Shaleen Vira

Spino-Pelvic Parameters After Surgery Can be Predicted: A Preliminary Formula and Validation of Standing Alignment

Study Design. Prospective and retrospective radiographic study of adult patients with spinal deformities. Objective. Construct predictive models for pelvic tilt (PT) and global sagittal balance (sagittal vertical axis [SVA]) and evaluate the effectiveness of these predictive models against a group of patients after pedicle subtraction osteotomy. Summary of Background Data. Spinal balance involves a complex interaction between the pelvis and vertebral column. In the setting of adult spinal deformity, prediction of postoperative alignment can be challenging. Methods. The study included 219 adult patients treated for spinal deformity. Full-length standing films were available for all subjects. Multilinear models with a stepwise condition were used on the first group of patients (n 5 179) to predict PT and global sagittal balance (measured by the SVA). Prediction models were then applied on a second group of patients (n 5 40) to estimate postoperative radiographic parameters after pedicle subtraction osteotomy surgery. Differences between estimated parameters and real values were evaluated. Results. Multilinear regression analysis applied on the first group of patients led to a predictive formula for PT (r 5 0.93, standard error = 4.4°) using the following parameters: pelvic incidence, maximal lordosis, and maximal kyphosis. These parameters with the addition of the predicted PT were then used to predict the SVA (r 5 0.89, standard error 5 32 mm). Validation of predictive models (second group of patients) used pelvic incidence and postoperative sagittal curves. Postoperative PT was predicted with a mean error of 4.3° (SD 3.5°) and postoperative SVA was predicted with a mean error of 29 mm (SD 5 23 mm). Conclusion. This is the first study to develop and validate pragmatic predictive models for key spino-pelvic parameters (PT and SVA) in the setting of adult spinal deformity. Using a morphologic pelvic parameter (pelvic incidence) and spinal parameters modifiable through surgery (lumbar lordosis and thoracic kyphosis), postoperative sagittal alignment can be predicted.

Does vertebral level of pedicle subtraction osteotomy correlate with degree of spinopelvic parameter correction?: Clinical article

OBJECT Pedicle subtraction osteotomy (PSO) is a spinal realignment technique that may be used to correct sagittal spinal imbalance. Theoretically, the level and degree of resection via a PSO should impact the degree of sagittal plane correction in the setting of deformity. However, the quantitative effect of PSO level and focal angular change on postoperative spinopelvic parameters has not been well described. The purpose of this study is to analyze the relationship between the level/degree of PSO and changes in global sagittal balance and spinopelvic parameters. METHODS In this multicenter retrospective study, 70 patients (54 women and 16 men) underwent lumbar PSO surgery for spinal imbalance. Preoperative and postoperative free-standing sagittal radiographs were obtained and analyzed by regional curves (lumbar, thoracic, and thoracolumbar), pelvic parameters (pelvic incidence and pelvic tilt [PT]) and global balance (sagittal vertical axis [SVA] and T-1 spinopelvic inclination). Correlations between PSO parameters (level and degree of change in angle between the 2 adjacent vertebrae) and spinopelvic measurements were analyzed. RESULTS Pedicle subtraction osteotomy distribution by level and degree of correction was as follows: L-1 (6 patients, 24°), L-2 (15 patients, 24°), L-3 (29 patients, 25°), and L-4 (20 patients, 22°). There was no significant difference in the focal correction achieved by PSO by level. All patients demonstrated changes in preoperative to postoperative parameters including increased lumbar lordosis (from 20° to 49°, p < 0.001), increased thoracic kyphosis (from 30° to 38°, p < 0.001), decreased SVA and T-1 spinopelvic inclination (from 122 to 34 mm, p < 0.001 and from +3° to -4°, p < 0.001, respectively), and decreased PT (from 31° to 23°, p < 0.001). More caudal PSO was correlated with greater PT reduction (r = -0.410, p < 0.05). No correlation was found between SVA correction and PSO location. The PSO degree was correlated with change in thoracic kyphosis (r = -0.474, p < 0.001), lumbar lordosis (r = 0.667, p < 0.001), sacral slope (r = 0.426, p < 0.001), and PT (r = -0.358, p < 0.005). CONCLUSIONS The degree of PSO resection correlates more with spinopelvic parameters (lumbar lordosis, thoracic kyphosis, PT, and sacral slope) than PSO level. More importantly, PSO level impacts postoperative PT correction but not SVA.

Role of pelvic translation and lower-extremity compensation to maintain gravity line position in spinal deformity

OBJECT Previous forceplate studies analyzing the impact of sagittal-plane spinal deformity on pelvic parameters have demonstrated the compensatory mechanisms of pelvis translation in addition to rotation. However, the mechanisms recruited for this pelvic rotation were not assessed. This study aims to analyze the relationship between spinopelvic and lower-extremity parameters and clarify the role of pelvic translation. METHODS This is a retrospective study of patients with spinal deformity and full-body EOS images. Patients with only stenosis or low-back pain were excluded. Patients were grouped according to T-1 spinopelvic inclination (T1SPi): sagittal forward (forward, > 0.5°), neutral (-6.3° to 0.5°), or backward (< -6.3°). Pelvic translation was quantified by pelvic shift (sagittal offset between the posterosuperior corner of the sacrum and anterior cortex of the distal tibia), hip extension was measured using the sacrofemoral angle (SFA; the angle formed by the middle of the sacral endplate and the bicoxofemoral axis and the line between the bicoxofemoral axis and the femoral axis), and chin-brow vertical angle (CBVA). Univariate and multivariate analyses were used to compare the parameters and correlation with the Oswestry Disability Index (ODI). RESULTS In total, 336 patients (71% female; mean age 57 years; mean body mass index 27 kg/m(2)) had mean T1SPi values of -8.8°, -3.5°, and 5.9° in the backward, neutral, and forward groups, respectively. There were significant differences in the lower-extremity and spinopelvic parameters between T1SPi groups. The backward group had a normal lumbar lordosis (LL), negative SVA and pelvic shift, and the largest hip extension. Forward patients had a small LL and an increased SVA, with a large pelvic shift creating compensatory knee flexion. Significant correlations existed between lower-limb parameter and pelvic shift, pelvic tilt, T-1 pelvic angle, T1SPi, and sagittal vertical axis (0.3 < r < 0.8; p < 0.001). ODI was significantly correlated with knee flexion and pelvic shift. CONCLUSIONS This is the first study to describe full-body alignment in a large population of patients with spinal pathologies. Furthermore, patients categorized based on T1SPi were found to have significant differences in the pelvic shift and lower-limb compensatory mechanisms. Correlations between lower-limb angles, pelvic shift, and ODI were identified. These differences in compensatory mechanisms should be considered when evaluating and planning surgical intervention for adult patients with spinal deformity.

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 (

Predicting Cervical Alignment Required to Maintain Horizontal Gaze Based on Global Spinal Alignment.

57,449.94 vs.

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

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 (

Use of Recombinant Bone Morphogenetic Protein Is Associated With Reduced Risk of Reoperation After Spine Fusion for Adult Spinal Deformity.

59,197.60 vs.

Patient-specific Hip Fracture Strength Assessment with Microstructural MR Imaging–based Finite Element Modeling

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.

The Interobserver and Intraobserver Reliability of the Sanders Classification Versus the Risser Stage.

Study Design. A retrospective cohort. Objective. The aim of this study was to investigate the cervical alignment necessary for the maintenance of horizontal gaze that depends on underlying thoracolumbar alignment. Summary of Background Data. Cervical Sagittal Curve (CC) is affected by thoracic and global alignment. Recent studies suggest large variability in normative CC ranging from lordotic to kyphotic alignment. No previous studies have assessed the effect of global spinal alignment on CC in maintenance of horizontal gaze. Methods. Patients without previous history of spinal surgery and able to maintain their horizontal gaze while undergoing full body imaging were included. Patients were stratified on the basis of thoracic kyphosis (TK) into (<30, 30–40, 40–50, and >50) and then by SRS-Schwab sagittal vertical axis (SVA) modifier into (posterior alignment SVA <0, aligned 0–50, and malaligned >50 mm). Cervical alignment was assessed among SVA grade in TK groups. Stepwise linear regression analysis was applied on random selection of 60% of the population. A simplified formula was developed and validated on the remaining 40%. Results. In each TK group (n = 118, 137, 125, 197), lower CC (C2-C7) was significantly more lordotic by increased Schwab SVA grade. T1 slope and cervical SVA significantly increased with increased thoracolumbar (C7-S1) SVA. Upper CC (C0-C2) and mismatch between T1 slope and CC (T1-CL) were similar. Regression analysis revealed LL minus TK (LL-TK) as an independent predictor (r = 0.640, r2 = 0.410) with formula: CC = 10- (LL-TK)/2. Validation revealed that the absolute difference between the predicted CC and the actual CC was 8.5°. Moreover, 64.2% of patients had their predicted C2-C7 values within 10° of the actual CC. Conclusion. Cervical kyphosis may represent normal alignment in a significant number of patients. However, in patients with SVA >50 and greater thoracic kyphosis, cervical lordosis is needed to maintain the gaze. Cervical alignment can be predicted from underlying TK and lumbar lordosis, which may be clinically relevant when considering correction for thoracolumbar or cervical deformity Level of Evidence: 3

Reoperation Rates After Long Posterior Spinal Fusion: Use of Recombinant Bone Morphogenetic Protein in Idiopathic and Non-idiopathic Scoliosis

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.