Assessment of malalignment at early stage in adolescent idiopathic scoliosis: a longitudinal cohort study

INTRODUCTION

Our objective was to assess abnormalities of the odontoid-hip axis (OD-HA) angle in a mild scoliotic population to determine whether screening for malalignment would help predict the distinction between progressive and stable adolescent idiopathic scoliosis (AIS) at early stage.

MATERIALS AND METHODS

All patients (non-scoliotic and AIS) underwent a biplanar X-ray between 2013 and 2020. In AIS, inclusion criteria were Cobb angle between 10° and 25°; Risser sign lower than 3; age higher than 10 years; and no previous treatment. A 3D spine reconstruction was performed, and the OD-HA was computed automatically. A reference corridor for OD-HA values in non-scoliotic subjects was calculated as the range [5th-95th percentiles]. A severity index, helping to distinguish stable and progressive AIS, was calculated and weighted according to the OD-HA value.

RESULTS

Eighty-three non-scoliotic and 205 AIS were included. The mean coronal and sagittal OD-HA angles in the non-scoliotic group were 0.2° and -2.5°, whereas in AIS values were 0.3° and -0.8°, respectively. For coronal and sagittal OD-HA, 27.5% and 26.8% of AIS were outside the reference corridor compared with 10.8% in non-scoliotic (OR = 3.1 and 3). Adding to the severity index a weighting factor based on coronal OD-HA, for thoracic scoliosis, improved the positive predictive value by 9% and the specificity by 13%.

CONCLUSION

Analysis of OD-HA suggests that AIS patients are almost three times more likely to have malalignment compared with a non-scoliotic population. Furthermore, analysis of coronal OD-HA is promising to help the clinician distinguish between stable and progressive thoracic scoliosis.

Biomechanical Effects of Thoracolumbosacral Orthosis Design Features on 3D Correction in Adolescent Idiopathic Scoliosis: A Comprehensive Multicenter Study

STUDY DESIGN

Multicenter numerical study.

OBJECTIVE

To biomechanically analyze and compare various passive correction features of braces, designed by several centers with diverse practices, for three-dimensional (3D) correction of adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

A wide variety of brace designs exist, but their biomechanical effectiveness is not clearly understood. Many studies have reported brace treatment correction potential with various degrees of control, making the objective comparison of correction mechanisms difficult. A Finite Element Model simulating the immediate in-brace corrective effects has been developed and allows to comprehensively assess the biomechanics of different brace designs.

METHODS

Expert clinical teams (one orthotist and one orthopedist) from six centers in five countries participated in the study. For six scoliosis cases with different curve types respecting SRS criteria, the teams designed two braces according to their treatment protocol. Finite Element Model simulations were performed to compute immediate in-brace 3D correction and skin-to-brace pressures. All braces were randomized and labeled according to 21 design features derived from Society on Scoliosis Orthopaedic and Rehabilitation Treatment proposed descriptors, including positioning of pressure points, orientation of push vectors, and sagittal design. Simulated in brace 3D corrections were compared for each design feature class using ANOVAs and linear regressions (significance P ≤ 0.05).

RESULTS

Seventy-two braces were tested, with significant variety in the design approaches. Pressure points at the apical vertebra level corrected the main thoracic curve better than more caudal locations. Braces with ventral support flattened the lumbar lordosis. Lateral and ventral skin-to-brace pressures were correlated with changes in thoracolumbar/lumbar Cobb and lumbar lordosis (r =- 0.53, r = - 0.54). Upper straps positioned above T10 corrected the main thoracic Cobb better than those placed lower.

CONCLUSIONS

The corrective features of various scoliosis braces were objectively compared in a systematic approach with minimal biases and variability in test parameters, providing a better biomechanical understanding of individual passive mechanisms' contribution to 3D correction.

Effect of curve location on the severity index for adolescent idiopathic scoliosis: a longitudinal cohort study

OBJECTIVES

Adolescent idiopathic scoliosis (AIS) is the most common spinal disorder in children. A severity index was recently proposed to identify the stable from the progressive scoliosis at the first standardized biplanar radiographic exam. The aim of this work was to extend the validation of the severity index and to determine if curve location influences its predictive capabilities.

METHODS

AIS patients with Cobb angle between 10° and 25°, Risser 0-2, and no previous treatment were included. They underwent standing biplanar radiography and 3D reconstruction of the spine and pelvis, which allowed to calculate their severity index. Patients were grouped by curve location (thoracic, thoracolumbar, lumbar). Patients were followed up until skeletal maturity (Risser ≥ 3) or brace prescription. Their outcome was compared to the prediction made by the severity index.

RESULTS

In total, 205 AIS patients were included; 82% of them (155/189, 95% confidence interval [74-90%]) were correctly classified by the index, while 16 patients were unclassified. Positive predictive ratio was 78% and negative predictive ratio was 86%. Specificity (78%) was not significantly affected by curve location, while patients with thoracic and lumbar curves showed higher sensitivity (≥ 89%) than those with thoracolumbar curves (74%).

CONCLUSIONS

In this multicentric cohort of 205 patients, the severity index was used to predict the risk of progression from mild to moderate scoliosis, with similar results of typical major curve types. This index represents a novel tool to aid the clinician and the patient in the modulation of the follow-up and, for progressive patients, their decision for brace treatment.

KEY POINTS

• The severity index of adolescent idiopathic scoliosis has the potential to detect patients with progressive scoliosis as early as the first exam. • Out of 205 patients, 82% were correctly classified as either stable or progressive by the severity index. • The location of the main curve had small effect on the predictive capability of the index.

Towards a predictive simulation of brace action in adolescent idiopathic scoliosis

Bracing is the most common treatment to stop the progression of adolescent idiopathic scoliosis. Finite element modeling could help improve brace design, but model validation is still a challenge. In this work, the clinical relevance of a predictive and subject-specific model for bracing was evaluated in forty-six AIS patients. The model reproduces brace action and the patient's spinopelvic adjustments to keep balance. The model simulated 70% or more patients with geometrical parameters within a preselected tolerance level. Although the model simulation of the sagittal plane could be improved, the approach is promising for a realistic and predictive simulation of brace action.

Idiopathic scoliosis and balance organisation in seated position on a seesaw

The aim was to determine the biomechanical processes involved in postural regulation when self-imposed disturbances occur in the seated position in the antero-posterior direction. Twelve female adolescents with right thoracic scoliosis (SG) (Cobb = 30.4 degrees +/- 9.7) and 15 control adolescents (CG) were included in this study. The ground reaction forces (GRF) were studied whilst the subjects maintained their balance in the sitting position on a seesaw. Six conditions were tested: eyes open and closed; with an additional load placed on the subject's right or left shoulder; and with an additional load on the subject's right or left pelvis. The SG showed significantly higher force amplitudes and variability and fewer oscillations than the CG in all the conditions. In the SG, the time analysis showed that the duration of the GRF was significantly higher in forward and left directions. Whatever the condition tested, the intra-group differences were not significant. The scoliotic patients in seated position were characterised by larger changes of the GRF, especially with a postural control in the forward and left directions, corresponding to that on the concave side of their spinal curvature. No significant differences were found to exist between the various conditions (load and unload, eyes open and eyes closed). Clinical tests and rehabilitation methods should include assessments of seated patients' spatio-temporal adaptation to GRF.

Analysis of the mechanisms of idiopathic scoliosis progression using finite element simulation

The mechanisms of idiopathic scoliosis progression are still not fully understood. The aim of this study is to explore, using finite element simulation, effect of the combination of gravity and anterior spinal overgrowth on scoliosis progression. 14 adolescents (10 girls, 4 boys) with an average age of 10.8 years [range 9; 13] were divided in three groups: thoraco-lumbar scoliosis (TL), lumbar scoliosis (L), asymptomatic patients (A). Accurate 3D reconstructions of the spine have been built using bi-planar X-rays. A patient specific validated finite element model has been used. Simulations have been launched with simulation of the combined effect of gravity and growth. The progression during the simulation was defined by a maximal axial rotation movement greater or equal than 4 degrees and a maximal lateral displacement greater or equal than 5 mm ("first order progression" for one criterion, "second order" for the both criteria). In the group TL, we notice an aggravation for 4 patients (Cobb angle increase at least by 4 degrees , mean at 5.9 degrees ). Only three patients of the group L show a progression with a smaller Cobb angle increase (mean 3.9 degrees ). For the group A, no progression is found for 3 and a progression is found for 1. An anterior spinal overgrowth combined with gravity and a pre-existent curve in the spine could lead to a progression of scoliosis. It seems necessary to consider differently lumbar curves from other curves. Numerical simulation with a patient specific model appears as a useful tool to investigate mechanisms of scoliosis aggravation.

Influence of school bag carrying on gait kinetics

The purpose of this study was to determine the effect of different methods of backpack carrying on gait kinetics in children, using a new treadmill that allowed three-dimensional measurement of right and left leg ground reaction forces (GRFs). Forty-one healthy children, with a mean age of 12 years, participated in this study. The mean height was 152 cm and the mean weight 40 kg. The three trials consisted of walking on the treadmill at the speed of 3.5 km/h, first without a backpack and then carrying a 10 kg school bag on the right shoulder or on both shoulders. For each carrying condition GRFs were recorded, averaged, and analyzed for 30 steps. Stride, stance, double stance, thirteen specific GRF parameters and the symmetry index were measured. The right leg produced higher propulsive fore-aft forces than the left one, whatever the walking conditions. For the two maximum peaks and the average vertical force during stance, a statistical difference was found between walking without a backpack and carrying a backpack on one or two shoulders (one or two shoulder carrying > no backpack) but never between one-shoulder and two-shoulder carrying. The children increased their stance and double stance when walking with a backpack compared with walking without a pack. The symmetry index increased with one-strap carrying (compared with no backpack and two-strap carrying) for the maximum force during the breaking phase (Fy1) when it decreased for the maximum propulsive horizontal force before taking-off (Fy2). Children should be advised to carry their backpack on two shoulders rather than use a one-strap backpack.

[Relationship between burden of care at home and functional independence level after stroke]

OBJECTIVE

To determine the relationship between functional disability assessed with the Functional Independence Measure (FIM) and burden of care in hemiplegic stroke patients living at home.

METHOD

The population is constituted of stroke survivors, initially treated in an academic inpatient Physical Medicine and Rehabilitation unit. Assessments included an evaluation of impairments (aphasia, negligence, cognitive impairment, motor impairment : Fugl-Meyer (FM) scale), disability (Functional Independence Measure (FIM) ), and burden of care (physical assistance and supervision).

RESULTS

Forty-five subjects and their caregiver completed the assessments. Time spent on physical assistance and supervision were significantly correlated with FM and FIM scores. Cognitive deficits correlated with supervision time but not with physical assistance time.

DISCUSSION-CONCLUSION

These results confirm the predictive value of functional independence measure relative to burden of care in a population of stroke patients with hemiplegia living at home. These results show that cognitive impairments are more specifically correlated with supervision time. This must be confirmed by studies taking into account functional and cognitive conditions of the patient, functional and psychological conditions of life of caregiver and also economical and environmental conditions of life.

[Gait analysis of 57 healthy children by measurement of ground reaction forces on an Adal treadmill]

PURPOSE OF THE STUDY

The purpose of this study was to present a new treadmill proposed for evaluating gait in children. We analysed differences in ground reaction forces between boys and girls, and we calculated the symmetry index in healthy children.

MATERIAL AND METHOD

Time and ground reaction forces of about 30 steps were measured using a new treadmill. The apparatus consists of 2 walking belts which function as two independent treadmills placed side by side, separated by 4 mm. The 2 treadmills were mechanically separated in order to allow independent measurement of the ground reaction forces induced by each lower limb during stance phase. The children (28 boys and 29 girls), all clinically healthy, were divided into three groups according to their height (between 105 and 150 cm). They walked at three different velocities (2.7 km/h, 3.6 km/h and 4.5 km/h according to their height). The graphs representing the subject's measurements were composed of fore-aft, medial-lateral, and vertical parameters. The analysis of these graphs considered stride, stance, double stance and nine specific points. We also calculated the symmetry index of each child.

RESULTS

We determined the values of the symmetry index in healthy children. We did not find any significant difference in gait between girls and boys, except for Fz3 at 2.7 kg/h, where Fz3 was higher in girls than in boys.

DISCUSSION

We compared our results with those reported in the literature and found that ADAL has a very important advantage in gait analysis in children because it is simple and easily accepted by children.