Cervical Sagittal Deformity Research Articles

Defining Cervical Sagittal Plane Deformity - When Are Sagittal Realignment Procedures Necessary in Patients Presenting Primarily With Radiculopathy or Myelopathy?

It remains unclear whether cervical sagittal deformity (CSD) should be defined by radiographic parameters alone versus both clinical and radiographic factors, and whether radiographic malalignment by itself warrants a CSD corrective surgery in patients who present primarily with neurologic symptoms. We administered a survey to a group of expert surgeons to evaluate whether radiographic parameters alone were sufficient to diagnose CSD, and in which scenarios surgeons recommend a CSD realignment procedure versus addressing the neurologic symptoms alone. No single radiographic criteria reached a 50% threshold as being sufficient to establish the diagnosis of CSD. When asymptomatic radiographic malalignment was present, a sagittal deformity correction was more likely to be recommended in patients with myelopathy versus those with radiculopathy alone. The majority of surgeons recommended deformity correction when symptoms of cervical deformity were present in addition to radiographic malalignment (85% with deformity symptoms and radiculopathy, 93% with deformity symptoms and myelopathy). There is no consensus on which radiographic and/or clinical criteria are necessary to define the presence of CSD. We recommend that symptoms of cervical deformity, in addition to radiographic parameters, be considered when deciding whether to perform deformity correction in patients who present primarily with myelopathy or radiculopathy.

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

BACKGROUND CONTEXTA previous study found that the cross-sectional area (CSA) of the preoperative cervical paraspinal extensors (CPEs) was associated with loss of cervical lordosis after laminoplasty, while a recent study found that CPE asymmetry was associated with symptoms of degenerative cervical myelopathy. Whether preoperative CPE asymmetry can predict cervical sagittal deformity (CSD) after laminoplasty is unknown. PURPOSETo assess whether asymmetry, degree of degeneration, and extension function of the CPE can be used as predictors of postoperative CSD in patients who undergo laminoplasty. STUDY DESIGNA retrospective study. PATIENT SAMPLEFrom January 2017 to December 2019, 55 patients with multilevel cord compression and myelopathic symptoms were enrolled. OUTCOME MEASURESThe visual analog scale (VAS), neck disability index (NDI), and modified Japanese Orthopedic Association (mJOA) were used to assess cervical spinal function and quality of life. METHODSFrom January 2017 to December 2019, 55 patients undergoing modified laminoplasty were included. The following parameters were measured preoperatively and 24 months postoperatively on X-ray: (1) C0–C2 Cobb angle; (2) C2–C7 Cobb angle (CL); (3) T1 slope (T1S); (5) C2–C7 sagittal vertical axis (SVA); (6) T1S minus CL; (7) Preoperative extension function: Extension CL minus Neutral CL (EF). Preoperative global alignment parameters: (8) spino cranial angle, (9) C7-S1 sagittal vertical axis (C7 SVA), (10) pelvic incidence, (11) lumbar lordosis, (12) thoracic kyphosis. (13) Preoperative CPE parameters: Summation of bilateral total cross-sectional area (STCSA), summation of bilateral total cross-sectional area ratio (STCSAR), total cross-sectional area asymmetry, summation of bilateral functional cross-sectional area of muscle (SFCSA), summation of bilateral functional cross-sectional area of muscle ratio (FCSAR), and functional cross-sectional area of muscle asymmetry (FCSAA). The VAS, mJOA, and NDI were used to evaluate cervical spine function and quality of life. Patients were divided into the CSD group and the non-deformed group (N-CSD) group postoperatively, and the parameters between the two groups were compared. The Pearson correlation coefficient was used to evaluate the relationship between the parameters, and multiple regression analysis and ROC curve analysis were used to determine the predictors and key values. RESULTSCompared with functional scores, mJOA in the CSD group was significantly lower than that in the N-CSD group, while NDI and VAS were significantly higher. Postoperative CL was significantly correlated with EF, SFCSA/STCSA (C3–C6), SFCSAR (C4 and C6), STCSAR (C6), and FSCAA (C6). T1S minus CL was significantly correlated with EF, SFCSA/STCSA (C3–4 and C6), SFCSAR (C4 and C6), STCSAR (C6) and FSCAA (C6). C2–7 SVA was significantly correlated with EF, SFCSAR (C4 and C6), STCSAR (C6), and FSCAA (C6). Multiple regression analysis showed that FCSAA (C6), SFCSAR (C6), SFCSAR (C4), and EF were significant predictors of postoperative CSD. ROC curve analysis showed that the optimal cutoff points were 18.405, 2.95, 4.47, and 11.96. CONCLUSIONSThe present study found that preoperative extension dysfunction of CPEs, asymmetry at the C6 level cervical extensors, and cervical extensor CSAs without fatty infiltration at the C4 and C6 levels were associated with cervical sagittal imbalance after modified laminoplasty. These factors can be considered when future spine surgeons formulate surgical plans.

Patients With Preoperative Cervical Deformity Experience Similar Clinical Outcomes to Those Without Deformity Following 1-3 Level Anterior Cervical Decompression and Fusion.

Retrospective cohort study. The aim was to compare the outcomes of patients with incompletely corrected cervical deformity against those without deformity following short-segment anterior cervical decompression and fusion for clinically significant radiculopathy or myelopathy. Cervical deformity has increasingly been recognized as a driver of disability and has been linked to worse patient-reported outcomes measures (PROMs) after surgery. Patients 18 years or above who underwent 1-3 level anterior cervical decompression and fusion to address radiculopathy and/or myelopathy at a single institution between 2014 and 2018 with at least 1 year of PROMs were reviewed. Patients were categorized based on cervical deformity into 2 groups: sagittal vertebral axis (cSVA) ≥40 mm as the deformity group, and cSVA <40 mm as the nondeformity group. Patient demographics, surgical parameters, preoperative and postoperative radiographs, and minimum 1-year PROMs were compared. Of the 230 patients, 191 (83%) were in the nondeformity group and 39 (17%) in the deformity group. Patients with deformity were more likely to be male (69.2% vs. 40.3%, P<0.001) and have a greater body mass index (32.8 vs. 29.7, P=0.028). The deformity group had significantly greater postoperative cSVA (44.2 vs. 25.1 mm, P<0.001) but also had significantly greater ∆cSVA (-4.87 vs. 0.25 mm, P=0.007) than the nondeformity group. Both groups had significant improvements in visual analog scale arm, visual analog scale neck, Short-Form 12 Physical Component Score, and neck disability index (NDI) (P<0.001). However, the deformity group experienced significantly greater ∆NDI and ∆mental component score (MCS)-12 scores (-19.45 vs. -11.11, P=0.027 and 7.68 vs. 1.32, P=0.009). Patients with preoperative cervical sagittal deformity experienced relatively greater improvements in NDI and MCS-12 scores than those without preoperative deformity. These results suggest that complete correction of sagittal alignment is not required for patients to achieve significant clinical improvement. III.

Quantitative Correction of Cervical Sagittal Deformity in Atlanto-Axial Dislocation.

A mechanism-based reasoning and retrospective cohort study. To establish a quantitative relationship between the change of clivo-axial angle (CXA) and the change of subaxial cervical lordosis (CL) in correction surgery of atlantoaxial dislocation (AAD). The evolving understanding of mechanism has dramatically improved the treatment modality of AAD. Cervical sagittal alignment is another important aspect of the surgery, in addition to reduction of odontoid process. However, a quantitative reference for correction surgery has not been established. Frankfort-axial angle (FXA) was introduced. Based on two assumptions, (1) sagittal alignment of the spine aims at keeping horizontal gaze and (2) deformities at craniovertebral junction make little impact on slope of T1 vertebra, we deduced that the change of CXA equaled change of CL (ΔCXA = -ΔCL). We retrospectively reviewed our case cohort to validate this finding with linear regression analysis. Sixteen cases (eight male and eight female, mean age 40.4±12.5 yr old) were included. Liner fitting equation for ΔFXA and ΔCXA is y=1.005x (coefficient of determination, R=0.966; significance of the estimated coefficients P<0.001, t-statistics) and that for ΔCL and ΔCXA is y=-1.023x (R=0.976, P<0.001). These results support our deduction that ΔCXA = -ΔCL, which can be used as a guidance of quantitative correction of sagittal deformity in AAD. Correction of CXA will influence the subaxial cervical lordosis (ΔCXA = -ΔCL) of AAD patients. This equation can serve as a quantitative reference for preoperative planning and intraoperative refining of the correction of cervical sagittal deformity in AAD. 4.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P105. Limited morbidity and possible radiographic benefit of C2 versus subaxial cervical upper-most instrumented vertebrae

BACKGROUND CONTEXT Use of cervical deformity (CD)-corrective instrumentation in the subaxial cervical spine is widely considered risky due to the narrow width of subaxial cervical pedicles and anatomy of the vertebral artery between C3 and C6. While C2 fixation provides increased biomechanical stability, the literature is sparse on guidelines indicating extension of CD-corrective fusion from the subaxial cervical spine to C2. PURPOSE Evaluate differences in alignment and clinical outcomes between surgical CD patients with subaxial upper-most instrumented vertebrae(UIV) and patients with UIV at C2. STUDY DESIGN/SETTING Retrospective review of prospective, multicenter CD database. PATIENT SAMPLE A total of 62 surgical CD patients (61±11 years, 65%F, BMI:30±9). OUTCOME MEASURES Cervical alignment parameters: cervical sagittal vertical axis (cSVA), C2–C7 cervical lordosis (CL), T1 slope minus CL (TS-CL). Upper cervical parameters: C0–C2 angle, slopes from C0, C1, and C2, McGregor's Slope (McGS). Clinical outcomes: EQ-5D, NDI, and mJOA questionnaires. METHODS Operative CD patients (C2–C7 Cobb>10°, CL>10°, cSVA>4 cm, or CBVA>25°) with baseline (BL) and 1-year postop (1Y) radiographic data, and cervical UIV>C2. Patients were grouped by UIV: C2 or subaxial (C3–C7) and propensity score matched(PSM) for BL cSVA. Mean comparison tests assessed differences in BL and 1Y patient-related, radiographic, and surgical data between UIV groups, as well as overall BL to 1Y changes in radiographic alignment and clinical outcomes. RESULTS PSM analysis included 62 patients (31 C2 UIV, 31 subaxial UIV) undergoing surgery for CD (7.4±3.6 lvls fused, 44% anterior approach, 19% posterior, 37% combined). Groups did not differ in BL comorbidity burden (P=0.175) or cervical sagittal alignment (cSVA,P=0.401). C2 UIV patients were older (64years vs. 58, P=0.040) and had longer fusions (10 lvls vs. 6, P 0.05); however, the overall cohort showed BL to 1Y increases in SVA (5 mm to 26, P=0.003) and TK (40°–44°, P=0.003). Flexibility of the cervical spine was maintained at 1Y regardless of UIV (CL flexibility was 15° between flexion and extension for C2 UIV and 17° for subaxial UIV, P=0.232). While both subaxial UIV and C2 UIV patients showed significant BL-1Y improvements in McGS (both p 0.05). Patients with C2 UIV showed higher operative complication rates (16% vs. 0%, P=0.020). CONCLUSIONS When presenting with similar preop cervical sagittal deformity, patients with instrumentation ending at C2 showed similar cervical range of motion and rates of reoperation, nonunion, and baseline to 1-year clinical outcome changes as patients with instrumentation ending in the subaxial cervical spine, though higher operative complication rates. Compared to subaxial UIV patients, C2 UIV patients showed greater baseline to 1-year horizontal gaze improvement, demonstrating the radiographic benefit and minimal clinical downside of extending fusion.

T1 Slope Minus Cervical Lordosis (TS-CL), the Cervical Answer to PI-LL, Defines Cervical Sagittal Deformity in Patients Undergoing Thoracolumbar Osteotomy.

Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL. A multicenter, retrospective analysis of patients with thoracolumbar deformity undergoing three-column osteotomy was performed. Preoperative and postoperative cervical parameters were investigated. Linear regression for postoperative values resulted in a CPL of 4 cm corresponding to a TS-CL threshold of 17°. Patients were classified based on postoperative TS-CL into uncompensated (TS-CL > 17°) or compensated cohorts (TS-CL < 17°); the two were compared using an unpaired t test. Logistic regression modeling was used to determine predictors of postoperative CSD. A total of 223 patients with thoracolumbar deformity (mean age, 57.56 years) were identified. CTPA correlated with CPL (preoperative r = .85, postoperative r = .69). TS-CL correlated with CTPA (preoperative r = .52, postoperative r = .37) and CPL (preoperative r = .52; postoperative r = .37). CSD had greater preoperative CPL (P < .001) and CTPA (P < .001). The compensated cohort had a decrease in TS-CL (from 10.2 to 8.0) with sagittal vertical axis (SVA) correction, whereas the uncompensated had an increase in TS-CL (from 22.3 to 26.8) with all P < .001. Reciprocal change was demonstrated in the compensated group given that CL decreased with SVA correction (r = .39), but there was no such correlation in the uncompensated. Positive predictors of postoperative CSD included baseline TS-CL > 17° (P = .007), longer fusion (P = .033), and baseline CTPA (P = .029). TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy. The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.

Cervical sagittal deformity develops after PJK in adult thoracolumbar deformity correction: radiographic analysis utilizing a novel global sagittal angular parameter, the CTPA.

To describe reciprocal changes in cervical alignment after adult spinal deformity (ASD) correction and subsequent development of proximal junctional kyphosis (PJK). This study also investigated these changes using two novel global sagittal angular parameters, cervical-thoracic pelvic angle (CTPA) and the T1 pelvic angle (TPA). Multicenter, retrospective consecutive case series of ASD patients undergoing thoracolumbar three-column osteotomy (3CO) with fusion to the pelvis. Radiographs were analyzed at baseline and 1year post-operatively. Patients were substratified into upper thoracic (UT; UIV T6 and above) and lower thoracic (LT; UIV below T6). PJK was defined by >10° angle between UIV and UIV+2 and >10° change in the angle from baseline to post-op. PJK developed in 29% (78 of 267) of patients. CTPA was linearly correlated with cervical plumbline (CPL) as a measure of cervical sagittal alignment (R=0.826, p<0.001). PJK patients had significantly greater post-operative CTPA and SVA than patients without PJK (NPJK) (p=0.042; p=0.021). For UT (n=141) but not LT (n=136), PJK patients at 1year had larger CTPA (4.9° vs. 3.7°, p=0.015) and CPL (5.1 vs. 3.8cm, p=0.022) than NPJK patients, despite similar corrections in PT and PI-LL. The prevalence of PJK was 29% at 1year follow-up. CTPA, which correlates with CPL as a global analog of cervical sagittal balance, and TPA describe relative proportions of cervical and thoracolumbar deformities. Patients who develop PJK in the upper thoracic spine after thoracolumbar 3CO also develop concomitant cervical sagittal deformity, with increases in CPL and CTPA.

Association between preoperative cervical sagittal deformity and inferior outcomes at 2-year follow-up in patients with adult thoracolumbar deformity: analysis of 182 patients.

A high prevalence of cervical deformity (CD) has been identified among adult patients with thoracolumbar spinal deformity undergoing surgical treatment. The clinical impact of this is uncertain. This study aimed to quantify the differences in patient-reported outcomes among patients with adult spinal deformity (ASD) based on presence of CD prior to treatment. A retrospective review was conducted of a multicenter prospective database of patients with ASD who underwent surgical treatment with 2-year follow-up. Patients were grouped by the presence of preoperative CD: 1) cervical positive sagittal malalignment (CPSM) C2-7 sagittal vertical axis ≥ 4 cm; 2) cervical kyphosis (CK) C2-7 angle > 0; 3) CPSM and CK (BOTH); and 4) no baseline CD (NONE). Health-related quality of life (HRQOL) scores included the Physical Component Summary and Mental Component Summary (PCS and MCS) scores of the 36-Item Short Form Health Survey (SF-36), Oswestry Disability Index (ODI), Scoliosis Research Society-22 questionnaire (SRS-22), and minimum clinically important difference (MCID) of these scores at 2 years. Standard radiographic measurements were conducted for cervical, thoracic, and thoracolumbar parameters. One hundred eighty-two patients were included in this study: CPSM, 45; CK, 37; BOTH, 16; and NONE, 84. Patients with preoperative CD and those without had similar baseline thoracolumbar radiographic measurements and similar correction rates at 2 years. Patients with and without preoperative CD had similar baseline HRQOL and on average both groups experienced some HRQOL improvement. However, those with preoperative CPSM had significantly worse postoperative ODI, PCS, SRS-22 Activity, SRS-22 Appearance, SRS-22 Pain, SRS-22 Satisfaction, and SRS-22 Total score, and were less likely to meet MCID for ODI, PCS, SRS-22 Activity, and SRS-22 Pain scores with the following ORs and 95% CIs: ODI 0.19 (0.07-0.58), PCS 0.17 (0.06-0.47), SRS-22 Activity 0.23 (0.09-0.62), SRS-22 Pain 0.20 (0.08-0.53), and SRS-22 Appearance 0.34 (0.12-0.94). Preoperative CK did not have an effect on outcomes. Interestingly, despite correction of the thoracolumbar deformity, 53.3% and 51.4% of patients had persistent CPSM and persistent CK, respectively. Patients with thoracolumbar deformity without preoperative CD are likely to have greater improvements in HRQOL after surgery than patients with concomitant preoperative CD. Cervical positive sagittal alignment in adult patients with thoracolumbar deformity is strongly associated with inferior outcomes and failure to reach MCID at 2-year follow-up despite having similar baseline HRQOL to patients without CD. This was the first study to assess the impact of concomitant preoperative cervical malalignment in adult patients with thoracolumbar deformity. These results can help surgeons educate patients at risk for inferior outcomes and direct future research to identify an etiology and improve patient outcomes. Investigation into the etiology of the baseline cervical malalignment may be warranted in patients who present with thoracolumbar deformity.

Cervical Sagittal Deformity Develops After PJK in Adult Thoracolumbar Deformity Correction: Radiographic Analysis Utilizing a Novel Global Sagittal Parameter, the CTPA

Cervical Sagittal Deformity Develops After PJK in Adult Thoracolumbar Deformity Correction: Radiographic Analysis Utilizing a Novel Global Sagittal Parameter, the CTPA

Health Impact Comparison of Cervical Sagittal Deformity and Thoracolumbar Sagittal Deformity on Baseline Disability and Surgical Outcomes: Cervical PSO Versus Lumbar PSO

Health Impact Comparison of Cervical Sagittal Deformity and Thoracolumbar Sagittal Deformity on Baseline Disability and Surgical Outcomes: Cervical PSO Versus Lumbar PSO

Effective lordosis: analysis of sagittal spinal canal alignment in cervical spondylotic myelopathy

Analysis of cervical sagittal deformity in patients with cervical spondylotic myelopathy (CSM) requires a thorough clinical and radiographic evaluation to select the most appropriate surgical approach. Angular radiographic measurements, which are commonly used to define sagittal deformity, may not be the most appropriate to use for surgical planning. The authors present a simple straight-line method to measure effective spinal canal lordosis and analyze its reliability. Furthermore, comparisons of this measurement to traditional angular measurements of sagittal cervical alignment are made in regards to surgical planning in patients with CSM. Twenty preoperative lateral cervical digital radiographs of patients with CSM were analyzed by 3 independent observers on 3 separate occasions using a software measurement program. Sagittal measurements included C2-7 angles utilizing the Cobb and posterior tangent methods, as well as a straight-line method to measure effective spinal canal lordosis from the dorsal-caudal aspect of the C2-7 vertebral bodies. Analysis of variance for repeated measures or Cohen 3-way (kappa) correlation coefficient analysis was performed as appropriate to calculate the intra- and interobserver reliability for each parameter. Discrepancies in angular and effective lordosis measurements were analyzed. Intra- and interobserver reliability was excellent (intraclass coefficient > 0.75, kappa > 0.90) utilizing all 3 techniques. Four discrepancies between angular and effective lordotic measurements occurred in which images with a lordotic angular measurement did not have lordosis within the ventral spinal canal. These discrepancies were caused by either spondylolisthesis or dorsally projecting osteophytes in all cases. Although they are reliable, traditional methods used to make angular measurements of sagittal cervical spine alignment do not take into account ventral obstructions to the spinal cord. The effective lordosis measurement method provides a simple and reliable means of determining clinically significant lordosis because it accounts for both overall alignment of the cervical spine as well as impinging structures ventral to the spinal cord. This method should be considered for use in the treatment of patients with CSM.

Cervical Kyphotic Deformity Correction Using 360-degree Reconstruction

The authors report on their experience with cervical sagittal deformity correction using 360-degree reconstruction. A paucity of literature exists concerning 360-degree approaches for the correction of cervical kyphotic sagittal deformity in which the amount of deformity correction achieved, as well as the maintenance of deformity correction, is detailed. The charts of all patients undergoing 360-degree cervical reconstruction for kyphotic sagittal plane deformity between 2000 and 2006 at Mayo Clinic Jacksonville and Mayo Clinic Scottsdale were retrospectively reviewed. Only patients with a minimum of 1-year follow-up were included in this study; 41 patients fit this criterion. The clinical data were further analyzed in this cohort to determine preoperative and postoperative sagittal angle, loss of correction, fusion rate, complications, and clinical status at last follow-up. Average follow-up was 19 months (range: 12 to 48 mo). The mean preoperative sagittal angle was 18 degrees of kyphosis (range: 3 to 58 degrees). The mean correction of sagittal angle was 22 degrees (range: 4 to 56 degrees), resulting in a postoperative mean sagittal angle of 4-degree lordosis. There was no loss of correction across the instrumented segments in any patient. Neurologic complications included 1 case of quadriparesis and 1 case of transient C8 radiculopathy. The correction of cervical kyphotic sagittal plane deformity can be accomplished safely and effectively using a 360-degree approach. The incidence of major complications in this study was low. All patients could be corrected to a neutral or lordotic alignment. No loss of deformity correction was seen in any patient, and a 97.5% fusion rate was obtained.

Surgical Treatment of Fixed Cervical Kyphosis With Myelopathy

A retrospective clinical study. To investigate clinical and radiographic outcomes following the surgical treatment of fixed cervical kyphosis with myelopathy. To our knowledge, a study specifically addressing the surgical treatment of fixed cervical sagittal deformity has never before been published. Sixteen patients treated surgically for fixed cervical kyphosis and myelopathy were followed for a mean of 4.5 years (range, 25-112 months). The study group consisted of 9 males and 7 females, with an average age of 52 years (range, 31-78 years). The principal etiologies of cervical deformity were prior laminectomy (63%), advanced spondylosis (19%), infection (6%), neuromuscular disease (6%), and metabolic disease (renal osteodystrophy) (6%). All patients were clinically evaluated by the Nurick classification and Odom criteria both before surgery and at the time of most recent follow-up. Radiographic analysis was performed using thin-cut CT scans, dynamic radiographs, and 14 x 36-inch scoliosis films. The mean preoperative cervical Cobb angle as measured from the C2-C7 was +38 degrees and improved to -10 degrees at final follow-up, yielding an average correction of 48 degrees . The mean number of anterior and posterior segments fused was 4.8 (range, 2-6) and 7.2 (range, 3-14), respectively. The mean Nurick score improved from 2.4 before surgery to 1.5 at the time of follow-up. According to Odom criteria, outcomes were as follows: excellent (38%), good (50%), fair (6%), and poor (6%). At the time of most recent follow-up, solid bony arthrodesis and maintenance of correction occurred in all patients; however, revision was required in one patient. The treatment of fixed cervical kyphosis with myelopathy using circumferential spinal osteotomies and instrumented reconstruction is technically demanding; however, restoration and maintenance of a neutral or lordotic cervical profile and excellent clinical outcomes are achievable.