical spinal lesion. Hence a spine surgeon diagnosed the patient with severe stenosis with OLF at the C2-C3 levels and OPLL at the C2-C4 levels. The patient presented with spastic gait and left-hand motor weakness. Computed tomography scan revealed the disappearance of the black line, indicating dural ossification surrounding the OLF. OPLL was observed in 61.5% of the C2 spinal canal. The K-line was (-); however, the alternative K-line between the C1 and C7 level was (+). Posterior laminectomy at the C2-C3 levels and laminoplasty at the C4-C7 levels with muscle preservation resulted in sufficient decompression. The patient's symptoms improved, and cervical alignment was maintained 2 years after surgery.

CONCLUSIONS

An alternative K-line comprised successful treatment for coexisting cervical OLF and OPLL. Surgeons must evaluate the severity of adhesion, damage of the paraspinal muscles, and necessity of posterior corrective surgery along with the patient's comorbidities and possible postoperative complications.

Clinical Impact of Cervical Imbalance on Surgical Outcomes of Laminoplasty: A Propensity Score-Matching Analysis

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

The objective of this study was to identify the impact of preoperative cervical sagittal balance on the 2-year surgical outcomes of laminoplasty.

SUMMARY OF BACKGROUND DATA

The cervical imbalance is considered associated with poor health-related quality of life and poor outcomes for cervical deformity surgery. However, the influences of cervical imbalance on the clinical outcomes of laminoplasty for cervical spondylotic myelopathy (CSM) patients are unclear.

MATERIALS AND METHODS

A total of 277 consecutive CSM patients who underwent laminoplasty were analyzed. From the last consecutive 136 patients, matched control group [cervical sagittal vertical axis (cSVA)<40 mm, n=30] and matched imbalance group (≥40 mm, n=30) were selected based on their propensity score adjusted for age, sex, cervical alignment, and preoperative Japanese Orthopaedic Association (JOA) score. Change in clinical outcomes and radiographic parameters at 2 years postoperatively were compared between the 2 matched groups using mixed-effects model. For the validation of the primary results, factors that correlated with the recovery rate of JOA score of another 141 patients were analyzed using multiple linear regression analysis.

RESULTS

There was no significant interaction between the 2 matched groups in all clinical outcomes, including the severity of myelopathy, patient-oriented health-related quality of life score, physical and mental status, physical functions, and pain score. Regarding the radiographic evaluation, change in cSVA showed significant differences (P=0.038); cSVA was kept stable in the matched control group, whereas its value significantly decreased in the matched imbalance group. Multiple linear regression models demonstrated that preoperative cSVA is not significantly related to the recovery rate of JOA score at 2 years postoperatively (P=0.114).

CONCLUSIONS

Preoperative cervical imbalance did not significantly affect the 2-year surgical outcomes of laminoplasty. Furthermore, cervical imbalance improved after surgery. These results can suggest physicians consider laminoplasty as a treatment for CSM patients regardless of their cervical balance.

LEVEL OF EVIDENCE

Level III-treatment benefits: nonrandomized controlled cohort/follow-up study.

Is Modified K-line a Powerful Tool of Surgical Decision Making for Patients With Cervical Spondylotic Myelopathy?

STUDY DESIGN

Prospective observational single-center study.

OBJECTIVE

To evaluate anterior decompression and fusion (ADF) or posterior surgery (PS) for patients with cervical spondylotic myelopathy (CSM) using the modified K-line (mK-line) and to compare clinical and radiologic outcomes between these 2 techniques.

SUMMARY OF BACKGROUND DATA

The authors have previously reported that insufficient posterior decompression is often seen after laminoplasty for CSM in patients with preoperative anterior clearance of the spinal cord <4 mm on the basis of the mK-line. However, to our knowledge, no study has investigated the role, if any, of the mK-line in surgical decision making for patients with CSM.

METHODS

A total of 87 patients were enrolled who underwent surgery for treatment of CSM between 2011 and 2015 at our hospital and who could be followed up for at least 2 years. ADF was selected as a more favorable procedure than PS in patients with anterior spinal clearance of <4 mm on preoperative midsagittal magnetic resonance imaging. On the basis of the Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy, the rate of recovery of the JOA scores at 2 years after surgery was investigated as a clinical outcome to compare these 2 groups.

RESULTS

Mean age was 65.1 (±12.9) years in the ADF group (n=26) and 70.5 (±8.6) years in the PS group (n=61). In the PS group, 10 patients underwent posterior decompression with fusion. Mean preoperative and postoperative JOA scores were 10.5 and 14.1 points in the ADF group and 9.8 and 13.1 points in the PS group, respectively, showing no significant difference in recovery rate of JOA score between the ADF (58.9%) and PS (47.1%) groups. However, patients with a minimum interval between the mK-line and the anterior compression factor on the midsagittal image (minimum interval of the spinal cord) <4 mm tended to have unsatisfactory outcomes (recovery rate 29.6%) compared with patients with minimum interval of the spinal cord >4 mm (53.6%, P=0.07) in the PS group.

CONCLUSION

Preoperative intervention using the mK-line is useful to predict residual cord compression and might homogenize postoperative clinical outcomes in both anterior surgery and PS.

Lack of Prognostic Model Validation in Low Back Pain Prediction Studies: A Systematic Review

OBJECTIVE

The objective of this study was to investigate the frequency with which prediction studies for low back pain outcomes utilize prospective methods of prognostic model validation.

METHOD

Searches of Medline and Embase for terms "predict/predictor," "prognosis," or "prognostic factor." The search was limited to studies conducted in humans and reported in the English language. Included articles were all those published in 2 Spine specialty journals (Spine and The Spine Journal) over a 13-month period, January 2013 to January 2014. Conference papers, reviews, and letters were excluded. The initial screen identified 55 potential studies (44 in Spine, 11 in The Spine Journal); 34 were excluded because they were not primary data collection prediction studies; 23 were not prediction studies and 11 were review articles. This left 21 prognosis papers for review, 19 in Spine, 2 in The Spine Journal.

RESULTS

None of the 21 studies provided validation for the predictors that they documented (neither internal or external validation). On the basis of the study designs and lack of validation, only 2 studies used the correct terminology for describing associations/relationships between independent and dependent variables.

DISCUSSION

Unless researchers and clinicians consider sophisticated and rigorous methods of statistical/external validity for prediction/prognostic findings they will make incorrect assumptions and draw invalid conclusions regarding treatment effects and outcomes. Without proper validation methods, studies that claim to present prediction models actually describe only traits or characteristics of the studied sample.

Review of Radiological Parameters, Imaging Characteristics, and Their Effect on Optimal Treatment Approaches and Surgical Outcomes for Cervical Ossification of the Posterior Longitudinal Ligament

Determining the optimal surgical method for cervical ossification of the posterior longitudinal ligament (OPLL) is challenging. The surgical indication should be made based on not only radiological findings, but also the patient’s age, preoperative neurological findings, social background, activities of daily life, and the presence or absence of comorbid diseases. Anterior resection for OPLL with or without wide corpectomy and fusion, posterior decompression with or without relatively long fusion, or anterior and posterior combined surgery may be considered. When evaluating the clinical condition of patients with cervical OPLL before surgery, various radiological parameters should be carefully considered, including the number of spinal segments involved, the cervical alignment or tilt angle, the relationship between OPLL and the C2–7 line (termed the “K-line”), the occupying ratio of OPLL, and the involvement of dural ossification. The objective of this article is to review the radiological parameters in current use for deciding upon the optimal surgical strategy and for predicting surgical outcomes, focusing on cervical OPLL.

Posterior Surgical Techniques for Cervical Spondylotic Myelopathy: WFNS Spine Committee Recommendations

Objective

This study was conducted to determine and recommend the most up-to-date information on the indications, complications, and outcomes of posterior surgical treatments for cervical spondylotic myelopathy (CSM) on the basis of a literature review.

Methods

A comprehensive literature search was performed, using the MEDLINE (PubMed), the Cochrane Register of Controlled Trials, and Web of Science databases, for peer-reviewed articles published in English during the last 10 years.

Results

Posterior techniques, which include laminectomy alone, laminectomy with fusion, and laminoplasty, are often used in patients with involvement of 3 or more levels. Posterior decompression for CSM is effective for improving patients’ neurological function. Complications resulting from posterior cervical spine surgery include injury to the spinal cord and nerve roots, complications related to posterior screw fixation or instrumentation, C5 palsy, spring-back closure of lamina, and postlaminectomy kyphosis.

Conclusion

It is necessary to consider multiple factors when deciding on the appropriate operation for a particular patient. Surgeons need to tailor preoperative discussions to ensure that patients are aware of these facts. Further research is needed on the cost-to-benefit analysis of various surgical approaches, the comparative efficacy of surgical approaches using various techniques, and long-term outcomes, as current knowledge is deficient in this regard.

Degenerative Cervical Myelopathy; A Review of the Latest Advances and Future Directions in Management

The assessment, diagnosis, operative and nonoperative management of degenerative cervical myelopathy (DCM) have evolved rapidly over the last 20 years. A clearer understanding of the pathobiology of DCM has led to attempts to develop objective measurements of the severity of myelopathy, including technology such as multiparametric magnetic resonance imaging, biomarkers, and ancillary clinical testing. New pharmacological treatments have the potential to alter the course of surgical outcomes, and greater innovation in surgical techniques have made surgery safer, more effective and less invasive. Future developments for the treatment of DCM will seek to improve the diagnostic accuracy of imaging, improve the objectivity of clinical assessment, and increase the use of surgical technology to ensure the best outcome is achieved for each individual patient.

Development and Achievement of Cervical Laminoplasty and Related Studies on Cervical Myelopathy

Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.