Bertrand Moal

Change in classification grade by the SRS-Schwab Adult Spinal Deformity Classification predicts impact on health-related quality of life measures: prospective analysis of operative and nonoperative treatment.

Study Design. Multicenter, prospective, consecutive series. Objective. To evaluate responsiveness of the Scoliosis Research Society (SRS)-Schwab adult spinal deformity (ASD) classification to changes in health-related quality of life (HRQOL) after treatment for ASD. Summary of Background Data. Ideally, a classification system should describe and be responsive to changes in a disease state. We hypothesized that the SRS-Schwab classification is responsive to changes in HRQOL measures after treatment for ASD. Methods. A multicenter, prospective, consecutive series from the International Spine Study Group. Inclusion criteria: ASD, age more than 18, operative or nonoperative treatment, baseline and 1-year radiographs, and HRQOL measures (Oswestry Disability Index [ODI], SRS-22, Short Form [SF]-36). The SRS-Schwab classification includes a curve descriptor and 3 sagittal spinopelvic modifiers (sagittal vertical axis [SVA], pelvic tilt, pelvic incidence/lumbar lordosis [PI-LL] mismatch). Changes in modifiers at 1 year were assessed for impact on HRQOL from pretreatment values based on minimal clinically important differences. Results. Three hundred forty-one patients met criteria (mean age = 54; 85% females; 177 operative and 164 nonoperative). Change in pelvic tilt modifier at 1-year follow-up was associated with changes in ODI and SRS-22 (total and appearance scores) (P ⩽ 0.034). Change in SVA modifier at 1 year was associated with changes in ODI, SF-36 physical component score, and SRS-22 (total, activity, and appearance scores) (P ⩽ 0.037). Change in PI-LL modifier at 1 year was associated with changes in SF-36 physical component score and SRS-22 (total, activity, and appearance scores) (P ⩽ 0.03). Patients with improvement of pelvic tilt, SVA, or PI-LL modifiers were significantly more likely to achieve minimal clinically important difference for ODI, SF-36 physical component score (SVA and PI-LL only), SRS activity, and SRS pain (PI-LL only). Conclusion. The SRS-Schwab classification provides a validated system to evaluate ASD, and the classification components correlate with HRQOL measures. This study demonstrates that the classification modifiers are responsive to changes in disease state and reflect significant changes in patient-reported outcomes. Level of Evidence: 3

Radiographic outcomes of adult spinal deformity correction: A critical analysis of variability and failures across deformity patterns

STUDY DESIGN Multicenter, prospective, consecutive, surgical case series from the International Spine Study Group. OBJECTIVES To evaluate the effectiveness of surgical treatment in restoring spinopelvic (SP) alignment. SUMMARY OF BACKGROUND DATA Pain and disability in the setting of adult spinal deformity have been correlated with global coronal alignment (GCA), sagittal vertical axis (SVA), pelvic incidence/lumbar lordosis mismatch (PI-LL), and pelvic tilt (PT). One of the main goals of surgery for adult spinal deformity is to correct these parameters to restore harmonious SP alignment. METHODS Inclusion criteria were operative patients (age greater than 18 years) with baseline (BL) and 1-year full-length X-rays. Thoracic and thoracolumbar Cobb angle and previous mentioned parameters were calculated. Each parameter at BL and 1 year was categorized as either pathological or normal. Pathologic limits were: Cobb greater than 30°, GCA greater than 40 mm, SVA greater than 40 mm, PI-LL greater than 10°, and PT greater than 20°. According to thresholds, corrected or worsened alignment groups of patients were identified and overall radiographic effectiveness of procedure was evaluated by combining the results from the coronal and sagittal planes. RESULTS A total of 161 patients (age, 55 ± 15 years) were included. At BL, 80% of patients had a Cobb angle greater than 30°, 25% had a GCA greater than 40 mm, and 42% to 58% had a pathological sagittal parameter of PI-LL, SVA, and/or PT. Sagittal deformity was corrected in about 50% of cases for patients with pathological SVA or PI-LL, whereas PT was most commonly worsened (24%) and least often corrected (24%). Only 23% of patients experienced complete radiographic correction of the deformity. CONCLUSIONS The frequency of inadequate SP correction was high. Pelvic tilt was the parameter least likely to be well corrected. The high rate of SP alignment failure emphasizes the need for better preoperative planning and intraoperative imaging.

Impact of Unilateral Corrective Tethering on the Histology of the Growth Plate in an Established Porcine Model for Thoracic Scoliosis

Study Design. Histological growth plate analysis. Objective. To evaluate the histological effects on vertebral growth plates following corrective mechanical tethering in the porcine scoliosis model. Summary of Background Data. Theoretically, growth modulation allows progressive vertebral correction in the setting of scoliosis (Hueter-Volkmann principle). Methods. This IACUC-approved study divided 9 immature Yorkshire pigs into 2 groups: deforming tether release (TR, n = 4) group and anterior corrective (AC, n = 5) tether group. Once 50° coronal Cobb was demonstrated, TR had release of the deforming tether, whereas AC had release of the deforming tether and additional placement of a corrective tether. After 20 weeks of observation, pigs were killed, spines were removed, and apical samples were prepared for histological study. Growth plate analysis included the following histological parameters: proliferative zone height, hypertrophic zone height, and cell heights within the hypertrophic zone. Student t test was used to evaluate differences within and between groups. Results. No significant differences were found within the release group on the concave versus convex side in terms of proliferative zone height, hypertrophic zone height, and cell heights in the hypertrophic zone. In the anterior correction group, the proliferative zone height was significantly smaller on the concave side than on the convex side (P < 0.01); no significant differences were found in AC on the concave versus convex side in terms of hypertrophic zone height and cell heights in the hypertrophic zone. No significant differences were found in any parameters between TR and AC on either the concave or the convex side. Conclusion. No significant decrease in any of the measured parameters was observed in the anterior correction group compared with the tether release group. These histological findings are consistent with preservation of growth potential.

Sagittal spine posture assessment: Feasibility of a protocol based on intersegmental moments

Evaluation of spinal posture has recently benefited from the contribution of three-dimensional reconstruction technologies that have helped improve our understanding of this dynamic balance. The aim of this study was to present the preliminary results of a three-dimensional protocol to analyze postural balance. This analytical method is not limited by certain constraints of the radiological approach and evaluates postural balance using a new approach taking into account the net efforts of different intersegmental centers. These preliminary results show the technical feasibility of the protocol. Its future development and clinical use could provide a better understanding of postural balance disorders, and help evaluate the impact of surgical correction on spinal balance.

Lumbar spinal muscles and spinal canal study by MRI three-dimensional reconstruction in adult lumbar spinal stenosis

BACKGROUND Lumbar spinal stenosis is degenerative disc disease most common manifestation. If stenosis degree seems poorly related to symptom severity, lumbar muscles role is recognized. Many studies report imaging methods, to analyze muscle volumes and fat infiltration (FI), but remain limited due to the difficulty to represent entire muscle volume variability. Recently a 3D muscle reconstruction protocol (using the deformation of a parametric specific object method (DPSO) and three-point Dixon images) was reported. It offers the ability to evaluate, muscles volumes and muscle FI. PURPOSE To describe, in a lumbar spinal stenosis population, muscle volumes, muscle FI and lumbar spinal canal volume with 3D MRI images reconstructions. MATERIALS AND METHODS Ten adults presenting L4-L5 lumbar stenosis, were included. After specific MRI protocol, three-dimensional, muscle and spinal canal, reconstructions were performed. Muscle (psoas and paraspinal muscles) volumes and fat infiltration (FI), the spinal canal volume, age, and height were correlated one to each other with Spearman correlation factor. An ANOVA was performed to evaluate the intervertebral level influence (P≤0.05). RESULTS Muscle volumes correlated with height (r=0.68 for psoas). Muscles FI correlated with age (r=0.66 for psoas) and lumbar spinal canal volume (r=0.91). Psoas and paraspinal volumes were maximum at L3-L4 level whereas FI increased from L1-L2 to L5-S1 level. DISCUSSION These first results illustrate the importance to consider muscles entirely and report correlations between muscles FI, lumbar spinal canal volume and age; and between muscle volumes and patients height. Muscle degeneration seems more related to muscle FI than muscle volume. LEVEL OF EVIDENCE 3.

Comparison of two MRI sequences for subject-specific 3D thigh muscle reconstruction

1. IntroductionFatatrophyofskeletalmuscleistheoutcomeoftheageingprocessorvariousneuromuscularpathologies.Toquantifymuscle volume and fat infiltration (FI), magneticresonance imaging (MRI) is used in clinical diagnosticsand research concerning the high image quality andabsence of irradiation. Although T1-weighted turbo spin-echo (TSE) sequence MRIs are used clinically, however,the acquisition duration is long, which raises acquisitioncosts and hardly avoids breathing artefacts in abdomenimages. T1-weighted, ultrafast gradient-echo, volumetricinterpolated breath-hold examination (VIBE) MRI canacquire datasets within a breath-hold (,25s), therebyreducing breathing artefacts. Therefore, VIBE MRI hasgreat potential for clinical research and applications,although image quality is limited by the reducedacquisition duration. To quantify FI in skeletal muscles,Dixon method is preferably considered for T1-weightedsequences. On the basis of differences of signal phase infat and water, this method is found to be insensitive to theinhomogeneity of the magnetic field (Dixon 1984);therefore, it allows whole body fat quantification.Three-dimensional (3D) subject-specific musclereconstruction allows quantitative analyses of musclemorphology. Semi-automated deformation of parametricspecific objects (DPSO) method (Jolivet etal. 2007)uses areduced datasets for muscle reconstruction, reducing timerequired by manual reconstruction.This study aims to compare the feasibility andaccuracy of VIBE and TSE MRI in 3D subject-specificthigh muscle geometry reconstruction and skeletal muscleFI quantification.2. MethodsTen female patients (average age 58.5