Michel A. Leroux

A noninvasive anthropometric technique for measuring kyphosis and lordosis: an application for idiopathic scoliosis.

STUDY DESIGN Cross-sectional measurement of the sagittal geometry of adolescent idiopathic scoliosis patients. OBJECTIVES To evaluate the accuracy of a noninvasive anthropometric approach for the measurement of kyphosis and lordosis. SUMMARY OF BACKGROUND DATA Noninvasive approaches were developed to estimate the sagittal curvatures of the spine. However, the magnitude of the estimation error could be high for an important proportion of patients, which leads to a difficult clinical application. METHODS The group was composed of 124 female patients with a mean age of 13.5 years (SD 2. 7 years) with Cobb angles ranging from 4 degrees to 66 degrees. Kyphosis and lordosis were measured on the lateral radiograph. The spine sagittal curvature of the same patients was also estimated using the spatial localization of skin markers placed overlying the spinous processes. These coordinates served as input into a simple trigonometric model. Data were collected by means of a stereovideographic technique (Motion Analysis Corp., Santa Rosa, CA). RESULTS The intraclass correlation coefficient between both approaches was 0.94 for kyphosis and 0.91 for lordosis; the mean absolute differences were 5 degrees (SD 4 degrees ) and 6 degrees (SD 6 degrees ), respectively. The difference was less than 10 degrees in 91% of the patients for kyphosis, and in 79% for lordosis. CONCLUSIONS The proposed technique appears to give more representative results than those presented in the literature. It has the advantage of being part of a global noninvasive postural evaluation. Using this approach in a systematic manner could help reduce radiograph exposure while keeping track of the spine sagittal curvatures.

SpineCor - a non-rigid brace for the treatment of idiopathic scoliosis: post-treatment results

Abstract. The objective of this study was to assess the success of treatment during the follow-up of a group of 195 idiopathic scoliosis (IS) patients consecutively treated with the SpineCor system. A survival analysis was performed to estimate the cumulative probability of success during treatment, at follow-up and for the combined treatment and follow-up period. Success was defined as either a correction or stabilization of ±5° or more, and failure as a worsening of more than 5°. The patient cohort was categorized before treatment into curves less than 30° (group 1), and curves greater than 30° (group 2). The survival analysis indicated a cumulative probability of success that increased during treatment with the patient wearing the brace (Year 1: 0.30, 0.39; Year 2: 0.62, 0.79; Year 3: 0.92, 0.89, for groups 1 and 2 respectively). During the post-treatment follow-up period, there was a stabilization (Year 1 post-treatment: 0.94, 0.89; Year 2 post-treatment: 0.85, 0.81), with an overall probability of success of 0.92 and 0.88 after 4 years of combined treatment and post-treatment follow-up. For the 29 patients who had a minimum follow-up of 2 years (initial Cobb angle: 30°±9°), the trend during treatment was a decrease in spinal curvature at 3 months, with a mean difference of 10° (SD 5°); at termination of treatment a mean difference of 7° (SD 7°); and at the time of the 1- and 2-year follow-ups there was a difference of 4° (SD 7°) and 5° (SD 7°) respectively, with reference to the initial out of brace condition. At 2 years follow-up there was an overall correction of greater than 5° for 55% of the patients, 38% had a stabilisation and 7% had worsened by more than 5°. This initial cohort of patients demonstrated a general trend of initial decrease in spinal curvature in brace, followed by a correction and/or stabilisation at the end of treatment, which was maintained through 1, and 2 years’ follow-up.

Acute systematic and variable postural adaptations induced by an orthopaedic shoe lift in control subjects

Abstract A small leg length inequality, either true or functional, can be implicated in the pathogenesis of numerous spinal disorders. The correction of a leg length inequality with the goal of treating a spinal pathology is often achieved with the use of a shoe lift. Little research has focused on the impact of this correction on the three-dimensional (3D) postural organisation. The goal of this study is to quantify in control subjects the 3D postural changes to the pelvis, trunk, scapular belt and head, induced by a shoe lift. The postural geometry of 20 female subjects (x– = 22, σ = 1.2) was evaluated using a motion analysis system for three randomised conditions: control, and right and left shoe lift. Acute postural adaptations were noted for all subjects, principally manifested through the tilt of the pelvis, asymmetric version of the left and right iliac bones, and a lateral shift of the pelvis and scapular belt. The difference in the version of the right and left iliac bones was positively associated with the pelvic tilt. Postural adaptations were noted to vary between subjects for rotation and postero-anterior shift of the pelvis and scapular belt. No notable differences between conditions were noted in the estimation of kyphosis and lordosis. The observed systematic and variable postural adaptations noted in the presence of a shoe lift reflects the unique constraints of the musculoskeletal system. This suggests that the global impact of a shoe lift on a patient’s posture should also be considered during treatment. This study provides a basis for comparison of future research involving pathological populations.

Relationship between gibbosity and Cobb angle during treatment of idiopathic scoliosis with the SpineCor brace.

Abstract The objective of this study was to quantify the relationship between gibbosity and spinal deformation expressed by the angle of Cobb before and during treatment with a brace for different classes of idiopathic scoliosis patients. As part of the standard treatment with the Dynamic Corrective Brace (SpineCor), 89 idiopathic scoliosis patients underwent an initial radiological examination and gibbosity measurement with a scoliometer wearing and not wearing the brace. The 89 patients were classified in relation to the apex of the scoliosis curves: thoracic (n = 29); thoracolumbar (n = 40); lumbar (n = 7) and double (n = 13). With the dynamic corrective brace, the patients showed a mean decrease of 8.3° for the major Cobb angle, and a mean decrease of 2.3° for their gibbosity. There was a significant positive relationship between gibbosity and Cobb angle with and without the brace for the thoracic and thoracolumbar curves. A linear regression analysis identified a small mean estimation error for the thoracic curves (7.4° no-brace; 2.7° with brace) and thoracolumbar curves (5.2° no-brace; 5.3° with brace), indicating a predictive potential of the scoliometer. The measure of gibbosity with the scoliometer provides a fairly reliable estimation of Cobb angle at the initial clinical examination of a scoliosis patient. However, when initial Cobb angle and gibbosity are considered, the measure of gibbosity when wearing a brace provides the clinician with a highly reliable estimation of the Cobb angle while in a brace. This relationship also exists for the follow-up with a brace, permitting a judgement of the patient’s evolution under the treatment with SpineCor.

Postural characteristics of adolescents with idiopathic scoliosis.

Background: The objectives of this study were to compare the postural characteristics of idiopathic scoliosis (IS) patients with different types of spinal curvature and to compare a motion capture and a sequential digitization technique to estimate the postural characteristics of the IS patients. Methods: A total of 57 IS patients underwent a radiological, clinical, and postural geometric evaluations in an upright standing position as part of their regular follow-up. The posteroanterior radiograph of the trunk was used to measure the amplitude of spinal curvature. The postural evaluation was performed using a motion capture and sequential digitization technique providing the necessary 3-dimensional positions of anatomical landmarks. These landmarks were used to calculate postural parameters defining the position and orientation of the pelvis, shoulders, and shoulder blades. These measurements included lateral shift and angular measures of rotation and tilt. Results: Significant differences in the frontal and transverse planes were found between the right thoracic (RTh), left thoracolumbar, and RTh-left lumbar (RThLL) patients. These characteristics were most prominent in the transverse plane for RTh patients, in the frontal plane for left thoracolumbar patients, and in the frontal and transverse planes for the RThLL lumbar patients. A strong positive intraclass correlation was also found between the parameters estimated with the motion capture system and with the sequential digitization system. Conclusions: Unique postural characteristics that are related to the type of the spinal curvature are evident in adolescents who have IS. Further work is necessary to assess how these measures may be used to monitor the progression of the spinal deformity. Clinical Relevance: Quantifying the postural alignment of IS patients using surface anthromopetric landmarks provides an opportunity to characterize the unique postural attributes that accompany each type of spinal curvature.

Osseointegration study of porous nitinol versus titanium orthopaedic implants

The functionality of a new metallic interbody fusion implant manufactured out of porous nitinol (PNT) was evaluated in sheep and compared to a conventional titanium (TiAIV) intervertebral cage packed with autologous iliac crest bone. Both device types were implanted at two non-contiguous intervertebral lumbar sites. The objective was to evaluate the osseointegration capacity after 3, 6 and 12 months of implantation in the presence of these two implant types subjected to the same mechanical loads. Two-dimensional radiology, computer tomography and histology were used as techniques of parameter evaluation. The results indicated that PNT obtained a better intervertebral osseointegration capacity compared to the TiAlV cage. The functional difficulties of the titanium implant were related to its instability at the implantation site possibly due to a biofunctionality problem. The biocompatibility of both implants seemed comparable, however.RésuméLa fonctionnalité d’un nouvel implant métallique de fusion intervertébrale en nitinol poreux (PNT) a été évaluée chez la brebis, puis comparée à celle de la cage de fusion intervertébrale conventionnelle en titane (TiAlV). Le titane, contrairement au PNT, nécessitait une greffe osseuse à partir de la crête iliaque lors de l’implantation. L’objectif de ces recherches était d’évaluer, après 3, 6 et 12 mois postopératoires, la capacité ostéointégrative de ces deux types d’implants soumis aux mêmes sollicitations mécaniques du rachis à deux niveaux lombaires non-contigus. La radiologie bidimensionnelle, la tomographie et l’histologie furent utilisées comme techniques d’évaluation des paramètres d’intégration osseuse. Les résultats ont indiqué que le PNT, comparé au TiAlV, avait une meilleure capacité ostéointégrative. Les difficultés fonctionnelles du TiAlV étaient liées à son instabilité dans le site d’implantation, possiblement à cause d’un problème de biofonctionnalité. La biocompatibilité des deux implants semblait toutefois comparable.

Estimated kyphosis and lordosis changes at follow-up in patients with idiopathic scoliosis

The objective of this study was to verify the accuracy of surface measurements to estimate the magnitude of sagittal curvature changes at follow-up. Ninety-seven patients with idiopathic scoliosis were evaluated at two different visits (interval: 15.7 months). Kyphosis and lordosis were measured on the lateral radiograph. Surface measurements rely on localization of spinous process landmarks using a video-based system. Multiple regression analyses were performed to estimate the sagittal curvatures on the second visit. The regression was significant for both kyphosis and lordosis. The mean absolute difference between the estimate and the radiologic measurement was 3.3° for kyphosis and 3.2° for lordosis. The difference between the estimated change and the observed change between visits showed mean absolute differences of 3.4° and 2.7°, respectively. The proposed strategy could be used during follow-up to reduce patient irradiation without loss of sagittal information.