Multilevel Analysis of Trunk Surface Measurements for Noninvasive Assessment of Scoliosis Deformities

Abstract

Study design: Reliability study. Objectives:To assess between-acquisition reliability of new multi-levels trunk cross-sections measurements, in order to define what is a real change when comparing two trunk surface acquisitions of a same patient, before and after surgery or throughout the clinical monitoring.Summary of background data: Several cross-sectional surface measurements have been proposed in the literature for non-invasive assessment of trunk deformity in patients with adolescent idiopathic scoliosis (AIS). However, only the maximum values along the trunk are evaluated and used for monitoring progression and assessing treatment outcome. Methods:Back surface rotation (BSR), trunk rotation (TR) and coronal and sagittal trunk deviation are computed on 300 cross-sections of the trunk. Each set of 300 measures is represented as a single functional data using a set of basis functions. To evaluate betweenacquisition variability at all trunk levels, a test-retest reliability study is conducted on 35 AIS patients. A functional correlation analysis is also carried out to evaluate any redundancy between the measurements.Results: Each set of 300 measures was successfully described using only 10 basis functions.The test-retest reliability of the functional measurements is good to very good all over the trunk, except above the shoulders levels. The typical errors of measurement are between 1.20 and 2.2 for the rotational measures and between 2 to 6 mm for deviation measures. There is a very strong correlation between BSR and TR all over the trunk, a moderate correlation between coronal trunk deviation and both BSR and TR and no correlation between sagittal trunk deviation and any other measurement. Conclusions:This novel representation of trunk surface measurements allows for a global assessment of trunk surface deformity. Multilevel trunk measurements provide a broader perspective of the trunk deformity and allow a reliable multi-level monitoring during clinical follow-up of patients with AIS and a reliable assessment of the esthetic outcome after surgery. KEY WORDS:Scoliosis, multi-level trunk surface measurement, functional data analysis, reliability, correlation. KEY POINTS:1) Trunk cross-sections measurements are reliable all along the trunk, except at the shoulders level.2) The maximum value of a measurement along the trunk overlooks the extent of the hump above and below the apex of the curve. MINI ABSTRACT / PRÉCIS:This study assesses the reliability of multi-levels trunk cross-sections measurements and defines the difference needed between trunk surface acquisitions to detect a real progression and/or surgical correction of trunk surface deformity at all trunk levels.

Changes in Trunk Appearance After Scoliosis Spinal Surgery and Their Relation to Changes in Spinal Measurements

“…While others have considered manual scoliometer measures (13,14) in forward bending position, our measurements are computed automatically, in the standing posture and have proven to be reliable (7). Furthermore, our measurements are multi-level and computed all along the trunk height, as opposed to the Suzuki hump sum calculated at 3 trunk levels, considered in the study of Asher et al(15).…”

“…To describe the trunk deformities, more specifically the rib hump and the trunk imbalance in the frontal plane, we used multi-level trunk measurements described in our previous paper (7). Briefly, the back surface rotation (BSR) and the trunk lateral shift (TLS) are computed on 300 regularly spaced cross-sections extracted along the trunk height ( Figure 1).…”

“…In a previous paper, we have introduced a novel and reliable approach to quantify trunk surface deformities, using a non-invasive 3D reconstruction of the full torso (7). The objectives of the current study are: 1) to use this new index to document AIS surgical outcome in terms of changes in trunk deformities in AIS patients with Lenke 1A curve type, 2) to compare these changes with the changes in 2D and 3D spinal measurements.…”

Is Breast Asymmetry Present in Girls with Adolescent Idiopathic Scoliosis?

“…We feel confident with the precision of our results using the MRI and believe that thoracic Cobb angle only partially explains the breast asymmetry observed. We also studied the correlation between breast asymmetry and the thoracic gibbosity angle as it was demonstrated by Seoud to be more closely correlated to vertebral rotation than the Cobb angle [53]. No statistical significant correlation was found between breast asymmetry and thoracic gibbosity angle (0.289, p=0.122), further reinforcing the fact that breast asymmetry is independent of spine and thoracic deformity.…”

Scoliosis Follow-Up Using Noninvasive Trunk Surface Acquisition

“…A drawback of these studies is that only the maximum index values along the trunk are used for monitoring AIS progression. To address that, Seoud and al [38] have proposed multilevel analysis using functional indices computed along the entire trunk. However, local 0000-0000/00$00.00 c 2011 IEEE trunk deformations such as asymmetry of the shoulders, waist or scapulae cannot been characterized by these functional indices.…”