Predictors of cervical lordosis loss after laminoplasty in patients with cervical spondylotic myelopathy

Deformity Considerations in Cervical Laminoplasty: A Narrative Review

OBJECTIVES

We discuss the incidence of postoperative kyphosis following laminoplasty and its impact on outcomes, as well as critical radiographic parameters, intraoperative technical factors, and postoperative protocols that can be used to improve results.

SUMMARY OF BACKGROUND DATA

When appropriately selected, cervical laminoplasty is a motion-sparing treatment option for cervical myelopathy and is a valid alternative to laminectomy and fusion procedures. However, like other posterior-based cervical decompression techniques, laminoplasty can cause postoperative kyphosis.

METHODS

A PubMed search was performed to gather articles that focus on cervical deformity in the context of cervical laminoplasty.

RESULTS

The reported conversion rates of lordotic to kyphotic cervical alignment after laminoplasty range from 5.2% to 11.3%. Kyphosis likely reduces the benefit from the operation as measured by postoperative mJOA scores. A surgeon can minimize the risk of causing a clinically significant reduction in lordosis by screening out patients with certain radiographic characteristics. Intraoperative decisions such as dissection techniques, levels chosen, and hybrid constructs can preserve the cervical tension band. Certain postoperative protocols can improve cervical posture.

CONCLUSIONS

Cervical laminoplasty is an effective tool for treating degenerative cervical myelopathy. Careful radiographic screening, intraoperative decision-making, and postoperative protocols can minimize the development of postoperative cervical deformity and improve outcomes.

LEVEL OF EVIDENCE

Level V.

The preservation of cervical flexibility helps maintain cervical sagittal alignment after laminoplasty

BACKGROUND CONTEXT

Cervical spine range of motion (ROM) is a critical factor in changes in cervical sagittal alignment (CSA) and clinical outcomes after cervical laminoplasty (LMP). However, the impact of postoperative cervical ROM on CSA after cervical LMP is still unclear.

PURPOSE

Evaluating the imaging and symptomatic data from patients with cervical spondylotic myelopathy (CSM) to identify the influence of postoperative cervical ROM on post-LMP CSA and surgical outcomes.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Eighty-six patients undergoing LMP due to multilevel CSM OUTCOME MEASURES: Radiographic parameters were measured before surgery and at follow-up: cervical lordosis (CL), T1 slope (T1S), cervical sagittal vertical axis (cSVA), CL in flexion (Flex CL), CL in extension (Ext CL), total cervical spine range of motion (ROM), cervical spine range of flexion (Flex ROM), and cervical spine range of extension (Ext ROM). Japanese Orthopedic Association (JOA) and visual analog score (VAS) were used to assessed clinical outcomes. Other parameters included age, gender, body mass index (BMI), follow-up time, number of surgical segments, proximal level, distalis level, and collar wear time.

METHODS

We divided patients according to the changes in CSA (loss of cervical lordosis (LCL)>10°, or ≤10°; an increase in cervical sagittal vertical axis (I-cSVA) >10mm, or ≤10mm). A receiver-operating characteristic curve (ROC) analysis was constructed to identify the optimal cut-off value to discriminate the patients with and without postoperative deterioration of CSA.

RESULTS

The postoperative total and Flex ROM were significantly lower in the LCL>10° and I-cSVA>10mm groups. Multivariate logistic regression analysis showed that low post-Flex ROM was significant risk factor for postoperative deterioration of CSA. ROC showed that the cut-off value for postoperative Flex ROM was 15.60°. Improvements in JOA recovery rate and neck pain were more significant in the flexibility group (post-Flex ROM ≥15.6°) after surgery. Patients in the stiffness group (post-Flex ROM <15.6°) wore a collar longer.

CONCLUSIONS

The preservation of cervical flexibility can maintain CSA after cervical LMP. Postoperative cervical stiffness is related to poor surgical outcomes because significant cervical kyphotic change and sagittal imbalance are likely to occur after surgery. Prolonged wearing of cervical collar is correlated with cervical stiffness following cervical LMP.

Greater cervical kyphosis during flexion increases the risk of kyphotic deformity after laminoplasty in patients with cervical spondylotic myelopathy

Kyphotic deformity following the loss of cervical lordosis can lead to unfavourable neurological recovery after cervical laminoplasty (CLP); therefore, it is essential to identify its risk factors. Recent studies have demonstrated that the dynamic parameters of the cervical spine, based on baseline flexion/extension radiographs, are highly useful to estimate the loss of cervical lordosis after CLP. However, it remains unclear whether such dynamic parameters can predict kyphotic deformity development after CLP. Hence, the present study aimed to investigate whether the dynamic parameters could predict kyphotic deformity in patients with cervical spondylotic myelopathy (CSM) after CLP. This retrospective study included 165 patients, consisting of 10 and 155 patients with and without cervical kyphosis of C2-C7 angle ≤ -10° at the final follow-up period, respectively. Among the static and dynamic parameters of the cervical spine, greater cervical kyphosis during flexion (fC2-C7 angle) demonstrated the best discrimination between these two cohorts, with an optimal cutoff value of -27.5°. Meanwhile, greater gap range of motion (gROM = flexion ROM - extension ROM ) had the highest ability to predict a loss of ≥ 10° in C2-C7 angle after CLP, with an optimal cutoff value of 28.5°. This study suggests that in patients with CSM, fC2-C7 angle ≤ -25° on baseline radiographs is a potential risk for kyphotic deformity after CLP. In clinical practice, the patients with this criterion (fC2-C7 angle ≤ -25°) along with gROM ≥ 30° are at high risk of developing significant kyphotic deformity after CLP.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament

PURPOSE

This study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS).

METHODS

We retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups.

RESULTS

At the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05).

CONCLUSION

CL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

Preoperative Cervical Range of Motion in Flexion as a Risk Factor for Postoperative Cervical Sagittal Imbalance After Laminoplasty

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate factors associated with cervical sagittal imbalance (CSI) after cervical laminoplasty (LMP).

SUMMARY OF BACKGROUND DATA

Preoperative dynamic cervical sagittal alignment is an important predictor for changes in cervical sagittal alignment and clinical outcomes after LMP. However, the impact of preoperative dynamic cervical sagittal alignment on postoperative changes in the cervical sagittal vertical axis (cSVA) after LMP remains unclear. We hypothesized that preoperative cervical flexion and extension function are associated with the changes in cSVA and clinical outcomes and found potential risk factors for post-LMP CSI.

PATIENTS AND METHODS

Patients undergoing LMP at a single institution between January 2019 and December 2021 were retrospectively reviewed. The average follow-up period was 19 months. The parameters were collected before the surgery and at the final follow-up. We defined the changes in cSVA (△cSVA) ≤ -10 mm as the improvement group, -10 mm < △cSVA ≤ 10 mm as the stable group, and △cSVA > 10 mm as the deterioration group. Multivariate logistic regression was used to evaluate factors associated with postoperative CSI. The χ 2 test was used to compare categorical data between groups. T tests, analysis of variance, Kruskal-Wallis tests, and Mann-Whitney Wilcoxon tests were used to assess the differences between radiographic and clinical parameters among groups. A receiver operating characteristic curve analysis was used to identify optimal cutoff values.

RESULTS

The study comprised 102 patients with cervical spondylotic myelopathy. The Japanese Orthopedic Association recovery rate was better in the improvement group and a significant aggravation in neck pain was observed in the deterioration group after surgery. Cervical Flex range of motion (ROM; spine range of flexion) was significantly higher in the deterioration group. The multivariate logistic regression model suggested that greater Flex ROM and starting LMP at C3 were significant risk factors for postoperative deterioration of cervical sagittal balance. Receiver operating characteristic curves showed that the cutoff value for preoperative Flex ROM was 34.10°.

CONCLUSION

Preoperative dynamic cervical sagittal alignment influences postoperative cervical sagittal balance after LMP. Cervical LMP should be carefully considered for patients with a preoperative high Flex ROM, as CSI is likely to occur after surgery.

LEVEL OF EVIDENCE

Level 3.

Current Concepts of Cervical Spine Alignment, Sagittal Deformity, and Cervical Spine Surgery

There are not many reports on cervical spine alignment, and only a few analyze ideal surgical approaches and optimal amounts of correction needed for the various types of deformity. We comprehensively reviewed the present literature on cervical spinal deformities (with or without myelopathy) and their surgical management to provide a framework for surgical planning. A general assessment of the parameters actually in use and correlations between cervical and thoracolumbar spine alignment are provided. We also analyzed posterior, anterior, and combined cervical surgical approaches and indications for the associated techniques of laminoplasty, laminectomy and fusion, and anterior cervical discectomy and fusion. Finally, on the basis of the NDI, SF-36, VAS, and mJOA questionnaires, we fully evaluated the outcomes and measures of postoperative health-related quality of life. We found the need for additional prospective studies to further enhance our understanding of the importance of cervical alignment when assessing and treating cervical deformities with or without myelopathy. Future studies need to focus on correlations between cervical alignment parameters, disability scores, and myelopathy outcomes. Through this comprehensive literature review, we offer guidance on practical and important points of surgical technique, cervical alignment, and goals surgeons can meet to improve symptoms in all patients.

Multilevel Laminoplasty for CSM: Is C3 Laminectomy Better Than C3 Laminoplasty at the Superior Vertebra?

INTRODUCTION

In a multilevel cervical laminoplasty operation for patients with cervical spondylotic myelopathy (CSM), a partial or complete C3 laminectomy may be performed at the upper level instead of a C3 plated laminoplasty. It is unknown whether C3 technique above the laminoplasty affects loss of cervical lordosis or range of motion.

METHODS

Patients undergoing multilevel laminoplasty of the cervical spine (C3-C6/C7) at a single institution were retrospectively reviewed. Patients were divided into two cohorts based on surgical technique at C3: C3-C6/C7 plated laminoplasty ("C3 laminoplasty only", N = 61), C3 partial or complete laminectomy, plus C4-C6/C7 plated laminoplasty (N = 39). All patients had at least 1-year postoperative X-ray treatment.

RESULTS

Of 100 total patients, C3 laminoplasty and C3 laminectomy were equivalent in all demographic data, except for age (66.4 vs. 59.4 years, p = 0.012). None of the preoperative radiographic parameters differed between the C3 laminoplasty and C3 laminectomy cohorts: cervical lordosis (13.1° vs. 11.1°, p = 0.259), T1 slope (32.9° vs. 29.2°, p = 0.072), T1 slope-cervical lordosis (19.8° vs. 18.6°, p = 0.485), or cervical sagittal vertical axis (3.1 cm vs. 2.7 cm, p = 0.193). None of the postoperative radiographic parameters differed between the C3 laminoplasty and C3 laminectomy cohorts: cervical lordosis (9.4° vs. 11.2°, p = 0.369), T1 slope-cervical lordosis (21.7° vs. 18.1°, p = 0.126), to cervical sagittal vertical axis (3.3 cm vs. 3.6 cm, p = 0.479). In the total cohort, 31% had loss of cervical lordosis >5°. Loss of lordosis reached 5-10° (mild change) in 13% of patients and >10° (moderate change) in 18% of patients. C3 laminoplasty and C3 laminectomy cohorts did not differ with respect to no change (<5°: 65.6% vs. 74.3%, respectively), mild change (5-10°: 14.8% vs. 10.3%), and moderate change (>10°: 19.7% vs. 15.4%) in cervical lordosis, p = 0.644. When controlling for age, ordinal regression showed that surgical technique at C3 did not increase the odds of postoperative loss of cervical lordosis. C3 laminectomy versus C3 laminoplasty did not differ in the postoperative range of motion on cervical flexion-extension X-rays (23.9° vs. 21.7°, p = 0.451, N = 91).

CONCLUSION

There was no difference in postoperative loss of cervical lordosis or postoperative range of motion in patients who underwent either C3-C6/C7 plated laminoplasty or C3 laminectomy plus C4-C6/C7 plated laminoplasty.

Preoperative Range of Motion in Extension May Influence Postoperative Cervical Kyphosis After Laminoplasty

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

The objective of this study was to investigate factors associated with cervical kyphosis after laminoplasty.

SUMMARY OF BACKGROUND DATA

Many factors are reportedly associated with the deterioration of cervical curvature after laminoplasty, including cervical lordosis angle, cervical spine range of motion (ROM), T1 slope, and C2-C7 sagittal vertical axis. Postlaminoplasty kyphosis or deterioration of cervical curvature is likely caused by multiple factors. There is currently no consensus on these issues.

MATERIALS AND METHODS

Data of patients treated with laminoplasty for degenerative cervical myelopathy at our institution during 2008-2018 were reviewed. The following variables were collected for each patient: age and sex; follow-up time; surgery involving C3 (yes or no); surgery involving C7 (yes or no); distribution of segments operated on; number of laminae operated on; flexion, extension, and total ROM; cervical lordotic angle; longitudinal distance index; curvature index; C2-C7 sagittal vertical axis; and T1 slope. Logistic regression analysis was used to assess possible risk factors for postoperative kyphosis. Receiver operating characteristic curves were constructed to determine the cutoff values of risk factors.

RESULTS

The study cohort comprised 151 patients. Logistic regression analysis indicated that sex, number of laminae operated on, and preoperative extension ROM were significantly associated with postoperative cervical kyphosis ( P <0.05). There was significantly greater postoperative kyphosis in women than in men; the more segments operated on, the greater the risk of postoperative kyphosis, and the larger the preoperative extension ROM, the lower the risk of postlaminoplasty kyphosis. Receiver operating characteristic curve analysis showed that the cutoff value for preoperative extension ROM is 22.1°.

CONCLUSIONS

Preoperative extension ROM may be associated with the development of postoperative kyphosis. The cutoff value of preoperative extension ROM that suggested the prospect of postoperative kyphosis in our sample was 22.1°.

Differences in Risk Factors for Decreased Cervical Lordosis after Multiple-Segment Laminoplasty for Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: A Pilot Study

STUDY DESIGN

Retrospective study.

PURPOSE

To compare the radiographic risk factors for decreased cervical lordosis (CL) after laminoplasty, focusing on the difference between cervical spondylotic myelopathy (CSM) and cervical ossification of the posterior longitudinal ligament (C-OPLL).

OVERVIEW OF LITERATURE

A few reports compared the risk factors for decreased CL between CSM and C-OPLL although these two pathologies have their characteristics.

METHODS

This study included 50 patients with CSM and 39 with C-OPLL who underwent multi-segment laminoplasty. Decreased CL was defined as the difference between preoperative and 2-year postoperative neutral C2-7 Cobb angles. Radiographic parameters included preoperative neutral C2-7 Cobb angles, C2-7 sagittal vertical axis (SVA), T1 slope (T1S), dynamic extension reserve (DER), and range of motion. The radiographic risk factors were investigated for decreased CL in CSM and C-OPLL. Additionally, the Japanese Orthopedic Association (JOA) score was assessed preoperatively and 2 years postoperatively.

RESULTS

C2-7 SVA (p =0.018) and DER (p =0.002) were significantly correlated with decreased CL in CSM, while C2-7 Cobb angle (p =0.012) and C2-7 SVA (p =0.028) were correlated with decreased CL in C-OPLL. Multiple linear regression analysis revealed that greater C2-7 SVA (B =0.22, p =0.026) and small DER (B =-0.53, p =0.002) were significantly associated with decreased CL in CSM. By contrast, greater C2-7 SVA (B =0.36, p =0.031) was significantly associated with decreased CL in C-OPLL. The JOA score significantly improved in both CSM and C-OPLL (p <0.001).

CONCLUSIONS

C2-7 SVA was associated with a postoperative decreased CL in both CSM and C-OPLL, but DER was only associated with decreased CL in CSM. Risk factors for decreased CL slightly differed depending on the etiology of the condition.

Can C7 Slope Accurately Substitute for an Invisible T1 Slope According to Age and Cervical Morphology in Cervical Lateral Radiographs?

STUDY DESIGN

A retrospective radiologic study.

OBJECTIVES

To identify age-associated changes in T1 slope (T1S) and C7 slope (C7S), as well as the difference between T1S and C7S (△, which was defined as T1S minus C7S) and to explore the cervical morphology that C7S can be the most accurate alternative for the invisible T1S.

METHODS

625 asymptomatic Chinese volunteers received cervical lateral radiographs from August 2021 to May 2022. Occipito-C2 angle (O-C2), C2-7 angle (C2-7), cranial arch, caudal arch, C7S, and T1S were examined. Thereafter, the △ was established. The correlations among T1S, C7S, △ and other cervical sagittal parameters, and between age and other cervical sagittal parameters were evaluated with the Pearson correlation coefficient analysis. Then, analysis of variance (ANOVA) was conducted to compare variations in cervical sagittal parameters among volunteers aged 40 to 59 years, 60 to 64 years, 65 to 69 years, 70 to 74 years, and ≥75 years of age, and among volunteers with 1 lordotic morphology, 2 lordotic morphology, straight morphology, kyphotic morphology, 1 sigmoid morphology, and 2 sigmoid morphology. Linear regression modeling of the correlation between C7S and T1S in various cervical alignment patterns was then established.

RESULTS

△ had the strongest correlation with caudal arch (r = .646), and weakest correlation with cranial arch (r = -.082). Age was significantly correlated with T1S (r = .250), C7S (r = .244), and △ (r = .112). Among them, △ was stable until 74 years after which it showed an elevation from 3.3° in the group 70-74 years to 4.1° in the group over 75 years. Moreover, there was marked variation between T1S and C7S at 1 lordotic, 2 lordotic, straight and 2 sigmoid alignment patterns, but no difference was seen between T1S and C7S at kyphotic and 1 sigmoid alignment patterns.

CONCLUSIONS

There was a progressive increase in T1S, C7S, and △ with age. Linear regression equations for accurate prediction of T1S were developed based on the C7S in 1 lordotic, 2 lordotic, straight and 2 sigmoid alignment patterns. C7S may be a reliable proxy for T1S in kyphotic and 1 sigmoid alignment patterns.

Indication of C2-C7 Cervical Laminoplasty with Muscle and Ligament Preservation in Patients with Kyphosis

OBJECTIVE

Cervical laminoplasty is generally not indicated in patients with kyphosis because of poor outcomes. Therefore, data on the effectiveness of posterior structure-preserving techniques in patients with kyphosis are limited. This study investigated how laminoplasty with muscle and ligament preservation can benefit patients with kyphosis via risk factor analyses of postoperative complications.

METHODS

Clinicoradiological outcomes of 106 consecutive patients, including patients with kyphosis, who had undergone C2-C7 laminoplasty in a muscle- and ligament-preserving fashion, were retrospectively analyzed. Surgical outcomes, including neurological recovery, were assessed, and sagittal parameters were measured on radiographs.

RESULTS

Surgical outcomes of patients with kyphosis were comparable to outcomes of other patients except for axial pain (AP), which was significantly more frequent in patients with kyphosis. Moreover, AP was significantly associated with alignment loss (AL) >0°. Substantial local kyphosis (local kyphosis angle >10°) and greater value of range of motion (ROM) during flexion minus ROM during extension were identified as risk factors for AP and AL >0°, respectively. Receiver operating characteristic curve analysis indicated ROM during flexion minus ROM during extension cutoff value of 0.7° for predicting AL >0° in patients with kyphosis (sensitivity: 77%; specificity: 84%). Substantial local kyphosis combined with ROM during flexion minus ROM during extension >0.7° had 56% sensitivity and 84% specificity for predicting AP in patients with kyphosis.

CONCLUSIONS

Although patients with kyphosis had a significantly higher incidence of AP, C2-C7 cervical laminoplasty with muscle and ligament preservation may not be contraindicated in selected patients with kyphosis by risk stratification for AP and AL using newly identified risk factors.

Factors related to T1 slope: spinopelvic balance and thoracic compensation

OBJECTIVE

To identify factors associated with T1 slope (T1S).

METHODS

A total of 215 patients over 18 years old who underwent whole-spine X-rays to evaluate lower back pain were enrolled in this study. T1S, pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), thoracic kyphosis (TK), lumbar lordosis (LL), cervical lordosis (CL), thoracolumbar kyphosis (TLK), and sagittal vertical axis (SVA) were measured. Patients were divided into balance, compensatory balance, thoracic compensation, and thoracic decompensation groups.

RESULTS

TK (p < 0.001), SVA (p < 0.001), and CL (p = 0.020) were significantly related to high T1S. The balance group had the smallest PT, largest SS and largest LL of the four groups (p < 0.001). The thoracic compensation group had the smallest TK of all groups (p < 0.001). There was no significant difference in T1S between the balance and thoracic compensation groups (p = 0.099). The thoracic decompensation group had a larger T1S than the balance group (p = 0.023).

CONCLUSIONS

Caudal spine segments had a sequential effect on cranial spine segments. T1S reflected the compensation ability of the spine. The absence of balance tended to increase the T1S. Pelvic posterior rotation and thoracic compensation were two crucial factors protecting against increased T1S in patients with ASD.

Effect of preoperative dynamic cervical sagittal alignment on the loss of cervical lordosis after laminoplasty

PURPOSE

Cervical laminoplasty (CLP) is a developed surgical procedure for the treatment of cervical spondylotic myelopathy (CSM), but only a few of those studies focus on preoperative dynamic cervical sagittal alignment and the study of different degrees of loss of cervical lordosis (LCL) is lacking. This study aimed to analyze patients who underwent CLP to investigate the effect of cervical extension and flexion function on different degrees of LCL.

METHODS

In this retrospective case-control study, we analyzed 79 patients who underwent CLP for CSM between January 2019 and December 2020. We measured the cervical sagittal alignment parameters on lateral radiographs (neutral, flexion, and extension positions) and used Japanese Orthopedic Association (JOA) score to assess clinical outcomes. We defined the extension ratio (EXR) as 100 × Ext ROM (cervical range of extension)/ROM (cervical range of motion). We observed the relationships between collected variables (demographic and radiological variables) and LCL. Patients were classified into the following three groups according to the LCL: stability group: (LCL ≤ 5°); mild loss group (5° < LCL ≤ 10°); and severe loss group (LCL > 10°). We compared the differences of collected variables (demographic, surgical and radiological variables) among the three groups.

RESULTS

Seventy-nine patients were enrolled (mean age 62.92 years; 51 men, 28 women) in the study. Among the three groups, cervical Ext ROM was the best in the stability group (p < 0.01). Compared with the stability group, range of flexion (Flex ROM) was significantly higher (p < 0.05) and EXR was significantly lower (p < 0.01) in the severe loss group. Compared with the severe loss group, JOA recovery rates were better (p < 0.01) in the stability group. Receiver-operating characteristic curve (ROC) analysis to predict LCL > 10° (area under the curve = 0.808, p < 0.001). The cutoff value for EXR was 16.80%, with sensitivity and specificity of 72.5% and 82.4%, respectively.

CONCLUSION

CLP should be carefully considered for patients with a preoperative low Ext ROM and high Flex ROM, as a significant kyphotic change is likely to develop after surgery. EXR is a useful and simple index to predict significant kyphotic changes.

Cervical sagittal alignment changes following anterior cervical discectomy and fusion, laminectomy with fusion, and laminoplasty for multisegmental cervical spondylotic myelopathy

OBJECTIVE

Cervical sagittal alignment changes (CSACs) influence outcomes and health-related quality-of-life. Anterior cervical discectomy and fusion (ACDF), laminectomy with fusion (LCF), and laminoplasty (LP) are common treatments for multisegmental cervical spondylotic myelopathy; however, these approaches need to be compared.

METHODS

Our study included 167 patients who underwent ACDF, LCF, or LP. Patients were divided into four groups according to C2-C7 Cobb angle (CL): kyphosis (CL < 0°), straight (0° ≤ CL < 10°), lordosis (10° ≤ CL < 20°), and extreme lordosis (20° ≤ CL) groups. CSACs consist of two parts. CSAC from the preoperative period to the postoperative period is surgical correction change (SCC). CSAC from the postoperative period to the final follow-up period is postoperative lordosis preserving (PLP). Outcomes were evaluated using the Japanese Orthopaedic Association score and the neck disability index.

RESULTS

ACDF, LCF, and LP had equivalent outcomes. ACDF had greater SCC than LCF and LP. During follow-up, lordosis decreased in the ACDF and LCF groups but increased in the LP group. For straight alignment, ACDF had greater CSAC and greater SCC than the LCF and LP groups but similar PLP. For lordosis alignment, ACDF and LP had positive PLP, and LCF had negative PLP. For extreme lordosis, ACDF, LP, and LCF had negative PLP; however, cervical lordosis in the LP group was relatively stable during follow-up.

CONCLUSIONS

ACDF, LCF, and LP have different CSAC, SCC, and PLP according to a four-type cervical sagittal alignment classification. Preoperative cervical alignment is an important consideration in deciding the type of surgical treatment in CSM.

Preoperative Decreased Hounsfield Unit Values of Cervical Vertebrae and the Relative Cross-Sectional Area of Flexion/Extension Paraspinal Muscles Are Novel Risk Factors for the Loss of Cervical Lordosis after Open-Door Laminoplasty

Open-door laminoplasty is widely used for patients with cervical spondylotic myelopathy (CSM). However, the loss of cervical lordosis (LCL) seems to be unavoidable in the long-term follow-up after surgery, which may affect the clinical outcomes. The risk factors for this complication are still unclear. In this study, patients who underwent open-door laminoplasty between April 2016 and June 2021 were enrolled. Cervical X-rays were obtained to measure the C2–7 Cobb angle, C2–7 sagittal vertical axis (SVA), T1 slope (T1S) and ranges of motion (ROM). Cervical computed tomography (CT) scans and magnetic resonance imaging (MRI) were collected to evaluate the cervical Hounsfield unit values (HU) and the relative cross-sectional area (RCSA) of paraspinal muscles, respectively. A total of 42 patients were included and the average follow-up period was 24.9 months. Among the patients, 24 cases (57.1%) had a LCL of more than 5° at a 1-year follow-up and were labeled as members of the LCL group. The follow-up JOA scores were significantly lower in the LCL group (13.9 ± 0.6 vs. 14.4 ± 0.8, p = 0.021) and the mean JOA recovery rate was negatively correlated with LCL (r = −0.409, p = 0.007). In addition, LCL was positively correlated to the preoperative T1S, flexion ROM, flexion/extension ROM and the RCSA of flexion/extension muscles, while it was negatively correlated to extension ROM and the HU value of cervical vertebrae. Furthermore, multiple linear regression showed that preoperative T1S, mean HU value of cervical vertebrae, flexion/extension ROM and the flexion/extension RCSA were independent risk factors for LCL. Spine surgeons should consider these parameters before performing open-door laminoplasty.

Cervical alignment and clinical outcome of open-door laminoplasty vs. laminectomy and instrumentation in kyphotic multilevel cervical degenerative myelopathy

INTRODUCTION

The aim of this study was to determine whether the sagittal lordotic alignment, clinical outcomes and axial symptoms (AS) could be improved by kyphotic correction through the posterior approach for the treatment of multilevel cervical degenerative myelopathy (CDM) and to further analyze the changes of cervical spinal alignment parameters after correction of kyphosis. The hypothesis was that correction of kyphosis can improve the severity of AS and neurological recovery.

MATERIALS AND METHODS

We retrospectively reviewed 109 patients who suffered from multilevel CDM combined with kyphosis. The patients had undergone open-door laminoplasty (Group LP, 53 patients) and laminectomy with instrumentation (Group LI, 56 patients) between January 2014 and December 2018. Cervical spinal alignment parameters, including curvature index (CI), T1 slope, C2-7 Cobb angle, C2-7 SVA, were measured on the pre- and postoperative lateral radiographs. The recovery rate was calculated based on the Japanese Orthopedic Association (JOA) score. AS severity was quantified using Neck Disability Index (NDI). A P value less than 0.05 was considered to be significant.

RESULTS

Analyses of postoperative follow-up data showed significant differences (P < 0.001) in CI, correction of CI, C2-7 Cobb angle, T1 slope, C2-7 SVA and NDI between Group LP and LI, but no significant differences in JOA score (P = 0.23) and recovery rate (P = 0.13). There were significant differences (P < 0.001) in CI, T1 slope, C2-7 Cobb angle, C2-7 SVA, JOA score, and NDI between pre- and postoperative follow-up in both groups. Correction of CI showed negative correlation with AS severity (r = -0.51, P < 0.001), and no association with recovery rate (r = 0.14, P = 0.15).

CONCLUSIONS

Satisfied neurological improvement was achieved by LP and LI for multilevel CDM combined with kyphosis. Cervical kyphotic correction produced significant improvement of AS and increase of T1 slope and C2-7 SVA. However, the kyphotic correction may not be associated with better neurological recovery in the short-term postoperative period.

Impact of cervical and global spine sagittal alignment on cervical curvature changes after posterior cervical laminoplasty

OBJECTIVE

To analyze the correlation between the changes in cervical curvature and the sagittal parameters of spino-pelvic and clinical efficacy after posterior laminoplasty (LP).

METHODS

The patients with cervical spondylosis treated with LP from June 2018 to December 2020 were reviewed. The preoperative and follow-up spine full-length films were measured. The measured data included C2-C7 Cobb angle, C2-7 sagittal vertical axis (SVA), T1 slope (T1S), pelvic incidence, sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), thoracic kyphosis (TK), and C7-SVA. Japanese Orthopaedic Association (JOA) score and neck disability index (NDI) score were recorded before surgery and follow-up.

RESULTS

There were 56 patients in this study. There were no significant differences in spino-pelvic sagittal parameters before and after surgery; however, the JOA score significantly improved. The changes in postoperative cervical lordosis correlated with SS, PT, LL, T1S, and C7-SVA (P < 0.05). Regression analysis showed that T1S and C7-SVA were associated with reducing cervical lordosis (P = 0.021 and P = 0.001, respectively). Patients with larger T1S combined with larger C7-SVA had more cervical lordosis loss, poor JOA improvement, and high postoperative NDI scores (P < 0.001, P = 0.018, and P < 0.001, respectively).

CONCLUSION

Patients should be examined with full-length spine film before surgery to evaluate the cervical and spino-pelvic sagittal balance. T1S and C7-SVA correlated with changes in cervical sagittal alignment after LP.

LEVEL OF EVIDENCE

III.

Does the asymmetry and extension function of the preoperative cervical paraspinal extensor predict postoperative cervical sagittal deformity in patients who undergo modified laminoplasty?

BACKGROUND CONTEXT

A previous study found that the cross-sectional area (CSA) of the preoperative cervical paraspinal extensors (CPEs) was associated with loss of cervical lordosis after laminoplasty, while a recent study found that CPE asymmetry was associated with symptoms of degenerative cervical myelopathy. Whether preoperative CPE asymmetry can predict cervical sagittal deformity (CSD) after laminoplasty is unknown.

PURPOSE

To assess whether asymmetry, degree of degeneration, and extension function of the CPE can be used as predictors of postoperative CSD in patients who undergo laminoplasty.

STUDY DESIGN

A retrospective study.

PATIENT SAMPLE

From January 2017 to December 2019, 55 patients with multilevel cord compression and myelopathic symptoms were enrolled.

OUTCOME MEASURES

The visual analog scale (VAS), neck disability index (NDI), and modified Japanese Orthopedic Association (mJOA) were used to assess cervical spinal function and quality of life.

METHODS

From January 2017 to December 2019, 55 patients undergoing modified laminoplasty were included. The following parameters were measured preoperatively and 24 months postoperatively on X-ray: (1) C0-C2 Cobb angle; (2) C2-C7 Cobb angle (CL); (3) T1 slope (T1S); (5) C2-C7 sagittal vertical axis (SVA); (6) T1S minus CL; (7) Preoperative extension function: Extension CL minus Neutral CL (EF). Preoperative global alignment parameters: (8) spino cranial angle, (9) C7-S1 sagittal vertical axis (C7 SVA), (10) pelvic incidence, (11) lumbar lordosis, (12) thoracic kyphosis. (13) Preoperative CPE parameters: Summation of bilateral total cross-sectional area (STCSA), summation of bilateral total cross-sectional area ratio (STCSAR), total cross-sectional area asymmetry, summation of bilateral functional cross-sectional area of muscle (SFCSA), summation of bilateral functional cross-sectional area of muscle ratio (FCSAR), and functional cross-sectional area of muscle asymmetry (FCSAA). The VAS, mJOA, and NDI were used to evaluate cervical spine function and quality of life. Patients were divided into the CSD group and the non-deformed group (N-CSD) group postoperatively, and the parameters between the two groups were compared. The Pearson correlation coefficient was used to evaluate the relationship between the parameters, and multiple regression analysis and ROC curve analysis were used to determine the predictors and key values.

RESULTS

Compared with functional scores, mJOA in the CSD group was significantly lower than that in the N-CSD group, while NDI and VAS were significantly higher. Postoperative CL was significantly correlated with EF, SFCSA/STCSA (C3-C6), SFCSAR (C4 and C6), STCSAR (C6), and FSCAA (C6). T1S minus CL was significantly correlated with EF, SFCSA/STCSA (C3-4 and C6), SFCSAR (C4 and C6), STCSAR (C6) and FSCAA (C6). C2-7 SVA was significantly correlated with EF, SFCSAR (C4 and C6), STCSAR (C6), and FSCAA (C6). Multiple regression analysis showed that FCSAA (C6), SFCSAR (C6), SFCSAR (C4), and EF were significant predictors of postoperative CSD. ROC curve analysis showed that the optimal cutoff points were 18.405, 2.95, 4.47, and 11.96.

CONCLUSIONS

The present study found that preoperative extension dysfunction of CPEs, asymmetry at the C6 level cervical extensors, and cervical extensor CSAs without fatty infiltration at the C4 and C6 levels were associated with cervical sagittal imbalance after modified laminoplasty. These factors can be considered when future spine surgeons formulate surgical plans.

Segmental cervical instability does not drive the loss of cervical lordosis after laminoplasty in patients with cervical spondylotic myelopathy

BACKGROUND/CONTEXT

Kyphotic deformity after cervical laminoplasty (CLP) often leads to unfavorable neurological recovery due to insufficient indirect decompression of the spinal cord. Existing literature has described that segmental cervical instability is a contraindication for CLP because it is a potential risk factor for kyphotic changes after surgery; however, this has never been confirmed in any clinical studies.

PURPOSE

To confirm whether segmental cervical instability was an independent risk factor for postoperative kyphotic change and to examine whether segmental cervical instability led to poor neurological outcomes after CLP for cervical spondylotic myelopathy (CSM).

STUDY DESIGN/SETTING

A retrospective study PATIENT SAMPLE: Patients who underwent CLP for CSM between January 2013 and January 2021 with a follow-up period of ≥1 year were enrolled.

OUTCOME MEASURES

Cervical radiographic measurements including C2-C7 lordosis (C2-7 angle), cervical sagittal vertical axis, C7 slope, flexion range of motion (fROM) and extension ROM (eROM) were assessed using neutral and flexion-extension views. Segmental cervical instability was classified into anterolisthesis (AL) of ≥2 mm displacement, retrolisthesis (RL) of ≥2 mm displacement, and translational instability (TI) of ≥3 mm translational motion. The amount of C2-7 angle loss at the follow-up period compared to the preoperative measurements was defined as cervical lordosis loss (CLL). Neurological outcomes were assessed using the recovery rate of the Japanese Orthopedic Association score (JOA-RR).

METHODS

CLL was compared among patients with and without segmental cervical instability. Further, multiple linear regression model for CLL was built for the evaluation with adjustment of the reported risks, including cervical sagittal vertical axis, C7 slope, fROM, eROM, and patient age together with AL, RL, and TI, as independent variables. The JOA-RR was also compared between patients with and without segmental cervical instability.

RESULTS

A total of 138 patients (mean age, 68.7 years; 65.9% male) were included in the analysis. AL, RL, and TI were found in 12 (8.7%), 33 (23.9%), and 16 (11.6%) patients, respectively. Comparisons among the groups showed that AL led to greater CLL; however, RL and TI did not. Multiple linear regression analysis revealed that greater CLL is significantly associated with greater fROM and smaller eROM (regression coefficient [β]=0.328, 95% confidence interval: 0.178 to 0.478, p<.001; β=-0.372, 95% confidence interval: -0.591 to -0.153, p=.001, respectively). However, there were no significant statistical associations in the AL, RL, and TI. Whereas, patients with AL tended to exhibit lower JOA-RR than those without AL (37.8% vs. 52.0%, p=.108).

CONCLUSIONS

Segmental cervical instability is not the definitive driver for loss of cervical lordosis after CLP in patients with CSM; thus, is not a contraindication in and of itself. However, it is necessary to consider the indications for CLP, according to individual cases of patients with AL on baseline radiograph, which is a sign of poor neurological recovery.

Impact of C3 Involvement on Postoperative Kyphosis Following Cervical Laminoplasty: A Comparison Between High and Low T1 Slope

BACKGROUND

The goal of the present study was to investigate the impact of C3 involvement on the postoperative kyphosis following cervical laminoplasty in patients with high and low T1S.

METHODS

The data from ossification of the posterior longitudinal ligament patients who had undergone laminoplasty between January 2016 and December 2019 were retrospectively reviewed. Patients were divided into low-and high-T1S groups according to preoperative T1S, and the postoperative alignment change was compared between the groups. The relationships between postoperative cervical kyphosis and preoperative variables, including gender, C3 laminoplasty, T1S, cervical lordosis (CL), C2-7 Sagittal Vertical Axis, and T1S minus CL (T1S-CL) were investigated.

RESULTS

Eighty-six patients were divided into 2 groups above and below median preoperative T1S (23.70). There were thirty-three patients (38.3%) in low-T1S group and fifty-three patients (61.7%) in high-T1S group. Twenty-three patients (26.7%) were performed with C3 involved laminoplasty. C3 laminoplasty (odds ratio [OR], 9.67; 2.82-33.16; P = 0.000), high T1S (OR, 4.89; 1.54-15.49; P = 0.007), and mismatched T1S-CL (OR, 5.96; 1.83-19.43; P = 0.003) were significantly associated with postoperative kyphosis. In high-T1S group, the loss of CL was significant (P = 0.017) when C3 laminoplasty was performed, whereas, in low-T1S group, the C3 laminoplasty did not show the statistically significant difference. (P = 0.194).

CONCLUSIONS

C3 laminoplasty, mismatched T1S-CL, and high T1S were found to increase the risk of postoperative kyphosis following cervical laminoplasty. Patients with high T1 slope tended to exhibit a greater loss of CL when the laminoplasty was performed extending to C3 segment.

Characterization of Clinical Symptoms of Cervical Spondylotic Myelopathy Based on DKI Imaging Parameter Ratios

In recent years, people's living conditions have significantly improved, and their lifestyles have been diversified. However, the incidence of various diseases has also increased with it, including cervical spondylotic myelopathy (CSM). Spinal cord cervical spondylosis is one of the spinal cord compression disorders that can be severely disabling and accounts for 10% to 15% of all cervical spondylosis. In this paper, DKI image processing technology is used to study the symptoms of cervical spondylosis, which is helpful to help them explore the symptoms and causes. The onset of cervical spondylosis has a longer period of time, and the period of conservative treatment will inevitably require a longer period of time. The clinical symptoms of cervical spinal cord compression are mainly pain, and after the cervical spinal cord nerve is compressed, ischemia and hypoxia will occur, the nerve sensitivity will increase, and the patient will have reflex neck muscle pain symptoms. This causes degeneration of the patient's intervertebral disc tissue, degeneration of facet joints, ossification of the posterior longitudinal ligament, and formation of spurs on the posterior edge of the vertebral body. The condition will become more complicated, so it is very important to identify the characteristics of the clinical symptoms of cervical spondylotic myelopathy to help patients with cervical spondylosis recover. This paper identifies the clinical symptoms of cervical spondylosis based on the parameter ratio method of Diffusional Kurtosis Imaging (DKI). The current state of diffusion kurtosis imaging and the treatment of cervical spondylosis and the treatment operation are introduced, and the image enhancement technology in medical imaging is used to analyze the disc herniation of each segment in the overflexion, neutral and hyperextension positions. After comparing the FA, MK, and MD values in the spinal cord between the normal group and the patient group, the results showed that the FA, MD and MK values in the patient group were lower than those in the normal group, and the findings showed that the MD and MK values were positively correlated with the JOA score, reflecting that as the clinical symptoms of spinal cervical spondylosis worsened. The size and number of cervical intervertebral disc bulge on the hyperextension image is obvious and the number increases (especially the C4/5, C5/6, and C6/7 intervertebral discs with greater mobility), and the highest is 0.82 and 27%, respectively.

Changes in T1 slope and cervical sagittal vertical axis correlate to improved neurological function recovery after cervical laminoplasty

Purpose

To investigate the influence of changes in T1 slope (T1S) and cervical sagittal vertical axis (CSVA) on cervical laminoplasty outcomes.

Methods

Eighty-one patients with cervical spondylotic myelopathy (CSM) treated with cervical laminoplasty were enrolled in this study. Demographic parameters included age and follow-up time. Imaging data included occiput-C2 lordosis (OC2), C2–C7 Cobb angle (CL), T1S, CSVA. Outcome assessment indicators included the Japanese Orthopedic Association (JOA) score, JOA recovery rate, and neck disability index (NDI). All patients were grouped based on preoperative T1S and variation in CL after surgery, respectively. Patients with decreased CL postoperatively were further grouped according to whether they were combined with T1S reduction.

Results

There were no significant differences in the final JOA score, JOA recovery rate, or NDI between patients with different T1S. Patients with loss of CL postoperatively had lower JOA score and JOA recovery rate, but higher NDI than patients with sustained CL. Furthermore, patients with CL loss but compensate for it with reduction in T1S had lower CSVA, higher JOA score and JOA recovery rate than those with CL loss alone.

Conclusions

Decreased T1S postoperatively prevents the tendency of the cervical spine to tilt forward by regulating CSVA and facilitates recovery of neurological function after cervical laminoplasty.

The discrepancy between preoperative cervical sagittal vertical axis and T1 slope predisposes inferior clinical outcomes in patients with cervical spondylotic myelopathy after cervical laminoplasty

Objective

Cervical sagittal parameters have been widely used to predict clinical outcomes in patients with cervical spondylotic myelopathy (CSM). This study aims to coin a novel cervical sagittal parameter defined as the ratio of cervical sagittal vertical axis to T1 slope (CSVA/T1S) and to investigate the correlation between CSVA/T1S and postoperative HRQOL after laminoplasty.

Methods

A total of 102 CSM patients treated with cervical laminoplasty from our database were retrospectively reviewed. All patients were followed up for >12 months. Radiological parameters were measured using lateral cervical radiographs, including occiput-C2 lordosis (OC2), cervical lordosis (CL), CSVA, and T1S. Clinical parameters included the Japanese Orthopedic Association (JOA) score, neck disability index (NDI), and JOA recovery rate. Patients were grouped by preoperative T1S, T1S-CL, and CSVA/T1S value, respectively. Clinical and radiological outcomes were compared between the groups.

Results

Patients with high CSVA/T1S had greater OC2 and CSVA but lower CL than those in the low CSVA/T1S group pre-and postoperatively. With respect to HRQOL results, the final NDI was 12.46 ± 9.11% in the low CSVA/T1S group, which was significantly lower than that in the high CSVA/T1S group (17.68 ± 8.81%, P = 0.040). Moreover, only CSVA/T1S was detected to be significantly correlated with final NDI (r = 0.310, P = 0.027). No significant correlation was found between clinical results and other cervical sagittal parameters, including T1S, CSVA, and T1S-CL.

Conclusions

Preoperative CSVA/T1S was correlated with postoperative NDI in patients with CSM after cervical laminoplasty. Patients with low preoperative CSVA/T1S achieved better neurological function improvement after cervical laminoplasty. Cervical laminoplasty could be an appropriate choice for patients with lower preoperative CSVA/T1S.

Does T1 slope minus cervical lordosis mismatch affect surgical outcomes of cervical laminoplasty in the absence of preoperative severe kyphosis?

Background

The impact of the T1 slope minus cervical lordosis (T1S-CL) on surgical outcomes in patients with degenerative cervical myelopathy undergoing laminoplasty (LP) remain uncertain.

Methods

One hundred patients who underwent cervical LP were retrospectively reviewed. Radiographic measurements included C2–C7 lordosis (CL), T1 slope (T1S), and C2–C7 sagittal vertical axis (SVA). Additionally, pain numeric rating scale, neck disability index (NDI), 12-Item Short-Form Health Survey, Euro QOL 5 dimensions (EQ5D), and Japanese Orthopedic Association score were investigated. According to past reports, T1S–CL > 20° was defined as mismatched. Then, based on T1S-CL mismatching, patients were divided into 2 groups.

Results

This research understudied 67 males and 33 females with a mean age of 67 y. Preoperatively, only eight patients showed a T1S-CL mismatch. While the C2–7 Cobb angles did not change significantly after surgery, the T1 slope (T1S) angle increased, increasing the T1S-CL as a result. As we compared the clinical outcomes based on the preoperative T1S-CL mismatching, there were no significant differences between the two groups. On the other hand, the number of patients in the mismatched group increased to 21 patients postoperatively. As we compared clinical outcomes based on the postoperative T1S-CL mismatching, the postoperative NDI score and preop/postop EQ5D score were significantly worse in the mismatch group.

Conclusions

Although cervical LP showed inferior outcomes in patients with postoperative T1S-CL mismatch even in the absence of severe preoperative kyphosis (> 10°), preoperative T1S-CL mismatch was not adversely prognostic.

Cervical foraminal stenosis as a risk factor for cervical kyphosis following cervical laminoplasty

BACKGROUND CONTEXT

Cervical laminoplasty (CLP) is an effective spinal cord decompression method for patients with cervical myelopathy. However, cervical kyphosis after CLP may cause insufficient decompression of the spinal cord. Thus, prevention of cervical kyphosis after CLP and identification of its risk factors are essential.

PURPOSE

This study aimed to investigate the relationship between preoperative cervical foraminal stenosis and kyphotic changes after CLP.

STUDY DESIGN

A retrospective study.

PATIENT SAMPLE

We reviewed 108 patients who underwent CLP for cervical myelopathy between May 2014 and May 2019 and who were followed up for at least 24 months.

OUTCOME MEASURES

For clinical assessments, neck pain, arm pain, neck disability index, Japanese Orthopedic Association scores, EuroQol 5-Dimension, and subjective improvement rate reported by the patients were evaluated. For radiologic parameters, C2-7 Cobb lordotic angle (CLA), C2-7 sagittal vertical axis, T1 slope (TS), TS minus CLA (TS-CLA), and cervical range of motion were assessed preoperatively and postoperatively for 24 months. Cervical foraminal stenosis was evaluated by magnetic resonance imaging and computed tomography.

METHODS

The study population was divided into the kyphosis group (n = 25 patients) and the lordosis group (n = 83 patients) according to the CLA at 24 months postoperatively. Preoperative risk factors related to postoperative kyphosis were analyzed. Statistical analyses were performed using independent two-sample t test, Chi-square test, logistic regression analysis, and linear mixed model.

RESULTS

Preoperative foraminal stenosis, CLA, TS, and TS-CLA were significantly different between the kyphosis and lordosis groups. In multivariate logistic regression analysis, foraminal stenosis (odds ratio [OR], 4.471; p = .0242) significantly increased the risk of kyphosis. The probability of developing kyphosis decreased with an increase in the CLA (OR, 0.840; p = .0001), while the probability of developing kyphosis increased with an increase in the TS-CLA (OR, 1.104; p = .0044).

CONCLUSIONS

Preoperative cervical foraminal stenosis is an independent risk factor for cervical kyphosis following CLP. Thus, CLP may not be a suitable surgical option for cervical myelopathy combined with foraminal stenosis.

The Preoperative Cross-sectional Area of the Deep Cervical Extensor Muscles Does Not Predict Loss of Lordosis After Cervical Laminoplasty

STUDY DESIGN

This was a retrospective, single center.

OBJECTIVES

The objective of this study was to investigate the association between the cross-sectional area (CSA) of the deep extensor muscles (DEM) and postlaminoplasty alignment.

SUMMARY OF BACKGROUND DATA

The preoperative CSA of the semispinalis cervicis (SC) has been reported to correlate with loss of lordosis (LL) after laminoplasty, with a CSA <154.5 mm2 associated with a 10 degrees LL.

METHODS

Laminoplasty patients at the University of California San Francisco between 2009 and 2018 by 2 spine surgeons were retrospectively studied. Patients with previous cervical surgery or nondegenerative diagnoses were excluded. Measurements included the C2-C7 Cobb, T1 slope, and cervical sagittal vertical axis. Preoperative DEM CSA was measured on magnetic resonance imaging. Variables associated with lordosis were analyzed with univariate analysis and multivariate logistic regression, and association between postoperative cervical alignment and the musculature was evaluated.

RESULTS

Seventy-six patients with a mean age of 64 years were included. The average follow-up was 22.53 months. The overall average CSA of the DEM was 2274.55 mm2 and that of the SC was 275.64 mm2. Means of both CSAs were higher in men (P<0.001). Linear regression showed no correlation between LL with CSA of the DEM or the SC (r=0.005, P=0.119; r=0.001, P=0.095). Univariate and multivariate regression showed no differences in the CSA of the DEM and SC between groups with and without LL (P=0.092, 0.117 and 0.163, 0.292). There was no correlation in LL with sex or body mass index (P>0.05).

CONCLUSIONS

Preoperative CSA of the deep cervical extensor muscles may not predict LL after cervical laminoplasty. The correlation between the preoperative SC CSA and postoperative cervical alignment may not be as strong as previously reported.

The Role of Nutrition in Degenerative Cervical Myelopathy: A Systematic Review

Introduction

Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord impairment worldwide, encompassing chronic compression of the spinal cord, neurological disability and diminished quality of life. Evidence on the contribution of environmental factors is sparse; in particular, the role of nutrition in DCM is unknown. The objective of this review was to assess the effect of nutrition on DCM susceptibility, severity and surgical outcome.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English papers, focussing on cervical myelopathy and nutrition, published before January 2020 were considered eligible. Quality assessments were performed using the GRADE assessment tool. Patient demographics, nutritional factor and DCM outcomes measures were recorded. Relationships between nutritional factors, interventions and disease prognosis were assessed.

Results

In total, 5835 papers were identified of which 44 were included in the final analysis. DCM patients with pathological weight pre-operatively were more likely to see poorer improvements post-surgically. These patients experienced poorer physical and mental health improvements from surgery compared to normal weight patients and were more likely to suffer from post-operative complications such as infection, DVT, PE and hospital readmissions. Two trials reporting benefits of nutritional supplements were identified, with 1 suggesting Cerebrolysin to be significant in functional improvement. An unbalanced diet, history of alcohol abuse and malnourishment were associated with poorer post-operative outcome.

Conclusion

Although the overall strength of recommendation is low, current evidence suggests nutrition may have a significant role in optimising surgical outcome in DCM patients. Although it may have a role in onset and severity of DCM, this is a preliminary suggestion. Further work needs to be done on how nutrition is defined and measured, however, the beneficial results from studies with nutritional interventions suggest nutrition could be a treatment target in DCM.

Spino cranial angle as a predictor of loss of cervical lordosis after laminoplasty in patients with cervical myelopathy

Background

To explore the relationship between spino cranial angle (SCA) and loss of cervical lordosis (LOCL), and to determine whether SCA has the ability to predict LOCL for patients with cervical myelopathy.

Methods

A total of 68 consecutive patients with cervical myelopathy who received laminoplasty (LAMP) were selected to the current study. C2–C7 lordosis was defined as a representation of the cervical alignment. Alignment change > 0° was considered LOCL. Multiple linear regression analysis was applied to evaluate the association between LOCL and various sagittal parameters at preoperative, such as SCA, CL, T1s and cSVA. Linear regression analysis was applied to evaluate the relationships between LOCL and preoperative SCA in each subgroup.

Results

Patients were assigned to three groups depending on the quartile of preoperative SCA. The first quarter of patients were defined as the low SCA group, the last quarter were defined as the high SCA group and the middle half were defined as the middle SCA group. There was no statistically significant difference in age, sex and the type of OPLL among the three groups. Patients in the low SCA group showed more cervical lordosis before surgery and more LOCL after LAMP (p < 0.001). After linear regression analysis for SCA and LOCL, preoperative SCA was negatively correlated with LOCL in the low SCA group (r = − 0.857, p < 0.001) and high SCA group (r = − 0.515, p = 0.034). However, there was no significant correlation between preoperative SCA and LOCL in the middle SCA group (r = 0.027, p = 0.881).

Conclusions

Patients with lower SCA had more lordosis preoperatively and performed more LOCL after LAMP at 2 years of follow-up. Both too high or low preoperative SCA were negatively correlated with the degree of LOCL, while when the SCA fluctuates in a suitable range, it is easier to compensate for the changes of cervical sagittal alignment.

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.

Laminoplasty with selective fusion at unstable segment versus laminectomy with fusion for multilevel cervical myelopathy: a case-control study

Background

Segmental cervical instability is a risk factor for the progression of osteophytic bone spurs and development of myelopathy, and is treated as a relative contraindication of cervical laminoplasty. The aim of this study was to compare laminoplasty with selective fixation (LPSF) versus laminectomy with fusion (LCF) in patients with multilevel cervical myelopathy accompanied by segmental instability.

Methods

A case-control study was conducted by reviewing data from 63 patients who underwent LPSF (n = 30) or LCF (n = 33). Cervical alignment, range of motion (ROM), neurologic status and axial symptom severity pre-operation, 3-days after operation, and at the final follow-up (minimum 24 months) were measured and compared between groups.

Results

Postoperation, patients in the LPSF group lost 31.1 ± 17.3 % of cervical lordosis and 43.2 ± 10.9 % cervical ROM while patients in the LCF group lost 5.7 ± 8.2 % and 67.9 ± 15.5 %, respectively. Both LPSF and LCF groups significantly improved neurologic status and axial symptom severity at the final follow-up with similar between-group results(P > 0.05). Blood loss, operation time, hospital stay, and medical cost in the LPSF group were significantly less than in the LCF group(P < 0.05).

Conclusions

In 2 years of clinical observation, LPSF was effective in maintaining the stability of the cervical spine with less sacrifice of mobility and surgical trauma for multilevel myelopathy with segmental instability compared to LCF.

Age-related Changes in T1 and C7 Slope and the Correlation Between Them in More Than 300 Asymptomatic Subjects

STUDY DESIGN

A cross-sectional analysis using T1 slope (T1S) and C7 slope (C7S) in asymptomatic individuals.

OBJECTIVE

The aim of this study was to identify normative values, ranges of motion (ROMs), age-related changes in T1S and C7S, and correlation between the two slopes.

SUMMARY OF BACKGROUND DATA

Few studies have reported age-related changes in the T1S and C7S angles. Additionally, studies investigating the effects of cervical position on these slopes are limited.

METHODS

A total of 388 asymptomatic subjects (162 males and 226 females) for whom T1S measurement was performed on radiographs were enrolled in the study. The T1S and C7S angles were measured using neutral radiography of the cervical spine. ROMs were assessed by measuring the difference in alignment in the neutral position, flexion, and extension.

RESULTS

The mean C7S and T1S angles were 19.6° (22.2° in males, 17.9° in females) and 24.0° (26.7° in men and 22.1° in women), respectively. The T1S angle was significantly greater than the C7S angle. Both the C7S and T1S angles significantly increased with age. The flexion ROM of C7S was higher than that of T1S, whereas no significant difference was detected between the extension ROMs of the two slopes. The flexion ROMs of the two slopes did not change, whereas the extension ROMs significantly increased with age. A significant positive correlation was observed between the C7S and T1S angles (r2 = 0.75).

CONCLUSION

The normative values and age-related changes in C7S and T1S were analyzed. Both the C7S and T1S angles increased with age. The C7S angle was strongly correlated with the T1S angle, suggesting that C7S can substitute T1S on radiographic images.Level of Evidence: 3.

Cervical Lordosis Ratio as a Novel Predictor for the Loss of Cervical Lordosis After Laminoplasty

Objective

Maintaining cervical lordosis (CL) after laminoplasty is important for indirect decompression of the spinal cord. This study aimed to identify preoperative dynamic radiographic predictors for the loss of CL after laminoplasty.

Methods

We retrospectively analyzed 141 consecutive patients who underwent cervical laminoplasty for cervical myelopathy. The following radiographic parameters were measured before surgery and at 1 year of follow-up: CL, C7 slope, C2–7 sagittal vertical axis (SVA), C2–7 range of motion (ROM), CL in flexion, CL in extension, ROM of flexion (Flex ROM), and ROM of extension. The CL ratio (CLR) was defined as 100 × Flex ROM/C2–7 ROM. ΔCL was defined as postoperative CL minus preoperative CL. Patients were classified into 2 groups: group K (kyphotic change group, ΔCL ≤ -10) and group C (control group, ΔCL > -10).

Results

The patient population comprised 94 men and 47 women (mean age, 70.9 ± 9.4 years), with 24 patients (17.0%) classified into group K. CL, C7 slope, and CLR were significantly higher in group K than in group C. The groups did not significantly differ in age, sex, C2–7 SVA, and C2–7 ROM. On multivariable analysis, the CLR was significantly associated with postoperative kyphotic changes. On receiver-operating characteristic curve analysis (area under the curve = 0.717, p < 0.001), the cutoff value for CLR was 68.9%, with sensitivity and specificity of 87.5% and 57.3%, respectively.

Conclusion

The CLR, reflecting the balance between flexion and extension mobility, was identified as a novel predictor for CL loss after laminoplasty, with a cutoff value of 68.9%.

Influence of SCA on clinical outcomes and cervical alignment after laminoplasty in patients with multilevel cervical spondylotic myelopathy

Background

To study the impact of changes in spino-cranial angle (SCA) on sagittal alignment and to investigate the relationship between SCA and Neck Disability Index (NDI) scores after laminoplasty (LP)

Material and methods

In total, 72 patients with multilevel cervical spondylotic myelopathy (MCSM) after laminoplasty (LP) were retrospectively enrolled. Based on the optimal cut-off values of preoperative SCA, patients were classified into low SCA and high SCA groups. Radiographic data were measured, including spino-cranial angle (SCA), T1-slope (T1s), C2–7 lordosis (CA), T1s minus CA (T1sCA), and C2–7 sagittal vertical axis (cSVA). JOA and NDI scores were both applied to assess postoperative and follow-up clinical efficacy. Pearson correlation coefficient and linear regression analysis were respectively calculated between radiographic data and between SCA and NDI.

Results

The preoperative SCA was significantly correlated with T1s (r = − 0.795), CA (r = − 0.857), and cSVA (r = 0.915). A receiver operating characteristic (ROC) curve model predicted a threshold of SCA (value of 85.2°). At the follow-up period, patients with lower SCA had a higher T1s and CA and a lower cSVA, simultaneously accompanied by greater △T1s, △CA, and △cSVA. The linear regression model demonstrated that SCA in the higher group was positively correlated with NDI, and patients with higher SCA had worse NDI scores (pre: p < 0.001; post: p < 0.001; F/U: p = 0.003) and greater changes of NDI (post: p < 0.010; F/U: p = 0.002).

Conclusion

SCA may be a good predictor of evaluating sagittal balance and planning surgery. Changes in sagittal alignment in the low SCA group were affected more easily, and a higher SCA was associated with worse quality of life. Laminoplasty could be a good choice for patients with lower SCA.

Prediction of angular kyphosis after cervical laminoplasty using radiologic measurements

Angular kyphosis is an important complication after cervical laminoplasty. Previous reports have suggested that T1 slope (T1s) and extension function (EF) have key roles in kyphosis, and no different radiologic measuments which affects postoperative kyphosis were seen between ossification of the posterior longitudinal ligament (OPLL) or cervical spondylotic myelopathy (CSM). We tried to find preoperative radiologic measurements predicting angular kyphosis after laminoplasty according to disease entities. We retrospectively analyzed 133 patients with OPLL or CSM who underwent expansive laminoplasty. Preoperative neutral and extension C2-7 cobb angle (CA), T1s, C2-7 sagittal vertical axis, and C2-7 slope angle (SA) were measured. EF of C2-7 CA and C2-7 SA was defined as extension CA/SA minus neutral CA/SA. Significant angular kyphosis was defined as LCL less than -10° after surgery. Mean loss of lordosis was -3.23, and 16.5% of patients showed significant kyphosis. Preoperative EF-CA, EF-SA, and T1s were found to be predictive for angular kyphosis by Pearson correlation analysis. The receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of radiologic measurements could not reach 0.7. In patients with OPLL, the AUC of preoperative neutral CA was 0.716. However, in patients with CSM ROC curve analysis revealed that EF-CA and EF-SA could predict the significant angular kyphotic changes. Examining OPLL and CSM separately, preoperative radiologic measurements were found to influence postoperative cervical kyphosis, respectively. However, preoperative C2-7 neutral CA in OPLL patients and both EF-CA and EF-SA in CSM patients could predict significant angular kyphosis after cervical laminoplasty.

The impact of plating level on the postoperative loss of cervical lordosis in alternative skipped-level plating laminoplasty

PURPOSE

The aim of this study is to evaluate the impact of plating level on the loss of cervical lordosis (LCL) after laminoplasty with skipped-level plating.

METHODS

This retrospective study included patients who underwent alternative skipped-level plating laminoplasty from C3 to C6. Patients were divided into two groups according to the plating level. Group 1 had miniplate fixed at C3 and C5 (C3/C5 group), while patients in group 2 were fixed at C4 and C6 (C4/C6 group). The outcome of interest was the difference of LCL between the two groups; meanwhile, kyphosis development after laminoplasty was also compared.

RESULTS

A total of 70 patients were included in our study with a mean age of 60.44 ± 9.97 years. The median follow-up was 15 (12, 16) months. Median lordosis was 15.43° (9.35°, 22.23°) before surgery and 9.88° (4.15°, 18.94°) after, with a median LCL of 4.48° (-0.66°, 8.11°). There were 17 patients in the C3/C5 group, whereas 53 patients in the C4/C6 group. While preoperative C2-C7 Cobb's angle was comparable between the two groups (15.32° (9.73°, 23.84°) vs. 15.51° (9.03°, 21.70°), p = 0.864), there were statistical differences regarding postoperative C2-C7 Cobb's angle (6.54° (2.49°, 16.42°) vs. 10.62° (5.89°, 18.85°), p = 0.006) and LCL (4.74° (4.17°, 12.03°) vs. 4.07° (-1.89°, 6.69°), p = 0.034) between the C3/C5 group and the C4/C6 group. In all, 94.1% (16 of 17) of patients showed some degree of LCL after laminoplasty in the C3/C5 group, which was significantly higher when compared with 64.2% (34 of 52) of C4/C6 group (p = 0.038). Before surgery, there were no kyphosis patients in either the C3/C5 group or the C4/C6 group. Postoperatively, four patients (23.5%) developed kyphotic alignment in the C3/C5 group, but only one (1.9%) in the C4/C6 group (p = 0.013).

CONCLUSIONS

Cervical alignment was compromised after laminoplasty. When alternative skipped-level plating is adopted in laminoplasty from C3 to C6, plating at C4/C6 may better preserve cervical lordosis than plating at C3/C5 after surgery.

The ratio of C2-C7 Cobb angle to T1 slope is an effective parameter for the selection of posterior surgical approach for patients with multisegmental cervical spondylotic myelopathy

BACKGROUND

To our knowledge, laminectomy with fusion (LCF) and laminoplasty alone (LP) are both effective posterior surgical approaches for decompression of cervical spondylotic myelopathy (CSM). However, which one is suitable for patients has no standard answer. This study estimated whether the ratio of C2-C7 Cobb angle to T1 slope (CL/T1S) could be an indication of posterior surgical approach.

METHODS

We retrospectively reviewed 128 patients with at least 6 months of follow-up who underwent LCF or LP. Radiological measurements, including C2-C7 Cobb angle, decompressed Cobb angle, T1 slope, cervical sagittal vertical axis, and curvature index (CI), and clinical outcomes, including Japanese Orthopedic Association score and visual analogue scale were evaluated. ROC curve analysis was used to identify discriminative power of CL/T1S ratio to predict kyphotic deformity and severe lordosis loss. The t-test and Mann-Whitney U-test were used to evaluate the difference between LCF and LP. Kruskal-Wallis H - test and ANOVA were used to evaluate the difference among different ratio CL/T1S groups.

RESULTS

The cervical lordosis decreased after LCF or LP (p < 0.001, p < 0.001, respectively). Based on ROC curve analysis, CL/T1S ratio had a good discriminative power to predict kyphotic deformity and severe lordosis loss (AUC = 0.70, AUC = 0.88, respectively). According to CI value changes, cervical lordosis losses in group LP were larger than that in group LCF (p = 0.006). However, there was no significant difference in CI changes of fair-ratio CL/T1S group between LCF and LP. For patients with low CL/T1S ratio or high CL/T1S ratio, CI changes in group LP were greater than that in group LCF (p = 0.037, p = 0.042, respectively).

CONCLUSIONS

CL/T1S ratio could be an indication of posterior surgical approach. Compared with LP, LCF reduces postoperative cervical lordosis losses in low-ratio and high-ratio CL/T1S groups.

Association between Changes in Sagittal X-ray Measurements and Neck Extensor Muscle Atrophy after Cervical Laminoplasty

BACKGROUND

To investigate the association between neck extensor muscles (NEM) atrophy and changes in the sagittal cervical X-ray measurements after cervical laminoplasty.

BASIC PROCEDURES

This retrospective analysis was conducted on 64 patients who underwent cervical laminoplasty from March 2016 to March 2019. The preoperative and postoperative sagittal cervical X-ray images were measured, including the C2-C7 cobb angle, the C2-7 sagittal vertical axis (SVA), and the angle between the plane of the upper endplate of T1 vertebra and the horizontal plane (T1 slope). The preoperative and postoperative steatosis ratios of the NEM were measured using magnetic resonance images.

MAIN FINDINGS

There were significant differences between the preoperative and postoperative measurements of the C2-7 cobb angle, the C2-7 SVA, and the T1 slope (P<0.05). The preoperative and postoperative steatosis ratios of each intervertebral level of the NEM also differed significantly (P<0.05). The muscle atrophy ratio at C3/4 was positively correlated with the change in the C2-7 SVA (R=0.646, P<0.001) and negatively correlated with the change in the C2-7 cobb angle (R=-0.445, P<0.001). The muscle atrophy ratio at C7/T1 was positively correlated with the T1 slope (R=0.446, P<0.001).

CONCLUSIONS

Muscle atrophy was more severe at the attachment points of the NEM (C3/4, C7T1). There was a significant association between the muscle atrophy ratio and the changes in sagittal cervical X-ray measurements.

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Background:

Laminoplasty is a method of posterior cervical decompression which indirectly decompresses the spinal column. Unfortunately, many patients undergoing laminoplasty develops postoperative loss of cervical lordosis (LCL) or kyphotic alignment of cervical spine even though they have sufficient preoperative lordosis which results in poor surgical outcome.

Objective:

We would like to highlight the relationship between various radiological parameters of cervical alignment and postoperative LCL in patients undergoing laminoplasty.

Methods:

We performed extensive literature search using PubMed, Google Scholar, and Web of Science for relevant articles that report factors affecting cervical alignment following laminoplasty.

Results:

On reviewing the literature, patients with high T1 slope have more lordotic alignment of cervical spine preoperatively. They also have more chances of LCL following laminoplasty. C2–C7 sagittal vertical axis (SVA) has no role in predicting LCL following laminoplasty though patients with low T1 slope (≤20°) and high C2–C7 SVA (>22 mm) had correction of kyphotic deformity following laminoplasty. C2–C7 lordosis, Neck Tilt, cervical range of motion, and thoracic kyphosis has no predictive value for LCL. Lower value of T1 slope (T1S-CL) and CL/T1S has more incidence of developing LCL following laminoplasty. The role of C2–C3 disc angle has not yet been evaluated in patients undergoing laminoplasty. Dynamic extension reserve determines the contraction reserve of SPMLC and lower dynamic extension reserve is associated with higher chances of LCL following laminoplasty.

Conclusions:

Cervical lordotic alignment is important in maintaining cervical sagittal balance which ultimately is responsible for global spinal sagittal balance and horizontal gaze. Among various radiological parameters, T1 Slope has been reported to be the most important factor affecting cervical alignment following laminoplasty.

Significance of flexion range of motion as a risk factor for kyphotic change after cervical laminoplasty

Kyphotic deformity is a rare but serious complication after cervical laminoplasty (CLP), and several studies have investigated its predictors. In these studies, a kyphotic Cobb angle of 0°-5° between C2 and C7 at a certain postoperative time-point was often used to detect kyphotic deformity. However, studies considering the amount of cervical lordosis loss compared to the preoperative measurement are scarce. This study aimed to elucidate risk factors for kyphotic change after CLP by comparing patients with and without marked loss of cervical lordosis postoperatively. The study population was divided into seven patients with and 92 patients without a loss of >10° of the C2-7 angle during the follow-up period compared to the preoperative measurements [cervical lordosis loss (CLL) group and no CLL (NCLL) group, respectively]; demographic characteristics, surgical information, preoperative radiographic sagittal parameters of the cervical spine, and posterior paravertebral muscle morphology evaluated by magnetic resonance imaging were compared between two groups. A univariate analysis revealed that the CLL group had significantly greater flexion range of motion (fROM) than the NCLL group (43.0° vs. 25.8°, P < 0.001); however, no statistical significance was identified for other parameters. The fROM had a high capacity to discriminate between the CLL and NCLL groups (area under the receiver-operating characteristic curve, 0.880; P < 0.001; 95% confidence interval, 0.589-0.974) with an optimal cutoff point of 37°. This study suggests that greater fROM is a risk factor for the development of kyphotic changes after CLP. For patients with preoperative fROM exceeding 40°, CLP should be carefully indicated.

Cervical alignment following laminoplasty for cervical spondylotic myelopathy

Background:

Laminoplasty can result in the loss of cervical lordosis (LOCL) or the development of kyphosis after surgery. Here, we evaluated the clinical and radiological parameters involved in predicting the postoperative LOCL following laminoplasty in patients with cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL).

Methods:

For 50 patients with CSM and 35 with OPLL undergoing laminoplasty, preoperative and 1-year postoperative X-rays were obtained to determine the incidence and risk factors contributing to postoperative LOCL. The patients were divided into two groups depending on whether the preoperative T1 slope was above or below the median preoperative T1S (26°); Group A – high T1 slope group (n = 40) and Group B – low T1 slope group (n = 45).

Results:

Following laminoplasty, Group A patients had significantly higher preoperative lordosis (C2-C7 Cobb’s angle) (P = 0.001) and significantly higher LOCL (P = 0.02) versus Group B patients with low T1 slopes. The preoperative T1 slope was also found to be significantly correlated with the preoperative C2-C7 Cobb’s angles (R = 0.619, P = 0.001), LOCL (R = 0.487, P = 0.001), and preoperative C2-C7 sagittal vertical axis (R = 0.480, P = 0.001). Utilizing multivariate analysis and a generalized linear model, the preoperative T1 slope significantly impacted the Oswestry disability index (ODI) index (P = 0.002) and frequency of LOCL (P = 0.001) following laminoplasty.

Conclusion:

The preoperative T1 slope is a significant predictor of the LOCL and change in ODI following laminoplasty for CSM/OPLL utilizing a cutoff value of 29.5°.

Association between sagittal balance and adjacent segment degeneration in anterior cervical surgery: a systematic review and meta-analysis

Background

ASD is a relatively common degenerative alteration after cervical surgery which occurs above or below the fused segment. In addition, some patients may need reoperation to treat severe ASD after the primary surgery. It was considered that sagittal balance is correlated with postoperative clinical outcomes; however, few studies have reported the influence of sagittal balance on ASD. The present study is designed to investigate whether sagittal balance impacts the pathology of adjacent segment disease (ASD) in patients who undergo anterior cervical surgery for degenerative cervical disease.

Methods

Databases including Pubmed, Embase, Cochrane library, and Web of Science were used to search for literature published before June 2018. Review Manager 5.3 was used to perform the statistical analysis. Sagittal balance parameters before and after surgery were compared between patients with and without ASD. Weighted mean difference (WMD) was summarized for continuous data and P < 0.05 was set for the level of significance.

Results

A total of 221 patients with ASD and 680 patients without ASD from seven articles were studied in this meta-analysis. There were no significant differences in most sagittal balance parameters between the two groups, except for postoperative cervical lordosis (CL) (WMD -3.30, CI -5.91, − 0.69, P = 0.01).

Conclusions

Some sagittal balance parameters may be associated with the development of ASD after anterior cervical surgery. Sufficient restoration of CL may decrease the incidence of ASD. The results in present study needed to be expanded carefully and further high-quality studies are warranted to investigate the impact of sagittal balance on ASD.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2800-0) contains supplementary material, which is available to authorized users.

Which factors predict the loss of cervical lordosis following cervical laminoplasty? A review of various indices and their clinical implications

Background:

Many patients undergoing laminoplasty develop postoperative loss of cervical lordosis or kyphotic alignment of cervical spine despite sufficient preoperative lordosis. This results in poor surgical outcomes.

Methods:

Here, we reviewed the relationship between multiple radiological parameters of cervical alignment that correlated with postoperative loss of cervical lordosis in patients undergoing laminoplasty.

Results:

Patient with a high T1 slope (T1S) has more lordotic alignment of the cervical spine preoperatively and is at increased risk for the loss of cervical lordosis postlaminoplasty. Those with lower values of difference between T1S and Cobb’s angle (T1S-CL) and CL-T1S ratio have higher risks of developing a loss of the cervical lordosis postoperatively. Alternatively, C2-C7 lordosis, neck tilt, cervical range of motion, and thoracic kyphosis had no role in predicting the postlaminoplasty kyphosis.

Conclusion:

Among various radiological parameters, the preoperative T1S is the most important factor in predicting the postoperative loss of the cervical lordosis/alignment following laminoplasty.

Does Extension Dysfunction Affect Postoperative Loss of Cervical Lordosis in Patients Who Undergo Laminoplasty?

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate whether loss of cervical lordosis (LCL) after laminoplasty can be predicted from specific preoperative dynamic radiograph measurements.

SUMMARY OF BACKGROUND DATA

Recent studies have focused on the correlation between LCL after laminoplasty and T1 slope. These studies explain this correlation through the injury of the posterior neck muscular-ligament complex (PMLC); however, this muscle injury model could not explain the less kyphotic change in high T1s patients, as reported in some studies as controversy. We have focused on the PMLC constriction reservoir which was represented by extension function (EF).

METHODS

We retrospectively analyzed 50 consecutive patients who underwent open-door laminoplasty (>1-year follow-up). EF is defined as extension C2-7 Cobb angle (CA) minus neutral C2-7 CA (Ext CA - CA). LCL is defined as follow-up CA minus preoperative CA (CA [FU] - CA [PRE]), and significant kyphotic change was defined as LCL smaller than -10°.

RESULTS

The distribution of LCL was -3.70 ± 7.98 and the significant kyphotic change occurred in 20% of the patients (10/50). EF, C2-7 sagittal vertical axis (PRE), and C2 slope (PRE) were found to be risk factors for LCL by multiple linear regression analysis. The receiver operating characteristic curve analysis revealed that EF could predict the significant kyphotic change well than previously known risk factors. The cutoff value of EF was 14°. No significant kyphotic change occurred at EF greater than or equal to 14°. Upon limiting the number of patients with preoperative straight curvature (n = 28), there is also no significant kyphotic change occurred in any patient whose EF was greater than or equal to 14°.

CONCLUSION

In our study sample, we found that there is no relation between T1 slope and LCL. We have identified a new factor, EF, that could predict LCL after laminoplasty. No significant kyphotic changes after laminoplasty occurred particularly when the EF was greater than or equal to 14°.

LEVEL OF EVIDENCE

3.

Influence of the Ratio of C2–C7 Cobb Angle to T1 Slope on Cervical Alignment After Laminoplasty

PURPOSE

To assess the relationship between the ratio of C2-C7 Cobb angle to T1 slope (CL/T1S) and cervical alignment changes after laminoplasty.

METHODS

78 consecutive patients with cervical myelopathy who underwent laminoplasty were enrolled. All patients with preoperative and follow-up cervical spine lateral x-ray images available for review were recruited in this study. Imaging data included C2-C7 Cobb angle, T1 slope, and cervical sagittal vertical axis (cSVA). All patients were classified into low-ratio group (bottom 25% of CL/T1S), fair-ratio group (middle 50% of CL/T1S), and high ratio group (top 25% of CL/T1S) according to CL/T1S ratio. The recovery rate was calculated based on the Japanese Orthopedic Association score.

RESULTS

The preoperative C2-C7 Cobb angle had significant correlations with the T1 slope (r = 0.528). Kyphotic alignment changes in the group with a high ratio of CL/T1S was greater than that of the other 2 groups (P < 0.001). The incidence of postoperative kyphosis in the group with a low ratio of CL/T1S was higher than that of the other 2 groups (P < 0.001). There was no postoperative kyphosis in the fair-ratio group. The surgical outcome in the low-ratio CL/T1S group and the high-ratio CL/T1S group was poorer than that in the fair-ratio CL/T1S group (P = 0.005).

CONCLUSIONS

The cervical alignment was kept well in the mid-range CL/T1S ratio group after laminoplasty. Patients with a high CL/T1S ratio were more likely to present with kyphotic alignment changes. Patients with a low CL/T1S ratio were more likely to have postoperative kyphosis.

Predictive factors of symptomatic lumbar canal stenosis in patients after surgery for cervical spondylotic myelopathy

Background

The aim of this study was to determine the incidence of coexisting symptomatic lumbar canal stenosis (LCS) in patients after surgery for cervical spondylotic myelopathy (CSM) and identify possible predictive factors associated with it.

Materials and methods

We retrospectively reviewed patients with CSM at our institution between January 2005 and December 2015. Clinical and radiographic factors including age, gender, body mass index, Japanese Orthopedic Association scores, cervical alignment, anteroposterior diameter of cervical canal, number of levels with CSM, and percentage of cervical cord compression were investigated. Symptomatic LCS was defined as leg symptoms and a narrowing of the lumbar spinal canal at one level at least, which is confirmed by magnetic resonance images of the lumbar spine. Univariate and multivariate analyses were used to identify possible predictive factors. Pearson correlation analysis was also conducted to analyze the association between cervical parameters and percentage of LCS.

Results

A total of 317 patients with CSM met the criteria for inclusion. There were 39 patients (12.3%) with LCS after cervical surgery during a mean of 7.3 years’ follow-up. In the multivariate logistic regression analysis, narrow diameter of cervical canal (OR, 3.96; 95% CI, 1.20–13.04) was identified as the only independent predictor of symptomatic LCS in CSM patients. The correlation coefficient between anteroposterior diameter of cervical canal and severity of LCS indicated a significantly positive linear relationship with 0.536 (P<0.001).

Conclusion

We found that narrow diameter of cervical canal was associated with symptomatic LCS in CSM patients. Patients with this risk factor should be informed the possibility of symptomatic LCS.

[Correlation analysis of preoperative T 1 slope in MRI and physiological curvature loss after expansive open-door laminoplasty]

Objective

To investigate whether preoperative T ₁ slope (T ₁S) in MRI can predict the changes of cervical curvature after expansive open-door laminoplasty (EOLP) in patients with cervical spondylotic myelopathy, so as to make up for the shortcomings of difficult measurement in X-ray film.

Methods

The clinical data of 36 patients with cervical spondylotic myelopathy who underwent EOLP were retrospectively analysed. There were 21 males and 15 females with an average age of 55.8 years (range, 37-73 years) and an average follow-up time of 14.3 months (range, 12-24 months). The preoperative X-ray films at dynamic position, CT, and MRI of cervical spine before operation, and the anteroposterior and lateral X-ray films at last follow-up were taken out to measure the following sagittal parameters. The parameters included C ₂-C ₇ Cobb angle and C ₂-C ₇ sagittal vertical axis (C ₂-C ₇ SVA) in all patients before operation and at last follow-up; preoperative T ₁S were measured in MRI, and the patients were divided into larger T ₁S group (T ₁S>19°, group A) and small T ₁S group (T ₁S≤19°, group B) according to the median of T ₁S, and the preoperative T ₁S, C ₂-C ₇ Cobb angle, C ₂-C ₇ SVA, and the C ₂-C ₇ Cobb angle and C ₂-C ₇ SVA at last follow-up, difference in axial distance (the difference of C ₂-C ₇ SVA before and after operation), postoperative curvature loss (the difference of C ₂-C ₇ Cobb angle before and after operation), the number of patients whose curvature loss was more than 5° after operation, and the number of patients whose kyphosis changed (C ₂-C ₇ Cobb angle was less than 0° after operation).

Results

The C ₂-C ₇ Cobb angle at last follow-up was significantly decreased when compared with preoperative value ( t=8.000, P=0.000), but there was no significant difference in C ₂-C ₇ SVA between pre- and post-operation ( t=-1.842, P=0.074). The preoperative T ₁S was (19.69±3.39)°; there were 17 cases in group A and 19 cases in group B with no significant difference in gender and age between 2 groups ( P>0.05). The preoperative C ₂-C ₇ Cobb angle in group B was significantly lower than that in group A ( t=-2.150, P=0.039), while there was no significant difference in preoperative C ₂-C ₇ SVA between 2 groups ( t=0.206, P=0.838). At last follow-up, except for the curvature loss after operation in group B was significantly lower than that in group A ( t=-2.723, P=0.010), there was no significant difference in the other indicators between 2 groups ( P>0.05).

Conclusion

Preoperative larger T ₁S (T ₁S>19°) in MRI had a larger preoperative lordosis angle, but more postoperative physiological curvature was lost; preoperative T ₁S in MRI can not predict postoperative curvature loss, but preoperative larger T ₁S may be more prone to kyphosis.

Predictive factors associated with neck pain in patients with cervical disc degeneration: A cross-sectional study focusing on Modic changes

The predictive factors associated with neck pain remain unclear. We conducted a cross-sectional study to assess predictive factors, especially Modic changes (MCs), associated with the intensity and duration of neck pain in patients with cervical disc degenerative disease.We retrospectively reviewed patients in our hospital from January 2013 to December 2016. Severe neck pain (SNP) and persistent neck pain (PNP) were the 2 main outcomes, and were assessed based on the numerical rating scale (NRS). Basic data, and also imaging data, were collected and analyzed as potential predictive factors. Univariate analysis and multiple logistic regression analysis were performed to assess the predictive factors for neck pain.In all, 381 patients (193 males and 188 females) with cervical degenerative disease were included in our study. The number of patients with SNP and PNP were 94 (24.67%) and 109 (28.61%), respectively. The NRS of neck pain in patients with type 1 MCs was significantly higher than type 2 MCs (4.8 ± 0.9 vs 3.9 ± 1.1; P = .004). The multivariate logistic analysis showed that kyphosis curvature (odds ratio [OR] 1.082, 95% confidence interval [CI] 1.044-1.112), spondylolisthesis (OR 1.339, 95% CI 1.226-1.462), and annular tear (OR 1.188, 95% CI 1.021-1.382) were factors associated with SNP, whereas kyphosis curvature (OR 1.568, 95% CI 1.022-2.394), spondylolisthesis (OR 1.486, 95% CI 1.082-2.041), and MCs (OR 1.152, 95% CI 1.074-1.234) were associated with PNP.We concluded that kyphosis curvature, spondylolisthesis, and annular tear are associated with SNP, whereas kyphosis curvature, spondylolisthesis, and MCs are associated with PNP. This study supports the view that MCs can lead to a long duration of neck pain.