C2-7 Angle Research Articles

Quantitative Reduction of Basilar Invagination With Atlantoaxial Dislocation by a Posterior Approach.

ObjectiveThis study evaluated the feasibility and efficacy of quantitative reduction and fixation to treat basilar invagination (BI) with atlantoaxial dislocation (AAD). MethodsPosterior occipitocervical angle (POCA), occiput–C2 angle (Oc–C2A), clivusaxial angle (CAA), and C2–7 angle (C2–7A) were considered for quantitative reduction. Twelve patients with BI complicated with AAD received posterior interarticular release and individualized cage implantation to restore vertical dislocation. The POCA was adjusted using cantilever technology to further reduce the horizontal dislocation and adjust lower cervical vertebral angle. All patients received a radiological follow-up for ≥12 months. Improvements in spinal cord function were evaluated using Japanese Orthopedic Association (JOA) score. ResultsAll the patients received successful quantitative reduction for BI-AAD, and bony fusion was achieved without spinal cord injury after surgery for 12 months. The JOA score was improved significantly to 15.2 ± 0.9 twelve months after surgery (p < 0.01). Radiological follow-up revealed that individualized cage and POCA play vital roles in quantitative correction: (1) distance of the dens above McRae’s line and atlantodens interval were restored to normal level, respectively; (2) changes in Oc–C2 angle (ΔOc–C2A), C2–7 angle (ΔC2–7A), clivus-axial angle (ΔCAA), and POCA (ΔPOCA) were all caused by changes in axis tilt. Based on the changes of radiological parameter we deduced the formula for quantitative reduction by linear regression analysis: -ΔPOCA = ΔOc–C2A = -ΔC2–7A = ΔCAA.ConclusionQuantitative posterior reduction by individualized cage and adjusting ΔPOCA is feasible for treating BI with AAD.

Impact of cervical sagittal balance and cervical spine alignment on craniocervical junction motion: an analysis using upright multi-positional MRI.

To evaluate the effect of cervical sagittal alignment on craniocervical junction kinematic. We retrospectively reviewed 359 patients (119 cervical lordosis, 38 cervical sagittal imbalances, 111 cervical straight, and 91 cervical kyphosis) who underwent cervical spine multi-positional magnetic resonance imaging (mMRI). The C2-7 angle, disc degeneration grading and cSVA were analyzed in neutral position. The C3-5 OCI, O-C2 angle, and OCD were analyzed in neutral, flexion, and extension position. The Kruskal-Wallis test was used to detect difference among four groups. The post hoc analysis was performed by Mann-Whitney U test. The cervical sagittal imbalance, cervical straight, and cervical kyphosis groups had significantly more lordosis angle in C3 and C4 OCI and O-C2 angle than the cervical lordosis group (p < 0.0125). Head motion in relation to C2, C3, and C4 (O-C2 angle, C3-4 OCI) in the kyphosis group was significantly greater than in the cervical lordosis group (p < 0.0125). The cervical sagittal imbalance group showed significantly increased O-C2 angle than the cervical lordosis group (p = 0.008). Regression analysis showed that an increase in O-C2 angle by one unit had a relative risk of 4.3% and 3.5% for a patient to be in the cervical sagittal imbalance and cervical kyphosis groups, respectively. Cervical sagittal alignment affected craniocervical junction motion with the head exhibiting greater extension and motion in the cervical sagittal imbalance and cervical kyphosis groups. Motion of the head in relation to C2 can be used to predict the cervical sagittal alignment.

Myovascular Preserving Open-Door Laminoplasty for Cervical Spondylotic Myelopathy With Miniplate Fixation.

Laminoplasty is an effective procedure for treating cervical spondylotic myelopathy. We conduct myovascular preserving open-door laminoplasty (MPLP) in combination with a laminoplasty plate to improve the stability of the enlarged lamina. We compare the details of the MPLP technique with conventional open-door laminoplasty. We compared 25 cases of MPLP (mean age = 70.5, mean follow-up period = 19 months) with 15 controls who received conventional open-door laminoplasty using hydroxyapatite spacers (mean age = 74, mean follow-up period = 53 months). Regarding surgical outcomes, blood loss, operative time, Japanese Orthopaedic Association score, and postoperative visual analog score for neck pain were measured. Regarding image analysis, preoperative and postoperative range of motion (ROM), C2-7 angle, implant back out, hinge bone fusion time, presence or absence of hinge bone union failure, and posterior neck fat infiltration rate were evaluated. Operative time was significantly shorter for MPLP, and postoperative neck pain was significantly decreased. In image evaluation, %ROM was significantly increased in MPLP, but no difference in C2-7 angle existed between the 2 groups. Implant back out was not recognized in either group. In MPLP, the hinge union period was significantly shortened, and the postoperative fat infiltration rate was significantly decreased. We were able to reduce neck pain after surgery by an approach entailing longitudinal splitting of the spinous processes. We were able to ensure shorter operation times due to cervical plates and better hinge bone fusion times due to initial stability. 4.

Age-related changes in upper and lower cervical alignment and range of motion: normative data of 600 asymptomatic individuals.

To identify age-related changes and the relationship between upper and lower cervical sagittal alignment and the range of motion (ROM). A total of 600 asymptomatic volunteers were enrolled. There were 50 males and 50 females in each decade of life between the third and the eighth. The O-C2 angle and the C2-7 angle were measured using the neutral radiographs of the cervical spine. ROM was assessed by measuring the difference in alignment in the neutral, flexion, and extension positions. The mean O-C2 angle in the neutral position was 14.0° lordotic. The mean ROM of the O-C2 angle was 23.1°. The mean C2-7 angle in the neutral position was 14.3° lordotic. The mean ROM of the C2-7 angle was 56.0°. The O-C2 angle was 16.1° in the third decade and gradually decreased to 11.4° in the eighth decade. There were no significant age-related changes in the ROM of the O-C2 angle. The C2-7 angle was 7.2° in the third decade and gradually increased to 20.8° in the eighth decade, and the ROM gradually decreased with increasing age. Significant negative correlation was observed between O-C2 angle and C2-7 angle. The O-C2 angle gradually decreased and the C2-7 angle increased with age. The ROM of the O-C2 angle did not change, but the ROM of the C2-7 angle decreased with age. The upper and lower cervical spine showed different age-related changes.

C1-2 facet disarticulation for correction of iatrogenic cervical kyphosis following occipital-cervical fusion.

The patient is a 69-year-old woman with a history of atlantoaxial instability and cervical pain who underwent an occipital-cervical fusion at an outside hospital. Five days following the procedure she required a PEG tube due to progressive dysphagia. Compared with preoperative imaging, x-ray shows cervical spine hyperextension with a significant decrease in the occipital–C2 angle. A swallow test confirmed aspiration and pharyngeal phase functional impairment. Two-stage surgery consisted of hardware removal, drilling the fused right C1–2 facet, reinstrumentation, and halo placement. The swallowing test confirmed there is no aspiration. We proceeded with rod placement. The patient recovered completely.The video can be found here: https://youtu.be/YzdJrOm46Y4

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

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. 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. 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. 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.

Mode of onset of dropped head syndrome and efficacy of conservative treatment.

The initial treatment of dropped head syndrome (DHS) is basically nonsurgical, but the mode of onset of DHS and efficacy of conservative treatment have not been fully clarified. The subjects were 38 DHS patients without neuromuscular disease (11 men and 27 women, average age 74.5 years). Cervical collar, physical therapy, and temporary medication for cervical pain were provided for all DHS patients. The following parameters were measured on lateral global spine standing radiographs: sagittal vertical axis (SVA), cervical sagittal vertical axis, C2-C7 angle, first thoracic slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. According to the mode of onset of DHS, the subjects were classified into acute-onset group (<3 months) and chronic-onset group (≥3 months). Acute- and chronic-onset DHS were observed in 20 and 18 patients, respectively. A history of cervical trauma was involved in nine and two cases of acute- and chronic-onset DHS, respectively. Acute-onset DHS included more balanced-SVA (B-SVA: -30 mm <SVA ≤40 mm) than chronic-onset DHS. In conservative cases, the recovery rate was better in acute-onset DHS with B-SVA. In acute-onset DHS treated conservatively, the recovery rate was significantly poor in cervical trauma cases. Acute-onset DHS includes more balanced SVA and a history of cervical trauma, while acute-onset DHS without a history of cervical trauma has better prognosis by conservative treatment. Surgical indications for DHS should be carefully determined, and sufficient conservative treatment is essential.

Occipitocervical measurements: correlation and consistency between multi-positional magnetic resonance imaging and dynamic radiographs.

To evaluate the reliability and validity of the multi-positional magnetic resonance imaging in measuring occipitocervical parameters using the standard cervical dynamic radiographs as a reference. Patients were included if they underwent both dynamic radiograph and cervical multi-positional MRI within a 2-week interval from January 2013 to December 2016. Twelve occipitocervical parameters were measured on both image modalities in all positions (neutral, flexion and extension): Posterior Atlanto-Dental Interval, Anterior Atlanto-Dental Interval (AADI), Dens-to-McRae distance, Dens-to-McGregor distance, Occipito-atlantal Cobb angle (C01 angle), Occipito-axis Cobb angle (C02 Cobb angle), Atlas-axis Cobb angle (C12 angle), Redlund-Johnell, Modified Ranawat, Clivus canal angle, Occiput inclination, and Occiput cervical distance. Pearson correlation and linear regression analysis were used to evaluate the correlation of both modalities for each parameter. A p value of < 0.05 was considered statistically significant. Cervical images of 70 patients were measured and analyzed. There was a significant positive correlation between dynamic X-ray and multi-positional MRI for all parameters (p < 0.05) except AADI. Dens-to-McGregor distance and Redlund-Johnell parameter demonstrated a very strong correlation in the neutral position (r = 0.72, r = 0.79 respectively) and moderate to very strong correlation(r > 0.4) for Modified Ranawat, Clivus canal angle, C02 Cobb angle and C02 distance in all neck position. The intra-class correlation (ICC) of intra- and inter-observer showed good to excellent reliability, and ICCs were 0.67-0.98. Multi-positional MRI can be a reliable imaging option for diagnosis of occipitocervical instability or basilar invagination compared to standard dynamic radiographs.

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

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

Analysis of the reciprocal changes in upper cervical profile and the risk factors for increasing cervical sagittal vertical axis after laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine

ObjectiveThe purpose of this study was to elucidate the reciprocal changes in the upper cervical profile and the risk factors for increasing cervical sagittal vertical axis (cSVA) after laminoplasty for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Patients and methodsThis retrospective study included thirty-nine consecutive patients (30 men and 9 women) with cervical OPLL who underwent cervical laminoplasty. We recorded the operative time, blood loss, Japanese Orthopaedic Association (JOA) score recovery rate. Radiological measurements were performed to analyze the following parameters: pre and 1- year postoperative chin-brow vertical angle (CBVA), McGregor’s slope (McGS), occiput to C2 Cobb angle (O-C2 angle), C2–C7 Cobb angle (C2–C7 angle), T1-slope (T1S), C2–C7 sagittal vertical axis (cSVA) and calculated the change (Δ). Patients were divided into two groups according to ΔcSVA: positive (ΔcSVA ≥ 0) and negative (ΔcSVA < 0). ResultsPostoperative O-C2 angle (P = 0.028), ΔO-C2 angle (P = 0.019), ΔC2-C7 angle (P = 0.030) and T1S (P = 0.009) diff ;ered between the two groups. ΔcSVA showed a positive correlation with ΔO-C2 (R = 0.365, P = 0.022) and T1S (R = 0.472, P = 0.002). ΔO-C2 showed a positive correlation with T1S (R = 0.478, P = 0.002) and a negative correlation with ΔC2-C7 (R=-0.443, P = 0.005). ΔC2-C7 showed a negative correlation with T1S (R=-0.415, P = 0.009). Stepwise multiple linear regression analysis showed that ΔcSVA increased by 0.757 mm for each T1 slope and increased by 0.905 mm for each ΔMcGS. ConclusionIncreasing the lordosis in the O-C2 segment compensates for the loss of lordosis in the C2-C7 segment after cervical laminoplasty. Higher T1S is a risk factor for increasing cSVA after laminoplasty for OPLL of the cervical spine.

Multilevel cervical arthroplasty-clinical and radiological outcomes.

Cervical disc arthroplasty (CDA) is a valid option for single-level cervical disc disease (CDD) as an alternative to fusion. However, the use in 3- and 4-level disc disease is under scrutiny with scarce data published so far. Our aim was to study clinical and radiological outcomes of arthroplasty in patients with multilevel CDD. Retrospective analysis of clinical records, pre- and post-operative neutral/dynamic X-rays of patients who underwent CDA in multilevel CDD (2-4 levels). We evaluated sagittal balance parameters (C2-7 and index angle, SVA), global and segmental range of motion (ROM)), neck and arm VAS, Odom's criteria, re-operation rate, adjacent segment disease (ASD), willingness to undertake the same procedure again. Rate of heterotopic ossification (HO) was studied for follow-up >2 years. A subgroup analysis was performed regarding 2-level versus 3- or 4-level arthroplasty. Thirty-two patients were included, 6 males and 26 females, mean age of 46 years (range, 30-63). Seventy-seven cervical disc levels were treated with the same artificial disc. Twenty-one patients were operated on 2 levels, nine in 3 levels, and 2 patients in 4 levels. Post-operatively, there was a decrease in SVA (-2.2±8.36 mm, P=0.098) and an increase in global (3.7±9.6º, P=0.042) and index (1.3±6.1º, P=0.071) ROM. Mean nVAS and aVAS decreased (7.5±1.1 to 2.5±1.5; 6.3±1.9 to 2.2±1.7, P<0.05). Two-level versus 3-4 level patient subgroups showed a lower SVA (-1.3±8.1 mm P=0.47; -3.4±6.3 mm P=0.107), a slight increase in global (1.6±9.4º P=0.44; 7.2±11.7º P=0.07) and index (1.1±4.7º P=0.12; 1.3±8.1º P=0.35) ROM. HO was present in 9.9% (7/71) of disc levels operated, none of them with grade 3 or 4. Multilevel CDA provides good clinical and radiological outcomes, preserving global and segmental cervical mobility, while having a beneficial effect on sagittal balance. These results hold for 2 to 4 levels, making this technique a valuable option in selected patients with cervical multilevel CDD.

Morphometry of the C2 Pedicle and Lamina in Thai Patients.

Background:Traumatic upper cervical spine leads to instability and neurological deficit. At present, C2 (axis) pedicle or lamina screws for fixation are popular because further external immobilization is not needed. However, these techniques demand experience inserting the screws and carry the risk of vertebral artery or spinal cord injury. In some patients, the C2 screws cannot be inserted because of limited C2 size.Objective:To determine the width, length, height, and angle in the C2 pedicle and lamina in the Thai population.Materials and Methods:Patient data were collected from the Picture Archiving and Communication System at the Faculty of Medicine, Prince of Songkla University from January 2016 to December 2017. The C2 parameters, i.e., width, length, height, and angle of the pedicle and lamina were recorded.Results:The CT C-spine scans of 270 patients were enrolled. The mean Thai C2 pedicle dimensions were width 5.51 mm, length 23.78 mm, angle 39.04°, and height 8.64 mm. The mean C2 lamina dimensions were width 5.88 mm, length 32.17 mm, angle 49.46°, and height 12.27 mm. Twenty-four patients from the 270 patients (8.8%) had a pedicle width <3.5 mm but all patients had a lamina width ≥3.5 mm.Conclusion:In the Thai samples, 8.8% had a C2 pedicle width <3.5 mm which would not allow insertion of screws; however, they could be replaced with lamina screws since the lamina width was ≥3.5 mm. In this study, all of the patients who could not be inserted pedicle can be replaced with lamina screws inserted.

Role of O-C2 angle in the development of dysphagia in patients with halo-vest fixation

BackgroundDysphagia is one of the most serious complications in patients treated with a halo-vest brace. However, the cause of dysphagia development by halo-vest fixation is not yet clear. We therefore investigated the incidence of dysphagia and cervical alignment as well as clinical data from medical charts in patients treated with a halo-vest brace.MethodsWe retrospectively reviewed clinical data from the medical charts of 49 patients who had undergone halo-vest fixation. Occipito (O)-C2 angle, C2-C6 angle, and pharyngeal inlet angle were assessed by lateral plain X-rays of the cervical spine. The impacts of these parameters on incidence and severity of dysphagia were analyzed.ResultsThirteen patients (32%) suffered from dysphagia during halo-vest fixation, and age and length of intensive care unit (ICU) stay were greater in the dysphagia group (p = 0.044 and 0.013, respectively) than in those who did not develop dysphagia. O-C2 angle was smaller in the dysphagia group (p = 0.016). After multivariate logistic analysis, body mass index, ICU stay, and O-C2 angle remained as independent risk factors related to incidence of dysphagia. Spearman rank correlation showed a negative correlation between ICU stay and Food Intake Level Scale (FILS) (p = 0.026), and a positive correlation between O-C2 angle and FILS (p = 0.008).ConclusionThis study suggested that O-C2 angle is related to both incidence and severity of dysphagia due to halo-vest fixation.

Is Initial Posterior Atlantoaxial Fixation and Fusion Applying Bilateral C1-2 Transarticular Screws and C1 Laminar Hooks Reliable for Acute Pediatric Atlantoaxial Instability?: A Minimal 10-Year Analysis of Outcome and Radiological Evaluation.

A retrospective case series study with at least 10 years of follow-up data. To validate the reliability of bilateral C1-2 transarticular screws and C1 laminar hooks and a bone autograft for acute pediatric atlantoaxial instability. The reliability of initial posterior atlantoaxial fusion in pediatric patients is still controversial. To date, however, only a few published articles with short-term follow-up data are available to help spinal surgeons understand the effects of posterior atlantoaxial fusion in the skeletally immature spine. Five pediatric patients with acute atlantoaxial instability underwent atlantoaxial fusion using the above technique over a 3-year period. During a minimum 10-year follow-up period, not only outcomes and complications were investigated, but the vertical growth of the constructed spine in relation to the growth of the entire cervical spine, overall cervical spinal alignment, and adjacent-segment instability were evaluated. The clinical follow-up indicated solid fusion and complete clinical relief from symptoms. No neural or vascular impairment was observed. The radiological evaluation showed that all patients had growth within the fusion construct reaching a mean 35.4% of the entire cervical spine. There were no radiological indicators of subaxial instability, even when cervical sagittal alignments became straight with a mean C2-7 angle of 6.4°. The results showed that initial posterior atlantoaxial fusion accomplished with bilateral C1-2 transarticular screws, C1 laminar hooks fixation, and bony autograft is a reliable surgical technique for treating acute pediatric atlantoaxial instability without negative effects on vertical growth at the fused level or the stability of the subaxial spine. 3.

The significance of cervical sagittal alignment for nonrecovery after whiplash injury

BACKGROUND CONTEXTWhiplash-associated disorder is a common cause of chronic neck pain. Several radiological cervical angular variables are suggested to have constitutional characteristics, that is, them being minimally influenced by body positioning. However, the association between these variables and pain conditions remains poorly understood. To our knowledge, no previous studies have investigated the association between constitutional angular variables and the outcome after whiplash trauma. PURPOSEOur objectives were (1) to study the inter-rater agreement of sagittal radiologic variables between 2 raters and (2) to investigate any association between these variables and self-perceived nonrecovery after whiplash injury. STUDY DESIGNProspective cohort study. PATIENT SAMPLEForty-six patients aged 16 to 70 years, attending an emergency department after a motor vehicle accident resulting in neck pain were recruited. OUTCOME MEASURESSelf-perceived nonrecovery (yes/no) was the primary outcome measure. The secondary outcome measure was pain level on a numeric rating scale. METHODSThe participants underwent computed tomography scans in a supine position. Sagittal alignment variables (T1 slope, neck tilt, thoracic inlet angle [TIA], and C2–C7 angle) on the computed tomography scans were measured by 2 independent raters. Inter-rater agreement was tested with a paired sample t test and Bland-Altman plots for each variable. The patients were followed up after 6 months. RESULTSNo systematic differences for the assessed variables were found between the 2 raters. The overall nonrecovery rate was 28%. For the group with low neck tilt, the nonrecovery rate was 50% (95% CI: 36%–78%) and for the group with high neck tilt, 8% (95% CI: 3%–25%). The nonrecovery rate for the group low TIA was 50% (95% CI 29%–72%) and for those with high TIA 14% (95% CI 4%–26%). The associations remained significant after adjustments for possible confounders. The inter-rater analysis shows satisfactory agreement without proportional bias. CONCLUSIONSThis study indicates the existence of an association between the constitutional sagittal alignment of the cervical spine and the outcome after whiplash injuries.

Safety of anterior cervical discectomy and fusion using titanium-coated polyetheretherketone stand-alone cages: Multicenter prospective study of incidence of cage subsidence

This multicenter prospective study investigated cage subsidence in anterior cervical discectomy and fusion (ACDF) using titanium-coated polyetheretherketone (PEEK) stand-alone cages. This study recruited patients who underwent 1- or 2-level ACDF using titanium-coated PEEK stand-alone cages for cervical disc disease. Patients with acute trauma or past cervical spine operations were excluded. Sixty-two cages in 42 patients were eligible for analysis. Minimum follow-up was 6 months after ACDF. Significant cage subsidence was recognized in 11 of 62 cages (17.7%). Cage subsidence was predominantly moderate (14.5%), with severe subsidence found in only 2 cages (3.2%). The slowest occurrence of cage subsidence was 6 months after surgery, in 4 of 11 cages. Frequency of cage subsidence did not differ significantly between patients <65 and ≥65 years old. Patients with and without cage subsidence both demonstrated significant improvement of neurological function. Cage subsidence resulted in aggravation of local angle, but finally did not affect C2-7 angle or cervical tilt angle. Severe cage subsidence was found in only 3.2% of patients within 6 months after ACDF. Cage subsidence aggravated local angle, but finally did not affect C2-7 angle or cervical tilt angle. One- or 2-level ACDF using titanium-coated PEEK stand-alone cages appears safe and justified, even in elderly patients.

Relationship between cervical and global sagittal balance in patients with dropped head syndrome

BackgroundDHS is characterized by chin-on-chest deformity and devastatingly impedes activities of daily living in affected individuals. There is a paucity of literature about the pathophysiology of DHS including knowledge about spinal sagittal alignment. We conducted this study to clarify the relationship between cervical sagittal alignment and global sagittal balance in DHS.MethodsThis is a retrospective radiographic study of a case series of DHS. Forty-one patients with diagnosed DHS were enrolled. Measurements were made using lateral standing radiograph.ResultsC2–C7 sagittal vertical axis (SVA) was estimated as 52.0 ± 2.4 mm. Among sagittal parameters, C7–S1 SVA positively correlated with C2–C7 angle (C2–C7 A) (r = 0.33). For the correlations between C7 and S1 SVA and C2–C7 A, both logistic and linear regression models were used to determine the threshold for C2–C7 A value responsible for global sagittal balance. C2–C7 A of − 15.0 and 6.0 were predicted by logistic and linear regression models and were considered responsible for the occurrence of global positive imbalance. Therefore, we divided into two groups, namely, cervical kyphosis group (C type) and diffuse kyphosis group (D type) by median value of C2–C7 A. Enlarged thoracic kyphosis and global positive imbalance were observed in D type compared to C type.ConclusionC2–C7 A exhibited correlations with cervical balance and also with global balance. There should be various type of thoraco-lumbar alignment in DHS.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Does preoperative inferior endplate morphology influence the outcomes of cervical disc arthroplasty at C5-C6 level: A retrospective study

ObjectivesDespite encouraging clinical results, the postoperative segmental kyphosis was observed in many cervical disc arthroplasty (CDA) studies. Most studies discussed technical factors related to kyphosis. However, the cervical endplate, which contacted directly with prostheses and distributed the compressive load across the vertebral body, was seldom investigated. The purpose of the study was to investigate the effects of the inferior endplate morphology on clinical and radiological outcomes after C5/C6-level CDA with Prestige-LP Disc. Patients and methodsOne hundred and thirty-two patients with C5/C6-level CDA were retrospectively reviewed. Their preoperative inferior endplates on the mid-sagittal plane were visually classified into 3 types: type I with the endplate concavity apex located posteriorly, type II with the apex located in the middle and type III with the apex located anteriorly. Sagittal diameter of endplate, endplate concavity depth and endplate concavity apex location were measured. Japanese Orthopedic Association (JOA), visual analogue scale (VAS) and Neck Disability Index (NDI) scores were used to evaluate clinical outcomes. Range of motion (ROM) and sagittal alignment including C2-7 and C5-6 angle were assessed. ResultsThe type I, type II and type III endplates accounted for 25.00 %, 51.52 % and 23.48 % of 132 individuals. Most patients achieved significant reduction in VAS scores and NDI but the significant increase in JOA scores. No substantial differences in clinical outcomes were found among the 3 endplate types. Compared with preoperative values, the C5-6 ROM, C2-7 ROM and C2-7 angle were preserved, while the C5-6 angle increased significantly from kyphosis to lordosis. At the last follow-up, type I endplate had the least C5-6 angle (2.03°, 3.94° and 4.46° for type I, II and III endplates) and the highest incidence of segmental kyphosis at C5-C6 level (33.30 %, 14.70 % and 9.70 % in the same order, P = 0.028). ConclusionsPatients achieved satisfactory clinical outcomes after C5/C6-level CDA without significant differences among three endplate types. Type I endplate had a high incidence of segmental kyphosis at C5-C6 level.

Predictive abilities of O-C2a and O-EAa for the development of postoperative dysphagia in patients undergoing occipitocervical fusion

Background ContextDysphagia is a common postoperative complication in patients undergoing occipitocervical fusion (OCF). Previous studies had proposed the use of two measures—the occipital to C2 angle (O-C2a) and the occipital and external acoustic meatus to axis angle (O-EAa)—to predict postoperative dysphagia after OCF. However, these studies had small sample sizes and the predictive abilities of both measures are still not clear. PurposeTo evaluate the predictive ability of O-EAa and O-C2a for dysphagia after OCF. Study DesignA retrospective clinical study. Patient SampleA total of 109 consecutive patients who had undergone OCF. Outcome MeasuresPresence of postoperative dysphagia, O-C2a, C2 tilting angle (C2Ta), O-EAa, and the narrowest oropharyngeal airway space (nPAS). MethodsBetween April 2010 and June 2018, 109 consecutive patients who had undergone OCF were reviewed. Patients were divided into two groups according to the presence of postoperative dysphagia. Radiographic measurements, including O-C2a, C2Ta, O-EAa, and nPAS, were evaluated at preoperative and 1 month postoperative and the findings were compared. Simple linear regression was used to measure the correlations between the parameters and the presence of dysphagia, and the correlations within the parameters. Multiple regression analysis was used to examine the variables that affected the change of nPAS (dnPAS%). Sensitivity and specificity analyses were used to evaluate the effectiveness of the previously proposed measures (“O-C2a change≤−5°” and “postoperative O-EAa<100°”) for prediction of post-OCF dysphagia. ResultsThe incidence of dysphagia after OCF was 26.6% (29/109). Preoperative values for the radiographic parameters were similar between patients with and without dysphagia. In the dysphagia group, both O-C2a and O-EAa values showed a dramatic decrease after surgery, which was accompanied by a decrease in nPAS. Postoperative O-C2a, O-EAa, and nPAS in the dysphagia group were significantly smaller than those in the nondysphagia group (p<.05). The changes in O-EAa, O-C2a, and nPAS showed a linear correlation with the presence of dysphagia (p<.05). In addition, linear correlations were found between two of the three parameters. Multiple regression showed the change of O-C2a and O-EAa were significant predictors for dnPAS% (β=0.200, p=.022 and β=0.549, p=.000). The sensitivity and specificity of “O-C2a change≤−5°” in predicting dysphagia were 75.9% and 80.0% respectively, and those of “postoperative O-EAa<100°” were 75.9% and 62.5%, respectively. However, the sensitivity of the combination of these two values in predicting postoperative dysphagia was as high as 96.6%. ConclusionBoth O-EAa and O-C2a could be critical predictors for postoperative dysphagia. During surgery, ensuring that the O-EAa exceeds 100° and simultaneously avoiding an O-C2a reduction greater than 5° could effectively avert postoperative dysphagia.

Photogrammetric analysis: An objective measure to assess the craniocervical range of motion after cervical laminoplasty surgeries

Surgical decompression using laminoplasty is commonly performed for multilevel stenosis with cervical spondylotic myelopathy. However, the long-term effects on the craniocervical range of motion (ROM) after surgery are not well understood. This study represents the first entry into the literature of photogrammetric analysis for clinical measurement of craniocervical ROM. All patients underwent a French-door laminoplasty from 1995 to 2016 and were evaluated radiologically and with postoperative photographs (photogrammetric analysis) to measure craniocervical ROM and axial rotation. Radiographic parameters were occiput to C2 angle, C1–2 angle, C2–7 angle/cervical lordosis (CL), T1-slope (T1S), and TS-CL were measured. Chin-brow vertical angle (CBVA) was utilized for flexion and extension, while nose-turn angle (NTA) was used to assess axial rotation. Forty-four patients (mean age: 65.7 years, 50% female) had a mean follow-up of 37.9 months. Mean values in neutral, flexion, and extension were occiput to C2 = 30°, 15°, and 43°; C1–C2 = −32°, −25°, −32°; and C2–C7 = −4°, 11°, −20°, respectively. Mean CL was within 1 SD of the established −17° (±13.86°). Mean T1S and TS-CL were 33° and 30° in the neutral position, respectively. Mean radiographic full range of motion from flexion to extension was 53°. NTA towards patients’ left was 48° and the right side was 45°. Mean CBVA, was −4°, mean flexion 37°, and extension −45°; full range was 81°. Global craniocervical ROM has proven to be well preserved for many years following cervical laminoplasty. Photogrammetric analysis is a cost-effective and radiation-free method, accurate for quantitative assessment of craniocervical and cervical ROM.