T1 Slope Minus Cervical Lordosis Research Articles

Early radiographic outcomes after anterior cervical discectomy and fusion with anatomic versus lordotic cages

BackgroundAnterior cervical discectomy and fusion (ACDF) interbody implants are shaped anatomically, with a convex superior aspect, or lordotically, with an angle and flat surfaces. However, the effect of implant shape on cervical sagittal balance (CSB) is not well described. MethodsOf the 192 cases reviewed from 2018 to 2019, 118 were included with matching pre- and postoperative imaging. Cases were categorized by interbody implant type (anatomic or lordotic) and number of levels fused (1-level, 2-level, etc.). SurgiMap was used to measure cervical lordosis (CL), C2–C7 sagittal vertical axis (cSVA), T1 slope (T1S), and T1S minus CL (T1S-CL) on pre- and postoperative imaging. Pre- and postoperative parameters were compared within and between each cohort. Change in CL (ΔCL), cSVA (ΔcSVA), and T1S-CL (ΔT1S-CL) were calculated as the difference between pre- and postoperative values and were compared accordingly (1) anatomic versus lordotic and (2) 1-level versus 2-level versus 3-level fusion. ResultsThirty-nine (33.1%), 57 (48.3%), and 22 (18.6%) cases comprised the anatomic, lordotic, and mixed (anatomic and lordotic) groups, respectively. ACDFs improved CL and T1S-CL by 5.71° (p<.001) and 3.32° (p<.01), respectively. CL was improved in the lordotic (5.27°; p<.01) and anatomic (4.57°; p<.01) groups, while only the lordotic group demonstrated improvement in T1S-CL (3.4°; p=.02). There were no differences in ΔCL (p=.70), ΔcSVA (p=.89), or ΔT1S-CL (p=.1) between the groups. Two- and 3-level fusions improved CL by 7.48° (p<.01) and 9.62° (p<.01), and T1S-CL by 4.43° (p<.01) and 5.96° (p<.01), respectively. ConclusionsOverall, ACDFs significantly improved CL and T1S-CL however, there were no differences in CSB correction between the anatomic and lordotic groups. Two- and 3-level fusions more effectively improved CL (vs. single-level) and T1S-CL (vs. 3-level). These results suggest that implants should continue to be personalized to the patient's anatomy, however, future research is needed to validate these findings and incorporate the effects of preoperative deformities.

Does the presence of cervical deformity in patients with baseline mild myelopathy increase operative urgency in adult cervical spinal surgery? A retrospective analysis.

The objective of this study was to assess whether delaying surgical management of cervical deformity (CD) in patients with concomitant mild myelopathy increases the risk of suboptimal outcomes. Patients aged ≥ 18 years who had a baseline diagnosis of mild myelopathy with baseline and up to 2 years of postoperative data were assessed. Patients were categorized as having CD (CD+) or not (CD-) at baseline. Patients with symptoms of myelopathy for more than 1 year after the initial visit prior to surgery were considered delayed. Clinical and radiographic data were assessed using means comparison analyses. Multivariate regression analysis assessed correlations between increasing time to surgery and peri- and postoperative outcomes adjusted for baseline age and frailty score. Backstep logistic regression analysis assessed the risk of complications or reoperation, while controlling for baseline T1 slope minus cervical lordosis (TS-CL). One hundred six patients were included (mean age 58.11 ± 11.97 years, 48% female, mean BMI 29.13 ± 6.89). Of the patients with baseline mild myelopathy, 22 (20.8%) were CD- while 84 (79.2%) were CD+. Overall, 9.5% of patients were considered to have delayed surgery. Linear regression revealed that both CD- and CD+ patients were more likely to require reoperation when there was more time between the initial visit and surgical admission (p < 0.001). Additionally, an adjusted logistic regression indicated that CD+ patients who had a greater length of time to surgery had a higher likelihood for major complications (p < 0.001). Conversely, CD+ patients who were operated on within 30 days of the initial visit had a significantly lower risk for a major complication (OR 0.901, 95% CI 0.889-1.105, p = 0.043), and a lower risk for reoperation (OR 0.954, 95% CI 0.877-1.090, p = 0.043), while controlling for the severity of deformity based on baseline TS-CL. The findings of this study demonstrate that a delay in surgery after the initial visit significantly increases the risk for major complications and reoperation in patients with CD with associated mild baseline myelopathy. Early operative treatment in this patient population may lower the risk of postoperative complications.

Clinical and Radiological Outcome of Disc Arthroplasty for the Treatment of Cervical Spondylotic Myelopathy.

The aim of this study is to evaluate the clinical and radiological results of cervical disc arthroplasty (CDA) in patients with cervical spondylotic myelopathy (CSM) using the CP ESP® disc prosthesis. Prospectively collected data of 56 patients with CSM have been analyzed. The mean age at surgery was 35.6 years (range: 25-43 years). The mean follow-up was 28.2 months (range: 13-42 months). The range of motion (ROM) of the index segments, as well as upper and lower adjacent segments, was measured before surgery and at final follow-up. The C2-C7 sagittal vertical axis (SVA), C2-C7 cervical lordosis (CL), and T1 slope minus cervical lordosis (T1s-CL) were analyzed as well. Pain intensity was measured preoperatively and during follow-up using an 11-point numeric rating scale (NRS). Modified Japanese Orthopaedic Association (mJOA) score was assessed preoperatively and during follow-up for the clinical assessment of myelopathy. Surgical and implant-associated complications were analyzed as well. The NRS pain score improved from a mean of 7.4 (±1.1) preoperatively to a mean of 1.5 (±0.7) at last follow-up (p < 0.001). The mJOA score improved from a mean of 13.1 (±2.8) preoperatively to a mean of 14.8 (±2.3) at last follow-up (p < 0.001). The mean ROM of the index levels increased from 5.2° (±3.0) preoperatively to 7.3° (±3.2) at last follow-up (p < 0.05). Four patients developed heterotopic ossifications during follow-up. One patient developed permanent dysphonia. CDA showed good clinical and radiological outcome in this cohort of young patients. The motion of index segments could be preserved. CDA may be a viable treatment option in selected patients with CSM.

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

BackgroundThe impact of the T1 slope minus cervical lordosis (T1S-CL) on surgical outcomes in patients with degenerative cervical myelopathy undergoing laminoplasty (LP) remain uncertain.MethodsOne hundred patients who underwent cervical LP were retrospectively reviewed. Radiographic measurements included C2–C7 lordosis (CL), T1 slope (T1S), and C2–C7 sagittal vertical axis (SVA). Additionally, pain numeric rating scale, neck disability index (NDI), 12-Item Short-Form Health Survey, Euro QOL 5 dimensions (EQ5D), and Japanese Orthopedic Association score were investigated. According to past reports, T1S–CL > 20° was defined as mismatched. Then, based on T1S-CL mismatching, patients were divided into 2 groups.ResultsThis research understudied 67 males and 33 females with a mean age of 67 y. Preoperatively, only eight patients showed a T1S-CL mismatch. While the C2–7 Cobb angles did not change significantly after surgery, the T1 slope (T1S) angle increased, increasing the T1S-CL as a result. As we compared the clinical outcomes based on the preoperative T1S-CL mismatching, there were no significant differences between the two groups. On the other hand, the number of patients in the mismatched group increased to 21 patients postoperatively. As we compared clinical outcomes based on the postoperative T1S-CL mismatching, the postoperative NDI score and preop/postop EQ5D score were significantly worse in the mismatch group.ConclusionsAlthough cervical LP showed inferior outcomes in patients with postoperative T1S-CL mismatch even in the absence of severe preoperative kyphosis (> 10°), preoperative T1S-CL mismatch was not adversely prognostic.

Trends in Outcomes of a Prospective Consecutively Enrolled Single-Center Adult Cervical Deformity Series.

Retrospective cohort. The aim was to describe the two-year outcomes for patients undergoing surgical correction of cervical deformity (CD). Adult CD has been shown to compromise health-related quality of life. While advances in spinal realignment have shown promising short-term clinical results in this parameter, the long-term outcomes of CD corrective surgery remain unclear. Operative CD patients >18 years with two-year (2Y) health-related quality of life/radiographic data were included. Improvement in radiographic, neurologic, and health-related quality of life outcomes were reported. Patients with a prior cervical fusion and patients with the greatest and smallest change based on Neck Disability Index (NDI), numeric rating scale (NRS) neck, modified Japanese Orthopaedic Association (mJOA) were compared using multivariable analysis controlling for age, and frailty, and invasiveness. One hundred and fifty-eight patients were included in this study. By 2Y, 96.3% of patients improved in Ames cervical sagittal vertical axis modifier, 34.2% in T1 slope minus cervical lordosis (TS-CL), 42.0% in horizontal gaze modifier, and 40.9% in SVA modifier. In addition, 65.5% of patients improved in Passias CL modifier, 53.3% in TS-CL modifier, 100% in C2-T3 modifier, 88.9% in C2S modifier, and 81.0% in MGS modifier severity by 2Y. The cohort significantly improved from baseline to 2Y in NDI, NRS Neck, and mJOA, all P <0.05. 59.3% of patients met minimal clinically important difference for NDI, 62.3% for NRS Neck, and 37.3% for mJOA. Ninety-seven patients presented with at least one neurologic deficit at baseline and 63.9% no longer reported that deficit at follow-up. There were 45 (34.6%) cases of distal junctional kyphosis (DJK) (∆DJKA>10° between lower instrumented vertebra and lower instrumented vertebra-2), of which 17 were distal junctional failure (distal junctional failure-DJK requiring reoperation). Patients with the greatest beneficial change were less likely to have had a complication in the two-year follow-up period. Correction of CD results in notable clinical and radiographic improvement with most patients achieving favorable outcomes after two years. However, complications including DJK or failure remain prevalent.

Association of long-term outcome of long cervical fusion with sagittal balance: the significance of T1 slope minus cervical lordosis.

Retrospective study to assess correlation between the sagittal alignment of the cervical spine and the long-term outcomes of long cervical fusion due to cervical spondylotic myelopathy (CSM), with the emphasis on T1 slope minus cervical lordosis (T1S-CL). Growing evidence shows that the sagittal profile can play a major role in the outcomes of treatment, but the role of its correction is yet to be established. We conducted a retrospective analysis of 54 patients treated for CSM from 2006 to 2012. The neck pain-related disability was measured using NDI, the myelopathy was measured with the mJOA and Nurick scales. Six years after the surgery, standardised X-ray measurements were obtained, including C2-C7 lordosis (CL), C2-C7 sagittal vertical alignment (SVAC2-C7), T1 slope (T1S), and T1S minus CL (T1S-CL). The patients were divided based on the T1S-CL into two groups, using the threshold value of 16.5 degrees. A statistically significant improvement was noted in the mean NDI, mJOA, and median Nurick scale during the initial two years in both groups. The better aligned group had a better outcome measured with NDI at all follow-ups. The mJOA was significantly better in the better aligned group, but only preoperatively; at all follow-ups, the difference was not significant. T1S-CL had the strongest correlation with the NDI at the final follow-up. T1S-CL is an effective prognostic factor of the long term outcome after long cervical fusion in CSM treatment.

Cervical Deformity Correction Fails to Achieve Age-Adjusted Spinopelvic Alignment Targets.

To assess whether surgical cervical deformity (CD) patients meet spinopelvic age-adjusted alignment targets, reciprocal, and lower limb compensation changes. Retrospective review. CD was defined as C2-C7 lordosis >10°, cervical sagittal vertical angle (cSVA) >4 cm, or T1 slope minus cervical lordosis (TS-CL) >20°. Inclusion criteria were age >18 years and undergoing surgical correction with complete baseline and postoperative imaging. Published formulas were used to create age-adjusted alignment target for pelvic tilt (PT), pelvic incidence and lumbar lordosis (PI-LL), sagittal vertical angle (SVA), and lumbar lordosis and thoracic kyphosis (LL-TK). Actual alignment was compared with age-adjusted ideal values. Patients who matched ±10-year thresholds for age-adjusted targets were compared with unmatched cases (under- or overcorrected). A total of 120 CD patients were included (mean age, 55.1 years; 48.4% women; body mass index, 28.8 kg/m2). For PT, only 24.4% of patients matched age-adjusted alignment, 51.1% overcorrected for PT, and 24.4% undercorrected. For PI-LL, only 27.6% of CD patients matched age-adjusted targets, with 49.4% overcorrected and 23% undercorrected postoperatively. Forty percent of patients matched age-adjusted target for SVA, 41.3% overcorrected, and 18.8% undercorrected. CD patients who had worsened in TS-CL or cSVA postoperatively displayed increased TK (-41.1° to -45.3°, P = 1.06). With lower extremity compensation, CD patients decreased in ankle flexion angle postoperatively (6.1°-5.5°, P = 0.036) and trended toward smaller sacrofemoral angle (199.6-195.6 mm, P = 0.286) and knee flexion (2.6° to -1.1°, P = 0.269). In response to worsening CD postoperatively, patients increased in TK and recruited less lower limb compensation. Almost 75% of CD patients did not meet previously established spinopelvic alignment goals, of whom a subset of patients were actually made worse off in these parameters following surgery. This finding raises the question of whether we should be looking at the entire spine when treating CD.

How do C2 tilt and C2 slope correlate with patient reported outcomes in patients after anterior cervical discectomy and fusion?

C2 tilt and C2 slope are quick and easy measurements to obtain on lateral radiographs and may be used to determine overall cervical sagittal alignment; however, the influence of these measurements on patient outcomes has not been well established in literature. To determine if C2 tilt and/or C2 slope predict patient outcomes better compared with conventional radiographic measures after an anterior cervical discectomy and fusion (ACDF). Retrospective cohort study. A total of 249 patients who underwent 1 to 3 level ACDF to address radiculopathy and/or myelopathy at a single academic institution between 2011 and 2015 were identified. Patients with less than 1 year of follow-up were excluded. Patient Reported Outcomes: Neck Disability Index (NDI), Physical Component Score-12 (PCS-12), and Mental Component Score (MCS-12), Visual Analog Score (VAS) Neck and Arm scores Cervical radiographic measurements: C2 tilt, C2 slope, C2-C7 lordosis, cervical SVA, T1 slope, T1 slope minus cervical lordosis (TS-CL), and C2-C7 ROM METHODS: Pearson correlation tests were performed to assess for significant associations between radiographic measurements and patient outcomes. Multiple linear regression models were developed adjusting for demographics and radiographic parameters to determine which factors were predictive of patient outcomes. C2 tilt and TS-CL correlated with all postoperative physical outcome scores (NDI, PCS-12, VAS Neck and ARM; p<.05), however no association was seen between C2 slope and postoperative outcomes. After accounting for the presence of subaxial deformity, C2 tilt and TS-CL remained strongly correlated to patient outcome scores. With multiple linear regression, C2 tilt was a significant predictor for NDI, whereas TS-CL was a significant predictor for PCS-12, VAS Neck and VAS Arm. C2 tilt significantly correlated with well-described conventional cervical parameters as well as postoperative physical outcomes measures, especially NDI, on multivariate analysis. C2 tilt may provide an easy and practical tool for predicting physical outcomes after ACDF.

126. Enhanced utility with greater number of levels treated for patient-specific, pre-contoured rods in posterior cervical fusion

BACKGROUND CONTEXT Patient-specific, pre-contoured rods are increasingly used in the surgical treatment of spinal pathologies. Previous studies show that pre-contoured rods help to achieve desired postoperative alignment goals, though it is unclear whether these benefits differ by fusion length. PURPOSE Assess how preoperative planning and patient-specific rods affect the outcomes of patients undergoing posterior cervical fusion surgery. STUDY DESIGN/SETTING Retrospective review of single-center cases of multilevel posterior cervical surgeries from 2014-2018. PATIENT SAMPLE This study included 65 patients. OUTCOME MEASURES Sagittal alignment: cervical sagittal vertical axis (cSVA), cervical lordosis (CL), T1 Slope (T1S) minus CL (TS-CL), and cervical-thoracic pelvic angle (CTPA). METHODS Patients undergoing posterior cervical fusion with available pre- and postop (3-month, 6-month, or 1-year) cervical radiographs were stratified: those whose surgeries involved preoperative planning and patient-specific, pre-contoured rods (PLAN), and those whose surgeries did not (NON). Independent samples t-tests assessed differences between PLAN and NON groups in alignment, and pre- to postop changes in alignment. Secondary analysis assessed differences in alignment between PLAN and NON groups for patients with lower-most instrumented vertebrae (LIV) above C7-T1, and below. RESULTS Included: 65 patients (55.1±9.9 years, 61% female) undergoing posterior cervical fusion (6.2±3.7 levels). Mean follow-up was 8.4±4.1 months. By group, 47.7% of patients had pre-contoured rods (PLAN, N=31), 53.3% did not (NON, N=34). Preoperatively, PLAN patients presented with greater cervical malalignment (CTPA: 4.0° vs 2.7°, p=0.015) and T1 Slope (33° vs 22°, p=0.013), but not global (SVA, TPA), or lumbopelvic alignment (PT, PI-LL, all p>0.05). Postoperatively, PLAN patients had greater C2-C7 lordosis than NON patients (18° vs 7°, p=0.001), and a trend of superior TS-CL alignment (19° vs 23°, p=0.075), but did not differ in any other cervical, global, or lumbopelvic parameters (all p>0.05). PLAN patients also showed superior pre- to postop changes in TS-CL (-7° vs 2.1°, p=0.026). Overall, 25% of patients had LIVs above C7-T1 (mean fusion length: 4.8±1.1 levels), while 75% had fusions extending lower (10.0±5.5 levels). For cases in which fusion extended below C7-T1, PLAN patients showed a trend of greater pre- to postop TS-CL correction (-3° vs 3°, p-0.076), more postop CL (14° vs 6°, p=0.007), and less lumbopelvic malalignment (PI-LL:-7.1° vs 0.1°, p=0.029) and (PT: 14° vs 19°, p=0.087), though this result is confounded by greater preop PI-LL and PT deformity for NON patients (both p 0.05). CONCLUSIONS For posterior cervical fusion cases, the use of preoperative planning and patient-specific, pre-contoured rods was associated with superior correction of cervical sagittal alignment. For cases in which fusion extended below C7-T1, use of contoured rods was associated with superior postop reciprocal alignment in the lumbopelvic spine, though this may be confounded by differences in preop alignment. For longer fusions, pre-planned and contoured rods may offer greater utility. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Characteristics affecting cervical sagittal alignment in patients with chronic low back pain

BackgroundSagittal spino-pelvic malalignment in patients with chronic low back pain (CLBP) have been reported in the past, which may also affect cervical spine lesions. The purpose of this study is to investigate the cervical alignment in patients with CLBP. MethodOf the patients who visited an orthopedic specialist due to low back pain lasting more than three months, 121 cases (average 71.5-years-old, 46 male and 75 female) with whole standing spinal screening radiographs were reviewed (CLBP group). Cervical parameters included cervical lordosis (CL), C2–C7 sagittal vertical axis (C2-7 SVA), and the T1 slope minus CL (T1S-CL). Cervical spine deformity was defined as C2-7 SVA >4 cm, CL <0°, or T1S-CL ≧20°. We compared the cervical alignment of these patients with 121 age and gender matched volunteers (control group). ResultsThe prevalence of cervical spine deformity was significantly higher in the CLBP group than in the control group (20.7% vs. 10.7%, P = 0.034). The mean CL was smaller in the CLBP group than in the control group (16.1° vs. 21.4°, P = 0.002). The mean C2-7 SVA was 17.6 mm vs. 18.7 mm in the CLBP group and in the control group, respectively (P = 0.817). The mean T1S-CL was larger in the CLBP group than in the control group (9.1° vs. 3.5°, P < 0.001). Multivariate analysis showed that people with CLBP were more likely to have cervical deformities than people without CLBP (odds ratio 2.16, 95% confidence interval 1.006 to 4.637). ConclusionsThis study results suggest that people with CLBP present with worse cervical sagittal alignment and higher prevalence of cervical spine deformities than age and gender matched volunteers with no CLBP. This means CLBP impacts cervical spine lesions negatively. Level of evidenceⅣ

Exploration on sagittal alignment and clinical outcomes after consecutive three-level hybrid surgery and anterior cervical discectomy and fusion: a minimum of a 5-year follow-up

PurposeTo compare sagittal alignment and clinical outcomes between three-level hybrid surgery (HS) and anterior cervical discectomy and fusion (ACDF) on cervical spondylotic myelopathy (CSM) over a 5-year follow-up.MethodThe study included 32 patients with ACDF, 36 patients with 1 prosthesis and 2 cages (HS1 group), and 25 cases with 2 prostheses and 1 cage (HS2 group). Alignment parameters included C2–C7 cervical lordosis (CL), C2–C7 sagittal vertical axis (SVA), T1 slope (T1S), and T1S minus CL (T1SCL). Radiographic parameters were range of motion (ROM), upper and lower adjacent ROM (UROM and LROM), and operated-segment lordosis (OPCL), as well as adjacent segment degeneration (ASD). Clinical outcomes included the neck disability index (NDI) and Japanese Orthopedic Association (JOA) score.ResultsThree groups were well-matched in demographics. All groups gained comparable improvement on NDI and JOA (P < 0.01). All groups gained CL improvement at the final visit (P < 0.05). There were no statistical differences on SVA and T1SCL among the groups and among preoperation, 1 week later, and final follow-up (P > 0.05) while T1S improved at 1 week later and final follow-up with HS2. The final change of all alignment parameters among the three groups was of no differences. ROM decreased and OPCL increased in all groups at the final follow-up (P < 0.05). UROM and LROM increased with ACDF but kept stable with HS1 and HS2. There was no inter-group difference on the incidence of ASD (P > 0.05).ConclusionCervical alignment was comparably improved. HS and ACDF provided identified mid-term efficacy, and it was not necessary to have to use prosthesis on three-level CSM.

Does Cervical Sagittal Balance Affect the Preoperative Neck Disability Index in Patients With Cervical Myelopathy?

This was a retrospective study. This study aimed to ascertain the relationship between preoperative Neck Disability Index (NDI) scores and cervical sagittal alignment in patients with cervical spondylotic myelopathy (CSM). Cervical alignment may influence postoperative clinical outcomes. However, the effect of preoperative sagittal balance on the preoperative status in CSM patients remains uncertain. From 2010 to 2016, 90 patients who underwent cervical surgery for CSM were enrolled. The inclusion criteria for this study included preoperative standing cervical radiographs and a preoperative NDI score. The following radiographic parameters were measured: (1) C0-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (SVA), (4) neck tilt, (5) thoracic inlet angle, (6) T1 slope, and (7) T1 slope minus cervical lordosis (T1S-CL). The Pearson product-moment correlation coefficients were calculated between all radiographic variables and the NDI scores, and multiple regression analysis was performed to determine the independent predictors of high preoperative NDI scores. Both C2-C7 SVA and T1S-CL were positively correlated with NDI scores (r=0.732, P<0.001 and r=0.333, P=0.001). Cervical lordosis was negatively correlated with NDI scores (r=-0.267, P=0.011). Significant correlations were found between C2-C7 SVA and the C0-C2 Cobb angle (r=0.244, P=0.020), C2-C7 SVA and the C2-C7 Cobb angle (r=-0.359, P=0.001), the C2-C7 Cobb angle and the C0-C2 Cobb angle (r=-0.457, P<0.001), and the C2-C7 Cobb angle and T1 slope (r=-0.385, P<0.001). The disability of the neck increased with increasing C2-C7 SVA and T1S-CL and decreasing cervical lordosis before surgical reconstruction. High C2-C7 SVA, low thoracic inlet angle, and high neck tilt values are independent predictors of high preoperative NDI scores.

Age-related Changes in Cervical Sagittal Alignment

Retrospective cohort study. To identify age-related changes in cervical sagittal parameters using standard radiographs. Cervical sagittal balance is important for the maintenance of neutral head posture and horizontal gaze. Degenerative changes in the cervical spine that occur with aging may alter cervical sagittal balance, which can lead to chronic neck pain and predispose to various cervical spine pathologies. We performed a retrospective cohort study of 151 patients with lateral cervical spine radiographs taken at our institution between December 2017 and June 2018. Cervical sagittal parameters were measured, including C1 inclination, C2 slope, C2-C7 Cobb angle, cervical sagittal vertical axis (cSVA), cervical tilt, upper and lower C7 slopes, T1 slope, and T1 slope minus cervical lordosis (TS-CL). The association between age and cervical sagittal parameters was assessed using the Pearson correlation coefficient and a linear regression analysis. An analysis of variance (ANOVA) with Tukey adjustments was then performed to identify differences in cervical sagittal parameters among patients aged 18 to 39 years, 40 to 64 years, and >64 years of age. There were positive correlations between age and C2-C7 Cobb angle (r = 0.231, P = 0.004), upper C7 slope (r = 0.280, P < 0.001), lower C7 slope (r = 0.283, P < 0.001), and T1 slope (r = 0.189, P = 0.020). Upper C7 slope (R = 0.079) and lower C7 slope (R = 0.074) had the strongest correlation with age in the linear regression analysis. The ANOVA found significant differences among the age subgroups in terms of C2-C7 Cobb angle (P = 0.002), upper C7 slope (P < 0.001), lower C7 slope (P < 0.001), and T1 slope (P = 0.031). Patients >64 years old had significantly higher C2-C7 Cobb angle, upper C7 slope, lower C7 slope, and T1 slope. Changes in cervical sagittal alignment with age are characterized by increased cervical lordosis and increased thoracic kyphosis. 3.

38. Prioritization of realignment associated with superior clinical outcomes for surgical cervical deformity patients

BACKGROUND CONTEXT Many patients are unable to undergo a major cervical deformity corrective surgery due to deformity severity, age, comorbidities, and overall frailty status. In order to optimize quality of life in patients with cervical deformity, there may be alignment targets to be prioritized. PURPOSE To prioritize the cervical parameter targets for alignment. STUDY DESIGN/SETTING Retrospective review of a multicenter prospective cervical deformity database. PATIENT SAMPLE Seventy-seven patients undergoing cervical deformity (CD) corrective surgery. OUTCOME MEASURES Cervical regional alignment parameters: cervical sagittal vertical axis(cSVA), cervical lordosis(CL), T1 Slope minus CL(TS-CL), chin brow vertical angle(CBVA), McGregor's slope(MGS), C2-T3 plumb line(C2-T3 SVA), C2-T3 angle, C2 Slope. Health-related quality of life measures: NDI. METHODS Included:CD patients (C2-C7 Cobb>10°, CL>10°, cSVA>4cm, or CBVA>25°) with full baseline (BL) and 1-year (1Y) radiographic parameters and NDI scores; patients with cervical or cervicothoracic Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA( RESULTS Seventy-seven CD patients included (62.1yrs, 64%F, 28.8kg/m2). Average CCI: 0.94, 7% current smokers. By approach, anterior: 19.4%, posterior: 41.6%, combined approach: 39%. Mean anterior levels fused: 3.5, posterior: 8.3, total: 7.5. Average op time: 553.1min; mean EBL: 1128.1ccs. 41.6% met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1 year for meeting MCID for NDI demonstrated an R2 of 0.820 (p=0.032) included TS-CL, cSVA, MGS, C2SS, C2-T3 angle, C2-T3 SVA, CL. By primary Ames driver, 67.5% of patients were categorized as C, and 32.5% as CT. Ratios of change in predictors for MCID NDI patients (BL -1Y) for C driver patients: 260.8% MGS, 140.3% CL, 121.2% C2-T3 angle, 49.6% C2 slope, 41.1% cSVA, 20.5% TS-CL, 3.1%C2-T3 SVA. While correction in CT driver patients included: 168.7% CL, 93% MGS, 70.8% C2-T3 angle, 31.1% cSVA, 27.5% C2 slope, 24.9% TS-CL, 13.7% C2-T3 SVA. The ratios were not significant between the two groups(p>0.050). Decision tree analysis determined cut-offs for radiographic change, prioritizing in the following order (based upon ordinal regression values): a correction ≤42.5°C2-T3 angle (OR: 5.667[1.074-29.891], p=0.041), -31.76°C2 slope (OR: 3.2 [0.852-12.026], p=0.085), >-11.57mm cSVA (OR: 3.185[1.137-8.917], p=0.027), >-2.16° MGS (OR: 2.724[0.971-7.636], p=0.057). CONCLUSIONS Certain ratios of correction of cervical parameters contribute to improving neck disability. Specific cut-offs of radiographic differences from baseline to 1 year were found prioritizing C2-T3 angle, followed by cervical lordosis, C2 slope, C2-C7 plumb line, and McGregor's slope, all strongly associated with meeting the minimal clinically important difference for the neck disability index score. Prioritizing these radiographic alignment parameters will optimize patient-reported outcomes for patients undergoing cervical deformity surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

McGregor's slope and slope of line of sight: two surrogate markers for Chin-Brow vertical angle in the setting of cervical spine pathology

BACKGROUND CONTEXTChin-Brow Vertical Angle (CBVA) is not routinely measured on radiographs even though it is a strong assessor of horizontal gaze. STUDY DESIGNRetrospective cohort study of patients with full-body stereoradiographs and a primary cervical diagnosis at the time of presentation. PURPOSEAssess the utility of McGregor's Slope (McGS) and Slope of Line of Sight (SLS) as surrogate markers for the CBVA in cervical spine pathology. METHODSA retrospective review of patients with full-body stereoradiographs was performed. Patients were ≥18 years of age with a primary cervical diagnosis. Analysis of CBVA, McGS, and SLS was conducted as markers of horizontal gaze. Sagittal alignment was characterized by: pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), T1-pelvic angle (TPA), sagittal vertical axis (SVA), T2-T12 thoracic kyphosis, C2-C7 SVA (cSVA), C2-C7 Cervical lordosis, T1-Slope minus Cervical Lordosis (TS-CL), and C2-Slope (C2S). A subgroup analysis was performed in patients with cervical deformity. Independent sample t tests and paired t tests compared radiographic alignment. Pearson correlations characterized linear relationships. Linear regression analysis identified relationships between the parameters. RESULTSIn all, 329 patients were identified with primary cervical spine diagnoses. Chin-Brow Vertical Angle was visible in 171 patients (52.0%), McGS in 281 (85.4%), and SLS in 259 (78.7%). Of the 171 patients with visible CBVA, the mean CBVA was 2.30±7.7, mean McGS was 5.02±8.1, and mean SLS was −1.588±2.03. Chin-Brow Vertical Angle strongly correlated with McGS (r=0.83) and SLS (r=0.89) with p<.001. McGregor's Slope positively correlated with SLS (r=0.89, p=.001). CONCLUSIONSThis study demonstrates that McGS and SLS serve as strong, positive correlates for CBVA. The reported mean differences between these measurements provide a useful conversion, broadening CBVA's use as a radiographic assessment of horizontal gaze.

PROMIS physical health domain scores are related to cervical deformity severity

Introduction:The aim of this study was to evaluate the association of available cervical alignment components through the Ames cervical deformity (CD) classification parameters with the Patient-Reported Outcomes Measurement Information System (PROMIS) physical health domain metrics.Methods:Surgical CD patients (C2–C7 Cobb >10° or C2–C7 sagittal vertical axis [cSVA] >4 cm or T1 slope minus cervical lordosis (TS-CL) >15°) ≥18 years with available baseline (BL) radiographic and PROMIS were isolated in a single-center spine database. Patients were classified according to the Ames CD modifiers for cSVA and TS-CL (low deformity [Low], moderate deformity [Mod], and severe deformity [Sev]). Descriptives and univariate analyses compared population-weighted PROMIS scores for Pain Intensity (PI), Physical Function (PF), and Pain Interference (Int) across CD modifiers. Conditional tree analysis with logistic regression sampling determined the threshold of PROMIS scores for which the correlation with Ames radiographic cutoffs was most significant. Reported cutoff values for Mod (cSVA: 4–8 cm; TS-CL: 15–20°) and Sev (cSVA: >8 cm; TS-CL: >20°) disabilities were used.Results:Two hundred and eight patients (58.8 years, female: 51%, 29.6 kg/m2, Charlson Comorbidity Index: 1.19). BL cSVA modifier by severity: 83.2% Low, 16.8% Mod. No patients met criteria for severe cSVA. BL TS-CL modifier by severity: 18.8% Low, 22.1% Mod, 59.1% Sev. Mean baseline PROMIS scores were as follows: PI score: 89.6 ± 15.4, PF score: 11.9 ± 13.1, Int score: 56.9 ± 6.8. PI did not differ between cSVA and TS-CL severity. Mod cSVA patients and Mod/Sev TS-CL modifier groups trended toward lower PF scores and higher Int scores. A PI score of >96 (odds ratio [OR]: 0.658 [0.303–1.430]), a PF score of <14 (OR: 1.864 [0.767–4.531]), and an Int score of > 57.4 (OR: 1.878 [0.889–3.967]) were predictors of Mod cSVA. A PI score of >87 (OR: 1.428 [0.767–2.659]), a PF score of <14 (OR: 1.551 [0.851–2.827]), and an Int score of >56.5 (OR: 1.689 [0.967–2.949]) were predictors of Sev TS-CL.Conclusions:PROMIS physical health domains were related to the Ames CD classification. Certain BL PROMIS thresholds can be connected to the severity of CD.

Assessment of T1 Slope Minus Cervical Lordosis and C2-7 Sagittal Vertical Axis Criteria of a Cervical Spine Deformity Classification System Using Long-Term Follow-up Data After Multilevel Posterior Cervical Fusion Surgery.

Recently, previous research proposed a cervical spine deformity (CSD) classification using a modified Delphi approach. However, C2-C7 sagittal vertical axis (SVA) and T1 slope minus C2-C7 lordosis (TS-CL) cut-off values for moderate and severe disability were based on expert opinion. To investigate the validity of a CSD classification system. From 2007 to 2012, 30 consecutive patients with a minimum 5-yr follow-up having 3- or more level posterior cervical fusion met inclusion criteria. The following radiographic parameters were measured: C0-C2 lordosis, C2-C7 lordosis, C2-C7 SVA, T1 slope, and TS-CL. Pearson correlation coefficients were calculated between pairs of radiographic measures and health-related quality of life. Average follow-up period was 7.3 yr. C2-C7 SVA positively correlated with neck disability index (NDI) scores (r = 0.554). Regression models predicted a threshold C2-C7 SVA value of 40.8 mm and 70.6 mm correlated with moderate and severe disability based on the NDI score, respectively. The TS-CL had positive correlation with C2-C7 SVA and NDI scores (r = 0.841 and r = 0.625, respectively). Regression analyses revealed that a C2-C7 SVA value of 40 mm and 70 mm corresponded to a TS-CL value of 20° and 25°, respectively. Regression models predicted a threshold C2-C7 SVA (value of 40.8 mm and 70.6 mm) and TS-CL (value of 20° and 25°) correlated with moderate and severe disability based on the NDI, respectively. The cut-off value C2-C7 SVA and TS-CL modifier of the CSD classification can be revised accordingly.

Primary Drivers of Adult Cervical Deformity: Prevalence, Variations in Presentation, and Effect of Surgical Treatment Strategies on Early Postoperative Alignment.

Primary drivers (PDs) of adult cervical deformity (ACD) have not been described in relation to pre- and early postoperative alignment or degree of correction. To define the PDs of ACD to understand the impact of driver region on global postoperative compensatory mechanisms. Primary cervical deformity driver/vertebral apex level were determined: CS = cervical; CTJ = cervicothoracic junction; TH = thoracic; SP = spinopelvic. Patients were evaluated if surgery included PD apex, based on the lowest instrumented vertebra (LIV): CS: LIV ≤ C7, CTJ: LIV ≤ T3, TH: LIV ≤ T12. Cervical and thoracolumbar alignment was measured preoperatively and 3 mo (3M) postoperatively. PD groups were compared with analysis of variance/Pearson χ2, paired t-tests. Eighty-four ACD patients met inclusion criteria. Thoracic drivers (n = 26) showed greatest preoperative cervical and global malalignment against other PD: higher thoracic kyphosis, pelvic incidence-lumbar lordosis (PI-LL), T1 slope C2-T3 sagittal vertical axis (SVA), and C0-2 angle (P < .05). Differences in baseline-3M alignment changes were observed between surgical PD groups, in PI-LL, LL, T1 slope minus cervical lordosis (TS-CL), cervical SVA, C2-T3 SVA (P < .05). Main changes were between TH and CS driver groups: TH patients had greater PI-LL (4.47° vs -0.87°, P = .049), TS-CL (-19.12° vs -4.30, P = .050), C2-C7 SVA (-18.12 vs -4.30 mm, P = .007), and C2-T3 SVA (-24.76 vs 8.50 mm, P = .002) baseline-3M correction. CTJ drivers trended toward greater LL correction compared to CS drivers (-6.00° vs 0.88°, P = .050). Patients operated at CS driver level had a difference in the prevalence of 3M TS-CL modifier grades (0 = 35.7%, 1 = 0.0%, 2 = 13.3%, P = .030). There was a significant difference in 3M chin-brow vertical angle modifier grade distribution in TH drivers (0 = 0.0%, 1 = 35.9%, 2 = 14.3%, P = .049). Characterizing ACD patients by PD type reveals differences in pre- and postoperative alignment. Evaluating surgical alignment outcomes based on PD inclusion is important in understanding alignment goals for ACD correction.

Pre-operative planning and rod customization may optimize post-operative alignment and mitigate development of malalignment in multi-segment posterior cervical decompression and fusion patients

Patient-specific rods designed based on a particular pre-operative plan are a recent advancement to help achieve desired operative alignment goals. This study investigated the role of pre-operative planning and patient-specific rods on post-operative alignment and outcomes. Patients were grouped according to use of pre-operative planning and patient-specific, pre-contoured rods (PLAN) or absence of planning/rods (NON). Pre-operative and post-operative alignment were measured: cervical sagittal vertical axis (cSVA), cervical lordosis (CL), T1 Slope minus CL (TS-CL). Alignment differences between the groups were assessed using independent and paired samples t-tests. 34 patients were identified (15 PLAN, 19 NON). Pre- and post-operative CL, cSVA and TS were similar between the two groups (p > 0.05), though pre-operative TS-CL was slightly higher in PLAN patients (28.13° versus 18.42°, p = 0.049). There were no improvement differences pre- to post-operative for CL, cSVA and TS between the groups (p > 0.05). However, PLAN patients exhibited a greater correction of TS-CL, with an average of 5.8° decrease versus a 3.5° increase in TS-CL for NON patients (p = 0.015). PLAN patients did not demonstrate a significant change from pre- to post-operative alignment for cSVA or TS-CL (cSVA: 27.5 mm to 31.1 mm, p = 0.255; TS-CL: 28.1° to 22.3°, p = 0.13), though their TS-CL did trend towards significant post-operative improvement. In contrast, NON patients worsened in cSVA and TS-CL post-operatively (cSVA: 21.8 mm to 30.3 mm, p < 0.001; TS-CL: 18.4° to 22.0°, p = 0.035). Multi-segment posterior decompression and fusion patients have the potential to worsen with regards to post-operative alignment without pre-operative planning. Patients with pre-contoured rods and pre-operative planning exhibited a greater correction of TS-CL after surgery than un-planned cases, though limited by the pre-operative difference in cervical-thoracic mismatch between planned and unplanned cases. Levels of evidenceIII.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P127. Redefining the cervical disability threshold of T1 slope minus cervical lordosis

BACKGROUND CONTEXT A T1 Slope minus cervical lordosis (TS-CL) angle of 20° has been described in the literature as a significant cutoff to define cervical deformity, however recent studies suggest that this cutoff needs to be redefined. PURPOSE The aim of this study was to develop a novel TS-CL threshold indicative of moderate to severe cervical disability. STUDY DESIGN/SETTING Single-center retrospective review. PATIENT SAMPLE A total of 69 cervical patients indicated for surgical treatment were included. OUTCOME MEASURES T1 slope minus cervical lordosis, neck disability index (NDI). METHODS Patients age 18years old with a primary cervical diagnosis indicated for surgical treatment were included. Patients with active infection, tumors or trauma were excluded. We tested possible cutoffs for TS-CL against the percentage of individuals meeting normative, mild, moderate (>25) and severe (>35) NDI scores at baseline. The TS-CL cutoff with the highest sensitivity to predict a normative, mild, moderate (>25) and severe (>35) NDI score was selected. RESULTS A total of 69 cervical patients indicated for surgical treatment were included (mean age 55.4±9.9years, 45% female, mean BMI 29.1±6.6 kg/m2). The average baseline NDI score was 39.9±20.9 for this cohort. At baseline, average TS-CL was 27.3°±18.8°, CL was 1.7°±17.6°, cSVA was 28.3 mm±17.3 mm. Spino-pelvic alignment parameters at baseline were as follows: PT 16.1°±8.3°, PI-LL −2.8°±11.9°, TK 38.8°±12.7° and SVA −6.3 mm±51.8 mm. Using previously established TS-CL severity breakdowns, 13 (18.8%) patients had mild TS-CL ( 20°). Using this cutoff of 20° as severe TS-CL, it did not correlate with NDI score (P=.390). After testing possible cutoffs of TS-CL that relate to moderate to severe NDI scores, a novel cutoff of 30.65° for TS-CL was related to an NDI score of ³25 points. CONCLUSIONS In a cohort of cervical surgery patients, a novel cutoff of 30.65°for TS-CL was predictive of moderate to severe neck disability, as described as an NDI score greater than or equal to 25 points. This criterion can be applied to cervical spine patients to better assess cervical disability.