Cervical radiographical alignment: comprehensive assessment techniques and potential importance in cervical myelopathy

Long-term follow-up of untreated Scheuermann's kyphosis

STUDY DESIGN

Long-term cross-sectional study.

OBJECTIVES

To investigate the long-term effects of untreated Scheuermann's kyphosis on quality of life, and its relationship to radiographic parameters of spinal deformity. Previous studies reported reduced self-image, increased pain and impaired physical status. Little is known of the long-term impact of sagittal plane deformity in untreated SK.

METHODS

One hundred and thirteen consecutive untreated patients with SK were identified from a national service database prior to 2000, when surgery was not offered at this unit. 81 of these patients were available for evaluation; 66 (81%) consented to questionnaire and clinical evaluation, and 47 (58%) consented to additional radiological evaluation. Health-related quality of life (HRQoL) was compared to normative population values. Mean age was 45.1 years (31-65), and mean follow-up was 27 years (16-36). 57 patients had thoracic kyphosis and 9 had thoracolumbar deformity.

RESULTS

SRS-22 and SF-36 scores were lower, and ODI was greater in patients with untreated SK compared to normative population values. Kyphosis progressed from mean 66° at skeletal maturity to 78° (p < 0.001) after mean follow-up of 27 years. Long-term progression of untreated SK was 0.45°/year (n = 47). Multilinear regression showed good correlation between increasing SVA and worse ODI scores (r = 0.59; p = 0.001). Increasing SVA also correlated with worse function, pain and mental health scores reported by SRS-22, and with worse physical function and bodily pain scores reported by SF-36. Increasing CL correlated with worse SF-36 physical function scores. Increasing cSVA and increasing TK correlated with worse SRS-22 self-image scores.

CONCLUSION

SRS-22 and SF-36 scores were lower, and ODI was greater in patients with untreated SK compared to normative data. Long-term progression of untreated SK was 0.45°/year (n = 47). Increasing SVA correlated with worse SF-36 physical function, SRS-22 function, SRS-22 pain and higher ODI scores. Total kyphosis (TK) and cSVA were independent predictors of low SRS self-image.

LEVEL OF EVIDENCE

III.

Degenerative Cervical Myelopathy: Towards a Personalized Approach

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

Restoring cervical lordosis by cervical extension traction methods in the treatment of cervical spine disorders: a systematic review of controlled trials

[Purpose] To systematically review the literature on the use of cervical extension traction methods for increasing cervical lordosis in those with hypolordosis and cervical spine disorders. [Methods] Literature searches for controlled clinical trials were performed in Pubmed, PEDro, Cochrane, and ICL databases. Search terms included iterations related to the cervical spine, neck pain and disorders, and extension traction rehabilitation. [Results] Of 1,001 initially located articles, 9 met the inclusion/exclusion criteria. The trials demonstrated increases in radiographically measured lordosis of 12-18°, over 5-15 weeks, after 15-60 treatment sessions. Untreated controls/comparison groups not receiving extension traction showed no increase in cervical lordosis. Several trials demonstrated that both traction and comparison treatment groups experienced immediate pain relief. Traction treatment groups maintained their pain and disability improvements up to 1.5 years later. Comparative groups not receiving lordosis improvement experienced regression of symptoms towards pre-treatment values by 1 years' follow-up. [Conclusion] There are several high-quality controlled clinical trials substantiating that increasing cervical lordosis by extension traction as part of a spinal rehabilitation program reduces pain and disability and improves functional measures, and that these improvements are maintained long-term. Comparative groups who receive multimodal rehabilitation but not extension traction experience temporary relief that regresses after treatment cessation.

Dynamic alignment changes during level walking in patients with dropped head syndrome: analyses using a three-dimensional motion analysis system

In patients with dropped head syndrome (DHS), cervical malalignment is one of the risk factors for impaired horizontal gaze and restrictions to ambulation. The characteristics of gait in patients with DHS have not been clarified biomechanically from the viewpoint of dynamic alignment and lower limb kinematics. This study aimed to clarify kinematic and kinetic differences during level walking in patients with DHS compared to the healthy elderly. Twelve patients with DHS and healthy elderly individuals performed level walking at a self-selected speed. Spatiotemporal, kinematic, and kinetic data were recorded using a three-dimensional motion analysis system. Statistical analysis was performed to compare these data between the two groups, respectively. Compared with the healthy elderly, stride length and peak hip-joint extension angle in patients with DHS were significantly shorter and smaller. The thorax was also significantly tilted backwards. Peak ankle-joint plantar-flexion moment was significantly smaller despite larger dorsiflexion angle compared with the healthy elderly. The walking of DHS patients demonstrated kinematic and kinetic characteristics of the lower limb joints and alignment of the thorax and pelvis corresponding to their short stride and walking speed.

The Effect of Seat Back Inclination on Spinal Alignment in Automotive Seating Postures

Experimental studies have demonstrated a relationship between spinal injury severity and vertebral kinematics, influenced by the initial spinal alignment of automotive occupants. Spinal alignment has been considered one of the possible causes of gender differences in the risk of sustaining spinal injuries. To predict vertebral kinematics and investigate spinal injury mechanisms, including gender-related mechanisms, under different seat back inclinations, it is needed to investigate the effect of the seat back inclination on initial spinal alignment in automotive seating postures for both men and women. The purpose of this study was to investigate the effect of the seat back inclination on spinal alignments, comparing spinal alignments of automotive seating postures in the 20° and 25° seat back angle and standing and supine postures. The spinal columns of 11 female and 12 male volunteers in automotive seating, standing, and supine postures were scanned in an upright open magnetic resonance imaging system. Patterns of their spinal alignments were analyzed using Multidimensional Scaling presented in a distribution map. Spinal segmental angles (cervical curvature, T1 slope, total thoracic kyphosis, upper thoracic kyphosis, lower thoracic kyphosis, lumbar lordosis, and sacral slope) were also measured using the imaging data. In the maximum individual variances in spinal alignment, a relationship between the cervical and thoracic spinal alignment was found in multidimensional scaling analyses. Subjects with a more lordotic cervical spine had a pronounced kyphotic thoracic spine, whereas subjects with a straighter to kyphotic cervical spine had a less kyphotic thoracic spine. When categorizing spinal alignments into two groups based on the spinal segmental angle of cervical curvature, spinal alignments with a lordotic cervical spine showed significantly greater absolute average values of T1 slope, total thoracic kyphosis, and lower thoracic kyphosis for both the 20° and 25° seat back angles. For automotive seating postures, the gender difference in spinal alignment was almost straight cervical and less-kyphotic thoracic spine for the female subjects and lordotic cervical and more pronounced kyphotic thoracic spine for the male subjects. The most prominent influence of seatback inclination appeared in Total thoracic kyphosis, with increased angles for 25° seat back, 8.0° greater in spinal alignments with a lordotic cervical spine, 3.2° greater in spinal alignments with a kyphotic cervical spine. The difference in total thoracic kyphosis between the two seatback angles and between the seating posture with the 20° seat back angle and the standing posture was greater for spinal alignments with a lordotic cervical spine than for spinal alignments with a kyphotic cervical spine. The female subjects in this study had a tendency toward the kyphotic cervical spine. Some of the differences between average gender-specific spinal alignments may be explained by the findings observed in the differences between spinal alignments with a lordotic and kyphotic cervical spine.

Sagittal wedging of intervertebral discs and vertebral bodies in the cervical spine and their associations with age, sex and cervical lordosis: A large-scale morphological study

Many recent studies have focused on the functional and clinical importance of cervical lordosis. However, there is little accurate knowledge of the anatomical parameters that constitute cervical lordosis (i.e., the sagittal wedging angles of intervertebral discs and vertebral bodies) and their associations with age and sex. Standing lateral cervical radiographs of 1020 subjects (424 males, 596 females) with a mean age of 36.6 ± 17.0 years (range 7-95 years) were evaluated retrospectively. Cervical lordosis, the sum of intervertebral disc wedging angles from C2/C3 to C6/C7 and the sum of vertebral body wedging angles from C3 to C7 were measured. The sum of intervertebral disc wedging and the sum of vertebral body wedging were 20.6° ± 14.7° and -12.8° ± 10.3°, respectively. The sum of intervertebral disc wedging increased significantly with age and was significantly greater in males than females, whereas there was no sex-related difference in the sum of vertebral body wedging. The sum of intervertebral disc wedging was negatively correlated with sum of vertebral body wedging. Wedging of discs contributed to C2-C7 cervical lordosis more significantly than wedging of vertebral bodies. There were moderate positive correlations between cervical lordosis and intervertebral disc wedging angles at C3/C4, C4/C5 and C5/C6; weak correlations were observed at C2/C3 and C6/C7. This study constitutes the largest currently available analysis comprehensively documenting the anatomical characteristics of sagittal wedging of intervertebral discs and vertebral bodies in the cervical spine. The findings could improve understanding of the internal architecture of cervical lordosis among clinicians.

The Effect of Cervical Paravertebral Extensor Degeneration on Sagittal Alignment and Functional Status of Cervical Spine in Patients With Cervical Spondylotic Myelopathy

STUDY DESIGN

This was a cross-sectional study.

OBJECTIVE

The objective of this study was to assess cervical paravertebral extensor degeneration in patients with cervical spondylotic myelopathy (CSM) and its impact on the sagittal parameters and functional status of the cervical spine.

SUMMARY OF BACKGROUND DATA

Paravertebral extensor degeneration is well-studied in CSM; however, the effect of extensor degeneration on the sagittal balance and functional status of the cervical spine is unclear.

MATERIALS AND METHODS

We enrolled 52 CSM patients (CSM group) and 52 age-matched and sex-matched healthy adults (control group). The C2-C7 and C0-C2 Cobb angles (CAs), C7 slope, T1 slope, cervical arc cord distance, cervical tilt (CERT), cranial tilt (CRAT), and C2-C7 sagittal vertical axis (SVA) were measured. The cross-sectional areas of the deep extensors (DEA), superficial extensors (SEA), and cervical vertebral body (VBA) of C4-C7 were measured. DEA/VBA and SEA/VBA were used to quantify the extensor volume. We analyzed the fatty infiltration ratio of the deep (DFIR) and superficial extensors (SFIR). The Visual Analog Scale, Neck Disability Index, and modified Japanese Orthopaedic Association Scale scores of the CSM group were calculated.

RESULTS

The DEA/VBA was significantly lower and the DFIR and SFIR were significantly higher in the CSM group. The C4 DEA/VBA correlated with the C2-C7 SVA, C2-C7 CA, CERT, and the Neck Disability Index and modified Japanese Orthopaedic Association Scale scores (r=-0.608, 0.291, 0.335,-0.649, and 0.409, respectively). The DEA/VBA of C5 correlated with the cervical arc cord distance and CRAT (r=-0.350 and -0.356, respectively). The C4 DFIR correlated with the C2-C7 SVA, C2-C7 CA, and the Visual Analog Scale (r=0.286, -0.297, and 0.429, respectively). The SFIR of C7 correlated with the T1 slope and C7 slope (r=0.368 and 0.319, respectively).

CONCLUSIONS

Paravertebral extensor degeneration negatively impacts the sagittal sequence and functional status of the cervical spine in CSM patients. Our study provides an insight into understanding the significance of cervical muscular degeneration in CSM patients.

LEVEL OF EVIDENCE

Level III.

A multicenter validation of the condylar-C2 sagittal vertical alignment in Chiari malformation type I: a study using the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

The condylar-C2 sagittal vertical alignment (C-C2SVA) describes the relationship between the occipitoatlantal joint and C2 in patients with Chiari malformation type I (CM-I). It has been suggested that a C-C2SVA ≥ 5 mm is predictive of the need for occipitocervical fusion (OCF) or ventral brainstem decompression (VBD). The authors' objective was to validate the predictive utility of the C-C2SVA by using a large, multicenter cohort of patients.

METHODS

This validation study used a cohort of patients derived from the Park-Reeves Syringomyelia Research Consortium; patients < 21 years old with CM-I and syringomyelia treated from June 2011 to May 2016 were identified. The primary outcome was the need for OCF and/or VBD. After patients who required OCF and/or VBD were identified, 10 age- and sex-matched controls served as comparisons for each OCF/VBD patient. The C-C2SVA (defined as the position of a plumb line from the midpoint of the O-C1 joint relative to the posterior aspect of the C2-3 disc space), pBC2 (a line perpendicular to a line from the basion to the posteroinferior aspect of the C2 body), and clival-axial angle (CXA) were measured on sagittal MRI. The secondary outcome was the need for ≥ 2 CM-related operations.

RESULTS

Of the 206 patients identified, 20 underwent OCF/VBD and 14 underwent repeat posterior fossa decompression. A C-C2SVA ≥ 5 mm was 100% sensitive and 86% specific for requiring OCF/VBD, with a 12.6% misclassification rate, whereas CXA < 125° was 55% sensitive and 99% specific, and pBC2 ≥ 9 was 20% sensitive and 88% specific. Kaplan-Meier analysis demonstrated that there was a significantly shorter time to second decompression in children with C-C2SVA ≥ 5 mm (p = 0.0039). The mean C-C2SVA was greater (6.13 ± 1.28 vs 3.13 ± 1.95 mm, p < 0.0001), CXA was lower (126° ± 15.4° vs 145° ± 10.7°, p < 0.05), and pBC2 was similar (7.65 ± 1.79 vs 7.02 ± 1.26 mm, p = 0.31) among those who underwent OCF/VBD versus decompression only. The intraclass correlation coefficient for the continuous measurement of C-C2SVA was 0.52; the kappa value was 0.47 for the binary categorization of C-C2SVA ≥ 5 mm.

CONCLUSIONS

These results validated the C-C2SVA using a large, multicenter, external cohort with 100% sensitivity, 86% specificity, and a 12.6% misclassification rate. A C-C2SVA ≥ 5 mm is highly predictive of the need for OCF/VBD in patients with CM-I. The authors recommend that this measurement be considered among the tools to identify the "high-risk" CM-I phenotype.

Preoperative paraspinal neck muscle characteristics predict early onset adjacent segment degeneration in anterior cervical fusion patients: A machine-learning modeling analysis

Early onset adjacent segment degeneration (ASD) can be found within six months after anterior cervical discectomy and fusion (ACDF). Deficits in deep paraspinal neck muscles may be related to early onset ASD. This study aimed to determine whether the morphometry of preoperative deep neck muscles (multifidus and semispinalis cervicis) predicted early onset ASD in patients with ACDF. Thirty-two cases of early onset ASD after a two-level ACDF and 30 matched non-ASD cases were identified from a large-scale cohort. The preoperative total cross-sectional area (CSA) of bilateral deep neck muscles and the lean muscle CSAs from C3 to C7 levels were measured manually on T2-weighted magnetic resonance imaging. Paraspinal muscle CSA asymmetry at each level was calculated. A support vector machine (SVM) algorithm was used to identify demographic, radiographic, and/or muscle parameters that predicted proximal/distal ASD development. No significant between-group differences in demographic or preoperative radiographic data were noted (mean age: 52.4 ± 10.9 years). ACDFs comprised C3 to C5 (n = 9), C4 to C6 (n = 20), and C5 to C7 (n = 32) cases. Eighteen, eight, and six patients had proximal, distal, or both ASD, respectively. The SVM model achieved high accuracy (96.7%) and an area under the curve (AUC = 0.97) for predicting early onset ASD. Asymmetry of fat at C5 (coefficient: 0.06), and standardized measures of C7 lean (coefficient: 0.05) and total CSA measures (coefficient: 0.05) were the strongest predictors of early onset ASD. This is the first study to show that preoperative deep neck muscle CSA, composition, and asymmetry at C5 to C7 independently predicted postoperative early onset ASD in patients with ACDF. Paraspinal muscle assessments are recommended to identify high-risk patients for personalized intervention.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cervical spine alignment and clinical outcomes after multilevel anterior cervical decompression and fusion with or without plate: A minimal 5-year follow-up of a CONSORT-compliant article

It was reported imperative on cervical sagittal alignment reconstruction after anterior multilevel procedures with self-locked stand-alone cage (SSC) or anterior cage-with-plate (ACP) system multilevel while there was little knowledge about the relationship on cervical alignment and clinical outcomes.To identify the importance of cervical sagittal alignment after 3-level anterior cervical discectomy and fusion on cervical spondylotic myelopathy with SSC and ACP system.Seventy-seven patients with SSC system (SSC group) and 52 cases with ACP system (ACP group) from February 2007 to September 2013 were enrolled with well-matched demographics. Cervical alignment included C2-7 lordosis (CL), operated-segment cervical lordosis (OPCL), upper and lower adjacent-segment cervical lordosis, range of motion of upper and lower adjacent segment at preoperation, immediate postoperation, and the final follow-up. Clinical outcomes contained the neck disability index (NDI), the Japanese Orthopaedic Association (JOA) score, visual analogous scale (VAS) of arm and neck and adjacent segment degeneration (ASD). Patients were then divided into CL improved subgroup (IM subgroup) and non-improved subgroup (NIM subgroup).There were improvements on CL and OPCL in both groups. The change of CL and OPCL larger in ACP group (P < .05) but upper adjacent-segment cervical lordosis/lower adjacent-segment cervical lordosis and range of motion of upper adjacent segment/range of motion of lower adjacent segment were of no significance. NDI, JOA, and VAS got improvement in both groups at immediate postoperation and the final follow-up while ASD was in no difference between SSC and ACP group. A total of 80 patients (39 vs 41) acquired CL improvement with a larger population in ACP group. There were no differences on the rate of ASD, NDI, JOA, VAS, and their change between IM and NIM subgroup. The changes of CL were not correlated to NDI, JOA, VAS, and their change.SSC and ACP group both provide improved OPCL and efficacy on 3-level cervical spondylotic myelopathy with little impact on adjacent segment. The change of CL is not correlated to clinical outcomes.

Demonstration of central conduction time and neuroplastic changes after cervical lordosis rehabilitation in asymptomatic subjects: a randomized, placebo-controlled trial

A randomized controlled study was conducted to evaluate the effect of rehabilitation of the cervical sagittal configuration on sensorimotor integration and central conduction time in an asymptomatic population. Eighty (32 female) participants with radiographic cervical hypolordosis and anterior head translation posture were randomly assigned to either a control or an experimental group. The experimental group received the Denneroll cervical traction while the control group received a placebo treatment. Interventions were applied 3 × per week for 10 weeks. Outcome measures included radiographic measured anterior head translation distance, cervical lordosis (posterior bodies of C2–C7), central somatosensory conduction time (latency) (N13–N20), and amplitudes of potentials for spinal N13, brainstem P14, parietal N20 and P27, and frontal N30. Outcomes were obtained at: baseline, after 10 weeks of intervention, and at 3 months follow up. After 10 weeks and 3-months, between-group analyses revealed statistically significant differences between the groups for the following measured variables: lordosis C2–C7, anterior head translation, amplitudes of spinal N13, brainstem P14, parietal N20 and P27, frontal N30 potentials (P < 0.001), and conduction time N13–N20 (P = 0.004). Significant correlation between the sagittal alignment and measured variables were found (P < 0.005). These findings indicate restoration of cervical sagittal alignment has a direct influence on the central conduction time in an asymptomatic population.

Cervical sagittal alignment in patients with dropped head syndrome

BACKGROUND

Dropped head syndrome (DHS) can be divided into two types, the positive sagittal vertical axis (SVA) type and the negative SVA type. However, the cervical sagittal alignment of DHS including global sagittal spinal alignment and the typical cervical alignment of the types of DHS is still unclear. The purpose of this study was to clarify the character of cervical sagittal alignment of DHS and analyze the relationship between cervical sagittal alignment and global sagittal spinal alignment.

METHODS

The subjects were 35 DHS patients (10 men, 25 women, mean 71.1 years old). They were divided into two groups: negative DHS (N-DHS group, SVA < 0 mm) and positive DHS group (P-DHS group, SVA ≥ 0 mm). As control, 28 age-matched cervical spondylosis patients (CS, 21 men, 7 women, mean 67.4 years old) were analyzed. The following parameters were measured on lateral global-spine standing radiographs: cervical SVA (C2-C7SVA), O-C2A (O-C2 angle), C2 slope (C2S), C2-7A (C2-7 angle), T1 slope (T1S) and C7SVA.

RESULTS

The results of measurements of each of the averaged sagittal alignment parameters were (CS, P-DHS, N-DHS): C2-7SVA(26.2 mm, 47.3 mm, 44.5 mm), O-C2 angle (35.0°, 37.1°, 39.3°), C2S (16.5°, 31.4°, 33.8°), C2-7A (9.3°, 9.9°, -16.6°), T1S (22.9°, 39.7°, 25.7°), C7SVA (35.3 mm, 51.0 mm, -43.1 mm). C2-C7SVA and C2S were significantly larger in both types of DHS compared to CS. Comparing P-DHS with N-DHS, C2-C7A and T1S were significantly smaller in N-DHS.

CONCLUSIONS

O-C2A did not differ significantly among CS, P-DHS and N-DHS. In DHS patients, C2-7SVA and C2S were significantly larger than those of CS regardless of the type of DHS. The typical cervical sagittal alignment of DHS was different between P-DHS and N-DHS. In P-DHS, C2-7A and T1S were larger than those in N-DHS and the imbalance of thoraco-lumbar alignment should be noted.

Fatty infiltration in cervical flexors and extensors in patients with degenerative cervical myelopathy using a multi-muscle segmentation model

Background

In patients with degenerative cervical myelopathy (DCM) that have spinal cord compression and sensorimotor deficits, surgical decompression is often performed. However, there is heterogeneity in clinical presentation and post-surgical functional recovery.

Objectives

Primary: a) to assess differences in muscle fat infiltration (MFI) in patients with DCM versus controls, b) to assess association between MFI and clinical disability. Secondary: to assess association between MFI pre-surgery and post-surgical functional recovery.

Study design

Cross-sectional case control study.

Methods

Eighteen patients with DCM (58.6 ± 14.2 years, 10 M/8F) and 25 controls (52.6 ± 11.8 years, 13M/12 F) underwent 3D Dixon fat-water imaging. A convolutional neural network (CNN) was used to segment cervical muscles (MFSS- multifidus and semispinalis cervicis, LC- longus capitis/colli) and quantify MFI. Modified Japanese Orthopedic Association (mJOA) and Nurick were collected.

Results

Patients with DCM had significantly higher MFI in MFSS (20.63 ± 5.43 vs 17.04 ± 5.24, p = 0.043) and LC (18.74 ± 6.7 vs 13.66 ± 4.91, p = 0.021) than controls. Patients with increased MFI in LC and MFSS had higher disability (LC: Nurick (Spearman’s ρ = 0.436, p = 0.003) and mJOA (ρ = -0.399, p = 0.008)). Increased MFI in LC pre-surgery was associated with post-surgical improvement in Nurick (ρ = -0.664, p = 0.026) and mJOA (ρ = -0.603, p = 0.049).

Conclusion

In DCM, increased muscle adiposity is significantly associated with sensorimotor deficits, clinical disability, and functional recovery after surgery. Accurate and time efficient evaluation of fat infiltration in cervical muscles may be conducted through implementation of CNN models.

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

OBJECTIVE

To compare the clinical and radiographic outcomes and complications in patients undergoing multilevel posterior cervical fusion surgery, ending at C7 or crossing the cervicothoracic junction (CTJ).

METHODS

A total of 96 patients undergoing multilevel posterior cervical fusion surgery ending at C7, T1, or T2 were screened. The patients who fulfilled the inclusion criteria were divided into 2 groups based on the lower instrumented vertebra (LIV) level: group C7 (ending at C7) and group T1-T2 (crossing the CTJ). The radiographic and clinical outcomes were compared between the 2 groups, and the risk factors for instrument failure at LIV were investigated.

RESULTS

In total, 73 patients (76%) completed at least 1 year follow-up and divided into group C7 (n = 43) and group T1-T2 (n = 30). Preoperative and postoperative radiographic parameters, the Japanese Orthopaedic Association score, and patient-reported outcomes were not significantly different between the 2 groups. Significantly longer surgical time, increased blood loss, and higher incidence rates of perioperative or postoperative complications were noted in group T1-T2. On the other hand, the incidence of instrument failures at LIV was significantly higher in group C7. Multivariate analysis showed that ending at C7, skipping screw insertion at the proximal vertebra adjacent to LIV, and a large postoperative cervical sagittal vertical axis (>40 mm) were risk factors for instrument failure at LIV.

CONCLUSIONS

Crossing the CTJ during multilevel posterior cervical fusion surgery reduced instrument failures at LIV, but increased the surgical invasiveness and perioperative and postoperative complications.

Cervicothoracic spinal alignment and neck flexor muscle endurance in young and older adult females with and without neck and shoulder pain (Katakori in Japanese)

[Purpose] The characteristics of neck and shoulder pain (NSP) in different age populations have not been sufficiently examined. Therefore, the purpose of this study was to compare and verify the cervicothoracic spinal alignment and neck flexor muscle endurance of young and older adult females with and without NSP. [Participants and Methods] We assessed 72 female participants (39 young participants, 33 elderly participants, 43 NSP, 29 non-NSP) aged 18–82 years who were recruited for this study. Cervicothoracic spinal alignment measurements were obtained with forward head alignment (FHA) along with the upper thoracic angle. The neck flexor endurance test was performed. [Results] There were no significant age-by-group interactions for any of the assessment variables. However, the upper thoracic angle and neck flexor muscle endurance showed significant effects in the groups. Age also had significant effects on FHA and upper thoracic angle. [Conclusion] These results suggested that the neck flexor muscle endurance was more appropriate as an evaluation tool for older adult females with NSP. It was also suggested that the cervical flexor muscle endurance and upper thoracic angle were more appropriate as evaluation tools for young adult females with NSP.

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.

Redefining cervical spine deformity classification through novel cutoffs: An assessment of the relationship between radiographic parameters and functional neurological outcomes

Purpose:

The aim is to investigate the relationship between cervical parameters and the modified Japanese Orthopedic Association scale (mJOA).

Materials and Methods:

Surgical adult cervical deformity (CD) patients were included in this retrospective analysis. After determining data followed a parametric distribution through the Shapiro–Wilk Normality (P = 0.15, P > 0.05), Pearson correlations were run for radiographic parameters and mJOA. For significant correlations, logistic regressions were performed to determine a threshold of radiographic measures for which the correlation with mJOA scores was most significant. mJOA score of 14 and <12 reported cut-off values for moderate (M) and severe (S) disability. New modifiers were compared to an existing classification using Spearman's rho and logistic regression analyses to predict outcomes up to 2 years.

Results:

A total of 123 CD patients were included (60.5 years, 65%F, 29.1 kg/m²). For significant baseline factors from Pearson correlations, the following thresholds were predicted: MGS (M:-12 to-9° and 0°–19°, P = 0.020; S: >19° and <−12°, χ²= 4.291, P = 0.036), TS-CL (M: 26°to 45°, P = 0.201; S: >45°, χ²= 7.8, P = 0.005), CL (M:-21° to 3°, χ²= 8.947, P = 0.004; S: <−21°, χ²= 9.3, P = 0.009), C2-T3 (M: −35° to −25°, χ²= 5.485, P = 0.046; S: <−35°, χ²= 4.1, P = 0.041), C2 Slope (M: 33° to 49°, P = 0.122; S: >49°, χ²= 5.7, P = 0.008), and Frailty (Mild: 0.18–0.27, P = 0.129; Severe: >0.27, P = 0.002). Compared to existing Ames- International Spine Study Group classification, the novel thresholds demonstrated significant predictive value for reoperation and mortality up to 2 years.

Conclusions:

Collectively, these radiographic values can be utilized in refining existing classifications and developing collective understanding of severity and surgical targets in corrective surgery for adult CD.

ANALYSIS OF CERVICAL SAGITTAL PARAMETERS IN PATIENTS WITH RHEUMATOID ARTHRITIS

ABSTRACT Objective: To analyze the cervical sagittal parameters of patients with rheumatoid arthritis (RA) and compare them with the parameters obtained from healthy patients in a sample of the Brazilian population. Methods: Epidemiological data were collected and 72 radiographs of the cervical spine in the sagittal plane were evaluated by measuring the cervical sagittal parameters COG-C7 (distance measured between the center of gravity of the head and the C7 plumb line -cranial offset), C2-C7 lordosis (vertebrae from C2 to C7), T1S (T1 slope), TIA (thoracic inlet angle) and NT (neck tilt). Statistical analysis was performed using the Student’s t and chi-square tests. Results: The TIA and NT values in the RA group were 88.8° ± 12.6° and 54.5° ± 9.3°, respectively, while for the control group, they were 77.7° ± 7.9° and 50.5° ± 7.7°, respectively, the RA group values being statistically higher than the control group values (p <0.001 and p = 0.050, respectively). The values obtained for COG-C7, C2-C7 lordosis and T1S for the RA group were 9.4 ± 16.4mm, 25° ± 22.4° and 2.6° ± 10.1°, respectively, while for the control group they were 11.8 ± 17.6mm, 26.8° ± 12.5° and 30.9° ± 8.4°, respectively. Conclusions: Patients with RA present changes in the thoracic inlet parameters as compared to the control group, with a statistically significant increase in the TIA and NT values, outlining a characteristic compensatory pattern for maintaining cervical sagittal balance. Level of evidence III; Controlled cross-sectional study.

Timing of conversion to cervical malalignment and proximal junctional kyphosis following surgical correction of adult spinal deformity: a 3-year radiographic analysis

OBJECTIVE

The goal of this study was to assess the conversion rate from baseline cervical alignment to postoperative cervical deformity (CD) and the corresponding proximal junctional kyphosis (PJK) rate in patients undergoing thoracolumbar adult spinal deformity (ASD) surgery.

METHODS

The operative records of patients with ASD with complete radiographic data beginning at baseline up to 3 years were included. Patients with no baseline CD were postoperatively stratified by Ames CD criteria (T1 slope-cervical lordosis mismatch [TS-CL] > 20°, cervical sagittal vertical axis [cSVA] > 40 mm), where CD was defined as fulfilling one or more of the Ames criteria. Severe CD was defined as TS-CL > 30° or cSVA > 60 mm. Follow-up intervals were established after ASD surgery, with 6 weeks postoperatively defined as early; 6 weeks-1 year as intermediate; 1-2 years as late; and 2-3 years as long-term. Descriptive analyses and McNemar tests identified the CD conversion rate, PJK rate (< -10° change in uppermost instrumented vertebra and the superior endplate of the vertebra 2 levels superior to the uppermost instrumented vertebra), and specific alignment parameters that converted.

RESULTS

Two hundred sixty-six patients who underwent ASD surgery (mean age 59.7 years, 77.4% female) met the inclusion criteria; 103 of these converted postoperatively, and the remaining 163 did not meet conversion criteria. Thirty-eight patients converted to CD early, 26 converted at the intermediate time point, 29 converted late, and 10 converted in the long-term. At conversion, the early group had the highest mean TS-CL at 25.4° ± 8.5° and the highest mean cSVA at 33.6 mm-both higher than any other conversion group. The long-term group had the highest mean C2-7 angle at 19.7° and the highest rate of PJK compared to other groups (p = 0.180). The early group had the highest rate of conversion to severe CD, with 9 of 38 patients having severe TS-CL and only 1 patient per group converting to severe cSVA. Seven patients progressed from having only malaligned TS-CL at baseline (with normal cSVA) to CD with both malaligned TS-CL and cSVA by 6 weeks. Conversely, only 2 patients progressed from malaligned cSVA to both malaligned cSVA and TS-CL. By 1 year, the former number increased from 7 to 26 patients, and the latter increased from 2 to 20 patients. The revision rate was highest in the intermediate group at 48.0%, versus the early group at 19.2%, late group at 27.3%, and long-term group at 20% (p = 0.128). A higher pelvic incidence-lumbar lordosis mismatch, lower thoracic kyphosis, and a higher thoracic kyphosis apex immediately postoperatively significantly predicted earlier rather than later conversion (all p < 0.05). Baseline lumbar lordosis, pelvic tilt, and sacral slope were not significant predictors.

CONCLUSIONS

Patients with ASD with normative cervical alignment who converted to CD after thoracolumbar surgery had varying radiographic findings based on timing of conversion. Although the highest number of patients converted within 6 weeks postoperatively, patients who converted in the late or long-term follow-up intervals had higher rates of concurrent PJK and greater radiographic progression.

Cervical spine lateral radiograph versus whole spine lateral radiograph: A retrospective comparative study to identify a better modality to assess cervical sagittal alignment

This study is aimed to compare whole-spine lateral radiograph (WLR) and cervical lateral radiograph (CLR) in terms of T1 slope visibility and cervical sagittal parameters and to identify the superior imaging modality for assessment of cervical sagittal parameters. We retrospectively reviewed the radiographic data of 60 consecutive adult patients (male-to-female ratio, 38:22; mean age, 55.6 ± 1.3 years) who presented with only neck pain (without radiculopathy or myelopathy). All the patients underwent standing CLR and WLR. The following parameters were measured and analyzed: 1. T1 slope visibility, 2. T1 slope, 3. C7 slope, 4. C0–C2 Cobb angle (CAC0–C2), 5. C2–C7 Cobb angle (CAC2–C7), and 6. cervical sagittal vertical axis (cSVA). The visibility of the T1 slope was significantly lower with WLR than with CLR (28.3% vs 83.3%, P  = .049). The mean CAC2–C7 on WLR was significantly less lordotic than that on CLR (11.2 ± 9.2° vs 14.3 ± 11.3°; P = .01). The mean cSVA was translated more posteriorly on WLR than on CLR (9.9 ± 18.9 mm vs 15.0 ± 13.4 mm, P = .04). However, no significant differences in T1 slope, C7 slope, and CAC0–C2 were found between CLR and WLR. This study shows that standing CLR could provide better visualization of the upper endplate of T1. Furthermore, WLR taken in hands on clavicle position distorted radiographic measurements such as CAC2-C7 and cSVA. Therefore, CLR performed in the standing position seems to allow more-accurate measurements of cervical sagittal parameters.

Cervicothoracic Versus Proximal Thoracic Lower Instrumented Vertebra Have Comparable Radiographic and Clinical Outcomes in Adult Cervical Deformity

STUDY DESIGN

Comparative cohort study.

OBJECTIVE

Factors that influence the lower instrumented vertebra (LIV) selection in adult cervical deformity (ACD) are less reported, and outcomes in the cervicothoracic junction (CTJ) and proximal thoracic (PT) spine are unclear.

METHODS

A prospective ACD database was analyzed using the following inclusion criteria: LIV between C7 and T5, upper instrumented vertebra at C2, and at least a 1-year follow-up. Patients were divided into CTJ (LIV C7-T2) and PT groups (LIV T3-T5) based on LIV levels. Demographics, operative details, radiographic parameters, and the health-related quality of life (HRQOL) scores were compared.

RESULTS

Forty-six patients were included (mean age, 62 years), with 22 and 24 patients in the CTJ and PT groups, respectively. Demographics and surgical parameters were comparable between the groups. The PT group had a significantly higher preoperative C2-C7 sagittal vertical axis (cSVA) (46.9 mm vs 32.6 mm, P = 0.002) and T1 slope minus cervical lordosis (45.9° vs 36.0°, P = 0.042) than the CTJ group and was more likely treated with pedicle-subtraction osteotomy (33.3% vs 0%, P = 0.004). The PT group had a larger correction of cSVA (-7.7 vs 0.7 mm, P = 0.037) and reciprocal change of increased T4-T12 kyphosis (8.6° vs 0.0°, P = 0.001). Complications and reoperations were comparable. The HRQOL scores were not different preoperatively and at 1-year follow-up.

CONCLUSIONS

The selection of PT LIV in cervical deformities was more common in patients with larger baseline deformities, who were more likely to undergo pedicle-subtraction osteotomy. Despite this, the complications and HRQOL outcomes were comparable at 1-year follow-up.

Cervical Alignment Following Posterior Cervical Fusion Surgery: Cervical Pedicle Screw Versus Lateral Mass Screw Fixation

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

The aim of this study was to compare cervical sagittal alignment after posterior fusion surgery with lateral mass screw (LMS) and cervical pedicle screw (CPS) fixation.

SUMMARY OF BACKGROUND DATA

LMS fixation in the subaxial cervical spine has become the preferred method of posterior cervical fusion. Although CPS has biomechanical benefits, it also has neurovascular risks. Few studies to date have compared sagittal alignment changes after posterior cervical fusion using CPS and LMS fixation.

METHODS

From 2006 to 2017, 71 consecutive patients underwent posterior cervical fusion using CPS (n = 51) or LMS (n = 20) fixation. Patients who underwent fusion with both types of screws and those who planned to undergo additional anterior fusion surgery were excluded. The minimum follow-up period was 12 months. C2-C7 Cobb angle for cervical lordosis (CL), fusion segmental angle (SA), C2-C7 sagittal vertical axis (SVA), and T1 slope (T1S) were measured.

RESULTS

Immediate postoperative SA and SVA differed significantly in patients who underwent CPS and LMS fixation. SA changes were more substantial after CPS fixation, with a significant difference maintained until final follow-up. Over time, CL, SVA, and T1S tended to return to their preoperative states regardless of screw type. Two patients who underwent LMS fixation, but none who underwent CPS fixation, required unplanned or additional anterior fusion surgery for revision.

CONCLUSION

The present study is the first radiologic comparison of LMS and CPS fixation after posterior-only fusion surgery. CPS resulted in more reliable and well-preserved SA correction, whereas CL and SVA did not differ between the two groups over time due to loss of correction.Level of Evidence: 4.

Alignment, Classification, Clinical Evaluation, and Surgical Treatment for Adult Cervical Deformity: A Complete Guide

Adult cervical deformity management is complex and is a growing field with many recent advancements. The cervical spine functions to maintain the position of the head and plays a pivotal role in influencing subjacent global spinal alignment and pelvic tilt as compensatory changes occur to maintain horizontal gaze. There are various types of cervical deformity and a variety of surgical options available. The major advancements in the management of cervical deformity have only been around for a few years and continue to evolve. Therefore, the goal of this article is to provide a comprehensive review of cervical alignment parameters, deformity classification, clinical evaluation, and surgical treatment of adult cervical deformity. The information presented here may be used as a guide for proper preoperative evaluation and surgical treatment in the adult cervical deformity patient.

Comparison of Clinical and Radiographic Outcomes After Standalone Versus Cage and Plate Constructs for Anterior Cervical Discectomy and Fusion

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) has conventionally been performed using an allograft cage with a plate-and-screw construct. Recently, standalone cages have gained popularity due to theorized decreases in operative time and postoperative dysphagia. Few studies have compared these outcomes. Here, we directly compare the outcomes of plated versus standalone ACDF constructs.

METHODS

A single-center retrospective review of patients undergoing ACDF after June 2011 with at least 6 months of follow up was conducted. Clinical outcomes were analyzed and compared between standalone and plated constructs. Multivariate regression analysis of the primary outcome, need for revision surgery, as well as several secondary outcomes, procedure duration, estimated blood loss (EBL), length of hospital stay, disposition, and incidence of dysphagia, hoarseness, or surgical site infection, was completed.

RESULTS

A total of 321 patients underwent ACDF and met inclusion-exclusion criteria, with mean follow-up duration of 20 months. Forty-six (14.3%) patients received standalone constructs, while 275 (85.7%) received plated constructs. Fourteen (4.4%) total revisions were necessary, 4 in the standalone group and 10 in the plated group, yielding revision rates of 8.7% and 3.6%, respectively (P = .125). Mean EBL was 98 mL in the standalone group and 63 mL in the plated group (P = .001). Mean procedure duration was 147 minutes in the standalone group and 151 minutes in the plated group (P = .800). Mean hospital stay was 3.6 days in the standalone group and 2.5 days in the plated group (P = .270). There was no significant difference in incidence of dysphagia (P = .700) or hoarseness (P = .700).

CONCLUSIONS

Standalone ACDF demonstrates higher, but not statistically significant, revision rates than plate-and-screw constructs, without the hypothesized decreased incidence of dysphagia or hoarseness and without decreased procedure duration or EBL. Surgeons may consider limiting use of these constructs to cases of adjacent segment disease. Larger studies with longer follow up are necessary to make more definitive conclusions.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

This study will help spine surgeons decide between using standalone or cage-and-plate constructs for ACDF.

K-Line Tilt is a Predictor of Postoperative Kyphotic Deformity After Laminoplasty for Cervical Myelopathy Caused by Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

Retrospective single-center study.

OBJECTIVES

K-line is a decision-making tool to determine the appropriate surgical procedures for patients with cervical ossification of the posterior longitudinal ligament (C-OPLL). Laminoplasty (LAMP) is one of the standard surgical procedures indicated on the basis of K-line measurements (+: OPLL does not cross the K-line). We investigated the impact of K-line tilt, a radiographic parameter of cervical sagittal balance measured using the K-line, on surgical outcomes after LAMP.

METHODS

The study included 62 consecutive patients with K-line (+) C-OPLL who underwent LAMP. The following preoperative and postoperative radiographic measurements were evaluated: (1) the K-line, (2) K-line tilt (an angle between the K-line and vertical line), (3) center of gravity of the head -C7 sagittal vertical axis, (4) C2-C7 lordotic angle, (5) C7 slope, and (6) C2-C7 range of motion. Clinical results were evaluated using the Japanese Orthopedic Association scoring system for cervical myelopathy (C-JOA score).

RESULTS

All the patients had non-kyphotic cervical alignment (CL ≥ 0°) preoperatively; however, kyphotic deformity (CL < 0°) was observed in 6 patients (9.7%) postoperatively. The recovery rate of the C-JOA scores was poor in the kyphotic deformity (+) group (7.8%) than in the kyphotic deformity (-) group (47.5%). The K-line tilt was identified to be a preoperative risk factor in the multivariate analysis, and the cutoff K-line tilt for predicting the postoperative kyphotic deformity was 20°.

CONCLUSIONS

LAMP is not suitable for K-line (+) C-OPLL patients with K-line tilts >20°.

Correlation of supine MRI and standing radiographs for cervical sagittal balance in myelopathy patients: a cross-sectional study

PURPOSE

Cervical sagittal alignment is correlated with myelopathy severity and used by spinal surgeons for surgical planification. Magnetic resonance imaging (MRI) is the gold standard for the evaluation of cervical myelopathy but may not be for the assessment of cervical sagittal balance compared to X-rays. The objective of this study was to assess the correlation of cervical alignment between supine MRI and standing radiographs in patients with cervical spondylotic myelopathy (CSM).

METHODS

Cobb, Jackson and Harrison methods were used to measure cervical sagittal alignment on supine MRI and standing radiographs of CSM adults. Cervical alignment was divided based on Cobb angle values on lordotic (> 4°), kyphotic (< - 4°) and rectitude (- 4° to 4°). Correlations between radiographic and MRI measurements were determined. Intra- and interobserver reliability were assessed and MRI and X-Ray-measured angles were compared.

RESULTS

One hundred and thirty patients with CSM were reviewed. Correlations of cervical lordosis measures between radiographs and MRI were strong using the Cobb (0.65) and Jackson (0.63) methods, and moderate using the Harrison (0.37) method. Mean cervical lordosis angle was significantly lower on supine MRI compared to standing radiographs for all methods (Cobb 11.6 Rx vs. 9.2 MRI, Jackson 14.6 vs. 11.6, Harrison 23.5 vs. 19.9). Eighteen patients (15.4%) without lordosis on supine MRI presented lordosis on standing radiographs.

CONCLUSION

A substantial proportion of patients has sagittal alignment discrepancies between supine MRI and standing radiographs. Therefore, standing radiographs of the cervical spine should always be included in surgical planning of CSM patients.

[Relationship between O-EA angle and lower cervical curvature in patients with anterior atlantoaxial dislocation before and after occipitocervical fusion]

Objective

To investigate the relationship between O-EA angle and lower cervical curvature in patients with anterior atlantoaxial dislocation undergoing occipitocervical fusion, and to analyze the effect of O-EA angle on lower cervical curvature.

Methods

The clinical data of 61 patients with anterior atlantoaxial dislocation undergoing occipitocervical fusion who were admitted between April 2010 and July 2018 and met the selection criteria were retrospectively analyzed. There were 32 males and 29 females, with an age of 14-76 years (mean, 50.7 years). The fixed segment included 19 cases of C ₀-C ₂, 27 cases of C ₀-C ₃, 14 cases of C ₀-C ₄, and 1 case of C ₀-C ₅. The O-EA angle, C _2-7 Cobb angle, and T ₁ tilt angle were measured before operation and at last follow-up. According to the O-EA angle measured at last follow-up, the patients were divided into <95° group (group A), 95°-105° group (group B), and >105° group (group C), and compared the differences of gender, age, fixed segment (short segment was at C ₃ and above, long segment was beyond C ₃), and C _2-7 Cobb angle. Correlation analysis between the O-EA angle and C _2-7 Cobb angle before operation and at last follow-up, as well as the changes of O-EA angle and C _2-7 Cobb angle between before operation and at last follow-up were analyzed.

Results

All 61 patients were followed up 12-24 months, with an average of 22.4 months. There was no significant difference in O-EA angle, C _2-7 Cobb angle, and T ₁ tilt angle before operation and at last follow-up ( P>0.05). According to the last follow-up O-EA angle grouping, there were 14 cases in group A, 29 cases in group B, and 18 cases in group C. There was no significant difference in age, gender composition, and fixed segment composition among the three groups ( P>0.05); the differences in C _2-7 Cobb angles among the three groups were significant ( P<0.05), groups A, B, and C showed a gradually increasing trend. The O-EA angle was positively correlated with C _2-7 Cobb angle before operation and at last follow-up ( r=0.572, P=0.000; r=0.618, P=0.000); O-EA angle change at last follow-up was also positively correlated with C _2-7 Cobb change ( r=0.446, P=0.000).

Conclusion

The O-EA angle of patients with anterior atlantoaxial dislocation is positively correlated with C _2-7 Cobb angle. Too large O-EA angle should be avoided during occipitocervical fixation, otherwise it may accelerate the degeneration of the lower cervical spine.

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.

Global sagittal spinal alignment at cervical flexion in patients with dropped head syndrome

PURPOSE

Dropped head syndrome (DHS) is characterized by the passively correctable chin-on-chest deformity. The characteristic feature is emphasized in the cervical flexion position. The purpose of this study was to analyze the influence of cervical flexion on sagittal spinal alignment in patients with DHS.

METHODS

The study included 15 DHS subjects and 55 cervical spondylosis (CS) subjects as the control group. The following parameters were analyzed: cervical sagittal vertical axis (C-SVA), occipitoaxial angle (O-C2A), C2 slope (C2S), C2-C7 angle (C2-C7A), T1 slope (T1S), sagittal vertical axis, T1-T4 angle (T1-T4A), T5-T8 angle (T5-T8A), T9-T12 angle, lumbar lordosis, sacral slope, and pelvic tilt, in cervical flexion and neutral positions.

RESULTS

The values of C-SVA, O-C2A, C2S, and T1S were significantly different between CS and DHS at cervical neutral and flexion positions. C2-C7A showed significant difference in cervical neutral position, but the difference disappeared in flexion position. T1-T4A did not present a significant difference, but T5-T8A showed a difference in neutral and flexion positions.

CONCLUSIONS

Malalignment of DHS extended not only to cervical spine but also to cranio-cervical junction and thoracic spine, except T1-T4. It is known that global sagittal spinal alignment is correlated with adjacent parameters, although in DHS the reciprocal change was lost from cranio-cervical junction to the middle part of thoracic spine at cervical flexion.

C2-C3 vertebral disc angle: An analysis of patients with and without cervical spondylotic myelopathy

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To define C2-C3 vertebral disc angle (VDA) in patients with and without cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

C2-C3 VDA is a new radiological index of cervical spine alignment. Recent studies have suggested that high postoperative values are associated with greater mechanical complications in patients with cervical spondylotic myelopathy. However, normative values for patients without myelopathy has yet to be defined.

METHODS

Patients with and without cervical myelopathy between 2017 and 2019 were included. Inclusion criteria were patients above 18 years of age with antero-posterior (AP) and lateral (LAT) cervical X-rays. In the non-myelopathic group, patients were excluded if they had neurological symptoms or deficits, presence of cervical axial pain, previous spinal surgery, or diagnosis of either spondylolisthesis or scoliosis. In the myelopathic group, patients were excluded if they had previous spinal surgery. Radiological indices evaluated include: C2-C3 disc angle, C2-C7 Cobb angle, C7 sagittal vertical axis, T1 slope.

RESULTS

In total, 99 patients without myelopathy and 22 patients with myelopathy were identified and analyzed. In patients without myelopathy, the mean for C2-C3 VDA was 25.9±7.9. For patients with myelopathy, preoperative values were 24.4±10.0 and 27.1±7.9 postoperatively. No statistically significant differences were found between patients with and without myelopathy. C2-C3 disc angle was not correlated with age (R=-0.173).

CONCLUSION

This study did not find statistically significant differences in C2-C3 VDA values between patients with and without cervical myelopathy. This study provides normative data for C2-C3 vertebral disc angle in patients with and without cervical spondylotic myelopathy. Furthermore, C2-C3 vertebral disc angle may be independent from age.

Assessment of spino cranial angle of cervical spine sagittal balance system after multi-level anterior cervical discectomy and fusion

Background

To analyze the impact of spino cranial angle (SCA) on alteration of cervical alignment after multi-level anterior cervical discectomy fusion (ACDF) and explore the relationship between SCA and health-related quality of life (HRQOL) scores.

Material and methods

In total, 49 patients following multi-level ACDF for multi-level cervical spondylotic myelopathy (MCSM) with more than 2 years follow-up period were enrolled. Radiographic data including SCA were measured. Receiver operating characteristics (ROC) curve analysis was applied to confirm the optimal cut-off values of SCA for predicting sagittal balance. Patients were divided into two groups on the basis of the cut-off value of preoperative SCA. Correlation coefficients were analyzed between SCA and HRQOL scores.

Results

Optimal cut-off values for predicting sagittal balance was SCA of 88.6°. Patients with higher SCA, no matter preoperatively, postoperatively and at follow-up, got lower T1-Slope (T1s), C2–C7 lordosis angle (CA) and higher △SCA (pre vs post: p = 0.036, pre vs F/U: p = 0.022). Simultaneously, pre-SCA, post-SCA, and F/U-SCA in the high SCA group were positively correlated with the pre-NDI, post-NDI, and F/U-NDI scores respectively (pre: p < 0.001, post: p = 0.015, F/U: p = 0.003). However, no correlation was performed in the low SCA group.

Conclusion

An excessive SCA can be considered to cause poorer clinical outcomes at preoperative and better correction after surgery. The SCA could be used as a new reference value to determine sagittal balance parameters of the cervical spine and to assess the quality of life.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

Reciprocal change of occipitocervical parameters after anterior cervical discectomy and fusion

To evaluate the reciprocal changes in occipitocervical parameters according to the recovery of cervical lordosis (CL) after anterior cervical discectomy and fusion (ACDF) in patients with sagittal imbalance. Sixty-five cases that underwent ACDF were followed. They were divided according to the recovery of the CL: Group 1 (ΔCL > 5°, 30 cases) and Group 2 (ΔCL < 5°, 35 cases). The following parameters were measured: occiput-cervical inclination (OCI), CL, occiput-C2 angle (OC2A), distance between external occipital protuberance and spinous process of C2 (OC2D), distance between spinous processes of C2 and C7 (C27D), and shortest distance between the plumb line of C2 body and posterosuperior corner of C7 (C27SVA). Overall, all parameters changed significantly after ACDF. Preoperative CL and preoperative C27D showed a correlation with ΔCL. ΔCL was negatively correlated with ΔC27D and ΔC27SVA. In Group 1, CL increased from − 2.60 ± 1.88° to 11.57 ± 1.83°, OC2A decreased from 23.96 ± 2.05° to 19.87 ± 1.36°, OC2D increased from 82.96 ± 1.48 mm to 86.50 ± 1.81 mm, C27D decreased from 95.61 ± 2.66 mm to 87.01 ± 2.50 mm, and C27SVA decreased from 24.14 ± 2.20 mm to 17.06 ± 2.14 mm. In Group 2, only OCI decreased significantly after ACDF. ACDF can increase CL postoperatively in patients with cervical sagittal imbalance. Patients with significant CL recovery after ACDF showed a reciprocal change in occipitocervical parameters. (OC2A, OC2D).

The association between cervical focal kyphosis and myelopathy severity in patients with cervical spondylotic myelopathy before surgery

PURPOSE

Cervical focal kyphosis could often be observed in patients with cervical spondylotic myelopathy (CSM). However, the association between it and myelopathy severity remains unclear. This study aims to elucidate the association between cervical focal kyphosis and myelopathy severity before surgery.

METHODS

A retrospective review of 191 consecutive patients treated for CSM from 2017 to 2019 was surveyed. Seven MRI and five radiographic parameters were measured, clinical parameters were included. Patients were divided into two sagittal focal angle groups (lordosis/kyphosis) and two disc herniation severity groups (severe/non-severe). The potential risk factors of myelopathy symptoms were analysed.

RESULTS

Significant correlations between cervical sagittal focal angles, several other imaging findings and myelopathy severity were found in both total patients (R² = 0.51, P < 0.001) and non-severe disc herniation patients (R² = 0.73, P < 0.001) in multivariate regression models. Compression ratio of spinal cord exhibited the strongest correlation with JOA scores (r = - 0.567, P < 0.001). Cervical focal angles on MRI exhibited a stronger negative correlation with JOA scores (r = - 0.429, P < 0.001) than did angles on the other three postures on radiographs. Dramatic differences in JOA scores could be found in patients with non-severe cervical disc herniation, when a subgroup analysis was performed between cervical lordosis group and more than 4° kyphosis group (14.2 ± 1.7 vs. 11.1 ± 1.7, P < 0.001).

CONCLUSION

Cervical focal kyphosis associates with severe myelopathy symptoms in patients with CSM, especially without severe disc herniation. This association may indicate an optimal cervical focal angle in surgical plan. It appeared feasible to assess both the cervical focal angles and spinal cord compression on supine MRI.

The Effect of High Volume Power Training on Repeated High-Intensity Performance and the Assessment of Repeat Power Ability: A Systematic Review

BACKGROUND

High volume power training (HVPT) involves high volumes of high-velocity resistance training, with the aim to improve repeated high-intensity efforts (RHIEs). Repeat power ability (RPA) is the ability to repeatedly produce maximal or near maximal efforts. Assessments of RPA using external loading may determine the ability to perform repeat RHIEs typical of many sports and, therefore, provide useful information on the effectiveness of training.

OBJECTIVES

(1) Identify the different HVPT protocols; (2) examine the acute responses and chronic adaptations to different HVPT protocols; (3) identify different lower body RPA assessment protocols and highlight similarities, differences and potential limitations between each protocol, and; (4) describe the reliability and validity of RPA assessments.

METHODS

An electronic search was performed using SPORTDiscus, PubMed, CINAHL and Embase for studies utilising HVPT protocols and assessments of RPA. Eligible studies included peer-reviewed journal articles published in English.

RESULTS

Twenty studies met the inclusion criteria of the final review. Of the eight longitudinal studies, three were rated as fair and five were rated as poor methodological quality, respectively. In contrast, all 12 cross-sectional studies were considered to have a low risk of bias. Preliminary evidence suggests that HVPT can enhance RHIE, RPA, anaerobic capacity, anaerobic power and aerobic performance. HVPT generally consists of 2-3 sessions per week, utilising loads of 30-40% 1 repetition maximum (RM), for 3-5 sets of 10-20 repetitions, with inter-set rest periods of 2-3 min. RPA assessments can be valid and reliable and may provide useful information on an athlete's ability to perform RHIE and the success of HVPT programmes.

CONCLUSIONS

HVPT can be used to improve a number of physical qualities including RPA and RHIE; while a variety of RPA assessments provide valid and reliable information regarding the athlete's ability to perform RHIEs. Considering the heterogeneity in the HVPT protocols currently used and the relatively low volume and quality of longitudinal publications in this area, further studies are needed to identify the effects of a variety of HVPT methods on RPA, RHIE and other performance outcomes and to identify the most valid and reliable RPA outcomes to use in such studies.

Update on Cervical Hernia Treatment: Conservative Management and Indications of Different Surgical Techniques

Cervical and root pain due to herniated disc is one a common cause of a visit to an orthopedic surgeon. It is important to know how to diagnose, treat and initially.

What are the best options to treat a herniated disc nowadays? The present article reviews the literature and updates on the clinical and surgical treatment of cervical disc herniation.

The Effect of Head Loading on Cervical Spine in Manual Laborers

STUDY DESIGN

A prospective case-control study.

PURPOSE

To determine the effect of axial loading on the cervical spine when weights are carried on the head.

OVERVIEW OF LITERATURE

Traditionally, carrying weights on the head has been a common practice in developing countries. The laborers working in agriculture, construction, and other industries, as well as porters at railway platforms, are required to lift heavy weights. Since controversy exists regarding carrying weights on the head, we decided to evaluate its effect on the cervical spine.

METHODS

The study comprised 62 subjects. Of this number, 32 subjects (group A) were unskilled laborers from the construction industry; the other 30 subjects (group B) were in the control group and had never previously carried heavy weights on their heads. Cervical spine radiographs were taken for all the 62 subjects. Subjects in group A were asked to carry a load (approximately 35 kg) on their heads and walk for about 65 m, with their cervical spine radiographs taken afterward.

RESULTS

The mean ages of patients in groups A and B were 27.17 and 25.75 years, respectively. The mean cervical lordosis observed in group A (18.96°) was dramatically less compared with group B (25.40°), showing a further decrease in head loading (3.35°). Five subjects had a reversal of lordosis (-5.61°). A statistically significant reduction in disc height and listhesis was observed when the load was carried on the head with a further decrease after walking with the load. Accelerated degenerative changes, particularly affecting the upper cervical spine, were observed in head loaders.

CONCLUSIONS

Carrying a load on the head leads to accelerated degenerative changes, which involve the upper cervical spine more than the lower cervical spine and predisposes it to injury at a lower threshold. Thus, alternative methods of carrying loads should be proposed.

Risk factors for determining length of intensive care unit and hospital stays following correction of cervical deformity: evaluation of early severe adverse events

OBJECTIVE

Correction of rigid cervical deformities can be associated with high complication rates and result in prolonged intensive care unit (ICU) and hospital stays. In this study, the authors aimed to examine the risk factors contributing to length of stay (LOS) in both the hospital and ICU following adult cervical deformity (ACD) surgery and to identify severe adverse events that occurred in this setting.

METHODS

A retrospective review of ACD patients who underwent posterior-based osteotomies for deformity correction from 2010 to 2019 was performed. Inclusion criteria were cervical kyphosis > 20° and/or cervical sagittal vertical axis (cSVA) > 4 cm. Multivariate analysis was used to identify risk factors independently associated with ICU and hospital LOS.

RESULTS

A total of 107 patients were included. The mean age was 63.5 years, and 61.7% were female. Over half (52.3%) underwent 3-column osteotomies, while 47.7% underwent posterior column osteotomies. There was significant correction of all cervical parameters: cSVA (6.0 vs 3.6 cm, p < 0.001), cervical lordosis (8.2° vs -5.3°, p < 0.001), cervical scoliosis (6.5° vs 2.2°, p < 0.001), and T1-slope (40.2° vs 34.5°, p < 0.001). There were also reciprocal changes to the distal spine: thoracic kyphosis (54.4° vs 46.4°, p < 0.001), lumbar lordosis (49.9° vs 45.8°, p = 0.003), and thoracolumbar scoliosis (13.9° vs 11.1°, p = 0.009). Overall, 4 patients (3.7%) suffered aspiration-related complications, 3 patients (2.8%) experienced dysphagia requiring a feeding tube, and 4 patients (3.7%) had compromised airways, with 1 resulting in death. The mean ICU and hospital LOS were 2.8 days and 7.9 days, respectively. Multivariate analysis identified three factors independently associated with longer ICU LOS: female sex (3.0 vs 2.4 days, p = 0.004), ≥ 12 segments fused (3.5 vs 1.9 days, p = 0.002), and postoperative complication (4.0 vs 1.9 days, p = 0.017). These same factors were independently associated with longer hospital LOS as well: female sex (8.3 vs 7.3 days, p = 0.013), ≥ 12 segments fused (9.4 vs 6.2 days, p = 0.001), and complication (9.7 vs 6.7 days, p = 0.026).

CONCLUSIONS

Posterior-based osteotomies are very effective for the correction of ACD, but postoperative hospital stays are relatively longer than those following surgery for degenerative disease. Risk factors for prolonged ICU and hospital LOS consist of both nonmodifiable (female sex) and modifiable (≥ 12 segments fused and presence of complication) risk factors. Additional multicenter prospective studies will be needed to validate these findings.

Cervical Deformity: Evaluation, Classification, and Surgical Planning

Cervical deformity is a challenging condition to treat and requires complex decision-making. Apart from a thorough history and physical examination, a thoughtful and quantitative analysis of multiple imaging modalities is critical for understanding the nature and driver of the cervical deformity. A few classification schemes have emerged, and it is now clear that dynamic films are invaluable as they capture the extension reserve that patients can use to compensate for malalignment. These classification systems can help guide surgical planning, because the various subgroups have different properties that lend themselves to specific treatment paradigms. Here we review the clinical and radiographic evaluation, classification, and surgical planning for cervical deformity.

Neuromuscular Scoliosis: Comorbidities and Complications

Study Design

Single-center, retrospective cohort study conducted from 2013 to 2017.

Purpose

To determine the risk factors for surgical complications in neuromuscular scoliosis based on known patient comorbidities.

Overview of Literature

The concept of neuromuscular scoliosis includes a wide variety of pathologies affecting the neuromuscular system. Complications are numerous and are often difficult to predict.

Methods

A retrospective analysis of a single-center database was conducted from 2013 to 2017. Inclusion criteria were patients aged <25 years, diagnosis of neuromuscular scoliosis, and history of posterior fusion deformity surgery. A total of 64 patients (mean age, 15 years; 63% females) were included in this study. Clinical, radiological, and laboratory parameters in the preoperative, intraoperative, and postoperative settings were analyzed. Univariate analysis was performed using Student t -test for continuous variables, and a chi-square test was used for noncontinuous variables. Multivariate analysis was performed to identify predictors of major, mechanical, and total complications.

Results

Complications were found in 44% of patients, with 46.9% consisting of major complications, and 84.4% being early complications. Univariate analysis revealed that the presence of perinatal comorbidities, independent of other comorbidities, increased the risk for complications (p =0.029). Preoperative hypoglycemia, high number of instrumented levels, longer surgical time, use of an all-screw construct, lower preoperative pelvic obliquity, postoperative lower kyphosis, high thoracic spinopelvic angle (as measured by T9 spino-pelvic inclination), absence of deep drain, and use of superficial drain were associated with postoperative complications (all p <0.05). Logistic regression demonstrated that comorbidities, longer surgical time, hypoglycemia, and absence of deep drains are predictors of complications. Independent variables that predicted major complications were the number of levels fused, postoperative kyphosis (p =0.025; odds ratio [OR], 1.074), and high screw density (p =0.014; OR, 4.380).

Conclusions

Complications in neuromuscular scoliosis are increased by comorbidities, long surgical time, and inadequate correction. Preventative measures to decrease these complications include appropriate preoperative patient preparation and surgical planning.

Correlations and Age-Related Changes of Cervical Sagittal Parameters in Adults Without Symptoms of Cervical Spinal Disease

STUDY DESIGN

Retrospective study.

OBJECTIVE

To determine the correlations and age-related changes of cervical sagittal parameters in adults without obvious cervical spinal disease.

SUMMARY OF BACKGROUND DATA

Cervical sagittal parameters play essential roles in the pathogenesis and therapy of cervical spinal diseases. However, few studies have investigated the correlations and age-related changes of cervical sagittal parameters.

METHODS

The enrolled participants were divided into three age groups and their cervical sagittal parameters were collected. Correlations and age-related changes of these parameters were analyzed.

RESULTS

Significant differences in the C2-C7 angle, center of gravity of the head-C7 sagittal vertical axis (CGH-C7 SVA), C2-C7 SVA, neck tilt (NT), and thoracic inlet angle (TIA) were found among the three age groups. Pearson correlation analysis showed positive correlations between the C0-C2 angle and CGH-C7 SVA, C0-C2 angle and C2-C7 SVA, C2-C7 angle and T1 slope, C2-C7 angle and TIA, CGH-C7 SVA and C2-C7 SVA, C2-C7 SVA and T1 slope, T1 slope and TIA, and NT and TIA as well as negative correlations between the C0-C2 angle and C2-C7 angle, C2-C7 angle and CGH-C7 SVA, and C2-C7 angle and C2-C7 SVA. Paired t tests showed significant changes in the C2-C7 angle in groups I and II, and in the CGH-C7 SVA and C2-C7 SVA in all age groups with increasing age.

CONCLUSION

The results indicate that cross correlations exist between different cervical sagittal parameters in adults without symptoms of cervical spinal disease, and the lower cervical curvature and SVA change obviously with increasing age.

LEVEL OF EVIDENCE

3.

Impact of resistance training status on trunk muscle activation in a fatiguing set of heavy back squats

Purpose

In this study we measured neural activation (EMG) in four trunk stabilizer muscles and vastus lateralis (VL) in trained and novice participants during a set of squat repetitions to volitional fatigue at 85% 1RM.

Methods

Forty males were recruited into two groups, novice (NG: n = 21) and experienced (EG: n = 19), according to relative squat 1RM. Participants were tested twice to: (1) determine squat 1RM, and (2) complete a single set of repetitions to volitional fatigue at 85% 1RM. Relative squat 1RM; NG < 140% body mass, EG > 160% body mass. Neuromuscular activation was measured by EMG for the following: rectus abdominus (RA), external oblique (EO), lumbar sacral erector spinae (LSES), upper lumbar erector spinae (ULES) and VL in eccentric and concentric phase. Completed repetitions, RPE and EMG in repetition 1 and at 20, 40, 60, 80 and 100% of completed repetitions were analysed.

Results

No group differences were found between number repetitions completed and RPE in repetitions to volitional fatigue at 85% 1RM. Neuromuscular activation increased significantly in all muscle groups in eccentric and concentric phase apart from RA in the eccentric phase. Trunk neuromuscular activation was higher in NG compared to EG and this was significant in EO, LSES and ULES in eccentric phase and LSES in the concentric phase. VL activation increased in both phases with no group differences.

Conclusion

Trunk neuromuscular activation increases in a fatiguing set of heavy squats regardless of training status. Increased back squat strength through training results in lower neuromuscular activation despite greater absolute external squat loads.

Relationship between the atlantodental interval and T1 slope after atlantoaxial fusion in patients with rheumatoid arthritis

BACKGROUND

Atlantoaxial fusion has been widely used for the treatment of atlantoaxial instability (AAI). However, atlantoaxial fusion sacrifices the motion of atlantoaxial articulation, and postoperative loss of cervical lordosis and aggravation of cervical kyphosis are observed. We investigated various factors under the hypothesis that the atlantodental interval (ADI) and T1 slope may be associated with sagittal alignment after atlantoaxial fusion in patients with rheumatoid arthritis (RA).

METHODS

We retrospectively investigated 64 patients with RA who underwent atlantoaxial fusion due to AAI. Radiological factors, including the ADI, T1 slope, Oc-C2 angle, cervical sagittal vertical axis, and C2-C7 angle, were measured before and after surgery.

RESULTS

The various factors associated with atlantoaxial fusion before and after surgery were compared according to the upper and lower preoperative ADIs. There was a significant difference in the T1 slope 1 year after surgery (p = 0.044) among the patients with lower preoperative ADI values. The multivariate logistic regression analysis showed that the preoperative ADI (> 7.92 mm) defined in the receiver-operating characteristic curve analysis was an independent predictive factor for the increase in the T1 slope 1 year after atlantoaxial fusion (odds ratio, 4.59; 95% confidence interval, 1.34-15.73; p = 0.015).

CONCLUSION

We found an association between the preoperative ADI and difference in the T1 slope after atlantoaxial fusion in the patients with RA. A preoperative ADI (> 7.92 mm) was an independent predictor for the increase in the T1 slope after atlantoaxial fusion. Therefore, performing surgical treatment when the ADI is low would lead to better cervical sagittal alignment.

Analysis of the impact of spinopelvic radiographic parameters on the severity of cervical spondylotic myelopathy

BACKGROUND

The correlation between spinal radiographic parameters and severity of cervical spondylotic myelopathy (CSM) is controversial. This study aimed to investigate the associations between spinal radiographic parameters and CSM severity, as well as between cervical and other spinopelvic radiographic parameters.

METHODS

Patients diagnosed with CSM (N = 118; 77 men) at our hospital from March 2013 to February 2017 were included. The patients' demographic data and the following radiographic parameters were investigated: cervical lordosis (CL), C2-C7 sagittal vertical axis (C2-C7 SVA), T1 slope, thoracic kyphosis, lumbar lordosis, pelvic incidence, sacral slope, pelvic tilt, and sagittal vertical axis (SVA). Cervical cord compression ratio (CCCR) was evaluated on sagittal magnetic resonance imaging. The Japanese Orthopaedic Association (JOA) scoring system was used for clinical evaluation. Correlation analyses were performed among the clinical and radiographic parameters.

RESULTS

The JOA score had the strongest correlation with SVA (r = -0.46, p < 0.01), followed by CCCR (r = -0.33, p < 0.01), CL (r = -0.29, p < 0.01), T1 slope (r = -0.29, p = 0.01), and C2-C7 SVA (r = -0.20, p = 0.03). Multivariate linear regression analysis revealed a model predicting the JOA score; JOA = 13.6 - 0.24 × SVA - 4.2 × CCCR (r = 0.51, p < 0.01). Although there was no significant correlation between the cervical and lumbopelvic radiographic parameters, the sequential correlation among the investigated spinopelvic parameters was identified.

CONCLUSIONS

CSM severity worsened with spinal malalignment, such as a larger SVA. Though lumbopelvic radiographic parameters did not significantly impact cervical alignment and CSM severity, the sequential correlations among cervical-thoracic-lumbopelvic radiographic parameters were observed. Therefore, SVA is the most relevant radiographic parameter for CSM, but we cannot preclude the possibility that lumbopelvic alignment also affects cervical alignment and CSM severity.

Three-Column Osteotomy for the Treatment of Rigid Cervical Deformity

Adult cervical deformity (ACD) has been shown to have a substantial impact on quality of life and overall health, with moderate to severe deformities resulting in significant disability and dysfunction. Fortunately, surgical management and correction of cervical sagittal imbalance can offer significant benefits and improvement in pain and disability. ACD is a heterogenous disease and specific surgical correction strategies should reflect deformity type (driver of deformity) and patient-related factors. Spinal rigidity is one of the most important considerations as soft tissue releases and osteotomies play a crucial role in cervical deformity correction. For ankylosed, fixed, and severe deformity, 3-column osteotomy (3CO) is often warranted. A 3CO can be done through combined anteriorposterior (vertebral body resection) and posterior-only approaches (open or closed wedge pedicle subtraction osteotomies [PSOs]). This article reviews the literature for currently published studies that report results on the use of 3CO for ACD, with a special concentration on posterior based 3CO (open and closed wedge PSO). More specifically, this review discusses the indications, radiographic corrective ability, and associated complications.

Magnetic resonance imaging and dynamic X-ray's correlations with dynamic electrophysiological findings in cervical spondylotic myelopathy: a retrospective cohort study

Background

Dynamic somatosensory evoked potentials (DSSEP) can be used to disclose abnormalities of ascending sensory pathways at dynamic positions and diagnose cervical spondylotic myelopathy (CSM). However, radiographic tests including magnetic resonance imaging (MRI) and dynamic X-ray are used much more widely in the management of CSM. Our study aims to clarify the correlations between several radiographic parameters and the DSSEP results, and further determine their reliability with clinical data.

Methods

We retrospectively enrolled 38 CSM patients with surgical intervention. DSSEP tests were performed before surgery. Amplitude ratios of DSSEP N13 and N20 waves at extension and flexion were calculated and recorded as N13_E, N20_E, N13_F, N20_F, respectively. Baseline severity was evaluated with the modified Japanese Orthopedic Association (mJOA) score and the Nurick grades. Prognosis was evaluated based on the 2-year recovery rate. Sagittal diameter and transverse areas of the cord and canal were measured and the the compressive ratios at the compressed site (Compression_Ratio), central (Central_Ratio), and 1/4-lateral points (1/4-Lateral_Compression_Ratio), and spinal cord/Canal Area Ratio were calculated. The intramedullary T2 hyperintensity patterns (Ax-CCM types) were also collected from MRI axial images. Dynamic X-rays were used to test for segmental instability of the cervical spine. The correlations between radiologic findings, DSSEP data, and clinical assessments were investigated.

Results

We found that DSSEP N13_E and N13_F correlated with the Compression_Ratio, Central_Ratio, 1/4-Lateral_Compression_Ratio (Pearson, p < 0.05) and Ax-CCM types (ANOVA, p < 0.05) in MRI axial images and cervical segmental instability in dynamic X-ray (t-test, p < 0.05). Apart from the 1/4-Lateral_Compression_Ratio, these radiographic parameters above also correlated with the baseline clinical assessments (Spearman or ANOVA or t-test, p < 0.05) and postoperative recovery rate (Pearson or ANOVA or t-test, p < 0.05).

Conclusions

We found that the preoperative Compression_Ratio, Central_Ratio and 1/4-Lateral_Compression_Ratio in MRI and cervical segmental instability in dynamic X-ray could reflect the dynamic neural dysfunction of the spinal cord. Different Ax-CCM types corresponded to different DSSEP results at extension and flexion, suggesting divergent pathophysiology. These radiographic parameters could help evaluate disease severity and predict postoperative prognosis.

Lumbar and cervical viscoelastic disc replacement: Concepts and current experience

The ideal lumbar and cervical discs should provide six degrees of freedom and tri-planar (three-dimensional) motion. Although all artificial discs are intended to achieve the same goals, there is considerable heterogeneity in the design of lumbar and cervical implants. The “second generation total disc replacements” are non-articulating viscoelastic implants aiming at the reconstruction of physiologic levels of shock absorption and flexural stiffness. This review aims to give an overview of the available implants detailing the concepts and the functional results experimentally and clinically. These monobloc prostheses raise new challenges concerning the choice of materials for the constitution of the viscoelastic cushion, the connection between the components of the internal structure and the metal endplates and even the bone anchoring mode. New objectives concerning the quality of movement and mobility control must be defined.

Correlation Between Parameters of Intervertebral Disc and Cervical Lordosis in Cervical Spondylotic Myelopathy

Background

In cervical disc degeneration, cervical disc height (CDH) and cervical disc angle (CDA)have a certain but unidentified relationship with cervical lordosis (CL). This study aimed to reveal the relationship among CDH, CDA, and CL in patients diagnosed with cervical spondylotic myelopathy (CSM).

Material/Methods

A retrospective analysis was conducted using the data of 212 CSM patients (136 males and 76 females). According to CL angle, patients were classified into 2 groups: patients with CL ≤10° constituted Group 1 (n=102); patients with CL >10° constituted Group 2 (n=110). The CDH, CDA, and CL were measured using X-ray imaging. Pearson correlation analysis measured the correlation between CDH, CDA, and CL. Multiple linear regression was utilized to analyze the effects of CDH and CDA on CL.

Results

The CDAs in every level were higher in Group 2 than those in Group 1 (P<0.05).CDH and CDA gradually increased with the increase in vertebral level and dropped at C5–C6 level in both groups. We found statistically significant correlations between C3/4H, C4/5H, C3/4A,C4/5A, C5/6A, and C6/7Aand CL in Group 1 (P<0.05), and between C4/5H, C3/4A, and C4/5Aand CL in Group 2 (P<0.05). C3/4A and C4/5A predicted CL in Group 1 (adjusted R²=0.176, P<0.001), while C4/5A predicted CL with high sensitivity in Group 2 (adjusted R²=0.198, P<0.001).

Conclusions

CDA contributes more than CDH to CL in CSM. Further studies are necessary to reveal the relationship between CL and cervical disc degeneration.