The effect of backpack weight on the standing posture and balance of schoolgirls with adolescent idiopathic scoliosis and normal controls

Influences of backpack loading on recovery from anterior and posterior losses of balance: An exploratory investigation

Backpacks are common devices for carrying external posterior loads. However, relatively little is known about how these external loads affect the ability to recover from balance loss. In this exploratory investigation, 16 young adults (8 female, 8 male) performed forward and backward lean-and-release balance recovery trials, while wearing a backpack that was unloaded or loaded (at 15% of individual body weight). We quantified the effects of backpack loading on balance recovery in terms of maximum recoverable lean angles, center-of-mass kinematics, and temporal-spatial stepping characteristics. Mean values of maximum lean angles were 20° and 9° in response to forward and backward perturbations, respectively. These angles significantly decreased when wearing the additional load for only backward losses of balance. During backward losses of balance, the additional load decreased peak center-of-mass velocity and increased acceleration by ∼10 and 18% respectively, which was accompanied by ∼5% faster stepping responses and steps that were ∼9% longer, 11% higher, and had an ∼10% earlier onset. Thus, wearing a backpack decreases backward balance recovery ability and changes backward recovery stepping characteristics.

Influence of Backpack Carriage and Walking Speed on Muscle Synergies in Healthy Children

Four to five muscle synergies account for children's locomotion and appear to be consistent across alterations in speed and slopes. Backpack carriage induces alterations in gait kinematics in healthy children, raising questions regarding the clinical consequences related to orthopedic and neurological diseases and ergonomics. However, to support clinical decisions and characterize backpack carriage, muscle synergies can help with understanding the alterations induced in this condition at the motor control level. In this study, we investigated how children adjust the recruitment of motor patterns during locomotion, when greater muscular demands are required (backpack carriage). Twenty healthy male children underwent an instrumental gait analysis and muscle synergies extraction during three walking conditions: self-selected, fast and load conditions. In the fast condition, a reduction in the number of synergies (three to four) was needed for reconstructing the EMG signal with the same accuracy as in the other conditions (three to five). Synergies were grouped in only four clusters in the fast condition, while five clusters were needed for the self-selected condition. The right number of clusters was not clearly identified in the load condition. Speed and backpack carriage altered nearly every spatial-temporal parameter of gait, whereas kinematic alterations reflected mainly hip and pelvis adaptations. Although the synergistic patterns were consistent across conditions, indicating a similar motor pattern in different conditions, the fast condition required fewer synergies for reconstructing the EMG signal with the same level of accuracy.

Changing the horizontal position of a fixed backpack load: The effect on postural stability in young adults

BACKGROUND

Modifying the horizontal position of the load in a backpack will change the size of the external torque it creates on the wearer but the effect on postural stability is unclear.

OBJECTIVE

To determine if changing the horizontal position of a fixed backpack load affects postural stability in young adults.

METHODS

A backpack was attached to a steel frame with a bar protruding posteriorly. A fixed load (5% body mass) was placed at three distances along the bar - 0 m, 0.20 m, and 0.40 m. Centre of pressure (CoP) derived measurements were recorded from a force platform sampling at 100 Hz. For each condition participants performed three 90s narrow stance trials with their eyes closed whilst standing on a firm surface. A comparison was made across unloaded (no backpack) and loaded conditions.

RESULTS

There was an immediate decrease in postural stability when a loaded backpack was worn. Only two of the CoP derived measures (Total Excursion - TEx, and Mean Velocity Total Excursion - MVel TEx) differed between the loaded at 0.20 m and loaded at 0 m conditions. All CoP derived measures differed between the loaded at 0.40 m and loaded at 0 m conditions. Furthermore, three of the CoP derived measures (Anterior/Posterior Root Mean Square - A/P RMSq, TEx, and MVel TEx) differed between the loaded at 0.40 m and loaded at 0.20 m conditions.

CONCLUSION

The distribution of a load within a backpack must be carefully considered. The findings for the 0.40 m condition are important for the use and design of large backpacks used by multi-day hikers, travellers, and the military.

Comparison of two periods of Schroth exercises for improving postural stability indices and Cobb angle in adolescent idiopathic scoliosis

BACKGROUND

Adolescents with idiopathic scoliosis present postural instability when compared with healthy subjects. Although Schroth exercises therapy (SET) is broadly utilized, its effect on postural stability is still not clear.

OBJECTIVES

To compare the two treatment periods of the SET for improving the postural stability indices and Cobb angle, and to examine the correlation between the Cobb angle and stability indices in adolescent idiopathic scoliosis (AIS).

METHODS

Twenty girls aged 10-16 years with AIS (study group) and 20 age-matched girls without AIS (control group) were examined. The Biodex Balance System was used to evaluate the overall stability index (OSI), anteroposterior index (APSI), and mediolateral stability index (MLSI) in the study group before SET and one and three months after the therapy. A plain X-ray was used to measure the Cobb angle before and three months after SET. Stability indices and Cobb angle were measured only once for the control group.

RESULTS

One-way repeated-measures ANOVA revealed that the three-month duration of SET was the most effective for improving OSI, APSI, and MLSI (p< 0.001). The significant proximities of OSI, APSI, and MLSI to the normal values post three months of SET were 29.65%, 24.07, and 20% respectively. The MLSI was robust and correlated with the Cobb angle (r= 0.85) three months post intervention.

CONCLUSION

Stability indices and Cobb angles were highly improved after three months of SET compared to one month among AIS patients. The MLSI is the most substantial index correlated with the Cobb angle.

Acute Effects of Self-Correction on Spine Deviation and Balance in Adolescent Girls with Idiopathic Scoliosis

Background: Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of spine and trunk with a higher incidence in girls. AIS alters and reduces postural control and balance. Self-correction movement (SCM) is a well-known non-invasive approach to ameliorate spine curve in AIS subjects. We aimed to evaluate the effects of SCM on the spine and on the balance of adolescents with AIS with a new non-invasive instrumentation. Methods: A total of 38 girls with AIS were recruited. To evaluate the acute effects of SCM and the oscillations of center of pressure (COP), we used LiDAR technology combined with a stabilometric platform to evaluate both changes in spinal curves and balance at the same time. Two tests were carried out simultaneously using the two instruments: before the execution of SCM, in the spontaneously assumed position of each subject (SP) and after the execution of SCM, during the achieved position (SC). Sway area, COP medio-lateral and antero-posterior directions, eccentricity of the ellipse and vertebral lateral deviation were recorded. The two conditions were compared with a Wilcoxon signed-rank test. Results: In general, all measures showed lower values in SC condition (p < 0.05), except the variation along the Y axis. Conclusions: Thanks to objective measured data, the therapists observed real-time changes during the performance of SCM, appreciating its efficacy on curve correction.

Effectiveness of a Back School and Postural Education Program on the improvement of literacy about postures and low back pain in adolescents: A 1-year follow-up study

BACKGROUND

Some health problems can be associated with the school environment and lifestyles, so it is necessary to carry out intervention actions that promote health and problem prevention. This study evaluates the effects of a Back School and Postural Education on improving short-term and long-term ergonomic knowledge of postures adopted at school and home, as well as reducing low back pain (LBP) in adolescents.

METHODS

The sample comprises 98 students, aged 10-16 years (11.61 ± 1.28 years), with 63 (64.3%) girls. The measuring instruments included a theoretical and a practical test, a low back pain (LBP) questionnaire and a scale. The tests and the scale have been applied 1 week before the intervention, 1 week following the Back School and Postural Education Program, and a 1 year later. The questionnaire was applied 1 week before of intervention and after 1 year. The intervention included three sessions of a theoretical and practical nature, each lasting 45 min, with intervals of 1 week.

RESULTS

The values of the theoretical test before the intervention, 1 week, and 1 year after the intervention were, respectively, 8.67 ± 2.64, 11.37 ± 1.93, and 11.11 ± 1.92 (p ≤ 0.001), and the practical test were 6.42 ± 2.47, 12.48 ± 2.25, and 12.83 ± 1.78 (p ≤ 0.001). The presence of LBP fell by 42.9%-25.5% after the 1-year period.

CONCLUSIONS

Our data show an improvement of ergonomic knowledge of postures adopted at school and home as a result of the education program and a decrease of self-reported LBP.

School physiotherapy programme: Improving literacy regarding postures adopted at home and in school in adolescents living in the south of Portugal

BACKGROUND

Health literacy consists of an individual's ability to make informed decisions in various sectors, including school. Most of the health problems and risky behaviours associated with the environment and lifestyle can be minimised or even prevented by increasing health literacy.

OBJECTIVES

This study aimed to evaluate the effectiveness of a school physiotherapy programme in improving literacy regarding postures adopted at home and in school in adolescents living in the south of Portugal.

METHODS

The sample was comprised of 84 students in the 5th grade, 42 (50%) were boys, aged to 10 and 13 years old (10.35±0.61). The measurement instruments included a theoretical and practical test applied one week before and one week after the school physiotherapy programme.

RESULTS

The values obtained on the theoretical test before and after the intervention ranged from 1-13 (7.70±2.47) and 5-13 (10.83±2.27), respectively (p≤0.001) and, on the practical test, before and after ranged from 0-10 (4.14±2.21) and 6-15 (11.8±2.28), respectively (p≤0.001).

CONCLUSION

This study found significant improvements in both theoretical and practical knowledge acquisition after participants attended a school physiotherapy programme. Thus, a school physiotherapy programme could be a useful tool to prevent and/or minimise musculoskeletal disorders in adolescents.

Spinal Compressive Forces in Adolescent Idiopathic Scoliosis With and Without Carrying Loads: A Musculoskeletal Modeling Study

The pathomechanisms of curve progression in adolescent idiopathic scoliosis (AIS) remain poorly understood and biomechanical data are limited. A deeper insight into spinal loading could provide valuable information toward the improvement of current treatment strategies. This work therefore aimed at using subject-specific musculoskeletal full-body models of patients with AIS to predict segmental compressive forces around the curve apex and to investigate how these forces are affected by simulated load carrying. Models were created based on spatially calibrated biplanar radiographic images from 24 patients with mild to moderate AIS and validated by comparing predictions of paravertebral muscle activity with reported values from in vivo studies. Spinal compressive forces were predicted during unloaded upright standing as well as standing with external loads of 10, 15, and 20% of body weight (BW) applied to the scapulae to simulate carrying a backpack in the regular way on the back as well as in front of the body and over the shoulder on the concave and convex sides of the scoliotic curve. The predicted muscle activities around the curve apex were higher on the convex side for the erector spinae (ES) and multifidi (MF) muscles, which was comparable to the EMG-based in vivo measurements from the literature. In terms of spinal loading, the implementation of spinal deformity resulted in a 10% increase of compressive force at the curve apex during unloaded upright standing. Apical compressive forces further increased by 50–62% for a simulated 10% BW load and by 77–94% and 103–128% for 15% and 20% BW loads, respectively. Moreover, load-dependent compressive force increases were the lowest in the regular backpack and the highest in the frontpack and convex conditions, with concave side-carrying forces in between. The predictions indicated increased segmental compressive forces during unloaded upright standing, which could be ascribed to the scoliotic deformation. When carrying loads, compressive forces further increased depending on the carrying mode and the weight of the load. These results can be used as a basis for further studies investigating segmental loading in AIS patients during functional activities. Models can thereby be created using the same approach as proposed in this study.

Postural control in girls with adolescent idiopathic scoliosis while wearing a Chêneau brace or performing active self-correction: a pilot study

Background

It is known that adolescent idiopathic scoliosis (AIS) is often accompanied by balance deficits. This reciprocal relationship must be taken into account when prescribing new therapeutic modalities because these may differently affect postural control, interacting with therapy and influencing its results.

Objective

The purpose was to compare postural control in girls with AIS while wearing the Chêneau brace (BRA) or performing active self-correction (ASC) with their postural control in a quiet comfortable stance.

Methods

Nine subjects were evaluated on a force plate in three series of two 20-s quiet standing trials with eyes open or closed; three blocks were randomly arranged: normal quiet stance (QST), quiet stance with BRA, and quiet stance with ASC. On the basis of centre-of-pressure (COP) recordings, the spatial and temporal COP parameters were computed.

Results and Discussion

Performing ASC was associated with a significant backward excursion of the COP mean position with eyes open and closed (ES = 0.56 and 0.65, respectively; p < 0.05). This excursion was accompanied by an increase in the COP fractal dimension (ES = 1.05 and 0.98; p < 0.05) and frequency (ES = 0.78; p = 0.10 and ES = 1.14; p < 0.05) in the mediolateral (ML) plane. Finally, both therapeutic modalities decreased COP sample entropy with eyes closed in the anteroposterior (AP) plane. Wearing BRA resulted in ES = 1.45 (p < 0.05) while performing ASC in ES = 0.76 (p = 0.13).

Conclusion

The observed changes in the fractal dimension (complexity) and frequency caused by ASC account for better adaptability of patients to environmental demands and for their adequate resources of available postural strategies in the ML plane. These changes in sway structure were accompanied by a significant (around 25 mm) backward excursion of the mean COP position. However, this improvement was achieved at the cost of lower automaticity, i.e. higher attentional involvement in postural control in the AP plane. Wearing BRA may have an undesirable effect on some aspects of body balance.

Effects of backpack and double pack loads on postural stability

Measurement of postural stability is crucial for identifying predictors of performance, determining the efficacy of physical training and rehabilitation techniques and evaluating and preventing injuries, particularly for heavy load carriage in hikers, mountain search and rescue personnel and soldiers. This study investigated the effect of load distribution on postural stability in an upright stance using backpack and double pack loads under conflicting or impaired somatosensory, visual and vestibular conditions. The sensory organisation tests were conducted on 20 young adults before and after a 10-min level walking exercise. Young adults' ability to use inputs from somatosensory and visual systems to maintain postural stability was significantly reduced following a 10-min walking exercise with a heavy backpack (30% of body weight), whereas no significant changes were observed for double pack carriage. Thus, the distribution of heavy loads to the front and back provides superior balance control compared with back-only loading. Practitioner summary: This study investigated the effects of heavy (30% of body weight) load distribution on postural stability after a 10-min walking exercise. Backpack carriage significantly reduced postural stability, whereas there was no significant effect under double pack loads. Distribution of heavy loads on the front-and-back is desirable for superior balance control.

Effects of asymmetric loading on lateral spinal curvature in young adults with scoliosis: A preliminary study

BACKGROUND

Usual guidelines recommend symmetric load carriage over asymmetric load carriage. Whether this recommendation is valid for subjects with asymmetric body alignment, such as those with scoliosis, remains unclear. Scoliosis is both a subject-dependent and time-variant condition. Interventions are generally employed to prevent the abnormal spinal curvature from progressing.

OBJECTIVES

To investigate the effects of an asymmetric load carriage on lateral spinal deformity in participant with scoliosis.

STUDY DESIGN

Repeated measure and single-case experimental designs Methods: Photogrammetry was employed to measure the scoliotic curvature changes in thoracic and lumbar regions without a load (0%) and with a single-strap cross-chest bag loaded at 2.5%, 5%, 7.5%, 10% and 12.5% of body weight. Statistical tests and programming models were adopted to determine the loading conditions (placement and weight of the bag) with optimal and minimal corrections of the affected and unaffected scoliotic spinal regions, respectively.

RESULTS

Significant short-term postural correction of scoliosis was achieved through applying an asymmetric load on the ipsilateral shoulder relative to the apex location of the major scoliotic curve.

CONCLUSION

A subject-specific optimal loading configuration was determined using a programming model. The results suggest that the application of a properly controlled asymmetric load carriage might be possible for reducing scoliotic spinal curvature. Further study of the long-term effects of subject-specific optimal asymmetric load carriage on scoliotic spinal curvatures is warranted. Clinical relevance Short-term reduction of scoliotic spinal curvatures under asymmetric load carriage was demonstrated. Thoracic curvatures could be reduced when asymmetric loading was applied on the ipsilateral shoulder relative to the scoliotic apex. Multiobjective programming was applied to determine the optimal weight of asymmetric load for participant with scoliosis.

Does postural stability differ between adolescents with idiopathic scoliosis and typically developed? A systematic literature review and meta-analysis

BACKGROUND

Postural stability deficits have been proposed to influence the onset and progression of adolescent idiopathic scoliosis (AIS). This study aimed to systematically identify, critically evaluate and meta-analyse studies assessing postural stability during unperturbed stance with posturography in AIS compared to typically developed adolescents.

METHODS

Studies from four electronic databases (PubMed, Scopus, CINAHL, PEDro) were searched and case-control methodological quality assessed using a risk-of-bias assessment tool and a posturography methodological quality checklist. Pooled data regarding centre of pressure (COP) parameters such as sway area, Mediolateral (ML) and Anteroposterior (AP) position and range were compared for AIS and typically developed adolescents using Cohen's d effect size (ES) and homogeneity estimates.

RESULTS

Eighteen studies for quality analysis and 9 of these for meta-analysis were identified from 971 records. Risk-of-bias assessment identified 6 high, 10 moderate and 2 low risk-of-bias studies. The posturography methodological quality checklist identified 4 low, 7 moderate and 7 high-quality studies. Meta-analysis was performed for sway area whereas ML and AP are presented in three different meta-analyses due to divergent measurement units used in the studies: ML position 1 (MLP1), ML position 2 (MLP2) and ML range (MLR); AP position 1 (APP1), AP position 2 (APP2) and AP range (APR). Cohen's d showed a medium ES difference in sway area 0.65, 95% CI (0.49-0.63), whereas ML showed no (MLP1, MLP2) and large (MLR) ES differences; MLP1 0.15, 95% CI (0.08-0.22); MLP2 0.14, 95% CI (0.08-0.19); and MLR 0.94, 95% CI (0.83-1.04). Cohen's d for AP showed small ES (APP1) and large ES difference (APP2 and APR); APP1 0.43, 95% CI (0.31-0.54); APP2 0.85, 95% CI (0.72-0.97); and APR 0.98, 95% CI (0.87-1.09). Cochran's Q and Higgins I2 showed homogeneity between studies.

CONCLUSIONS

There is moderate quality evidence for decreased postural stability in AIS measured as COP parameters sway area, ML and AP range with a positional shift posteriorly in the sagittal plane. The findings support studying postural stability in early stage AIS and also prospectively identify cause and effect of the curvature as well as effectiveness of postural control interventions in the prevention of scoliosis progression.

Analysis of sensory system aspects of postural stability during quiet standing in adolescent idiopathic scoliosis patients

Background

The aim of this study was to quantitatively analyze quite standing postural stability of adolescent idiopathic scoliosis (AIS) patients in respect to three sensory systems (visual, vestibular, and somatosensory).

Method

In this study, we analyzed the anterior-posterior center of pressure (CoP) signal using discrete wavelet transform (DWT) between AIS patients (n = 32) and normal controls (n = 25) during quiet standing.

Result

The energy rate (∆E_EYE%) of the CoP signal was significantly higher in the AIS group than that in the control group at levels corresponding to vestibular and somatosensory systems (p < 0.01).

Conclusions

This implies that AIS patients use strategies to compensate for possible head position changes and spinal asymmetry caused by morphological deformations of the spine through vestibular and somatosensory systems. This could be interpreted that such compensation could help them maintain postural stability during quiet standing. The interpretation of CoP signal during quiet standing in AIS patients will improve our understanding of changes in physical exercise ability due to morphological deformity of the spine. This result is useful for evaluating postural stability before and after treatments (spinal fusion, bracing, rehabilitation, and so on).

Postural balance and neck angle changes in school children while carrying a traditional backpack versus a double-sided bag

Study aim: This study compared the body balance and neck angle differences in children when carrying a traditional backpack versus a double-sided bag. Material and methods: By using the Biodex balance system and a three dimensional motion analysis system, the postural bal­ance and neck angles were assessed in 33 school children while carrying a traditional backpack or a double-sided bag, weigh­ing 15% of body weight. Results: The overall and anteroposterior stability indices were significantly higher when carrying a traditional backpack com­pared to no load and a double-sided bag (p < 0.05). The mediolateral stability index was significantly higher when carrying the traditional backpack and the double-sided bag compared to no load (p < 0.05). The craniohorizontal angle was significantly greater, and the craniovertebral angle and sagittal shoulder posture were significantly lesser when carrying the traditional back­pack compared to no load and the double-sided bag conditions (p < 0.05). Conclusion: Carrying the double-sided bag restores the body balance and head posture to a condition that is similar to the no load condition.

Destabilization of the Upright Posture Through Elevation of the Center of Mass

The inverted pendulum model predicts that the major challenge for neural control of the upright posture is the inherent instability of the body due to the center of mass (COM) being above the base of support (BOS). If so, even slight elevation of the COM may substantially destabilize posture. The destabilizing effect of heavy load positioned above the COM has been demonstrated. We examined sensitivity of posture to light (1-5% of body weight) load by placing weights on the shoulders and assessing functional reach distance in the forward, right, and left directions and postural sway during quiet stance. At each load level, the quiet stance task was tested with and without vision. The 1% of body weight load significantly shortened reach distance in the forward direction. It also increased postural sway. Interestingly, additional weight did not result in further deficits. The results support high sensitivity of postural stability to COM elevation that increases the challenge for neural control of posture and that can potentially be used for early detection of declines in postural stability.

Additional helmet and pack loading reduce situational awareness during the establishment of marksmanship posture

The pickup of visual information is critical for controlling movement and maintaining situational awareness in dangerous situations. Altered coordination while wearing protective equipment may impact the likelihood of injury or death. This investigation examined the consequences of load magnitude and distribution on situational awareness, segmental coordination and head gaze in several protective equipment ensembles. Twelve soldiers stepped down onto force plates and were instructed to quickly and accurately identify visual information while establishing marksmanship posture in protective equipment. Time to discriminate visual information was extended when additional pack and helmet loads were added, with the small increase in helmet load having the largest effect. Greater head-leading and in-phase trunk-head coordination were found with lighter pack loads, while trunk-leading coordination increased and head gaze dynamics were more disrupted in heavier pack loads. Additional armour load in the vest had no consequences for Time to discriminate, coordination or head dynamics. This suggests that the addition of head borne load be carefully considered when integrating new technology and that up-armouring does not necessarily have negative consequences for marksmanship performance. Practitioner Summary: Understanding the trade-space between protection and reductions in task performance continue to challenge those developing personal protective equipment. These methods provide an approach that can help optimise equipment design and loading techniques by quantifying changes in task performance and the emergent coordination dynamics that underlie that performance.

Postural habits and weight of backpacks of Portuguese adolescents: Are they associated with scoliosis and low back pain?

BACKGROUND

The adoption of incorrect postures or carrying overweight backpacks may contribute to the development of musculoskeletal disorders in school children.

OBJECTIVE

This study evaluated the weight of backpacks and the postural habits adopted in schools by Portuguese adolescents, and their association with scoliosis and low back pain (LBP).

METHOD

The sample comprised 966 Portuguese students, aged between 10 and 16 years. The instruments included a questionnaire to characterize the presence of LBP and the postural habits adopted by students, the weighing of backpacks and a scoliometer to evaluate scoliosis.

RESULTS

No association was observed between assuming incorrect postures and carrying overweight backpacks, in students with scoliosis. Students who adopted incorrect sitting postures had 1.77 times the risk (95% CI: 1.32-2.36; p < 0.001) of developing LBP; those positioned incorrectly whilst watching TV and playing games had 1.44 times the risk (95% CI: 1.08-1.90; p = 0.012) of developing LBP; and those standing incorrectly had 2.39 the risk (95% CI: 1.52-3.78; p < 0.001) of developing LBP.

CONCLUSIONS

The results revealed that students who sat with the spine positioned wrongly, as well as those who were standing incorrectly, were more likely to present with LBP.

Multi-objective analysis for assessing simultaneous changes in regional spinal curvatures under backpack carriage in young adults

Change in sagittal spinal curvature from the neutral upright stance is an important measure of the heaviness and correctness of backpack use. As current recommendations, with respect to spinal profile, of backpack load thresholds were based on the significant curvature change in individual spinal region only, this study investigated the most critical backpack load by assessing simultaneously the spinal curvature changes along the whole spine. A motion analysis system was used to measure the curvature changes in cervical, upper thoracic, lower thoracic and lumbar regions with backpack load at 0, 5, 10, 15 and 20% of body weight. A multi-objective goal programming model was adopted to determine the global critical load of maximum curvature change of the whole spine in accordance with the maximum curvature changes of the four spinal regions. Results suggested that the most critical backpack load was 13% of body weight for healthy male college students. Practitioner Summary: As current recommendations of backpack load thresholds were based on the significant curvature change in individual spinal region only, this study investigated the backpack load by considering simultaneously the spinal curvature changes along the whole spine. The recommendation, in terms of the global critical load, was 13% of body weight for healthy male college students.

The influence of thermoplastic thoraco lumbo sacral orthoses on standing balance in subjects with idiopathic scoliosis

BACKGROUND

Idiopathic scoliosis patients have postural equilibrium problems.

OBJECTIVE

The objective of this study was to assess postural control in subjects with idiopathic scoliosis following a 4-month intervention in an unbraced position.

STUDY DESIGN

Quasi-experimental.

METHODS

Eight healthy girls and eight girls with idiopathic scoliosis took part. A Kistler force platform was used with a frequency of 100 Hz for recording data. The center of pressure was recorded in different positions out of brace for scoliosis and healthy subjects. Test conditions were single limb and double limb stance, with eyes open and closed, and foam and rigid surfaces.

RESULTS

The data reflected a weak balance of idiopathic scoliosis subjects compared to healthy subjects. After 1 and 4 months of wearing the brace, center of pressure and center of gravity sway increased in the majority of the tests, although there were no significant differences in any of the test conditions (p > 0.05). While the center of pressure sway in medio-lateral direction decreased after 4 months of wearing a brace, in other variables center of pressure and center of gravity sway increased.

CONCLUSION

Idiopathic scoliosis patients have weak balance in comparison to healthy subjects. In addition, following a period of 4 months of wearing a brace, balance parameters in the scoliosis subjects did not improve. The results show that we need more follow-up of orthoses wearing in idiopathic scoliosis subjects and suggest more studies at least 1-year follow-up to identify the efficiency of brace wear on balance.

CLINICAL RELEVANCE

Scoliosis can alter postural stability and balance performance during quiet standing. Spinal deformity can alter a subject's ability to compensate for postural changes and cause gait deviations. This study investigated balance differences between the healthy and idiopathic scoliosis patients and the results of thoraco lumbo sacral orthosis brace wear. It might provide some new insight into the conservative treatment of idiopathic scoliosis patients for clinicians and researchers.

Postural Rehabilitation for Adolescent Idiopathic Scoliosis during Growth

Long-term follow-up of untreated patients with adolescent idiopathic scoliosis (AIS) indicates that, with the exception of some extremely severe cases, AIS does not have a significant impact on quality of life and does not result in dire consequences. In view of the relatively benign nature of AIS and the long-term complications of surgery, the indications for treatment should be reviewed. Furthermore, recent studies have shown that scoliosis-specific exercises focusing on postural rehabilitation can positively influence the spinal curvatures in growing adolescents. Experiential postural re-education is a conservative, non-invasive approach, and its role in the management of AIS warrants further study. This article reviews current evidence for the inclusion of various forms of postural reeducation in the management of AIS. Recent comprehensive reviews have been researched including a manual and PubMed search for evidence regarding the effectiveness of physical/postural re-education/physiotherapy programs in growing AIS patients. This search revealed that there were few studies on the application of postural re-education in the management of AIS. These studies revealed that postural re-education in the form of exercise rehabilitation programs may have a positive influence on scoliosis; however, the various programs were difficult to compare. More research is necessary. There is at present Level 1 evidence for the effectiveness of Schroth scoliosis exercises in the management of AIS. Whether this evidence can be extrapolated to include other forms of scoliosis- pattern-specific exercises requires further investigation. Because corrective postures theoretically reduce the asymmetric loading of the spinal deformities and reverse the vicious cycle of spinal curvature progression, their integration into AIS programs may be beneficial and should be further examined.

Traditional posterior load carriage: effects of load mass and size on torso kinematics, kinetics, muscle activity and movement stability

Traditional posterior load carriage (PLC), done without the use of an assistive device (e.g., backpack), has been associated with low back pain (LBP) development. This study evaluated the effects of important task demands, related to load mass and size, on potential mechanisms linking traditional PLC with LBP. Nine healthy participants completed PLC tasks with three load masses (20%, 35% and 50% of individual body mass) and three load sizes (small, medium and large). Torso kinematics, kinetics, muscle activity and slip risk were evaluated during PLC on a walkway, and torso movement stability was quantified during PLC on a treadmill. Increasing load mass caused increased torso flexion, L5/S1 flexion moment, abdominal muscle activity and torso movement stability in the frontal plane. Increasing load size also caused higher torso flexion, peak torso angular velocity and acceleration, and abdominal muscle activity. Complex interactive effects of load mass and size were found on paraspinal muscle activity and slip risk. Specific task demands, related to load mass and size, may thus influence the risk of LBP during PLC.

PRACTITIONER SUMMARY

This study examined the effects of load mass and size on low back pain (LBP) risk using intermediary measures derived from torso kinematics, kinetics and muscle activity. Our current findings, along with earlier work, suggest that load mass and size can influence LBP risk, and that use of smaller and light loads may be beneficial during PLC.

The effects of backpack loads and spinal stabilization exercises on the dynamic foot pressure of elementary school children with idiopathic scoliosis

[Purpose] The purpose of this study was to measure and observe the changes in dynamic plantar pressures when school children carried specific bag loads, and to determine whether improved physical balance after an eight-week spinal stabilization exercise program can influences plantar pressures. [Subjects] The subjects were 10 school students with Cobb angles of 10° or greater. [Methods] Gait View Pro 1.0 (Alfoots, Korea) was were based on to measure the pressure of the participants' feet. Spinal stabilization exercises used TOGU Multi-roll Functional (TOGU, Germany) training. Dynamic plantar pressures were measured with bag loads of 0% no bag and 15% of subjects' body weight. The independent t test was performed to analyze changes in plantar pressures. [Results] The plantar pressure measurements of bag load of 0% of subjects' body weight before and after the spinal stabilization exercise program were not significantly different, but those of two foot areas with a 15% load were statistically significant (mt5, 67.32±24.25 and 51.77±25.52 kPa; lat heel, 126.00±20.46 and 102.08±23.87 kPa). [Conclusion] After performance of the spinal stabilization exercises subjects' overall plantar pressures were reduced, which may suggest that physical balance improved.

The effect of hip belt use and load placement in a backpack on postural stability and perceived exertion: a within-subjects trial

The purpose of this study was to assess the effects of hip belt use and load placement in a backpack on perceived exertion and postural stability. Thirty participants were instructed to stand on a force plate and walk along a designated route under five conditions: unloaded, high-load placement, low-load placement, hip belt on and hip belt off. The average velocity and sway area from the force plate were measured. Participants also rated their perceived stability and exertion. Compared to the unloaded condition, all loaded conditions significantly increased average velocity, sway area, perceived stability and exertion. Hip belt use did not affect average velocity and sway area; however, participants reported higher levels of stability and lower levels of exertion with hip belt use. Load placement did not affect average velocity, sway area, perceived stability or exertion. This study showed that wearing a backpack loaded to 20% of body weight reduced postural stability, while manipulation of load placement in a backpack did not affect subjective and objective measures of postural stability. Also, hip belt use only improved subjective measures of postural stability.

The influence of thoracolumbosacral orthoses on standing balance in patients with adolescent idiopathic scoliosis: a pilot study

BACKGROUND AND AIM

The objective of this study was to assess the effect of thoracolumbosacral orthoses (TLSOs) on antero-posterior (AP) sway, medio-lateral (ML) sway and displacement of the center of pressure (COP) during a longitudinal study in patients with adolescent idiopathic scoliosis (AIS).

METHODS

Eight females aged between 12 and 14.5 years participated in this study. Evaluations were performed prior to the TLSO intervention as a baseline condition, after 1 month, and after 4 months of orthosis use by assessing balance when standing statically on different surfaces.

RESULTS

When standing on both lower limbs on a solid surface there were significant differences in ML sway with the eyes both open and closed, and also in A/P sway but only when standing on a solid surface with the eyes open and also when standing on a foam surface with the eyes closed with TLSO use. When standing on the dominant leg, ML sway significantly improved, but AP sway only improved with a foam base surface with the eyes open.

CONCLUSION

This study demonstrated positive effects of wearing a TLSO in improving quiet standing balance and standing on the dominant lower extremity in subjects with AIS after 4 months of brace use. Implications for Rehabilitation Due to a change in body shape such as that caused by scoliosis, human posture changes and spinal deformities affect the position of the center of support, and thus balance ability may change. AIS subjects have poor standing stability compared to a healthy matched control group. Brace wearing had positive effect in improving quiet standing balance and standing on the dominant lower extremity in subjects with AIS undergoing brace treatment after 4 months of TLSO use.

The effects of backpack load and carrying method on the balance of adolescent idiopathic scoliosis subjects

BACKGROUND CONTEXT

Concerns have been raised about the effect of backpack carrying on adolescent balance. For adolescent idiopathic scoliosis (AIS) subjects, the effect of backpack carrying method on their balance has not been determined. Our aim is to examine the effects of backpack load and carrying method on AIS subjects' balance.

STUDY DESIGN/SETTING

Paired sample matched for age and sex.

PATIENT SAMPLE

Twelve healthy adolescents matched for age and sex with 14 adolescents with mild AIS participated in this study.

OUTCOME MEASURES

A test battery including clinical examination, radiological assessment, and stabilometric measurements of the postural sways in the upright standing posture were conducted.

METHODS

Center of pressure excursions of our subjects were recorded with a stabilometric platform during the upright standing posture without a backpack and while carrying a backpack symmetrically and asymmetrically on each shoulder. For each carrying method, the backpack is loaded at 10% and 15% of body weight (BW).

RESULTS

Our results indicated that postural sways increased with increasing backpack load. These postural sways were observed when normal adolescents carried a backpack loaded with 15% BW load, whereas, for age- and sex-matched AIS subjects, these postural responses were observed for the 10% BW load. The symmetrical backpack carrying induced better balance compared with the asymmetrical one. Asymmetrical carrying on the convex side of the scoliotic curve affects AIS subjects' balance more than carrying it on the concave side.

CONCLUSIONS

Load carriage of 10% BW seems to alter AIS subjects' balance. Asymmetrical carrying should be avoided especially on the convex side of the scoliotic curve because it causes balance impairments that may increase spinal pain.

Influência de calços na orientação postural de indivíduos com escoliose idiopática

INTRODUÇÃO: A relação entre a orientação dos segmentos e os ajustes que podem ser desencadeados por calços e palmilhas em pacientes escolióticos durante a manutenção da posição ortostática é pouco conhecida. OBJETIVO: Verificar alterações estáticas e associadas com mudanças unilaterais de calços na orientação postural de indivíduos com escoliose idiopática. MATERIAIS E MÉTODOS: Grupo experimental com dez indivíduos com escoliose idiopática com curva dupla (menor 10°) e grupo controle com dez indivíduos sem escoliose (faixa etária de 13 a 24 anos). Participantes foram filmados na posição ortostática sem calço, com calço baixo (1 cm) e com calço alto (3 cm); estes foram colocados sob o pé direito e pé esquerdo dos indivíduos. Em cada condição, o participante manteve a posição estática durante 15 segundos e marcadores refletivos foram colocados em pontos anatômicos específicos. Foram calculados ângulos posturais: torácico alto; torácico médio; toracolombar e lombar e ângulos segmentares: ombro; escápula; pelve e joelho. RESULTADOS: Na condição sem calço, diferenças foram observadas entre grupos para os ângulos posturais toracolombar e lombar e para o ângulo segmentar do ombro. Com calço baixo e alto, sob o pé direito, diferença foi observada entre calços para os ângulos lombar, da pelve e do joelho. Com calço baixo e alto, sob o pé esquerdo, diferença foi observada entre grupos para o ângulo toracolombar e entre calços para os ângulos da pelve e do joelho. CONCLUSÕES: A utilização de calço promove reorientação nas regiões mais baixas da coluna e nos segmentos da pelve e do joelho. Estes resultados sugerem que nas escolioses duplas, manipulação da base de apoio modifica o alinhamento do tronco que pode provocar reorganização das estruturas e busca de um novo arranjo entre segmentos em indivíduos com escoliose idiopática.

Effect of Milwaukee brace on static and dynamic balance of female hyperkyphotic adolescents

BACKGROUND

Biomechanical factors, such as spinal deformities can result in balance control disorders.

OBJECTIVES

The purpose of this study was to examine the effect of bracing on static and dynamic balance control of hyperkyphotic female adolescents.

STUDY DESIGN

Clinical trial.

METHODS

A force platform was employed to record center of pressure (COP) parameters. Ten adolescents undergoing Milwaukee brace for hyperkyphosis and 14 normal subjects participated in the study. The COP data were collected with and without brace immediately on first day and after 120 days of continuous brace wear.

RESULTS

No significant difference was found in dynamic and static balance tests with and without brace on the first day (P > 0.05). After 120 days, the values of COP displacement in functional reach to the right and left for the hyperkyphotic adolescents when performing without brace enhanced significantly compared to the first day. The forward reach distance was not significantly different between the normal and hyperkyphotic subjects (P = 0.361); however, hyperkyphotic participants had significantly smaller reach distance in the functional reach to the right (21.88 vs. 25.56 cm) and left (17.04 vs. 21.25 cm).

CONCLUSION

It might be concluded that bracing had a possible effect on improvement of dynamic balance performance, because the subjects could reach the target in dynamic reach tests with higher displacement in sagittal plane without losing their balance control. Clinical relevance Little is known about the biomechanical aspects of brace wear in individuals with hyperkyphosis. This study investigated balance differences between the healthy and hyperkyphotic individuals, and outcomes of Milwaukee brace wear. It might provide some new insight into the conservative treatment of hyperkyphosis for clinicians and researchers.

Postural compensations and subjective complaints due to backpack loads and wear time in schoolchildren

PURPOSE

This study investigated the effects of carrying weighted backpacks of up to 20% of body weight on the posture and pain complaints of elementary-school children.

METHODS

Craniovertebral, forward trunk lean and pelvic tilt angles were measured from sagittal photographs of 62 children (8-11 years old) before and after walking while carrying backpacks containing 10%, 15%, or 20% of body weight. Pain severity after a 6-minute walk with the loaded backpack was recorded. Subjective complaints of pain were assessed using a visual analog scale after walking.

RESULTS

Repeated-measures ANOVA revealed statistically significant differences in postural angles and increased complaints of pain after walking with increased backpack loads.

CONCLUSION

These results indicate that typical backpack loads create worsening postural changes due to backpack loads and time spent carrying those loads, putting children at increased risk for injury and pain, the latter of which is a strong predictor for back pain in adulthood.

Effects of a postural education program on school backpack habits related to low back pain in children

PURPOSE

Population based studies have demonstrated that children and adolescents often complain of low back pain. A group-randomized controlled trial was carried out to investigate the effects of a postural education program on school backpack habits related to low back pain in children aged 10-12 year.

METHODS

The study sample included 137 children aged 10.7 years (SD = 0.672). Six classes from two primary schools were randomly allocated into experimental group (EG) (N = 63) or control group (CG) (N = 74). The EG received a postural education program over 6 weeks consisting of six sessions, while the CG followed the usual school curriculum. A questionnaire was fulfilled by the participants at pre-test, post-test, and 3 months after the intervention finished. The outcomes collected were: (1) try to load the minimum weight possible, (2) carry school backpack on two shoulders, (3) belief that school backpack weight does not affect to the back, and (4) the use of locker or something similar at school. A sum score was computed from the four items.

RESULTS

Single healthy items mostly improved after the intervention and remained improved after 3-month follow-up in EG, while no substantial changes were observed in the CG. Healthy backpack use habits score was significantly increased at post-test compared to baseline in the EG (P < 0.000), and remained significantly increased after 3-month, compared to baseline (P = 0.001). No significant changes were observed in the CG (P > 0.2).

CONCLUSIONS

The present study findings confirm that children are able to learn healthy backpack habits which might prevent future low back pain.

Loading rate patterns in scoliotic children during gait: the impact of the schoolbag carriage and the importance of its position

PURPOSE

Concerns have been raised regarding the effects of schoolbag carriage on adolescent schoolchildren and particularly those with a pre-existing spinal deformity. The purpose of this study was to determine the effect of school backpack loads in scoliotic and healthy school-age children during walking, in terms of peak vertical ground reaction forces and loading rates. We hypothesized that walking with a loaded backpack would have a greater effect on gait kinetics of scoliotic compared to healthy.

METHODS

Eight children with idiopathic scoliosis and eight healthy children were assessed. Kinetic data were collected using two AMTI OR6-7 force-plates, while the subjects walked freely along a 6-m walkway under three walking conditions: (1) without a schoolbag, (2) carrying a schoolbag bilaterally (over both shoulders-symmetrical load) and (3) carrying a schoolbag unilaterally (over each shoulder-asymmetrical load). Kinetic data were collected and four parameters were calculated; peak ground reaction force at the first maximum force peak (F1), time needed to reach F1 (T1), loading rate of F1 (LRF1) and total contact time (T2).

RESULTS

We found no significant differences between the scoliotic and healthy children for any of the kinetic variables examined. In addition, the position of the bag did not seem to have any effect on loading rate.

CONCLUSIONS

The results of this study indicate that in terms of kinetic parameters during normal gait, the schoolbag load (symmetrical or asymmetrical) does not have a different effect on children with mild adolescent idiopathic scoliosis compared to normal controls.

Independent effects of adding weight and inertia on balance during quiet standing

Background

Human balance during quiet standing is influenced by adding mass to the body with a backpack, with symmetrically-applied loads to the trunk, or with obesity. Adding mass to the body increases both the weight and inertia of the body, which theoretically could provide counteracting effects on body dynamics and balance. Understanding the independent effects of adding weight and inertia on balance may provide additional insight into human balance that could lead to novel advancements in balance training and rehabilitation. Therefore, the purpose of this study was to investigate the independent effects of adding weight and inertia on balance during quiet standing.

Methods

Sixteen normal-weight young adult participants stood as still as possible on a custom-built backboard apparatus under four experimental conditions: baseline, added inertia only, added weight only, and added inertia and weight.

Results

Adding inertia by itself had no measurable effect on center of pressure movement or backboard movement. Adding weight by itself increased center of pressure movement (indicated greater effort by the postural control system to stand as still as possible) and backboard movement (indicating a poorer ability of the body to stand as still as possible). Adding inertia and weight at the same time increased center of pressure movement but did not increase backboard movement compared to the baseline condition.

Conclusions

Adding inertia and adding weight had different effects on balance. Adding inertia by itself had no effect on balance. Adding weight by itself had a negative effect on balance. When adding inertia and weight at the same time, the added inertia appeared to lessen (but did not eliminate) the negative effect of adding weight on balance. These results improve our fundamental understanding of how added mass influences human balance.

The effect of school bag design and load on spinal posture during stair use by children

Thirteen male children ascending and descending stairs with loads that equalled 0%, 10%, 15% and 20% of their body weight were the subject of our research: the boys were wearing an asymmetrical single-strap athletic bag or a symmetrical double-strap backpack during our experiments with them. The maximum spinal tilt to the loading side and to the support side, and the range of spinal motions, were obtained by using a motion analysis system. Our results showed that symmetry of spinal posture was observed both when they ascended staircase with all loads and descended in a backpack. When carrying an athletic bag with 15% and 20% of their body weight while ascending the staircase, the lateral spinal tilt to the supporting side was significantly increased. We concluded that a symmetrical backpack with a load not exceeding 20% or an asymmetrical single-strap athletic bag with a load not exceeding 10% should be recommended for school children in order to promote safer staircase use. STATEMENT OF RELEVANCE: Children carrying heavy school bags may develop spinal problems. This study suggested that when they are using stairs, a symmetrical backpack with a load within 20% body weight is acceptable for them. When they are carrying an asymmetrical single-strap athletic bag, the bag's weight should not exceed 10% of the body weight in order to avoid excessive spinal tilt.

Reliability of a quantitative clinical posture assessment tool among persons with idiopathic scoliosis

OBJECTIVE

To determine overall, test-retest and inter-rater reliability of posture indices among persons with idiopathic scoliosis.

DESIGN

A reliability study using two raters and two test sessions.

SETTING

Tertiary care paediatric centre.

PARTICIPANTS

Seventy participants aged between 10 and 20 years with different types of idiopathic scoliosis (Cobb angle 15 to 60°) were recruited from the scoliosis clinic.

MAIN OUTCOME MEASURES

Based on the XY co-ordinates of natural reference points (e.g., eyes) as well as markers placed on several anatomical landmarks, 32 angular and linear posture indices taken from digital photographs in the standing position were calculated from a specially developed software program. Generalisability theory served to estimate the reliability and standard error of measurement (SEM) for the overall, test-retest and inter-rater designs. Bland and Altman's method was also used to document agreement between sessions and raters.

RESULTS

In the random design, dependability coefficients demonstrated a moderate level of reliability for six posture indices (ϕ=0.51 to 0.72) and a good level of reliability for 26 posture indices out of 32 (ϕ≥0.79). Error attributable to marker placement was negligible for most indices. Limits of agreement and SEM values were larger for shoulder protraction, trunk list, Q angle, cervical lordosis and scoliosis angles. The most reproducible indices were waist angles and knee valgus and varus.

CONCLUSIONS

Posture can be assessed in a global fashion from photographs in persons with idiopathic scoliosis. Despite the good reliability of marker placement, other studies are needed to minimise measurement errors in order to provide a suitable tool for monitoring change in posture over time.

Idiopathic scoliosis: relations between the Cobb angle and the dynamical strategies when sitting on a seesaw

The aim of this study was to determine the influence of the severity of the spinal curve on the postural regulation when self-imposed disturbances occur in a seated position in anteroposterior (AP) and mediolateral (ML) orientations. Twelve female adolescents with a right thoracic scoliosis (Cobb = 30.4° ± 9.7) were included in this study. The ground reaction forces (GRF) were studied while the subjects were maintaining their sitting on a seesaw (ML or AP destabilisation). Five conditions were tested: eyes open; with additional loads placed onto the subject's right or left shoulder; or onto the subject's right or left pelvis. We tested the correlation between the Cobb angle and the postural parameters (index of performance and GRF variability) for each condition. When the destabilisation was AP, the Cobb angle was significantly correlated with GRF variability and anterior and concavity index of performance. Two conditions showed higher correlations: stabilisation with the concavity pelvis load (GRF variability) and the open eyes (index of performance). In contrast, whatever the condition tested was, no link was found when the destabilisations were applied in ML direction. The destabilisation in a seated position highlights the influence of the curve severity on the postural organisation. In seated position, the postural control strategies specific to the scoliotic patients were always correlated by severity of curve, especially when the destabilisation is applied in AP directions. This study showed that the unstable seating position can be considered as a pertinent paradigm to help finding a postural clinical index for adolescent idiopathic scoliosis.

Validity of a quantitative clinical measurement tool of trunk posture in idiopathic scoliosis

STUDY DESIGN

Concurrent validity between postural indices obtained from digital photographs (two-dimensional [2D]), surface topography imaging (three-dimensional [3D]), and radiographs.

OBJECTIVE

To assess the validity of a quantitative clinical postural assessment tool of the trunk based on photographs (2D) as compared to a surface topography system (3D) as well as indices calculated from radiographs.

SUMMARY OF BACKGROUND DATA

To monitor progression of scoliosis or change in posture over time in young persons with idiopathic scoliosis (IS), noninvasive and nonionizing methods are recommended. In a clinical setting, posture can be quite easily assessed by calculating key postural indices from photographs.

METHODS

Quantitative postural indices of 70 subjects aged 10 to 20 years old with IS (Cobb angle, 15 degrees -60 degrees) were measured from photographs and from 3D trunk surface images taken in the standing position. Shoulder, scapula, trunk list, pelvis, scoliosis, and waist angles indices were calculated with specially designed software. Frontal and sagittal Cobb angles and trunk list were also calculated on radiographs. The Pearson correlation coefficients (r) was used to estimate concurrent validity of the 2D clinical postural tool of the trunk with indices extracted from the 3D system and with those obtained from radiographs.

RESULTS

The correlation between 2D and 3D indices was good to excellent for shoulder, pelvis, trunk list, and thoracic scoliosis (0.81>r<0.97; P<0.01) but fair to moderate for thoracic kyphosis, lumbar lordosis, and thoracolumbar or lumbar scoliosis (0.30>r<0.56; P<0.05). The correlation between 2D and radiograph spinal indices was fair to good (-0.33 to -0.80 with Cobb angles and 0.76 for trunk list; P<0.05).

CONCLUSION

This tool will facilitate clinical practice by monitoring trunk posture among persons with IS. Further, it may contribute to a reduction in the use of radiographs to monitor scoliosis progression.

Comparisons of the gait parameters of young Korean women carrying a single-strap bag

This study compared the gait parameters of young women using various methods to carry a single-strap bag during walking. Twenty-one Korean healthy women walked on a GAITRite-instrumented carpet at a self-paced speed for each of the four following conditions in random order: no bag, carrying a bag over the shoulder, carrying a bag on the forearm, and carrying a bag by the hand on the dominant (right) side. There was a significant reduction in the stride length for the contralateral leg when carrying a bag on the forearm, a significant decrease in the heel-to-heel base of support, and a significant increase in the toe angle on the ipsilateral leg when carrying a bag by hand. The results of our study suggest that, among the asymmetric bag-carrying methods preferred by Korean young women during walking, the "over-the-shoulder" method has the least effect on gait parameters relative to not carrying a bag.

Postural sway modifications induced by backpack carriage in primary school children: a case study in Italy

The aim of this investigation is to assess modifications in sway parameters introduced by backpack carriage in Italian primary school children (6-10 years old, n = 447). Two 30-s trials (without and with backpack) were performed directly at a school on a regular school day to collect data on sway area, centre of pressure path length and maximum displacement range in antero-posterior and medio-lateral directions. The results show a significant load-induced increase in all sway parameters and the existence of a linear relationship between sway area and backpack weight. Since postural sway represents an effective indicator of balance abilities, the alterations observed suggest that backpack carriage originates balance impairment and thus may increase the risk of unintentional falls in children. STATEMENT OF RELEVANCE: Loss of balance is among the primary causes of unintentional falls and postural sway represents an effective indicator of balance abilities. In this study, sway parameters were assessed in primary school children wearing backpacks. The differences that were observed show that backpack carriage potentially increases the risk of falls.

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.

The effect of backpacks on the lumbar spine in children: a standing magnetic resonance imaging study

STUDY DESIGN

This study is a repeated measures design to measure the lumbar spine response to typical school backpack loads in healthy children. The lumbar spine in this setting was measured for the first time by an upright magnetic resonance imaging (MRI) scanner.

OBJECTIVE

The purpose of this study is to measure the lumbar spine response to typical school backpack loads in healthy children. We hypothesize that backpack loads significantly increase disc compression and lumbar curvature.

SUMMARY OF BACKGROUND DATA

Children commonly carry school backpacks of 10% to 22% bodyweight. Despite growing concern among parents about safety, there are no imaging studies which describe the effect of backpack loads on the spine in children.

METHODS

Three boys and 5 girls, age 11 +/- 2 years (mean +/- SD) underwent T2 weighted sagittal and coronal MRI scans of the lumbar spine while standing. Scans were repeated with 4, 8, and 12 kg backpack loads, which represented approximately 10%, 20%, and 30% body weight for our sample. Main outcome measures were disc compression, defined as post- minus preloading disc height, and lumbar asymmetry, defined as the coronal Cobb angle between the superior endplates of S1 and L1.

RESULTS

Increasing backpack loads significantly compressed lumbar disc heights measured in the midline sagittal plane (P < 0.05, repeated-measures analysis of variance [ANOVA]). Lumbar asymmetry was: 2.23 degrees +/- 1.07 degrees standing, 5.46 degrees +/- 2.50 degrees with 4 kg, 9.18 degrees +/- 2.25 degrees with 8 kg, and 5.68 degrees +/- 1.76 degrees with 12 kg (mean +/- SE). Backpack loads significantly increased lumbar asymmetry (P < 0.03, one-way ANOVA). Four of the 8 subjects had Cobb angles greater than 10 degrees during 8-kg backpack loads. Using a visual-analogue scale to rate their pain (0-no pain, 10-worst pain imaginable), subjects reported significant increases in back pain associated with backpack loads of 4, 8, and 12 kg (P < 0.001, 1-way ANOVA).

CONCLUSION

Backpack loads are responsible for a significant amount of back pain in children, which in part, may be due to changes in lumbar disc height or curvature. This is the first upright MRI study to document reduced disc height and greater lumbar asymmetry for common backpack loads in children.

Short-term effects of backpack load placement on spine deformation and repositioning error in schoolchildren

Backpack weight of 10-15% has been recommended as an acceptable limit for schoolchildren. However, there is still no clear guideline regarding where the backpack centre of gravity (CG) should be positioned. The changes of spinal curvature and repositioning error when carrying a backpack loaded at 15% of body weight at different CG locations (anterior or posterior at T7, T12 or L3) in schoolchildren were analysed. Both spinal curvature and repositioning error were found to be affected by backpack anterior-posterior position and CG level. A relatively smaller change was observed during anterior carriage with the least change when the backpack CG was positioned at T12. The results also suggested that alternative carriage by changing the backpack position occasionally between anterior and posterior positions might help to relieve the effects of backpack on spine. However, future study is recommended to further substantiate the beneficial effects of alternative carriage on children. STATEMENT OF RELEVANCE: Anteriorly carried backpack with centre of gravity positioned at T12 was shown to induce relatively less effect on spinal deformation and repositioning error in schoolchildren. Changing backpack carriage position occasionally may help to relieve its effects on spinal deformation. The findings are important for ergonomic schoolbag design and determining a proper load carriage method.

Changes in postural sway as a consequence of wearing a military backpack

Military personnel are often required to carry all of their personal supplies and equipment for long distances during both training and combat situations, creating many biomechanical and postural challenges for these individuals. In addition to other problems such as generalized fatigue and the development of stress fractures, significant external loads may also affect a soldier's postural sway. The purpose of this study was to assess changes in postural sway as a consequence of wearing a military backpack in females. Forty-three female subjects between the ages of 18 and 25 volunteered to participate. There were two conditions: unloaded and while wearing an 18.1 kg military backpack. Each subject stood with two feet on a force platform for 30s under both conditions while center of pressure (COP) data were collected. COP path length increased 64%, medial-lateral excursion increased 131%, anterior-posterior excursion increased 54%, and COP area increased 229% with addition of the backpack (p<0.0001 for all of these measures). These data show that wearing 18.1 kg of external weight in a military backpack increases the postural sway of females, which may in turn increase the likelihood of falls and injury.

Dynamical asymmetries in idiopathic scoliosis during forward and lateral initiation step

Adolescent idiopathic scoliosis (AIS) is characterized by morphological trunk modifications acting on body mass distribution. Some specific biomechanical strategies during postural regulation have been reported. Given that spinal deformity is three-dimensional, some strategy analysis resulting from different stepping directions should lead to a better understanding of the dynamic adaptation of behaviour. The aim of this study is to identify dynamic strategies of AIS patients stepping in lateral and forward directions. Ten AIS patients with a right thoracic curve and 15 controlled volunteers have been tested. Ground reaction forces (GRF) have been recorded for right-limb stepping and for left-limb stepping associated to forward and lateral directions. Force amplitudes, corresponding occurrences, impulses of stepping phases and an asymmetry index have been computed. Asymmetry and variability increased in the AIS group, compared to the control group, whatever the stepping direction is. Asymmetry for AIS patients systematically provides an increased left initiation GRF compared to a right initiation. Nevertheless, for both groups, lateral initiation shows the largest asymmetry index reported for a forward initiation. More precisely, adaptive dynamic strategies for the AIS group have been characterized by an asymmetry between right and left limbs for lateral and forward initiation. These results can be explained by the influence of scoliosis pathology on dynamic movements due to spinal deformity. A right thoracic curve leads to an extra weight on the limb, which needs to be moved; consequently, stepping initiation with the right limb was more challenging for patients than stepping with the left limb. For the AIS group, the observed variability can also depend on the ontogenesis of adaptive strategies. Lateral step initiation has to be considered as the most relevant paradigm to study scoliosis and may also serve as a clinical basis for treatment to analyse the dynamic postural control and asymmetry strategies of the scoliosis patient.

Effects of external loads on balance control during upright stance: experimental results and model-based predictions

The purpose of this study was to identify the effects of external loads on balance control during upright stance, and to examine the ability of a new balance control model to predict these effects. External loads were applied to 12 young, healthy participants, and effects on balance control were characterized by center-of-pressure (COP) based measures. Several loading conditions were studied, involving combinations of load mass (10% and 20% of individual body mass) and height (at or 15% of stature above the whole-body COM). A balance control model based on an optimal control strategy was used to predict COP time series. It was assumed that a given individual would adopt the same neural optimal control mechanisms, identified in a no-load condition, under diverse external loading conditions. With the application of external loads, COP mean velocity in the anterior-posterior direction and RMS distance in the medial-lateral direction increased 8.1% and 10.4%, respectively. Predicted COP mean velocity and RMS distance in the anterior-posterior direction also increased with external loading, by 11.1% and 2.9%, respectively. Both experimental COP data and model-based predictions provided the same general conclusion, that application of larger external loads and loads more superior to the whole body center of mass lead to less effective postural control and perhaps a greater risk of loss of balance or falls. Thus, it can be concluded that the assumption about consistency in control mechanisms was partially supported, and it is the mechanical changes induced by external loads that primarily affect balance control.

Idiopathic-type scoliosis is not exclusive to bipedalism

Human familial/idiopathic-type scoliosis (IS) is a complex genetic disorder for which the cause is unknown. The curve phenotype characteristically demonstrates pronounced morphological and developmental variability that is likely a consequence of biomechanical, environmental, and genetic differences between individuals. In addition, risk factors that affect the propensity for curves to progress to severity are unknown. Progress in understanding the fundamental biology of idiopathic-type scoliosis has been limited by the lack of a genetic/developmental animal model. Prior to consideration of teleosts, developmental idiopathic-type scoliosis has been considered to be exclusive to humans. Consequently, there is the notion that the syndrome is a result of bipedalism, and many studies try to explain the deformity from this anthrocentric viewpoint. This perspective has been reinforced by the choice of animals used for study, in that chickens and bipedal rats and mice demonstrate idiopathic-type curvature when made melatonin-deficient, but quadrupedal animals do not. Overlooked is the fact that teleosts also demonstrate similar curvature when made melatonin-deficient. Our characterization of the guppy curveback has demonstrated that non-induced idiopathic-type curvature is not exclusive to humans, nor bipedalism. We hypothesize that unique morphological, developmental and genetic parallels between the human and guppy syndromes are due to common molecular pathways involved in the etiopathogenesis of both phenotypes. We explore established gene conservation between human and teleost genomes that are in pathways hypothesized to be involved in the IS syndrome. We present non-induced vertebral wedging as a unique shared feature in IS and curveback that suggests a similar interaction between a molecular phenotype on the level of the vertebral anatomy, and biomechanics. We propose that rather than bipedalism per se, expression of idiopathic-type scoliosis is dependent on normal spinal loading applied along the cranio-caudal axis that interacts with an unknown factor causing the primary curve. In this regard, a comparative biological approach using a simplified teleost model will promote discovery of basic processes integral to idiopathic-type scoliosis in teleosts and humans, and highlight human-specific aspects of the deformity.