Karl Zabjek

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.

Active Video Game Play in Children With Cerebral Palsy: Potential for Physical Activity Promotion and Rehabilitation Therapies

OBJECTIVE To evaluate the potential of active video game (AVG) play for physical activity promotion and rehabilitation therapies in children with cerebral palsy (CP) through a quantitative exploration of energy expenditure, muscle activation, and quality of movement. DESIGN Single-group, experimental study. SETTING Human movement laboratory in an urban rehabilitation hospital. PARTICIPANTS Children (N=17; mean age ± SD, 9.43±1.51y) with CP. INTERVENTION Participants played 4 AVGs (bowling, tennis, boxing, and a dance game). MAIN OUTCOME MEASURES Energy expenditure via a portable cardiopulmonary testing unit; upper limb muscle activations via single differential surface electrodes; upper limb kinematics via an optical motion capture system; and self-reported enjoyment via the Physical Activity Enjoyment Scale (PACES). RESULTS Moderate levels of physical activity were achieved during the dance (metabolic equivalent for task [MET]=3.20±1.04) and boxing (MET=3.36±1.50) games. Muscle activations did not exceed maximum voluntary exertions and were greatest for the boxing AVG and for the wrist extensor bundle. Angular velocities and accelerations were significantly larger in the dominant arm than in the hemiplegic arm during bilateral play. A high level of enjoyment was reported on the PACES (4.5±0.3 out of 5). CONCLUSIONS AVG play via a low-cost, commercially available system can offer an enjoyable opportunity for light to moderate physical activity in children with CP. While all games may encourage motor learning to some extent, AVGs can be strategically selected to address specific therapeutic goals (eg, targeted joints, bilateral limb use). Future research is needed to address the challenge of individual variability in movement patterns/play styles. Likewise, further study exploring home use of AVGs for physical activity promotion and rehabilitation therapies, and its functional outcomes, is warranted.

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.

Simultaneous, bilateral, and three-dimensional gait analysis of elderly people without impairments.

Sadeghi H, Prince F, Zabjek KF, Labelle H: Simultaneous, bilateral, and three-dimensional gait analysis of elderly people without impairments. Am J Phys Med Rehabil 2004;83:112-123. ObjectiveThe main objectives of this study were to determine if the right and left lower limbs in the gait of elderly people developed similar muscle moment and power patterns and to determine whether their associated mechanical energies were different during two consecutive gait cycles. DesignA total of 18 able-bodied male subjects aged 71 ± 6.8 yrs participated in this study. Data were collected using three Optotrak position sensors and two AMTI force platforms. ResultsThe peak muscle powers were very similar in the sagittal plane and reflected gait symmetry, except for greater and significant differences produced by the hip extensors. Differences in the frontal and transverse planes were mainly attributed to the actions taken by the muscles, leading the lower limbs to compensate and to dynamically balance and propel the body forward during two consecutive gait cycles. In terms of mechanical energy, 13% greater positive work was done in the left limb and was associated with asymmetrical behavior of the lower limbs to propel the body forward. The total negative work was similar for both limbs, and substantial work was done in the frontal plane by the hip, indicating the role of muscle activity in this plane to control the pelvis and trunk against gravitational forces. ConclusionsIn addition to the importance of a balance-control function in the gait of healthy, elderly subjects, muscle activity made an important contribution to propelling the body forward. Gait asymmetry in elderly subjects seems to be related to different degrees of energy generated by the lower limbs for the propulsion function, whereas both limbs contribute similarly to the balance-control function.

Assessment of the postural control strategies used to play two Wii Fit™ videogames

The Nintendo Wii Fit™ may provide an affordable alternative to traditional biofeedback or virtual reality systems for retraining or improving motor function in populations with impaired balance. The purpose of this study was to evaluate postural control strategies healthy individuals use to play Wii Fit™ videogames. Sixteen young adults played 10 trials of Ski Slalom and Soccer Heading respectively. Centre of pressure (COP) excursion and three-dimensional movement data were acquired to determine variability in medial-lateral COP sway and shoulder-pelvic movement. While there was no difference in medial-lateral COP variability between games during trial 1, there was a significant difference after 10 trials. COP sway increased (59-75 mm) for Soccer Heading while it decreased (67-33 mm) for Ski Slalom from trial 1 to trial 10. During Ski Slalom participants demonstrated decreased shoulder and pelvic movement combined with increased pelvic-shoulder coupling. Conversely, participants demonstrated greater initial shoulder tilt when playing Soccer Heading, with no reduction in pelvic rotation and tilt. Participants decreased pelvic and trunk movements when skiing, suggesting a greater contribution of lower extremity control while they primarily used a trunk strategy to play Soccer Heading.

Development of a robotic device for upper limb stroke rehabilitation: A user-centered design approach

Stroke is one of the major causes of permanent adult disability. Stroke frequently affects motor control of the arm, leading to diffculties in doing activities of daily living. This research focuses on developing an upper limb rehabilitation robotic prototype through user-centered design to aid stroke survivors in rehabilitating their arm. To gather requirements from end users, stroke therapy sessions were observed and a survey of stroke therapists was conducted. End user requirements were evaluated to determine technical targets for the mechanical design of the prototype. Evaluation of the prototype was done with stroke therapists in a focus group and a preliminary biomechanical study. As user-centered design would require more iterations of design, testing and evaluation, this project reports a first step in developing an affordable, portable device, which could increase access to stroke rehabilitation for the arm.

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.

Frontal plane standing balance with an ambulation aid:Upper limb biomechanics

Despite widespread acceptance of clinical benefits, empirical evidence to evaluate the advantages and limitations of ambulation aids for balance control is limited. The current study investigates the upper limb biomechanical contributions to the control of frontal plane stability while using a 4-wheeled walker in quiet standing. We hypothesized that: (1) upper limb stabilizing moments would be significant, and (2) would increase under conditions of increased stability demand. Factors influencing upper limb moment generation were also examined. Specifically, the contributions of upper limb center-of-pressure (COP(hands)), vertical and horizontal loads applied to the assistive device were assessed. The results support a significant mechanical role for the upper limbs, generating 27.1% and 58.8% of overall stabilizing moments under baseline and challenged stability demand conditions, respectively. The increased moment was achieved primarily through the preferential use of phasic upper limb control, reflected by increased COP(hands) (baseline vs. challenged conditions: 0.29 vs. 0.72cm). Vertical, but not horizontal, was the primary force direction contributing to stabilizing moments in quiet standing. The key finding that the upper limbs play an important role in effecting frontal plane balance control has important implications for ambulation aid users (e.g., elderly, stroke, and traumatic brain injury).