Vincent Challier

Defining Spino-pelvic Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for Age?

Study Design. Retrospective review of prospective, multicenter database. Objective. The aim of the study was to determine age-specific spino-pelvic parameters, to extrapolate age-specific Oswestry Disability Index (ODI) values from published Short Form (SF)-36 Physical Component Score (PCS) data, and to propose age-specific realignment thresholds for adult spinal deformity (ASD). Summary of Background Data. The Scoliosis Research Society-Schwab classification offers a framework for defining alignment in patients with ASD. Although age-specific changes in spinal alignment and patient-reported outcomes have been established in the literature, their relationship in the setting of ASD operative realignment has not been reported. Methods. ASD patients who received operative or nonoperative treatment were consecutively enrolled. Patients were stratified by age, consistent with published US-normative values (Norms) of the SF-36 PCS (<35, 35–44, 45–54, 55–64, 65–74, >75  y old). At baseline, relationships between between radiographic spino-pelvic parameters (lumbar-pelvic mismatch [PI-LL], pelvic tilt [PT], sagittal vertical axis [SVA], and T1 pelvic angle [TPA]), age, and PCS were established using linear regression analysis; normative PCS values were then used to establish age-specific targets. Correlation analysis with ODI and PCS was used to determine age-specific ideal alignment. Results. Baseline analysis included 773 patients (53.7 y old, 54% operative, 83% female). There was a strong correlation between ODI and PCS (r = 0.814, P < 0.001), allowing for the extrapolation of US-normative ODI by age group. Linear regression analysis (all with r > 0.510, P < 0.001) combined with US-normative PCS values demonstrated that ideal spino-pelvic values increased with age, ranging from PT = 10.9 degrees, PI−LL = −10.5 degrees, and SVA = 4.1 mm for patients under 35 years to PT = 28.5 degrees, PI−LL = 16.7 degrees, and SVA = 78.1 mm for patients over 75 years. Clinically, older patients had greater compensation, more degenerative loss of lordosis, and were more pitched forward. Conclusion. This study demonstrated that sagittal spino-pelvic alignment varies with age. Thus, operative realignment targets should account for age, with younger patients requiring more rigorous alignment objectives. Level of Evidence: 3

Recruitment of Compensatory Mechanisms in Sagittal Spinal Malalignment Is Age and Regional Deformity Dependent A Full-Standing Axis Analysis of Key Radiographical Parameters

Study Design. Retrospective review, full-body radiographical analysis of adult patients with sagittal spinal malalignment (SSM). Objective. To investigate the compensatory mechanisms involved in the sagittal plane of the body after progressive spinal sagittal malalignment and to study the impact of age on compensatory mechanism recruitment. Summary of Background Data. Patients with SSM recruit compensatory mechanisms to maintain erect posture and horizontal gaze. Mechanisms such as pelvic retroversion, knee flexion, and pelvic shift have been proposed, but how they contribute and how age affects their recruitment are poorly understood. Methods. Retrospective review of adult patients with SSM who underwent full-standing axis stereoradiography (EOS imaging). Radiographical measurements were performed with Surgimap. Patients were categorized on the basis of the mismatch between pelvic incidence (PI) and lumbar lordosis (PI-LL). Compensatory mechanisms were normalized to each patients PI-LL and compared by mismatch groups. In addition, patients were subcategorized into 2 age groups (≥65 and <65 yr) and compared within the same groups of mismatch. Results. A total of 161 patients with a mean age of 62.93 ± 12.8 years. Mean sagittal vertical axis = 62.3 ± 61.5 mm; pelvic tilt (PT) = 29.2° ± 8.4°; and PI-LL = 21.0° ± 14.9°. Mismatch groups were as follows: group 1: PI-LL 0°–10°; group 2: 10°–20°; group 3: 20°–30°; and group 4: >30°. There were significant differences between all groups with regard to thoracic kyphosis (TK), PT, knee flexion angle, and pelvic shift by analysis of variance (P < 0.001). As PI-LL increased, TK and PT contribution to the compensation cascade decreased and knee flexion angle and pelvic shift contribution increased. Patients with PI-LL of more than 30° who were older had significantly less PT and more TK than patients with similar PI-LL who were younger. Conclusion. Spinopelvic mismatch is an important driver in SSM. Pelvic retroversion and flattening of TK (reduction) become exhausted with increasing mismatch, at which point there seems to be a steady transfer of compensation toward significant participation of the lower limbs. Further analysis suggests differential recruitment of these compensatory mechanisms based upon age. Level of Evidence: 3

Validation of a new computer-assisted tool to measure spino-pelvic parameters

BACKGROUND CONTEXT Evaluation of sagittal alignment is essential in the operative treatment of spine pathology, particularly adult spinal deformity (ASD). However, software applications for detailed spino-pelvic analysis are usually complex and not applicable to routine clinical use. PURPOSE This study aimed to validate new clinician-friendly software (Surgimap) in the setting of ASD. STUDY DESIGN/SETTING Accuracy and inter- and intra-rater reliability of spine measurement software were tested. Five users (two experienced spine surgeons, three novice spine research fellows) independently performed each part of the study in two rounds with 1 week between measurements. PATIENT SAMPLE Fifty ASD patients drawn from a prospective database were used as the study sample. OUTCOME MEASURES Spinal, pelvic, and cervical measurement parameters (including pelvic tilt [PT], pelvic incidence [PI], lumbar-pelvic mismatch [PI-LL], lumbar lordosis [LL], thoracic kyphosis [TK], T1 spino-pelvic inclination [T1SPI], sagittal vertical axis [SVA], and cervical lordosis [CL]) were the outcome measures. METHODS For the accuracy evaluation, 30 ASD patient radiographs were pre-marked for anatomic landmarks. Each radiograph was measured twice with the new software (Surgimap); measurements were compared to those from previously validated software. For the reliability and reproducibility evaluation, users measured 50 unmarked ASD radiographs in two rounds. Intra-class correlation (ICC) and International Organization for Standardization (ISO) reproducibility values were calculated. Measurement time was recorded. RESULTS Surgimap demonstrated excellent accuracy as assessed by the mean absolute difference from validated measurements: PT: 0.12°, PI: 0.35°, LL: 0.58°, PI-LL: 0.46°, TK: 5.25°, T1SPI: 0.53°, and SVA: 2.04 mm. The inter- and intra-observer reliability analysis revealed good to excellent agreement for all parameters. The mean difference between rounds was <0.4° for PT, PI, LL, PI-LL, and T1SPI, and <0.3 mm for SVA. For PT, PI, LL, PI-LL, TK, T1SPI, and SVA, the intra-observer ICC values were all >0.93 and the inter-observer ICC values were all >0.87. Parameters based on point landmarks rather than end plate orientation had a better reliability (ICC≥0.95 vs. ICC≥0.84). The average time needed to perform a full spino-pelvic analysis with Surgimap was 75 seconds (+25). CONCLUSIONS Using this new software tool, a simple method for full spine analysis can be performed quickly, accurately, and reliably. The proposed list of parameters offers quantitative values of the spine and pelvis, setting the stage for proper preoperative planning. The new software tool provides an important bridge between clinical and research needs.

The Impact of Advanced Age on Peri-Operative Outcomes in the Surgical Treatment of Cervical Spondylotic Myelopathy: A Nationwide Study Between 2001 and 2010.

Study Design. Retrospective multicenter database review. Objective. The aim of this study was to evaluate national postoperative outcomes and hospital characteristics trends from 2001 to 2010 for advanced age CSM patients. Summary of Background Data. Recent studies show increases in US cervical spine surgeries and CSM diagnoses. However, few have compared national outcomes for elderly and younger CSM patients. Methods. A Nationwide Inpatient Sample (NIS) analysis from 2001 to 2010, including CSM patients 25+ who underwent anterior and/or posterior cervical fusion or laminoplasty. Fractures, 9+ levels fused, or any cancers were excluded. Measures included demographics, outcomes, and hospital-related data for 25 to 64 versus 65+ and 65 to 75 versus 76+ age groups. Univariate and logistic regression modeling evaluated procedure-related complications risk in 65+ and 76+ age groups (OR[95% CI]). Results. Discharges for 35,319 patients in the age range of 25 to 64 years and 19,097 at the age 65+ years were identified. Average comorbidity indices for patients at 65+ years were higher compared to the 25 to 64 years age group (0.79 vs. 0.0.44, P < 0.0001), as was the total complications rate (11.39% vs. 5.93%, P < 0.0001) and charges (

Global sagittal axis: a step toward full-body assessment of sagittal plane deformity in the human body.

57,449.94 vs.

Impact of dynamic alignment, motion, and center of rotation on myelopathy grade and regional disability in cervical spondylotic myelopathy

49,951.11, P < 0.0001). Hospital course for aged 65+ patients was longer (4.76 vs. 3.26 days, P < 0.0001). Mortality risk was higher in the 65+ cohort (3.38[2.93–3.91]), adjusted for covariates. 65+ patients had increased risk of all complications except device-related, for which they had decreased risk (0.61[0.56–0.67]). Patients 76+ years displayed increased hospital charges (

Advantages and Disadvantages of Adult Spinal Deformity Surgery and its Impact on Health-related Quality of Life.

59,197.60 vs.

Comparing Quality of Life in Cervical Spondylotic Myelopathy with Other Chronic Debilitating Diseases Using the SF-36 Survey.

56,601.44, P < 0.001) and courses (5.77 vs. 4.28 days, P < 0.001) compared to those in the age group 65 to 75 years. These same patients presented with increased Deyo scores (0.83 vs. 0.77, P < 0.001), had increased total complications rate (13.87% vs. 10.20%, P < 0.001), and displayed increased risk for postoperative shock (6.34 [11.16–3.60], P < 0.001), digestive system (1.92 [2.40–1.54], P < 0.001), and wound dehiscence (1.71 [2.56–1.15], P < 0.001). Conclusion. Patients aged 65+ years undergoing CSM surgical management have a higher mortality risk, more procedure-related complications, higher comorbidity burden, longer hospital course, and higher charges. This study provides clinically useful data for surgeons to educate patients and to improve outcomes.

A novel index for quantifying the risk of early complications for patients undergoing cervical spine surgeries

OBJECTIVE Sagittal malalignment requires higher energy expenditure to maintain an erect posture. Because the clinical impact of sagittal alignment is affected by both the severity of the deformity and recruitment of compensatory mechanisms, it is important to investigate new parameters that reflect both disability level and compensatory mechanisms for all patients. This study investigated the clinical relevance of the global sagittal axis (GSA), a novel measure to evaluate the standing axis of the human body. METHODS This is a retrospective review of patients who underwent full-body radiographs and completed health-related quality of life (HRQOL) questionnaires: Oswestry Disability Index (ODI), Scoliosis Research Society-22, EuroQol-5D (EQ-5D), and the visual analog scale for back and leg pain. The GSA was defined as the angle formed by a line from the midpoint of the femoral condyles to the center of C-7, and a line from the midpoint between the femoral condyles to the posterior superior corner of the S-1 sacral endplate. After evaluating the correlation of GSA/HRQOL with sagittal parameters, linear regression models were generated to investigate how ODI and GSA related to radiographic parameters (T-1 pelvic angle, pelvic retroversion, knee flexion, and pelvic posterior translation). RESULTS One hundred forty-three patients (mean age 44 years) were included. The GSA correlated significantly with all HRQOL (up to r = 0.6 with EQ-5D) and radiographic parameters (up to r = 0.962 with sagittal vertical axis). Regression between ODI and sagittal radiographic parameters identified the GSA as an independent predictor (r = 0.517, r2 = 0.267; p < 0.001). Analysis of standardized coefficients revealed that when controlling for deformity, the GSA increased with a concurrent decrease in pelvic retroversion (-0.837) and increases in knee flexion (+0.287) and pelvic posterior translation (+0.193). CONCLUSIONS The GSA is a simple, novel measure to assess the standing axis of the human body in the sagittal plane. The GSA correlated highly with spinopelvic and lower-extremities sagittal parameters and exhibited remarkable correlations with HRQOL, which exceeded other commonly used parameters.

Novel Method Using Baseline Normalization and Area Under the Curve to Evaluate Differences in Outcome Between Treatment Groups and Application to Patients With Cervical Spondylotic Myelopathy Undergoing Anterior Versus Posterior Surgery.

OBJECT Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM. METHODS A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures. RESULTS At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2-7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = -0.377, p = 0.003; mJOA score, Extension R = -0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade. CONCLUSIONS Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.