Gait in adolescent idiopathic scoliosis: energy cost analysis

Wearable accelerometers reveal objective assessment of walking symmetry and regularity in idiopathic scoliosis patients

Background

Scoliosis is a multifaceted three-dimensional deformity that significantly affects patients' balance function and walking process. While existing research primarily focuses on spatial and temporal parameters of walking and trunk/pelvic kinematics asymmetry, there remains controversy regarding the symmetry and regularity of bilateral lower limb gait. This study aims to investigate the symmetry and regularity of bilateral lower limb gait and examine the balance control strategy of the head during walking in patients with idiopathic scoliosis.

Methods

The study involved 17 patients with idiopathic scoliosis of Lenke 1 and Lenke 5 classifications, along with 17 healthy subjects for comparison. Three-dimensional accelerometers were attached to the head and L5 spinous process of each participant, and three-dimensional motion acceleration signals were collected during a 10-meter walking test. Analysis of the collected acceleration signals involved calculating five variables related to the symmetry and regularity of walking: root mean square (RMS) of the acceleration signal, harmonic ratio (HR), step regularity, stride regularity, and gait symmetry.

Results

Our analysis reveals that, during the walking process, the three-dimensional motion acceleration signals acquired from the lumbar region of patients diagnosed with idiopathic scoliosis exhibit noteworthy disparities in the RMS of the vertical axis (RMS-VT) and the HR of the vertical axis (HR-VT) when compared to the corresponding values in the healthy control (RMS-VT: 1.6 ± 0.41 vs. 3 ± 0.47, P < 0.05; HR-VT: 3 ± 0.72 vs. 3.9 ± 0.71, P < 0.05). Additionally, the motion acceleration signals of the head in three-dimensional space, including the RMS in the anterior-posterior and vertical axis, the HR-VT, and the values of step regularity in both anterior-posterior and vertical axis, as well as the values of stride regularity in all three axes, are all significantly lower than those in the healthy control group (P < 0.05).

Conclusion

The findings of the analysis suggest that the application of three-dimensional accelerometer sensors proves efficacious and convenient for scrutinizing the symmetry and regularity of walking in individuals with idiopathic scoliosis. Distinctive irregularities in gait symmetry and regularity manifest in patients with idiopathic scoliosis, particularly within the antero-posterior and vertical direction. Moreover, the dynamic balance control strategy of the head in three-dimensional space among patients with idiopathic scoliosis exhibits a relatively conservative nature when compared to healthy individuals.

Neurophysiological, balance and motion evidence in adolescent idiopathic scoliosis: A systematic review

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is a spinal deformity that affects approximately 4% of the world's population. Several hypotheses regarding the etiology of AIS have been investigated. In the last decades, impaired visual-spatial perception, alterations in spatial body orientation and sensory integration deficits have been documented.

OBJECTIVE

We aimed to summarize the neurophysiological, balance, and motion evidence related to AIS published in the last fifteen years, between January 2008 and April 2023. Both observational and interventional studies were considered. Only studies using quantitative assessment methods, such as electroencephalography (EEG), electromyography (EMG), magnetic resonance imaging (MRI), somatosensory evoked potentials, force platform, or motion capture, were included.

METHODS

1250 eligible records identified from online database searching were filtered by duplicate removal, title and abstract screening, and qualitative analysis. 61 articles met the inclusion criteria (i.e., Cobb range 10°-35°, age range 10-18 years) and were summarized.

RESULTS

We found significant evidence of impaired standing balance in individuals with AIS who greatly rely on visual and proprioceptive information to stay upright. EMG studies frequently reported an increased activity on the convex side of the intrinsic spinae muscles. EEG data show increased delta and theta power, higher alpha peak frequencies, and significant suppression in the alpha and beta bands in subjects with AIS during standing tasks. MRI studies report changes in white matter structures, differences in the vestibular system, and abnormal cortical activations over motor-related areas in subjects with AIS. Bracing appears to be an effective treatment for AIS, leading to improvements in static balance and gait. Methodological issues prevent reliable conclusions about the effects of other treatment options.

CONCLUSIONS

This review underscores the importance of quantitative assessment methods to explore the etiology and pathophysiology of AIS. Further research is needed to measure the impact of physical therapy and orthotic treatments on the neurophysiological mechanisms of the disease.

The Effect of Leg Length Discrepancy on Paraspinal Muscles Activation Using Surface Electromyography

OBJECTIVE

The aim of the study is to assess the effects of leg length discrepancy on paraspinal muscle activity and kinematic variables during gait.

DESIGN

Thirty-nine healthy participants aged 5-12 yrs performed the 10-m walk test using the surface electromyography and G-walk sensor for the following conditions: (1) non-leg length discrepancy condition (leg length discrepancy 0 cm) and (2) leg length discrepancy condition with an insole on the right leg at three different heights (leg length discrepancy 0.5 cm, 1.0 cm, and 1.5 cm). The root mean square was normalized using maximal voluntary contraction and reference voluntary contraction methods (RMS_MVC and RMS_ref) and compared between the sides.

RESULTS

The mean RMS_MVC of the 12th thoracic erector spinae on the right side was significantly higher at a leg length discrepancy 0.5 cm and 1 cm. Regarding the 3rd lumbar multifidus, the mean RMS_MVC on the right side was significantly higher at a leg length discrepancy 1.5 cm. The mean RMS_ref exhibited similar patterns. Pelvic obliquity and rotation showed asymmetry at a leg length discrepancy 1.5 cm compared with a leg length discrepancy 0 cm.

CONCLUSIONS

A small leg length discrepancy significantly affected the asymmetric hyperactivation of the 3rd lumbar multifidus and 12th thoracic erector spinae muscles during gait. Considering the action of these muscles, asymmetric hyperactivation might result in rotation and bending of the lumbar spine and the bending of the thoracolumbar spine.

Can external work during walking in scoliosis patients be estimated from spatiotemporal parameters?

BACKGROUND

Patients with scoliosis present gait impairments compared to healthy subjects. Clinically, spine deformity is evaluated with Cobb angle, a standard measurement to determine and track the progression of scoliosis. Scoliosis is a biomechanical trouble, dependant of external forces and muscular activity. External work is currently analyzed in patients with scoliosis because this work sums up consequences and evolutions of spine deformity. Habitually, biomechanics approach is used to compute this work. For asymptomatic subjects, a regression model let to compute external work. So, considering the area of research to facilitate the follow-up at lower cost, this regression function could be applied to patients with scoliosis but need to be validated.

RESEARCH QUESTION

can external work during walking in scoliosis patients be estimated from spatiotemporal parameters with a regression model?

METHOD

This retrospective study included twenty untreated patients with idiopathic scoliosis and sixteen asymptomatic participants. We used a regression model defined in case of asymptomatic subjects in literature and proposed a new specific model in case of patients with scoliosis.

FINDINGS

The external work in patients with scoliosis calculated with the Wirta's regression eq. (0.23 ± 0.04 J.kg-1.m-1) was underestimated compared to the external work calculated using a biomechanical method (0.33 ± 0.06 J.kg-1.m-1). A new regression model including Cobb angle and spatio-temporal parameter presents a high coefficient of determination.

INTERPRETATION

In opposition to biomechanical method, our new model let to compute external work without expensive gait laboratory. This specific model is more reliable than the model developed from asymptomatic subjects.

Biomechanical changes in adolescent idiopathic scoliosis during walking: A protocol for systematic review and meta-analysis

BACKGROUND

To clarify the differences in biomechanical characteristics present in adolescent idiopathic scoliosis (AIS) patients during walking.

METHODS

Cross-sectional studies related to the biomechanical characteristics of AIS were included by searching 7 major databases and analyzed using RevMan 5.4 software.

RESULTS

There were a total of 15 trials involving 377 AIS patients. The results showed that during walking, AIS had increased pelvic coronal tilt (effect size [ES] = -1.34, 95% confidence intervals [CI] = -2.41 to -0.27, P = .01), knee and ankle sagittal mobility were reduced (ES = -5.22, 95% CI = -7.51 to -2.94, P < .001; ES = -3.58, 95% CI = -5.93 to -1.22, P = .003). The duration of electromyogram activity was prolonged in the gluteus medius (ES = 7.65, 95% CI = 5.33-9.96, P < .001), lumbar square (ES = 10.73, 95% CI = 6.97-14.49, P < .001), and erector spinae (ES = 14.35, 95% CI = 6.94-21.76, P < .001) muscles. The results of subgroup analysis showed that the step length of the concave side of the spine was reduced (ES = -0.36, 95% CI = -0.71 to -0.01, P = .04).

CONCLUSION

AIS has characteristic biomechanical changes in spatiotemporal, phase kinematics, motor mechanics, and electromyographic signatures. Further comprehensive studies are required in the future to analyze the biomechanical and electromyographic differences among different degrees and types of scoliosis, as well as the differences between the concave and convex sides of scoliosis during walking.

Comparison of gait and sagittal plane arm swing between individuals with adolescent idiopathic scoliosis and healthy individuals

Arm swing and energy consumption play an important role in the realization of an effective gait. However, research on arm swing and energy consumption during gait in individuals with adolescent idiopathic scoliosis (AIS) is limited. The aim of this study was to investigate the spatiotemporal characteristics of gait, arm swing angles in the sagittal plane, energy consumption in individuals with AIS, to compare them with their healthy peers in this regard. 26 diagnosed with AIS and 21 healthy were included in this study. Evaluation measures were based on the Cobb angle, axial trunk rotation, trunk symmetry, sagittal curve measurements, spatiotemporal characteristics of gait with the GAITRite electronic walkway, sagittal plane arm swing with two video-camera recordings, and energy consumption. There were a decrease in right- sided sagittal arm swing, an increase in energy consumption, in left-side step time and right-side double support time in the scoliosis group compared to the control group. The other spatiotemporal characteristics of the gait were similar in both groups. The evaluation of arm swing, energy consumption, and gait of individuals with AIS may contribute to the development of rehabilitation programs by better identifying the deficiencies of individuals with AIS.

Lower limb joint burden during walking in adolescent idiopathic scoliosis: investigation of mechanical work during walking

BACKGROUND CONTEXT

Adolescent idiopathic scoliosis (AIS) is the most prevalent spinal deformity in adolescents. However, pathophysiology and long-term complications remain unclear. Characteristics of the mechanical work in AIS gait have not been well-studied.

PURPOSE

This study aimed to elucidate the characteristics of mechanical work in AIS gait.

STUDY DESIGN

Observational comparison study.

PATIENT SAMPLE

Participants were composed of two groups: scoliosis group with 68 participants and a control group with 17 participants.

OUTCOME MEASURES

Spinal deformity and coronal spinal balance in the scoliosis group were assessed with Cobb angle, coronal balance, and apical vertebra translation. Three-dimensional motion analysis during walking was conducted to calculate lower limb joint works and external work on the whole body's center of mass.

METHODS

Lower limb joint work (JW) and external work on the whole body center of mass (CoM) were compared between the 2 groups with an independent t-test. Inter-limb and intra-limb comparisons of mechanical work were conducted with a paired t-test. The relationships between mechanical work and frontal trunk deformity were investigated in the scoliosis group.

RESULTS

Walking speed and external work on whole body CoM did not differ between the two groups. Compared to the control group, the scoliosis group showed significantly larger JW on the convex and concave sides.

CONCLUSION

The scoliosis group showed increased lower limb joint burden and limited trunk function for mechanical work during walking. Investigation of mechanical work during walking provides insight into the biomechanical characteristics of AIS. Therefore, future studies should be conducted to verify mechanical work characteristics which have relevance to the progression of spinal deformity and the development of lower limb complications in AIS.

PosturAll: A Posture Assessment Software for Children

From an early age, people are exposed to risk factors that can lead to musculoskeletal disorders like low back pain, neck pain and scoliosis. Medical screenings at an early age might minimize their incidence. The study intends to improve a software that processes images of patients, using specific anatomical sites to obtain risk indicators for possible musculoskeletal problems. This project was divided into four phases. First, markers and body metrics were selected for the postural assessment. Second, the software's capacity to detect the markers and run optimization tests was evaluated. Third, data were acquired from a population to validate the results using clinical software. Fourth, the classifiers' performance with the acquired data was analyzed. Green markers with diameters of 20 mm were used to optimize the software. The postural assessment using different types of cameras was conducted via the blob detection method. In the optimization tests, the angle parameters were the most influenced parameters. The data acquired showed that the postural analysis results were statistically equivalent. For the classifiers, the study population had 16 subjects with no evidence of postural problems, 25 with mild evidence and 16 with moderate-to-severe evidence. In general, using a binary classification with the train/test split validation method provided better results.

A preliminary study in classification of the severity of spine deformation in adolescents with lumbar/thoracolumbar idiopathic scoliosis using machine learning algorithms based on lumbosacral joint efforts during gait

To assess the severity and progression of adolescents with idiopathic scoliosis (AIS), radiography with X-rays is usually used. The methods based on statistical observations have been developed from 3D reconstruction of the trunk or topography. Machine learning has shown great potential to classify the severity of scoliosis on imaging data, generally on X-ray measurements. It is also known that AIS leads to the development of gait disorder. To our knowledge, machine learning has never been tested on spine intervertebral efforts during gait as a radiation-free method to classify the severity of spinal deformity in AIS. Develop automated machine learning algorithms in lumbar/thoracolumbar scoliosis to classify the severity of spinal deformity of AIS based on the lumbosacral joint (L5-S1) efforts during gait. The lumbosacral joint efforts of 30 individuals with lumbar/thoracolumbar AIS were used as distinctive features fed to the machine learning algorithms. Several tests were run using various classification algorithms. The labeling consisted of three classes reflecting the severity of scoliosis i.e. mild, moderate and severe. The ensemble classifier algorithm including k-nearest neighbors, support vector machine, random forest and multilayer perceptron achieved the most promising results, with accuracy scores of 91.4%. This preliminary study shows lumbosacral joint efforts can be used to classify the severity of spinal deformity in lumbar/thoracolumbar AIS. This method showed the potential of being used as an assessment tool to follow-up the progression of AIS as a radiation-free method, alternative to radiography. Future studies should be performed to test the method on other categories of AIS.

Patients with Adolescent Idiopathic Scoliosis Have Higher Metabolic Cost during High-Intensity Interval Training

BACKGROUND

Patients with adolescent idiopathic scoliosis (AIS) are found to have a lower level of physical activity, and may have reduced exercise capacity due to spinal deformity. Previous study showed the benefits of high-intensity interval training (HIIT), named E-Fit, which is specifically designed for patients with AIS to improve musculoskeletal health and psychological well-being. To optimize the beneficial effects of training, the current study aimed to investigate the appropriate exercise intensity and metabolic demand in patients with AIS when performing E-Fit.

METHODS

In all, 22 female subjects, 10 diagnosed with AIS and 12 gender-matched healthy controls, aged between 10 and 16 years, were recruited. Subjects were instructed to perform two trials of a seven min E-Fit. Breath-by-breath gas exchange parameters including oxygen consumption (VO₂), heart rate (HR) and the rate of perceived exertion (PRE) were measured during exercise. Demographic data and clinical features of AIS and body composition were obtained. Metabolic demand between AIS and control groups was compared using MANOVA with covariates adjustment.

RESULTS

Patients with AIS had an earlier onset of menarche (p = 0.01), higher visceral adipose tissue (p = 0.04) and percentage body fat (p = 0.03) as compared to controls. Patients with AIS showed a significantly higher adjusted means of VO₂ average in both the first (p = 0.014) and second trials (p = 0.011) of E-Fit. The adjusted mean of the highest measured VO₂ was higher than healthy controls and reached statistical significance in the second trial (p = 0.004). Both the AIS and control group exercised at a similar percentage of VO₂ peak (64.26% vs. 64.60%).

CONCLUSION

Patients with AIS showed higher oxygen consumption during E-Fit than heathy controls, which might indicate a higher metabolic cost. Patients with AIS could carry out exercise at a moderate exercise intensity similar to that of healthy controls, but special considerations in designing an exercise program, such as frequent rest intervals, would be useful to avoid fatigue among patients with AIS.

Compensatory Ground Reaction Forces during Scoliotic Gait in Subjects with and without Right Adolescent Idiopathic Scoliosis

Although the asymmetries of scoliotic gait in adolescent idiopathic scoliosis (AIS) groups have been extensively studied, recent studies indicated conflicting results regarding the ground reaction forces (GRFs) during gait in subjects with spinal deformity. The asymmetry during the stance phase might be clarified with three-dimensional (3D) compensations of GRFs between similar characteristics of subjects with and without AIS. The purpose of this study was to compare the normalized 3D GRF differences during the stance phase of gait while considering age, BMI, and Cobb angle between subjects with and without right AIS. There were 23 subjects with right convexity of thoracic idiopathic scoliosis and 22 age- and gender-matched control subjects. All subjects were right upper/lower limb dominant, and the outcome measures included the Cobb angles, normalized GRF, and KAI. The mediolateral (M/L) third peak force on the dominant limb decreased in the AIS group (t = 2.58, p = 0.01). Both groups demonstrated a significant interaction with the 3D indices (F = 5.41, p = 0.02). The post-hoc analysis identified that the M/L plane of asymmetry was significantly different between groups. The Cobb angles were negatively correlated with the vertical asymmetry index (r = −0.45, p = 0.03); however, there was no significant correlation with age (r = −0.10, p = 0.65) or body mass index (r = −0.28, p = 0.20). The AIS group demonstrated decreased GRF in the dominant limb M/L plane of the terminal stance phase. This compensatory motion was confirmed by a significant group difference on the M/L plane of the KAI. This KAI of vertical asymmetry correlated negatively with the Cobb angle. The asymmetric load transmission with compensatory vertical reactions was evident due to abnormal loading in the stance phase. These kinetic compensatory patterns need to be considered with asymmetry on the dominant limb when developing rehabilitation strategies for patients with AIS.

Accelerometer based assessment of daily physical activity and sedentary time in adolescents with idiopathic scoliosis

BACKGROUND

Studies have shown a positive correlation between higher physical activity (PA) and health benefits. However, device-based assessment of PA and sedentary time (ST) in people with adolescent idiopathic scoliosis (AIS) has not been deeply investigated.

OBJECTIVE

Analysis and comparison of weekend and weekdays PA and ST using multiple accelerometers in people with AIS with different curvature severity compared to healthy controls.

METHODS

24 participants with AIS divided into 2 groups of 12 with Cobb angles < 40° and > 40°, along with 12 age and BMI matched healthy controls. Daily PA and ST during four consecutive days were measured using four tri-axial accelerometers. Clinical functional assessment was performed using the scoliosis research society (SRS-22) questionnaire.

RESULTS

The combined weekend and weekdays average daily step count was found to be 22% and 29% lower in the AIS groups with Cobb angle < 40° and > 40°, respectively, compared to the controls. The average ST was also reported to be 5% and 7% higher in the AIS groups with Cobb angle < 40° and > 40°, respectively, compared to the controls. The reported differences were significant in the AIS group with higher Cobb angle (p≤0.05). No significant differences in PA or ST were reported between the AIS groups based on curvature severity.

CONCLUSIONS

Decreased PA and increased ST observed in patients with AIS may have long term health implications and may play a role in the disease process. The device-based assessment of PA to understand potential benefits in clinical practice is recommended.

Gait oxygen consumption in adolescent idiopathic scoliosis and the effect of brace use

BACKGROUND

Despite studies showing that gait is affected in adolescent idiopathic scoliosis (AIS), it remains unclear whether gait oxygen consumption is altered.

RESEARCH QUESTION

The aims of the present study were to compare energy consumption during gait between subjects with AIS and healthy controls, and to examine the effect of brace use on gait energy expenditure.

METHODS

This prospectively designed study included 15 AIS and 15 healthy girls, whose ages ranged from 10 to 16 years old and Cobb angles from 20 and 45°. At the end of the first month of brace use for the first time in individuals with AIS, oxygen consumption was measured with and without brace use on a treadmill at a gait speed of 4 km.h^-1 using a metabolic analyzer.

RESULTS

There was no statistically significant difference in gross and net gait oxygen consumption measurements between AIS and healthy individuals or between individuals with AIS with or without brace use (p >  0.05).

SIGNIFICANCE

After one month of brace treatment, AIS is not associated with an additional metabolic load with or without the brace during gait when compared to healthy subjects.

Usefulness of a combined approach of DIERS Formetric 4D® and QUINTIC gait analysis system to evaluate the clinical effects of different spinal diseases on spinal-pelvic-lower limb motor function

BACKGROUND

To investigate the alterations in body movement and their compensatory characteristics under different spinal diseases through an objective and quantitative analysis of the spinal-pelvic-lower limb motor function.

METHODS

A total of 120 subjects were recruited from October 2016 to April 2017. The patients were classified into 2 groups in which 65 patients with cervical spondylotic myelopathy (CSM) and 25 patients with idiopathic scoliosis (IS). The former group was evaluated with JOA score while those in the IS group underwent Lenke classification. A control group was set up with 30 healthy subjects. All the subjects were instructed to walk at a constant speed for one minute on a treadmill, and their spinal-pelvic-lower limb motions were monitored simultaneously with a DIERS Formetric 4D® grating system and a QUINTIC gait analysis system.

RESULTS

The rotation angle of thoracic and lumbar vertebrae in IS group were larger than those in the control group (P < 0.05), and the knee joint angle A in the CSM group and IS group were larger than the control group (P < 0.05). In the CSM group, the knee joint angular velocity and angular acceleration were both greater than the control group (P < 0.05). And there was a negative linear correlation between the JOA score for the lower extremity of CSM patients and their knee joint angular acceleration.

CONCLUSION

IS patients tend to demonstrate increased swing amplitude of the trunk. Those with CSM will also have larger knee joint angular velocity and angular acceleration.

The Correlation of Spinopelvic Parameters With Biomechanical Parameters Measured by Gait and Balance Analyses in Patients With Adult Degenerative Scoliosis

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

The objective of this study was to establish the correlation between radiographic spinopelvic parameters with objective biomechanical measures of function in patients with adult degenerative scoliosis (ADS).

SUMMARY OF BACKGROUND DATA

Gait and balance analyses can provide an objective measure of function. Patients with ADS demonstrate altered gait and balance patterns. Spinopelvic parameters are commonly used by clinicians to evaluate patients with ADS. However, to the best of our knowledge, no studies have examined the correlation between patients' radiographic spinopelvic parameters and biomechanical gait and balance parameters.

PATIENT SAMPLE

Forty-four patients with symptomatic ADS who have been deemed, appropriate surgical candidates.

METHODS

Radiographic spinopelvic parameters (CVA: central vertical axis, SVA: sagittal vertical axis, Cobb angle, PI-LL mismatch: pelvic incidence lumbar lordosis mismatch, and T1PA: T1 pelvic angle) were obtained the week before surgery. Then, gait and functional balance analyses (spatiotemporal parameters, center of mass, and head sway parameters) were performed on the same day. Correlations were determined between the radiographic spinopelvic parameters and biomechanical gait and balance parameters using Pearson product correlation.

RESULTS

Our results show that patients with higher Cobb angle and CVA tend to walk slower (r=-0.494, P<0.05). Furthermore, the higher the Cobb angle (r=0.396), CVA (r=0.412), SVA (r=0.440), and PI-LL mismatch (r=0.493), the more time ADS patients spend with their feet planted during single and double support phases of gait (P<0.05). In addition, patients with a higher Cobb angle, CVA, SVA, PI-LL mismatch, and T1PA, exhibited more trunk sway, increased lower extremity neuromuscular activity, and decreased spine neuromuscular activity (0.331<r<0.716, P<0.05).

CONCLUSIONS

This study demonstrated a moderate correlation between the biomechanical parameters as measured with gait and balance analyses and the radiographic spinopelvic parameters in ADS patients. With higher pathologic spinopelvic parameters, single support time, center of mass, and head sway and lower extremity neuromuscular activity were all increased. Quantified gait and balance analyses can be a useful tool to evaluate patient outcomes. Objective functional performance measures can help to improve the evaluation and understanding of the biomechanical effects of spinal disorders on locomotion.

The Motion of Body Center of Mass During Walking: A Review Oriented to Clinical Applications

Human walking is usually conceived as the cyclic rotation of the limbs. The goal of lower-limb movements, however, is the forward translation of the body system, which can be mechanically represented by its center of mass (CoM). Lower limbs act as struts of an inverted pendulum, allowing minimization of muscle work, from infancy to old age. The plantar flexors of the trailing limbs have been identified as the main engines of CoM propulsion. Motion of the CoM can be investigated through refined techniques, but research has been focused on the fields of human and animal physiology rather than clinical medicine. Alterations in CoM motion could reveal motor impairments that are not detectable by clinical observation. The study of the three-dimensional trajectory of the CoM motion represents a clinical frontier. After adjusting for displacement due to the average forward speed, the trajectory assumes a figure-eight shape (dubbed the “bow-tie”) with a perimeter about 18 cm long. Its lateral size decreases with walking velocity, thus ensuring dynamic stability. Lateral redirection appears as a critical phase of the step, requiring precise muscle sequencing. The shape and size of the “bow-tie” as functions of dynamically equivalent velocities do not change from child to adulthood, despite anatomical growth. The trajectory of the CoM thus appears to be a promising summary index of both balance and the neural maturation of walking. In asymmetric gaits, the affected lower limb avoids muscle work by pivoting almost passively, but extra work is required from the unaffected side during the next step, in order to keep the body system in motion. Generally, the average work to transport the CoM across a stride remains normal. In more demanding conditions, such as walking faster or uphill, the affected limb can actually provide more work; however, the unaffected limb also provides more work and asymmetry between the steps persists. This learned or acquired asymmetry is a formerly unsuspected challenge to rehabilitation attempts to restore symmetry. Techniques of selective loading of the affected side, which include constraining the motion of the unaffected limb or forcing the use of the affected limb on split-belt treadmills which impose a different velocity and power to either limb, are now under scrutiny.

Association between physical activity and scoliosis: a prospective cohort study

BACKGROUND

Little is understood about the causes of adolescent onset idiopathic scoliosis (AIS). No prospective studies assessing the association between physical activity and idiopathic adolescent scoliosis have been carried out. We aimed to carry out the first prospective population-based study of this association.

METHODS

The Avon Longitudinal Study of Parents and Children (ALSPAC) collected self-reported measures of physical ability/activity at ages 18 months and 10 years. Objective measures of physical activity were collected by accelerometry at age 11 years. scoliosis was identified using the dxa scoliosis Method at age 15 years. Participants with scoliosis at age 10 years were excluded.

RESULTS

Of 4640 participants at age 15 years who had DXA scans, 267 (5.8%) had scoliosis. At age 18 months, those infants who were able to stand up without being supported were 66% less likely to have developed scoliosis by age 15 (P = 0.030) compared with infants who could not. Those children whose mothers reported they did most vigorous physical activity at age 10 years were 53% less likely to develop scoliosis (P = 0.027). Those children who did more objectively measured moderate/vigorous physical activity at age 11 were 30% less likely to have developed scoliosis (P < 0.001). Results were not affected by adjustment for age, gender, lean mass, fat mass or back pain.

CONCLUSIONS

We report reduced physical ability and activity as early as age 18 months in those who go on to develop scoliosis by age 15 years. Further research is justified to examine the mechanisms underlying this association.

A Comparison of Muscular Activity During Gait Between Walking Sticks and a Walker in Patients With Adult Degenerative Scoliosis

STUDY DESIGN

A repeated measurement, single-center, prospective study.

OBJECTIVE

The purpose of this study is to compare and contrast the benefits of walking sticks versus a walker on the trunk and lower extremity muscular control in patients with adult degenerative scoliosis (ADS).

SUMMARY OF BACKGROUND DATA

ADS patients demonstrate an altered gait pattern. Walking aids help maintain mobility in those patients. Whereas a walker forces patients into kyphosis, the higher grips of walking sticks allows for more upright posture, arm swing, and improved sagittal alignment.

METHODS

Twenty ADS patients with symptomatic degenerative scoliosis performed over-ground walking at self-selected speed under 3 testing conditions: 1) with walking sticks (WS); 2) with walker (WR); and 3) without any device (ND). Trunk and lower extremity peak muscle activation, time to peak muscle activity, muscle duration, muscle onset, and integrated electromyography (iEMG) were measured and compared.

RESULTS

The use of WS produced increases in muscle activity in the external oblique (WS: 44.3% vs. WR: 7.4% of submaximum voluntary contraction [sMVC], p = .007) and medial gastrocnemius (WS: 78.8% vs ND: 43.7% of sMVC, p = .027) in comparison to the walker and no device, respectively. When using WS, shorter muscle activity time was observed for rectus femoris (WS: 62.9% vs. WR: 88.8% of gait cycle, p = .001), semitendinosus (WS: 64.3% vs. WR: 93.0% of gait cycle, p = .003), tibialis anterius (WS: 59.4% vs. WR: 85.1% of gait cycle, p = .001), and medial gastrocnemius (WS: 67.3% vs. WR: 98.0% of gait cycle, p = .006) in comparison to the walker.

CONCLUSIONS

The use of walking sticks can potentially promote trunk and lower extremity neuromuscular control and gait mechanics comparable to gait without any assistive devices. Although the differences in magnitudes between comparisons were small and should be cautiously interpreted on a case-by-case basis, based on this study's results and our anecdotal experience treating patients with ADS, we recommend the use of walking sticks to assist with their gait prior to and after surgical intervention.

LEVEL OF EVIDENCE

Level III.

Postural adjustments in adolescent idiopathic thoracic scoliosis during walking

INTRODUCTION

Adolescent idiopathic scoliosis (AIS) is the most common type of three-dimensional spinal deformity. Identifying the postural adjustments or changes for different phases and events is needed for developing programs to improve the AIS gait, but such information has been limited. The current study aimed to fill the gap via three-dimensional motion analysis of quiet standing and level walking in patients with severe thoracic AIS.

MATERIALS AND METHODS

Sixteen female adolescents with AIS (Lenke 1 or 2, age: 14.9 ± 1.7 years, height: 154.7 ± 5.0 cm, mass: 41.7 ± 7.2 kg) and sixteen sex-, age- and BMI-matched healthy controls (age: 14.8 ± 2.7 years, height: 154.9 ± 5.6 cm, mass: 44.7 ± 6.3 kg) participated in the current study with informed written consent. The kinematic and kinetic changes between the trunk, pelvis, and lower limb segments, and at the lumbosacral level at different gait events were measured during quiet standing and level walking.

RESULTS

The homogeneity of the current patient group helped reduce the effects of the level and severity of spinal deformity on inter-subject variability that has been associated with controversies over reported gait variables in AIS. The current results support the hypothesis that postural adjustments involving the trunk, pelvis and lower limb segments were needed in severe thoracic AIS during both quiet standing and level walking, and differed between concave and convex sides at different key gait events during level walking.

CONCLUSIONS

Although scoliotic spinal deformity occurred mainly in the frontal plane, postural adjustments in all three planes were present at key events during level walking with associated joint loading changes in patients with severe thoracic AIS. Monitoring of such adjustments and the associated joint kinetic changes will be helpful for assessing the disease and treatment outcomes.

Efficacy of Corrective Surgery for Gait and Energy Expenditure in Patients with Scoliosis: A Literature Review

The aim of this literature review was to evaluate selected original papers that measured gait parameters and energy expenditure in idiopathic scoliosis (IS) treated with surgical intervention. IS is a progressive growth disease that affects spinal anatomy, mobility, and left–right trunk symmetry. Consequently, IS can modify human gait. Spinal fusions remain the primary approach to correcting scoliosis deformities, thereby halting progression. Using the population intervention comparison outcome measure framework and selected keywords, 15 studies that met the inclusion criteria were selected. Alteration of spatial and temporal variables in patients with IS was contradictory among the selected studies. Ankle and foot kinematics did not change after surgery; however, pelvic and hip frontal motions increased and pelvic rotation decreased following surgery. Patients with IS continued to show excessive energy expenditure following surgery in the absence of a physical rehabilitation protocol. Spinal surgery may be considered for gait improvement and IS treatment. There were inadequate data regarding the effect of corrective surgery on the kinetics, energy expenditure, and muscle activity parameters.

Spinal correction surgery improves asymmetrical trunk kinematics during gait in adolescent idiopathic scoliosis with thoracic major curve

PURPOSE

To clarify the effect of posterior correction and fusion surgery on the trunk-pelvic kinematics during gait in adolescent idiopathic scoliosis (AIS) patients with single thoracic major curve.

METHODS

Among preoperative AIS patients who planned correction surgery, 18 patients with Lenke type 1A or B were selected for this study. All patients were female. The patients' trunk and pelvic kinematics during gait were measured three-dimensionally and dynamically using reflective markers, optoelectronic motion capture system. The gait analysis was performed before and 1-2 years after surgery. The trunk and pelvic symmetry during gait was evaluated at coronal, sagittal, and transverse planes between concave and convex sides.

RESULTS

The trunk and pelvic angles in sagittal and coronal planes were equivalent between concave and convex sides before and after surgery. Preoperatively, transverse trunk rotation angles were significantly deviated toward the concave (left) side during both static standing (4.3 ± 2.0°) and gait (8.8 ± 0.6°, p < 0.01). Preoperative transverse pelvic rotation angles were significantly deviated toward the convex side during static standing (4.0 ± 3.8°). However, pelvis displayed with symmetric rotational kinematics during gait. Postoperatively, the deviated transverse trunk rotation angle significantly decreased (1.6 ± 0.3°), and the transverse rotational kinematics of both trunk and pelvis improved to symmetric.

CONCLUSIONS

Posterior correction and fusion surgery have improved preoperative asymmetric global rotational kinematics of trunk and pelvis in transverse plane to symmetric postoperatively in AIS patients with thoracic single major curve. These slides can be retrieved under Electronic Supplementary Material.

The Relationship Between Fear-Avoidance and Objective Biomechanical Measures of Function in Patients With Adult Degenerative Scoliosis

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

The current study utilized quantitative gait analysis to examine the relationship of fear-avoidance beliefs to gait patterns in patients with adult degenerative scoliosis (ADS).

SUMMARY OF BACKGROUND DATA

Among patients with chronic spine pain, fear-avoidance beliefs are predictive of behavioral deficiencies, poor work, and surgery outcomes. The impact of such beliefs on patients with major spinal deformity has yet to be investigated. Patients with ADS have previously been shown to have an altered gait pattern. Utilizing quantified gait analysis, this study aims to examine correlations between fear-avoidance and various aspects of gait in patients with ADS.

METHODS

Twenty-five ADS patients completed the Tampa Scale for Kinesiophobia (TSK) questionnaire and the Fear Avoidance Beliefs Questionnaire (FABQ). Each patient performed a series of overground gait trials at a self-selected comfortable speed. Pearson product correlation analysis was used to determine the relationship between the self-reported fear of movement measures and the objective gait analysis biomechanical data.

RESULTS

TSK score correlated strongly with gait speed, stride, step, double support times, and step length, and correlated moderately with cadence, and stride length. The FABQ physical portion strongly correlated with stride length and step length. The FABQ physical portion was moderately correlated with gait speed and single support time. The FABQ work portion was correlated with stride length and step length.

CONCLUSION

This study demonstrates a strong correlation between biomechanical gait parameters, as measured with gait analysis, and fear-avoidance of movement, as measured with the TSK and FABQ. Further, it demonstrates that quantified gait analysis can be a useful tool to evaluate patients with spine deformity and to assess the outcomes of treatments in this group of patients. This study extends previous research on the role of fear-avoidance to include patients with spinal deformity.

LEVEL OF EVIDENCE

3.

Gait in patients with adolescent idiopathic scoliosis. Effect of surgery at 10 years of follow-up

PURPOSE

To assess radiological and gait biomechanical changes before, at one and 10 years after surgery in AIS patients.

METHODS

This clinical prospective study included fifteen adult women (mean[SD] age: 26 [1] years) diagnosed with thoraco-lumbar/lumbar AIS and operated 10 years ago. Clinical, radiological and gait variables, including kinematics, electromyography (EMG), mechanics and energetics were compared between presurgery (S0), 1 year (S1) and 10 years (S2) postsurgery period using a one way repeated measure ANOVA.

RESULTS

The Cobb angle of the scoliosis curve was reduced by 55% at 1 year postsugery but only by 37% at 10 years postsurgery suggesting a loss of 32% over time. Frontal plumb line C7-S1 distance was significantly improved by surgery (-44%) and remained stable at 10 years postsurgery. Lower limb kinematics was not affected by the surgery at long term. Excessive bilateral activation of lombo-pelvic muscles, observed before surgery, decreased significantly at S1 and S2 period. Mechanical energy increased significantly between S0, S1 and S2 session, without any change for the energetic variables.

CONCLUSIONS

Between 1 and 10 years post-surgery, thoraco-lumbar/lumbar AIS women showed a few decompensation of the curve without any change of the improved frontal body balance. Lower limbs and pelvic motion, during gait, was not affected by the surgery. But presurgical excessive EMG activity of the lumbo-pelvic muscle and reduced mechanical energy produced to walk get similar to normal patterns. Only the oxygen consumption remained excessive probably due to physical deconditioning or postural instability.

Spinal fusion limits upper body range of motion during gait without inducing compensatory mechanisms in adolescent idiopathic scoliosis patients

INTRODUCTION

Previous studies show a limited alteration of gait at normal walking speed after spinal fusion surgery for adolescent idiopathic scoliosis (AIS), despite the presumed essential role of spinal mobility during gait. This study analyses how spinal fusion affects gait at more challenging walking speeds. More specifically, we investigated whether thoracic-pelvic rotations are reduced to a larger extent at higher gait speeds and whether compensatory mechanisms above and below the stiffened spine are present.

METHODS

18 AIS patients underwent gait analysis at increasing walking speeds (0.45 to 2.22m/s) before and after spinal fusion. The range of motion (ROM) of the upper (thorax, thoracic-pelvic and pelvis) and lower body (hip, knee and ankle) was determined in all three planes. Spatiotemporal parameters of interest were stride length and cadence.

RESULTS

Spinal fusion diminished transverse plane thoracic-pelvic ROM and this difference was more explicit at higher walking speeds. Transversal pelvis ROM was also decreased but this effect was not affected by speed. Lower body ROM, step length and cadence remained unaffected.

DISCUSSION

Despite the reduction of upper body ROM after spine surgery during high speed gait, no altered spatiotemporal parameters or increased compensatory ROM above or below the fusion (i.e. in the shoulder girdle or lower extremities) was identified. Thus, it remains unclear how patients can cope so well with such major surgery. Future studies should focus on analyzing the kinematics of individual spinal levels above and below the fusion during gait to investigate possible compensatory mechanisms within the spine.

Gait and energy consumption in adolescent idiopathic scoliosis: A literature review

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is a progressive growth disease that affects spinal anatomy, mobility, and left-right trunk symmetry. The disease can modify human gait.

OBJECTIVE

We aimed to review articles describing the measurement of gait parameters and energy consumption in AIS during walking without any intervention.

STUDY DESIGN

Literature review.

METHODS

The search strategy was based on the Population Intervention Comparison Outcome method and included all relevant articles published from 1996 to 2015. Articles were searched in MEDLINE via PubMed, Science Direct, Google Scholar, and ISI Web of Knowledge databases.

RESULTS

We selected 33 studies investigating the effect of scoliosis deformity on gait parameters and energy expenditure during walking. Most of the studies concluded no significant differences in walking speed, cadence and step width in scoliosis patients and normal participants. However, patients showed decreased hip and pelvic motion, excessive energy cost of walking, stepping pattern asymmetry and ground reaction force asymmetry.

CONCLUSION

We lack consistent evidence of the effect of scoliosis on temporal spatial and kinematic parameters in AIS patients as compared with normal people. However, further research is needed to assess the effect of scoliosis on gait and energy consumption.

Efficacy of corrective spinal orthoses on gait and energy consumption in scoliosis subjects: a literature review

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is a progressive growth disease that affects spinal anatomy, mobility, and left-right trunk symmetry. As a consequence, AIS can modify human gait. Spinal orthoses are a commonly used conservative method for the treatment of AIS.

OBJECTIVE

This review evaluated the AIS spinal orthosis literature that involved gait and energy consumption evaluations.

STUDY DESIGN

Literature review.

METHOD

According to the population intervention comparison outcome measure methods and based on selected keywords, 10 studies met the inclusion criteria.

RESULTS

People with AIS who wore a spinal orthosis, compared with able-bodied participants, walked slower with decreased hip and pelvic movements, decreased hip mediolateral forces, ground reaction force asymmetry, and excessive energy cost. Pelvis and hip frontal plane motion decreased when wearing an orthosis. Hip and pelvis movement symmetry improved when using an orthosis. Ankle and foot kinematics did not change with orthotic intervention. People with AIS continued to have excessive energy expenditure with an orthosis.

CONCLUSION

Spinal orthoses may be considered for improving the walking style, although energy cost does not decline following the orthotic intervention. Implications for Rehabilitations Problems related to scoliosis include reduced quality of life, disability, pain, postural alterations, sensory perturbations, standing instability and gait modifications. Wearing corrective spinal orthoses in AIS subjects produce a reduction in walking speed and cadence, increase in stride length and reduction of gait load asymmetry compared to without brace condition. Spinal orthoses do not decline excessive energy expenditure to walk versus without it.

A Cross-sectional Study of Chest Kinematics and VO2 in Children With Adolescent Idiopathic Scoliosis During Steady-state Walking

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The aim of this study was to identify the differences in oxygen consumption in children with adolescent idiopathic scoliosis (AIS) and age-matched control subjects using traditional methods and chest kinematics.

SUMMARY OF BACKGROUND DATA

AIS is a disorder affecting 2 to 3% of children between the ages of 10 and 16 and accounts for up to 85% of all scoliosis cases. The spinal deformities and subsequent rib conformational changes associated with AIS can have a significant deleterious effect on the oxygen consumption for children with mild to severe scoliosis. Previous studies found that the oxygen consumption in children with AIS was significantly more than that of peers and during walking require more energy than typically developing children.

METHODS

Thirty children (four male, 26 female), 11.7 to 18.7 years of age, were enrolled: 15 adolescent children diagnosed with mild to moderate AIS (mean cobb angle 36.2 degrees) and 15 matched adolescents. Oxygen consumption during steady-state treadmill walking was measured using a traditional methods and simultaneous kinematic analysis of the chest wall.

RESULTS

There were no significant differences in the volume of oxygen consumed in any of the phases of treadmill walking (resting, exercise, and recovery) or in breath per minute ventilation and tidal volume between control subjects and children with scoliosis (P > 0.05). Significant differences were found between assessment methods, with the kinematic analysis overestimating the average tidal volume while walking (P < 0.05).

CONCLUSION

Children with mild to moderate AIS and typically developing children do not demonstrate oxygen consumption differences when walking at a steady state on a treadmill. However, kinematic analysis of the chest wall tends to overestimate the tidal volume when walking. An offset equation is required for some variables when using kinematic data to assess oxygen consumption in children who would otherwise not comply with traditional oxygen consumption testing.

LEVEL OF EVIDENCE

3.

Postural spinal balance defined by net intersegmental moments: Results of a biomechanical approach and experimental errors measurement

AIM: To describe initial results and experimental error measurement of a protocol analyzing Human posture through sagittal intersegmental moments.

METHODS: Postural analysis has been recently improved by development of three-dimensional radiographic imaging systems. However, in various situations such as global sagittal anterior malalignment interpretation of radiographs may not represent the real alignment of the subject. The aim of this study was to present initial results of a 3D biomechanical protocol. This protocol is obtained in a free standing position and characterizes postural balance by measurement of sagittal intersegmental net moments. After elaboration of a specific marker-set, 4 successive recordings were done on two volunteers by three different operators during three sessions in order to evaluate the experimental error measurement. A supplementary acquisition in a “radiographic” posture was also obtained. Once the data acquired, joint center, length, anatomical frame and the center of mass of each body segment was calculated and a mass affected. Sagittal net intersegmental moments were computed in an ascending manner from ground reaction forces at the ankles, knees, hips and the lumbo-sacral and thoraco-lumbar spinal junctions. Cervico-thoracic net intersegmental moment was calculated in a descending manner.

RESULTS: Based on average recordings, clinical interpretation of net intersegmental moments (in N.m) showed a dorsal flexion on the ankles (8.6 N.m), a flexion on the knees (7.5 N.m) and an extension on the hips (8.5 N.m). On the spinal junctions, it was flexion moments: 0.34 N.m on the cervico-thoracic; 6.7 N.m on the thoraco-lumbar and 0.65 N.m on the lumbo-sacral. Evaluation of experimental error measurement showed a small inter-trial error (intrinsic variability), with higher inter-session and inter-therapist errors but without important variation between them. For one volunteer the “radiographic” posture was associated to significant changes compared to the free standing position.

CONCLUSION: These initial results confirm the technical feasibility of the protocol. The low intrinsic error and the small differences between inter-session and inter-therapist errors seem to traduce postural variability over time, more than a failure of the protocol. Characterization of sagittal intersegmental net moments can have clinical applications such as evaluation of an unfused segment after a spinal arthrodesis.

Effect of Nonspecific Chronic Low Back Pain on Walking Economy: An Observational Study

The authors investigated the effects of chronic low back pain (LBP) and walking speed (WS) on metabolic power and cost of transport (CT). Subjects with chronic nonspecific LBP (LBP group [LG]; n = 9) and healthy (control group [CG]; n = 9) were included. The test battery was divided into 3 blocks according to WS as follows: preferred self-selected speed (PS), and lower and higher than the PS. In each block, the volunteers walked 5 min, during which oxygen consumption was measured. Although without differences between groups, the LG had CT lower in slower speeds than in faster speeds. Walking speed affected CT only in the LG, which the group had the greatest walking economy at slower speeds.

Energetics and mechanics of walking in patients with chronic low back pain and healthy matched controls

PURPOSE

Walking in patients with chronic low back pain (cLBP) is characterized by motor control adaptations as a protective strategy against further injury or pain. The purpose of this study was to compare the preferred walking speed, the biomechanical and the energetic parameters of walking at different speeds between patients with cLBP and healthy men individually matched for age, body mass and height.

METHODS

Energy cost of walking was assessed with a breath-by-breath gas analyser; mechanical and spatiotemporal parameters of walking were computed using two inertial sensors equipped with a triaxial accelerometer and gyroscope and compared in 13 men with cLBP and 13 control men (CTR) during treadmill walking at standard (0.83, 1.11, 1.38, 1.67 m s(-1)) and preferred (PWS) speeds. Low back pain intensity (visual analogue scale, cLBP only) and perceived exertion (Borg scale) were assessed at each walking speed.

RESULTS

PWS was slower in cLBP [1.17 (SD = 0.13) m s(-1)] than in CTR group [1.33 (SD = 0.11) m s(-1); P = 0.002]. No significant difference was observed between groups in mechanical work (P ≥ 0.44), spatiotemporal parameters (P ≥ 0.16) and energy cost of walking (P ≥ 0.36). At the end of the treadmill protocol, perceived exertion was significantly higher in cLBP [11.7 (SD = 2.4)] than in CTR group [9.9 (SD = 1.1); P = 0.01]. Pain intensity did not significantly increase over time (P = 0.21).

CONCLUSIONS

These results do not support the hypothesis of a less efficient walking pattern in patients with cLBP and imply that high walking speeds are well tolerated by patients with moderately disabling cLBP.

Scoliosis: lower limb asymmetries during the gait cycle

Background

Several studies indicate that the gait pattern of subjects suffering from scoliosis differs from the norm. However, there is conflicting evidence regarding the source of this discrepancy.

Objective

To evaluate lower limb asymmetries in selected gait variables.

Study design

A case–control study on lower limb asymmetries during gait which can be related to scoliosis.

Methods

31 subjects with scoliosis (Study Group - SG) and an equal comparative control sample (Control Group – CG) of subjects underwent objective gait analysis with the Vicon® motion caption system whilst walking at a comfortable speed along the gait laboratory walkway. Analysis was performed at three levels: (1) Asymmetry in the SG against asymmetry in the CG, (2) Difference in magnitude of asymmetry between the SG and CG, and (3) Global mean values in the SG vs. CG. The Paired Student T-Test was used for intra-group analysis whilst the Independent Student T-Test was used for inter-group analysis of the selected parameters, which include temporal parameters (stride length, stride time, step length, individual step speed, speed of gait, cadence, swing-to-stance ratio), ground reaction force (peak GRF values during Loading and Propulsion phases, vertical component only) and electromyography (peak EMG values and their time of onset, as a percentage of the gait cycle) of two lower limb muscles (Gastronemius and Vastus Medialis).

Results

No intra-group variation was found to be significant. However, the speed of gait was found to be significantly slower (p = 0.03) in scoliotic subjects when compared to the norm, as a result of the shorter stride length (p = 0.002 and longer stride time (p = 0.001) in the SG. Furthermore, there was statistical significance in the time of onset of EMG peaks for the Lateral Gastrocnemius (p = 0.02) with regards to inter-group difference in magnitude of lower limb asymmetry and global mean values.

Conclusions

Scoliosis is a tri-planar deformity which has some impact on the gait pattern. This research study concludes that scoliotic subjects have a slower speed of gait due to a shorter stride length and a longer stride time, together with variations in the timing of muscle activation.

Scoliosis: lower limb asymmetries during the gait cycle

Background

Several studies indicate that the gait pattern of subjects suffering from scoliosis differs from the norm. However, there is conflicting evidence regarding the source of this discrepancy.

Objective

To evaluate lower limb asymmetries in selected gait variables.

Study design

A case-control study on lower limb asymmetries during gait which can be related to scoliosis.

Methods

31 subjects with scoliosis (Study Group - SG) and an equal comparative control sample (Control Group - CG) of subjects underwent objective gait analysis with the Vicon® motion caption system whilst walking at a comfortable speed along the gait laboratory walkway. Analysis was performed at three levels: (1) Asymmetry in the SG against asymmetry in the CG, (2) Difference in magnitude of asymmetry between the SG and CG, and (3) Global mean values in the SG vs. CG. The Paired Student T-Test was used for intra-group analysis whilst the Independent Student T-Test was used for inter-group analysis of the selected parameters, which include temporal parameters (stride length, stride time, step length, individual step speed, speed of gait, cadence, swing-to-stance ratio), ground reaction force (peak GRF values during Loading and Propulsion phases, vertical component only) and electromyography (peak EMG values and their time of onset, as a percentage of the gait cycle) of two lower limb muscles (Gastronemius and Vastus Medialis).

Results

No intra-group variation was found to be significant. However, the speed of gait was found to be significantly slower (p = 0.03) in scoliotic subjects when compared to the norm, as a result of the shorter stride length (p = 0.002 and longer stride time (p = 0.001) in the SG. Furthermore, there was statistical significance in the time of onset of EMG peaks for the Lateral Gastrocnemius (p = 0.02) with regards to inter-group difference in magnitude of lower limb asymmetry and global mean values.

Conclusions

Scoliosis is a tri-planar deformity which has some impact on the gait pattern. This research study concludes that scoliotic subjects have a slower speed of gait due to a shorter stride length and a longer stride time, together with variations in the timing of muscle activation.

Gait behaviors as an objective surgical outcome in low back disorders: A systematic review

BACKGROUND

Objective motor performance measures, especially gait assessment, could improve evaluation of low back disorder surgeries. However, no study has compared the relative effectiveness of gait parameters for assessing motor performance in low back disorders after surgery. The purpose of the current review was to determine the sensitive gait parameters that address physical improvements in each specific spinal disorder after surgical intervention.

METHODS

Articles were searched with the following inclusion criteria: 1) population studied consisted of individuals with low back disorders requiring surgery; 2) low back disorder was measured objectively using gait assessment tests pre- and post-surgery. The quality of the selected studies was assessed using Delphi consensus, and meta-analysis was performed to compare pre- and post-surgical changes.

FINDINGS

Thirteen articles met inclusion criteria, which, almost exclusively, addressed two types of spinal disorders/interventions: 1) scoliosis/spinal fusion; and 2) stenosis/decompression. For patients with scoliosis, improvements in hip and shoulder motion (effect size=0.32-1.58), energy expenditure (effect size=0.59-1.18), and activity symmetry of upper-body muscles during gait were present after spinal fusion. For patients with spinal stenosis, increases in gait speed, stride length, cadence, symmetry, walking smoothness, and walking endurance (effect size=0.60-2.50), and decrease in gait variability (effect size=1.45) were observed after decompression surgery.

INTERPRETATION

For patients with scoliosis, gait improvements can be better assessed by measuring upper-body motion and EMG rather than the lower extremities. For patients with spinal stenosis, motor performance improvements can be captured by measuring walking spatio-temporal parameters, gait patterns, and walking endurance.

Are the mediolateral joint forces in the lower limbs different between scoliotic and healthy subjects during gait?

Introduction

The quantification of internal joint efforts could be essential in the development of rehabilitation tools for patients with musculo-skeletal pathologies, such as scoliosis. In this context, the aim of this study was to compare the hips joint mediolateral forces during gait, between healthy subjects and adolescents with left lumbar or thoracolumbar scoliosis (AIS), categorized by their Cobb angle (CA).

Material and methods

Twelve healthy subjects, 12 AIS with CA between 20° and 40° and 16 AIS in pre-operative condition (CA : > 40°) walked at 4 km/h on an instrumented treadmill. The experimental set-up include six infrared cameras allow the computation of the tridimensional (3D) angular displacement and strain gauges located under the motor-driven treadmill allow the computation of ground reaction forces (GRF). The hips joint mediolateral forces were calculated using a 3D inverse dynamic of human body. One-way ANOVA was performed for the maximum, the minimum and the range of medio-lateral forces at each joint of the lower limbs. When appropriate, a Tukey's post hoc was performed to determine the differences.

Results

The mediolateral forces were significantly lower at the right hip for AIS with CA between 20° and 40° compared to healthy subject.

Conclusion

The spinal deformation leads to a reduced medio-lateral force at the right hip, which could gradually change the scheme of postural adjustments for AIS during gait. Further research on the quantification of the joint lower limb efforts should include the knee and ankle joints to evaluate the impact of spinal deformation on the lower limb dynamic behaviour in AIS patients.

Do postoperative radiographically verified technical success, improved cosmesis, and trunk shift corroborate with patient-reported outcomes in Lenke 1C adolescent idiopathic scoliosis?

PURPOSE

To examine correlation between postoperative radiographic and cosmetic improvements in Lenke 1C adolescent idiopathic scoliosis (AIS) with patients' self-rated outcomes of health and disability at follow-up as determined by the Scoliosis Research Society questionnaire (SRS-30), Oswestry Disability Index score (ODI) and measure of overall health quality Euroqol-5d (EQ-5D).

METHODS

24 Lenke 1C scoliosis patients, mean age 16.5 (12.8-38.1) years, treated with posterior pedicle screw-only construct, were included. The coronal profile indices (radiographic and cosmetic) regarding magnitude of spinal deformity and truncal balance were measured preoperatively, postoperatively and at final follow-up. A comprehensive index of overall back symmetry was also measured by means of the Posterior Trunk Symmetry Index (POTSI). Pearson's correlation analysis determined the association between the radiographic-cosmetic indices and patient-rated outcomes.

RESULTS

Mean follow-up for the cohort was 4.4 (±1.86) years. The thoracic apical vertebra-first thoracic vertebra horizontal distance (AV-TI) correction had significant correlation with function, self-image, and mental health SRS-30 scores (0.55, 0.54, 0.66). Similarly, thoracic apical vertebra horizontal translation from central sacral vertical line (AV-CSVL) correction at follow-up had significant correlation with self-image and management domains (0.57, 0.50). Follow-up POTSI correlated well with SRS-30 and EQ-5D scores (r = -0.64, -0.54). Postoperative leftward trunk shift/spinal imbalance did not influence overall cosmesis and outcomes; significant spinal realignment was evident in follow-up resulting in physiological balance and acceptable cosmesis and outcomes.

CONCLUSION

Significant, but less than "perfect" correlations were observed between the radiographic, cosmetic measures and patient-rated outcomes. Thoracic AV-CSVL, AV-T1 correction and POTSI associated significantly with SRS-30 scores. Whereas, thoracic Cobb angle, Cobb correction, and coronal balance did not correlate with any patient-rated outcome measure. It is, therefore, inferred that the patients-rated subjective outcomes are only poorly reflected by the objectively measured radiographic and cosmetic measures of deformity correction.

Gait stability improvement after fusion surgery for adolescent idiopathic scoliosis is influenced by corrective measures in coronal and sagittal planes

To achieve optimal results after fusion for adolescent idiopathic scoliosis (AIS), radiographic parameters must be aligned with motion and performance. The effects of fusion on balance are poorly understood. Center of mass (COM) excursion and instantaneous interaction with center of pressure (COP) provides information about patients' balancing ability during gait. This study investigates the interaction between COM and COP (COM-COP) in AIS patients before and one year after spine fusion and determines what radiographic goals predict restoration of harmonious COM-COP. This was a prospective study that investigated sixteen adolescents with AIS curvature >30˚ requiring surgical correction. Clinical outcomes measures, X-rays, and 3D motion-capture gait analysis were collected. Sagittal and coronal COM and COP offsets and inclination angles were calculated from positional data. COM excursion was calculated as peak COM displacement based on mediolateral and vertical deviation from a line fitted to the patient's path. Radiographic parameters were measured to determine variables predictive of change in COM excursion. Post-operatively, average COM peak displacement decreased (42.6 to 13.1 mm, p=0.001) and COM peak vertical displacement remained unchanged (17.0 to 16.3 mm, p=0.472). COM-COP inclination angles reduced in the coronal, but not sagittal plane. Coronal lower extremity peak inclination angles reduced (8.8˚ to 7.5˚, p=0.025), correlating with C7 plumb-line offset (R=0.581, p=0.018). Thoracic Cobb, thoracic kyphosis, and C7 plumb-line were predictors of change in COM excursion. Mediolateral COM excursion post-surgery may reflect an attempt to reduce kinetic demands with improved spinal alignment. Although AIS correction has historically focused on the coronal plane, sagittal parameters may be more important for motion than previously theorized.

Effect of long-term orthotic treatment on gait biomechanics in adolescent idiopathic scoliosis

BACKGROUND CONTEXT

A previous study showed subtle biomechanical changes in the gait of unbraced adolescent idiopathic scoliosis (AIS) patients such as a reduction of pelvic, hip, knee, and ankle displacements. However, lumbopelvic muscles' timing activity was bilaterally increased during gait and correlated to excessive oxygen consumption as compared with healthy subjects. Usually, a brace, when indicated, is worn strictly for 22 hours every day in skeletally immature idiopathic scoliotic girls. To our knowledge, no study has assessed the long-term brace effect (6 months) on functional activities such as level walking.

PURPOSE

To assess the stiffening effects of 6 months' brace wearing on instrumented gait analysis in girls with thoracolumbar/lumbar adolescent idiopathic scoliosis.

STUDY DESIGN/SETTING

Clinical prospective study.

PATIENT SAMPLE

Thirteen girls diagnosed as progressive adolescent idiopathic scoliosis with left thoracolumbar/lumbar curves (curves ranging 25°-40°).

OUTCOME MEASURES

All patients underwent a radiographic and instrumented gait analysis, including assessment of kinematics, mechanics, electromyography (EMG), and energetics of walking.

METHODS

The scoliotic girls were prospectively studied at S1 (before bracing) and 6 months later at S2 (out-brace: treatment effect). The gait parameters were compared with those of 13 matched healthy girls. A t paired test was conducted to evaluate the effect of the 6-month orthotic treatment in AIS girls. Student t test was performed to compare the scoliotic group at S2 and the healthy subjects to identify if the observed changes in gait parameters meant improvement or worsening of gait.

RESULTS

After 6 months of orthotic treatment in AIS, thoracolumbar/lumbar curves and apical rotation remained reduced by 25% and 61%, respectively. During gait, frontal pelvis and hip motions were significantly increased. Muscular mechanical work increased becoming closer but still different as compared with healthy subjects. Bilateral lumbopelvic muscles were almost 40% more active in AIS at S1 compared with healthy subjects and did not change at S2 except for the erector spinae muscles EMG activity, which decreased significantly. Energy cost exceeded by 30% in AIS at S1 compared with healthy subjects and did not change at 6 months' follow-up.

CONCLUSIONS

After 6 months of orthotic treatment, in an out-brace situation, the main structural thoracolumbar/lumbar curve remained partly corrected. Frontal pelvis and hip motion increased, contributing to an improvement of muscular mechanical work during walking. EMG activity duration of lumbopelvic muscles did not change except for the erector spinae muscles, which was decreased but without any beneficial change in the energy cost of walking. In summary, brace treatment, after 6 months, did not significantly influence the gait variables in AIS girls deleteriously, but did not reduce the excessive energy cost, which was 30% above the values of normal adolescents.

Three-dimensional spinopelvic relative alignment in adolescent idiopathic scoliosis

STUDY DESIGN

Three-dimensional (3D) analysis of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To study the 3D pelvic alignment with respect to the spinal deformities in AIS subgroups.

SUMMARY OF BACKGROUND DATA

Spinopelvic alignment is subject to change in scoliosis. Many sacropelvic parameters were developed to characterize spinopelvic alignment in the sagittal plane. However, not much is known about the 3D pelvic alignment with respect to the thoracic and lumbar spinal deformities in AIS.

METHODS

Eighty AIS subjects with right main thoracic (MT), 80 AIS with left thoracolumbar/lumbar (TL/L) curves, and 35 asymptomatic controls were included. Thoracic and lumbar Cobb angles, kyphosis, lordosis, pelvic incidence, pelvic tilt, and sacral slope were measured. Pelvic tilt and axial rotation in the coronal and transverse planes, respectively, were computed using the ipsilateral anterior superior iliac spine and posterior superior iliac spine positions. Leg length discrepancy was determined by the vertical difference in the position of the center of the femoral heads in the coronal plane.

RESULTS

In 59% of the MT subjects and 79% of the TL/L subjects in the erect position, the pelvis was tilted toward the convex side of the major curve in the coronal plane. The direction of the pelvic axial rotation in the transverse plane was in the same direction as the MT apical vertebra rotation in 84% of the MT subjects and 55% of the TL/L group. The pelvic incidence correlated to the lumbar lordosis in AIS (r = 0.41, P < 0.001). Pelvic coronal tilt correlated significantly to the leg length discrepancy in MT (r = 0.67) and TL/L (r = 0.61) subjects (P < 0.001).

CONCLUSION

Novel pelvic parameters were introduced to characterize the spinopelvic relative alignment in scoliotic subgroups. The proposed method related the orientation of the pelvis in the coronal and transverse planes to both thoracic and lumbar spinal deformities.

Head and trunk mass and center of mass position estimations in able-bodied and scoliotic girls

Anthropometric tables are not applicable to calculate the scoliotic trunk mass and center of mass (COM). The purposes of this study were: (1) to estimate the head and trunk mass and COM in able-bodied and scoliotic girls using a force plate method, (2) to estimate head and trunk COM offset compared to those of the body, and (3) the use of mean ratios to estimate the head and trunk COM calculated in this study and that calculated according to a conventional three-dimensional (3D) method compared to the measured values. Twenty-one scoliotic and twenty able-bodied girls participated. The subjects stood upright with arms beside the trunk on a force plate that collected data at 60 Hz for a period of 5s. The anteroposterior and mediolateral positions of the body COM were obtained from the mean center of pressure values. The height of the body COM was estimated by the reaction board method. Afterwards a body segment was displaced and changes in force plate readings were recorded and applied to estimate the head and trunk mass and COM. Trunk offset was defined as the difference between the COM of the body and head and trunk. The measured head and trunk COM was compared to values obtained by the mean ratios calculated from this study and given by the conventional 3D method. The relative head and trunk mass and the anteroposterior trunk offset were larger in scoliotic girls. The force plate method gave similar results to measured COM values for both groups underlying its capability to provide a more accurate estimation of COM related values. Thus, the use of mean ratios of 0.5538 and 0.6438 obtained in this study to estimate the head and trunk mass and COM position in scoliotic girls can overcome the main drawbacks of current anthropometric methods, if direct measurements cannot be taken.

Very short-term effect of brace wearing on gait in adolescent idiopathic scoliosis girls

PURPOSE

Adolescent idiopathic scoliotic (AIS) deformity induces excessive oxygen consumption correlated to a bilateral increase of lumbo-pelvic muscles timing activity (EMG) during gait. Wearing a brace, the usual treatment for AIS, by supporting the spine and the pelvis, would generate lumbo-pelvic muscular relaxation and consequently reduce excessive oxygen consumption. The purpose of this study was to evaluate the short-term effect of bracing on gait biomechanics in scoliotic spine when compared with normal braced spine.

METHODS

Thirteen healthy volunteers were compared to 13 AIS girls. In both samples, gait analysis was assessed using a three-dimensional motion analysis, including synchronous kinematic, electromyographic, mechanical and energy measurements, first without brace, then wearing a brace.

RESULTS

For scoliotic patients, comparison of in-brace and out-brace situations revealed a significant decrease of frontal pelvis (p < 0.001), hip (p < 0.001) and shoulder (p = 0.004) motion in brace associated with a significant reduction of pelvis rotation (p = 0.003). However, the brace did not change significantly the lumbo-pelvic muscle activity duration (EMG) or the mechanical and energetic parameters. Transversal pelvis motion was reduced by 39% (p = 0.04), frontal hip and shoulder motions by 23% (p = 0.004) and 30% (p = 0.01) respectively, and energy cost of walking remained increased by 37% in braced AIS girls relatively to braced healthy subjects. Mechanical and electromyographic variables were not significantly different between the two braced populations during gait except for the gluteus medius muscle that showed bilaterally an increase of duration of electrical activity in healthy subjects and contrarily a decrease in AIS patients (healthy: -3.5 ± 9.6% of gait cycle vs. scoliotic: 3.7 ± 7.7% of gait cycle; p = 0.04).

CONCLUSIONS

Bracing changed neither the oxygen consumption nor the timing of the lumbo-pelvic muscles activity in both groups during gait. However, in brace the timing activity of bilateral gluteus medius muscles tended to decrease in AIS patients and increase in healthy subjects. Moreover, braced AIS patients had more restricted frontal hips and shoulder motion as well as pelvis rotation than braced healthy subjects.

Impact of ankle osteoarthritis on the energetics and mechanics of gait: the case of hemophilic arthropathy

BACKGROUND

Osteoarthritis may affect joints in any part of the body, including the ankle. The purpose of this study was to assess the impact of ankle osteoarthritis on the energetics and mechanics of gait, while taking into account the effect of slower speed generally adopted by patients with osteoarthritis.

METHODS

Using a motion analysis system, synchronous kinematic, kinetics, spatiotemporal, mechanics and metabolic gait parameters were measured in 10 patients diagnosed with ankle osteoarthritis consecutive to hemophilia. The subjects walked at a self-selected speed and their performance was compared to speed-matched normal values obtained in healthy control subjects.

FINDINGS

Speed-normalization using a Z-score transformation showed a significant increase in metabolic cost (Z=1.78; P=0.006) and decrease in mechanical work (Z=-0.97; P=0.009). As a consequence, muscular efficiency also decreased (Z=-0.97; P=0.001). These changes were associated with a surprising efficacy of the pendular mechanism, i.e., an improved recovery index (Z=0.97; P=0.004).

INTERPRETATION

Our findings suggest that patients with ankle osteoarthritis adopt a walking strategy which improves recovery through the pendular mechanism. This may be a compensatory mechanism in order to economize energy which would counterbalance the energy waste due to low muscle efficiency. These modifications are proportional to the impaired ankle function. Our data provides a quantitative baseline to better understand the dynamics of ankle osteoarthritis and determine the individual role that lower limb joints play in the multiple chronic joint affections.

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.

Idiopathic scoliosis and pelvic floor dysfunction

Background: Research suggests that trunk and pelvic floor muscles work as a functional unit for postural and continence activities. Back pain increases the risk of incontinence, and practitioners treating incontinence often treat trunk muscles, while those treating back and sacroiliac problems often incorporate pelvic floor treatments in management programmes. It was hypothesized that women with scoliosis might have pelvic floor dysfunction.

Methods: Pelvic floor function was evaluated in a convenience sample of four nulliparous women with idiopathic scoliosis. Evaluation included scoliometer and perineometer measures, manual muscle testing of the pelvic floor, the Pelvic Floor Distress Inventory-Short Form 20 (PFDI-20), and the Scoliosis Research Society Outcomes Instrument (SRS-22)

Findings: Half the participants reported clinically significant PFDI-20 score elevations. All had back pain, attributed to their scoliosis.

Conclusion: Pelvic floor strength assessments lacked sensitivity in this population of young women, but PFDI-20 scores identified who might benefit from further evaluation. Practitioners treating women with scoliosis should be aware of possible co-existing pelvic floor disorders and of the known link between back pain and incontinence. By raising this issue or using a sensitive tool like the PFDI-20 it may be possible to identify and treat problems early, and implement pelvic floor disorder prevention programmes.

2011 Compendium of Physical Activities: a second update of codes and MET values

PURPOSE

The Compendium of Physical Activities was developed to enhance the comparability of results across studies using self-report physical activity (PA) and is used to quantify the energy cost of a wide variety of PA. We provide the second update of the Compendium, called the 2011 Compendium.

METHODS

The 2011 Compendium retains the previous coding scheme to identify the major category headings and specific PA by their rate of energy expenditure in MET. Modifications in the 2011 Compendium include cataloging measured MET values and their source references, when available; addition of new codes and specific activities; an update of the Compendium tracking guide that links information in the 1993, 2000, and 2011 compendia versions; and the creation of a Web site to facilitate easy access and downloading of Compendium documents. Measured MET values were obtained from a systematic search of databases using defined key words.

RESULTS

The 2011 Compendium contains 821 codes for specific activities. Two hundred seventeen new codes were added, 68% (561/821) of which have measured MET values. Approximately half (317/604) of the codes from the 2000 Compendium were modified to improve the definitions and/or to consolidate specific activities and to update estimated MET values where measured values did not exist. Updated MET values accounted for 73% of all code changes.

CONCLUSIONS

The Compendium is used globally to quantify the energy cost of PA in adults for surveillance activities, research studies, and, in clinical settings, to write PA recommendations and to assess energy expenditure in individuals. The 2011 Compendium is an update of a system for quantifying the energy cost of adult human PA and is a living document that is moving in the direction of being 100% evidence based.

Prospective evaluation of physical activity in patients with idiopathic scoliosis or kyphosis receiving brace treatment

Bracing is an established method of conservative treatment for adolescent idiopathic scoliosis and kyphosis. Compliance among adolescents is frequently inadequate due to the discomfort of wearing a brace, cosmetic issues, and fear on the part of patients and parents that bracing may reduce everyday physical activities. The aim of this prospective, controlled study was to objectify the impact of spinal bracing on daily step activity in patients receiving conservative treatment for adolescent idiopathic scoliosis (AIS) or adolescent kyphosis (AK). Forty-eight consecutive patients (mean age 13.4 ± 2.3 years), consisting of 38 AIS patients (33 girls, 5 boys) and 10 AK patients (6 girls, 4 boys) were included. Once the decision to carry out bracing had been taken and while the patients were waiting for the individual brace to be built, step activity was assessed without braces by means of step activity monitoring (SAM) for seven consecutive days. After 8 weeks of brace wearing, step activity was assessed during regular brace treatment, again for seven consecutive days. In addition, brace-wearing times were simultaneously recorded using temperature probes implanted in the braces to measure compliance. Before and during brace treatment, patients completed the Scoliosis Research Society (SRS-22) questionnaire. The SAM was worn for an average of 12.7 ± 1.5 h/day during the first measurement and 12.3 ± 1.9 h on average during the second measurement. The mean gait cycles (GCs) per day and per hour before treatment were 5,036 ± 1,465 and 395 ± 105, respectively. No significant reduction in step activity was found at the follow-up measurement during bracing, at 4,880 ± 1,529 GCs/day and 403 ± 144 GCs/h. Taking the 23-h recommended time for brace wearing as a basis (100%), patients wore the brace for 72.7 ± 27.6% of the prescribed time, indicating an acceptable level of compliance. Girls showed a higher compliance level (75.6 ± 25.6%) in comparison with boys (56.7 ± 31.9%), although the difference was not significant (P = 0.093). The SRS-22 total score showed no differences between the two measurements (2.57 ± 0.23 vs. 2.56 ± 0.28). Implementing a simultaneous and objective method of assessing step activity and brace-wearing times in everyday life proved to be feasible, and it expands the information available regarding the impact of bracing on patients' quality of life. The results clearly show that brace treatment does not negatively interfere with daily step activity in AIS and AK patients. This is an important finding that should help reduce patients' and parents' worries concerning bracing.

Uncommon features in Cuban families affected with Friedreich ataxia

This report describes two families who presented with autosomal recessive ataxia. By means of Polymerase Chain Reaction (PCR) molecular testing we identified expansions in the gene encoding Frataxin (FTX) that is diagnostic of Friedreich ataxia. A history of reproductive loss in the two families, prominent scoliosis deformity preceding the onset of ataxic gait, the presence of a sensitive axonal neuropathy, as well as the common origin of ancestors are unusual features of these families. These cases illustrate the importance of molecular diagnosis in patients with a recessive ataxia. The origin of the expanded gene and the GAA repeat size in the normal population are issues to be further investigated. The molecular diagnosis of Friedreich ataxia is now established in Cuba.

Gait in thoracolumbar/lumbar adolescent idiopathic scoliosis: effect of surgery on gait mechanisms

For patients whose scoliosis progresses, surgery remains the ultimate way to correct and stabilise the deformity while maintaining as many mobile spinal segments as possible. In thoracolumbar/lumbar adolescent idiopathic scoliosis (AIS), the spinal fusion has to be extended to the lumbar spine. The use of anterior spinal fusion (ASF) instead of the classic posterior fusion (PSF) may preserve more distal spinal levels in attempt to limit the consequences of surgery on trunk mobility. The effects of surgery on body shape, pain and the decompensation phenomenon have all been well evaluated. Very few studies have addressed the effect of ASF or PSF on basic activities, such as walking. Before any treatment, AIS patients already have reduced pelvis, hip and shoulder motion when walking at a normal speed compared with adolescents without scoliosis (control group). Additionally, they have longer contraction time of the lumbar and pelvic muscles leading to an excessive energy cost and reduced muscle efficiency. In addition, if these changes are associated with spinal stiffness, spinal fusion could further negatively affect this pre-surgical inefficient walk. The goals of this study were (a) to compare pre- and 1-year post-surgery conditions in order to assess the effects of spinal arthrodesis on gait parameters and (b) to compare the anterior versus the posterior surgical approaches. Nineteen young females with thoracolumbar/lumbar AIS were assessed by radiological and clinical examination and by conventional gait analysis before surgery and at almost 12 months after surgery. Seven subjects underwent surgery using ASF and 12 using PSF. Three-dimensional gait analysis was performed on a motor-driven treadmill at spontaneous self-selected speed to record kinematic, electromyographic (EMG), mechanical and energetic measurements synchronously. Although it was expected that the instrumentation would modify the characteristics of normal walking, this study showed that surgery does not induce asymmetric gait or any significant differences between the ASP and the PSF surgery groups. One year after surgery, the changes observed consisted of improvements in the gait and mechanical parameters. In the PSF group, 11-14 vertebrae were fused while only 3-4 were fused in the ASF group. In both AIS groups, step length was increased by 4% and cadence reduced by 2%. There was a slight increase in pelvis and hip frontal motion. Only the transverse shoulder motion was mildly decreased by 1.5 degrees . All the other gait parameters were left unchanged or were improved by surgery. Notably, the EMG timing activity did not change. The total muscular mechanical work (W (tot)) increased by 6% mainly due to the external work (W (ext)), i.e. the work performed by the body muscles to move the body in its surroundings. The energy cost, although showing a tendency towards a reduction, remained globally excessive, probably due to the excessive co-contraction of the lumbo-pelvic muscles.