Purpose

The external knee adduction moment during gait has previously been associated with knee osteoarthritis, and although it has been shown to be greater following anterior cruciate ligament (ACL) reconstruction surgery compared to a control group, it has not been compared between different graft types. Given that the incidence of radiographic knee osteoarthritis appears to be greater following patellar tendon compared to hamstring tendon ACL reconstruction, this study tested the hypothesis that the knee adduction moment would also be increased following patellar tendon ACL reconstruction.

Methods

In 48 male participants (16 patellar tendon graft, 16 hamstring graft and 16 controls), the external knee adduction moment was measured during level walking in a gait laboratory at mean of 10 months after surgery.

Results

There was no difference in the knee adduction moment between the hamstring and patellar tendon groups, and both patient groups had a significantly reduced knee adduction moment compared to the control group. In the hamstring group, the smaller adduction moment was associated with the patients walking with less knee varus whereas in the patellar tendon group, the smaller moment was associated with the patients walking with a decreased vertical ground reaction force.

Conclusions

These results indicate that in male patients during the early stages of recovery from ACL reconstruction, the knee adduction moment is not greater than controls for either hamstring or patellar tendon graft types. Although the knee adduction moment was similar between the two graft types, the overall magnitude of the moment was influenced by different biomechanical factors.

Level of evidence

III.

The paper describes an original wearable plantar dynamics analysis system, which puts subjects under particularly unrestraining walking conditions. It is based on foot-pressure distribution measurement in soft, thin, but reliable multisensor soles composed of 2×127 barosensitive cells. The system was applied to gait and posture studies of ten nonpathologic subjects. Specific computing and graphic programs were developed for gait analysis and clinical applications. Online visualisation of footprints allowed the operator to monitor the experiments. Because of human gait variability, data were collected over a prolonged sequence, and a ‘mean step’ was statistically computed, which is more representative of individual walking. Initial graphic and numerical results confirm the value of the method and offer encouragement for further studies intended to define normal or pathologic gait patterns. The system included additional signal inputs for correlative studies with kinematic or physiological parameters.

We present a telemetry system developed for use with a conductive walkway. A transmitter, a receiver, a conductive walkway and a PC with the appropriate software form the entire system, which is used for the assessment of the temporal parameters of gait and the gait speed. The technique is easy to use in routine clinical practice, easily reproducible and commercially available for research laboratories with restricted financial support. The telemetry system was found to be sufficiently accurate and repeatable, and was validated with a group of 20 healthy male adults (mean age, 34 years). The present results are similar to those reported in the literature for an alike group of subjects.

This article is a review of the book “orthopaedic biomechanics” edited by Beth A. Winkelstein. This book (hardcover) was published by CRC Press, Taylor & Francis Group, FL in 2012. The contents of the book and its relevance to orthopedic research or practice is discussed in this invited review.

This paper proposes a novel computer vision approach that processes video sequences of people walking and then recognises those people by their gait. Human motion carries different information that can be analysed in various ways. The skeleton carries motion information about human joints, and the silhouette carries information about boundary motion of the human body. Moreover, binary and gray-level images contain different information about human movements. This work proposes to recover these different kinds of information to interpret the global motion of the human body based on four different segmented image models, using a fusion model to improve classification. Our proposed method considers the set of the segmented frames of each individual as a distinct class and each frame as an object of this class. The methodology applies background extraction using the Gaussian Mixture Model (GMM), a scale reduction based on the Wavelet Transform (WT) and feature extraction by Principal Component Analysis (PCA). We propose four new schemas for motion information capture: the Silhouette-Gray-Wavelet model (SGW) captures motion based on grey level variations; the Silhouette-Binary-Wavelet model (SBW) captures motion based on binary information; the Silhouette–Edge-Binary model (SEW) captures motion based on edge information and the Silhouette Skeleton Wavelet model (SSW) captures motion based on skeleton movement. The classification rates obtained separately from these four different models are then merged using a new proposed fusion technique. The results suggest excellent performance in terms of recognising people by their gait.

A method of gait analysis was used to estimate the loads in the knee joint. An analysis was made of the repeatability of the measurements for a group of 72 patients. Data from 418 patients were reviewed to show the variation with coronal angle of the knee of the loading.

The application of deep brain stimulation (DBS) to the pedunculopontine tegmental nucleus (PPTg) has required profound modifications of classic neurosurgical techniques and of the criteria for evaluation of clinical results. This review analyzes a novel method of targeting the PPTg, based on angio-computerized tomography (angio-CT) scans and the tridimensional reconstruction of nuclei and cerebral vessels, and considers the advantages of applying these methods in comparison to the more traditional approach based on reference points obtained through the evaluation of the bicommessural line. Validation of the results obtained following unilateral PPTg DBS through neurophysiological recordings and objective measurements of functional parameters suggests that the PPTg may be considered as an initial target for the treatment of motor symptoms in selected patients affected by idiopathic Parkinson’s disease (PD), which, if required, could be followed by DBS of other target areas. Moreover, on the basis of the observations derived from stimulating the PPTg, the potential utility attributed up to date to intraoperative neurophysiological recordings for identifying neurosurgical targets should be revisited, and the need for changes in the intraoperative management of patients has arisen from the body of evidence accumulated over recent years. The results obtained by different groups following PPTg DBS in parkinsonian patients are not uniform, most likely due to a cautious acceptance of this methodology, the experience progressively acquired, the criteria for patient selection and to subtle differences in target location. Although the role of PPTg in PD and/or in other pathologies remains to be clarified, pursuing the traditional approach on classical basal ganglia targets may limit the perspective of DBS based on multiple implantations.

Objective

To investigate the clinical outcome and gait analysis findings by dynamic pedobarography in patients following surgically treated single, closed, dislocated intra-articular calcaneal fractures.

Design

Retrospective single-center study with 26 patients. The average follow-up period was 34 months (range 18–61 months). We used the Zwipp score and a score based on a visual analog scale (VAS) to assess the subjective and objective clinical outcome. Dynamic pedobarography (EMED-M, 38 × 42 cm, four sensors per square centimeter, 50 Hz; Novel GmbH., Munich, Germany) was performed to retrieve gait patterns. Analysis was performed using the Emed-Software (Novel GmbH., Munich, Germany).

Results

For the Zwipp score (±200 points), the average was +54.4 points (±48.2); for the VAS score (0–100 points), the average was 58.3 points (±24.3). There was limited mobility in the upper and lower ankle joint. Pedobarography showed a clearly disturbed gait with increased pressure for the fractured side (157 vs. 119 kPa) in the midfoot region (71.8 vs. 68 kPa) and under fifth metatarsal bone (234 vs. 160 kPa). The gait line was lateralized. The force–time-integral (fractured vs. healthy side) showed significant differences for the medial (18 vs. 7 N s) and lateral (61 vs. 36 N s) midfoot region.

Conclusions

We found only an average clinical outcome and clear pathological gait patterns in our cohort with lateralization of the gait line.

The purpose of the present study was to investigate whether different walking patterns in healthy subjects and in coper and non-coper subjects with deficient anterior cruciate ligaments could be quantified. An inverse dynamics approach was used to calculate joint kinematics and kinetics for flexion and extension. EMG signals of the hamstrings and quadriceps muscles were recorded. The results showed that the peak knee flexion angle was greater in the copers than in the controls. There was a positive correlation between the peak knee extensor moment and peak knee flexion angle. Furthermore, at a given peak knee flexion angle, the peak knee extensor moment was significantly larger in the controls than in the non-copers. The hip extensor moment in the copers was significantly larger than that of the non-copers and the controls. In conclusion, the three groups walked according to different patterns. It is suggested that the copers stabilized their knee joint by co-contraction of the hamstrings and quadriceps muscles, while the non-copers lacked this ability. Instead, the non-copers reduced the knee extensor moment in order to decrease anterior displacement of the tibia. The walking pattern differences observed between the copers and non-copers may explain their different post-injury activity levels.

Cerebellar ataxia is associated with unsteady, stumbling gait, and affected patients report a high rate of falls, particularly during locomotor tasks. U-turns (180° turns while walking) require a high level of coordination in order to completely reverse the body trajectory during ongoing motion, and they are particularly challenging for patients with cerebellar ataxia. The aim of this study was to investigate the kinematic strategies adopted by ataxic patients when performing U-turns. Nine ataxic patients and ten controls were analysed as they performed 180° turns to the right while walking. We evaluated the following aspects: centre of mass velocity, body rotation, number of steps needed to complete the task, step length and step width, lower limb joint kinematics and segmental reorientation. Compared with controls, the ataxic patients showed slower deceleration and re-acceleration of the body, needed more steps to complete the U-turn, showed markedly reduced step length and were unable to modulate step width between steps. Furthermore, the patients adopted an extended joint rather than a flexed joint turning strategy, and the degree of knee flexion was found to be negatively correlated with the number of falls. Ataxic patients show an abnormal U-turn in comparison to age-matched healthy subjects. Some of the observed alterations are indicative of a primary deficit in limb-joint coordination, whereas others suggest that patients choose a compensatory strategy aimed at reducing the instability.

Zusammenfassung

Fragestellung. In der vorliegenden Untersuchung wurden zusätzlich zu den klinischen Ergebnissen die der Ganganalyse und EMG-Untersuchungen nach Implantation einer gekoppelten Kniegelenksendoprothese erhoben und miteinander korreliert.

Material und Methode. Nach durchschnittlich 28,5 Monaten (6,5–61,4 Monate) wurden 14 Patienten, deren primäre Kniegelenksprothese mit gekoppelten Kniegelenksprothesen (“Genesis constrained”, “Blauth”) ausgetauscht worden waren, am operierten und nicht-operierten Bein klinisch wie auch mit Ganganalyse und EMG-Ableitungen untersucht und mit einer gesunden Kontrollgruppe verglichen. Die klinische Untersuchung wurde mit dem HSS und Knee-Society-Score, dem Tegner Activity-Score, dem Patella-Score sowie mit der visuellen Analogskala durchgeführt. Die Ganganalyse erfolgte mit einem 3-dimensionalem Bewegungsanalysesystem, die EMG-Ableitungen von den Muskeln M. rectus femoris, M. vastus medialis und lateralis, M. semitendinosus, M. biceps femoris (Caput longum), M. tibialis anterior, M. gastrocnemius (Caput mediale) epikutan.

Ergebnisse. Beim Vergleich mit der Kontrollgruppe zeigten sich deutliche Einschränkungen hinsichtlich der Funktion. Die elektromyographischen Untersuchungen ergaben in der Patientengruppe bei 5 von 7 abgeleiteten EMG-Amplituden der operierten Seite im Vergleich zum Kontrollkollektiv deutlich niedrigere Maximalwerte. In der Ganganalyse fiel der Vergleich zwischen Patienten und Probanden in allen Parametern außer der Kniegelenksextension signifikant unterschiedlich aus, wohingegen zwischen nicht-operierter und operierter Seite der Patienten bei gleichen Untersuchungsparametern nur ein einziger signifikanter Unterschied, nämlich in der Kniegelenksextension deutlich wurde.

Schlussfolgerung. Mögliche Defizite scheinen nicht nur in der Revision einer Totalendoprothese begründet, sondern evtl. schon präoperativ bedingt zu sein. Die besondere Rolle des M. gastrocnemius wird durch die auffallend hohe Korrelation mit den klinischen Ergebnissen unterstrichen und unterstützt die Forderung nach einem ausgeprägten prä- und postoperativen Muskelaufbautraining zur Vermeidung bzw. Reduzierung späterer funktioneller Defizite.

Previous studies suggested that the small fluctuations present in movement patterns from one stride to the next during walking can be useful in the investigation of various pathological conditions. Previous studies using nonlinear measures have resulted in the development of the “loss of complexity hypothesis” which states that disease can affect the variability and decrease the complexity of a system, rendering it less able to adjust to the ever changing environmental demands. The nonlinear measure of the Lyapunov Exponent (LyE) has already been used for the assessment of stride-to-stride variability in the anterior cruciate ligament (ACL) deficient knee in comparison to the contralateral intact knee. However, there is biomechanical evidence that after ACL rupture, adaptations are also present in the contralateral intact knee. Thus, our goal was to investigate stride-to-stride variability in the ACL deficient knee as compared to a healthy control knee. Seven subjects with unilateral ACL deficiency and seven healthy controls walked at their self-selected speed on a treadmill, while three-dimensional knee kinematics was collected for 80 consecutive strides. A nonlinear measure, the largest LyE was calculated from the resulted knee joint flexion-extension data of both groups. Larger LyE values signify increased variability and increased sensitivity to initial conditions. Our results showed that the ACL deficient group exhibited significantly less variable walking patterns than the healthy control. These changes are not desirable because they reflect decreases in system’s complexity, which indicates narrowed functional responsiveness, according to the “loss of complexity hypothesis.” This may be related with the increased future pathology found in ACL deficient patients. The methods used in the present paper showed great promise to assess the gait handicap in knee injured patients.

Background

Falls are among the predominant causes for morbidity and mortality in elderly persons and occur most often in geriatric clinics. Despite several studies that have identified parameters associated with elderly patients’ fall risk, prediction models – e.g., based on geriatric assessment data – are currently not used on a regular basis. Furthermore, technical aids to objectively assess mobility-associated parameters are currently not used.

Objectives

To assess group differences in clinical as well as common geriatric assessment data and sensory gait measurements between fallers and non-fallers in a geriatric sample, and to derive and compare two prediction models based on assessment data alone (model #1) and added sensory measurement data (model #2).

Methods

For a sample of n=110 geriatric in-patients (81 women, 29 men) the following fall risk-associated assessments were performed: Timed ‘Up & Go’ (TUG) test, STRATIFY score and Barthel index. During the TUG test the subjects wore a triaxial accelerometer, and sensory gait parameters were extracted from the data recorded. Group differences between fallers (n=26) and non-fallers (n=84) were compared using Student’s t-test. Two classification tree prediction models were computed and compared.

Results

Significant differences between the two groups were found for the following parameters: time to complete the TUG test, transfer item (Barthel), recent falls (STRATIFY), pelvic sway while walking and step length. Prediction model #1 (using common assessment data only) showed a sensitivity of 38.5% and a specificity of 97.6%, prediction model #2 (assessment data plus sensory gait parameters) performed with 57.7% and 100%, respectively.

Discussion and conclusion

Significant differences between fallers and non-fallers among geriatric in-patients can be detected for several assessment subscores as well as parameters recorded by simple accelerometric measurements during a common mobility test. Existing geriatric assessment data may be used for falls prediction on a regular basis. Adding sensory data improves the specificity of our test markedly.

Many studies have confirmed that gait analysis can be used as a new biometrics. In this research, gait analysis is deployed for people identification in multi-camera surveillance scenarios. We present a new method for viewpoint independent markerless gait analysis that does not require camera calibration and works with a wide range of walking directions. These properties make the proposed method particularly suitable for gait identification in real surveillance scenarios where people and their behaviour need to be tracked across a set of cameras. Tests on 300 synthetic and real video sequences, with subjects walking freely along different walking directions, have been performed. Since the choice of the cameras’ characteristics is a key-point for the development of a smart surveillance system, the performance of the proposed approach is measured with respect to different video properties: spatial resolution, frame-rate, data compression and image quality. The obtained results show that markerless gait analysis can be achieved without any knowledge of camera’s position and subject’s pose. The extracted gait parameters allow recognition of people walking from different views with a mean recognition rate of 92.2% and confirm that gait can be effectively used for subjects’ identification in a multi-camera surveillance scenario.

We have developed a new long leg brace fitted with a computer-controlled knee joint that allows the user to go up and down a slope and stairs. Using this new brace, we analyzed gait under various conditions in ten normal men in terms of dynamic electromyography. Walking up a slope with normal step produced discharges in the leg muscles other than the gastrocnemius lateral head before and after the heel-strike on the ground, which indicated the absorption of the impact of landing. Going down a slope with controlled step resulted in lower activities of the tibialis anterior and the gastrocnemius lateral head than doing so with non-locked step or locked step. In subjects walking up stairs with tandem gait, the large discharges of the gastrocnemius lateral head that were observed in the late stance phase with normal step disappeared when the brace was applied. These results indicated that the muscle activity levels decreased during controlled walking with this new brace, and that the new brace can compensate for reduced muscle strength of the lower leg during walking. Kinematic analysis of walking revealed no significant difference between normal walking and controlled walking under any walking conditions.

Background

It is difficult to identify objective parameters for assessing the joint function when dealing with the evaluation of orthopaedic procedures, especially endoprosthetic hip replacement. Clinical gait analysis enables parameters of force and movement to be quantified. However, the influence of gait speed on these parameters has hardly been taken into consideration so far. The objective of the present study was therefore to investigate the effect of gait speed on gait parameters and to simplify the clinical conditions in patients with osteoarthritis of the hip by determining a standardised gait speed.

Methods

A total of 28 patients with severe unilateral osteoarthritis of the hip were investigated at different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable treadmill with force plates and an infrared video system. A special control mechanism permitted adjustment of the treadmill speed to a patient's self-determined pace.

Results

The mean gait speed of all patients with osteoarthritis of the hip was set at 2.20 km/h (0.61 m/s). Eight of the 10 gait parameters assessed increased significantly with changing gait speed. Pathological changes in gait patterns were found at the three gait speeds investigated, with the changes more accentuated at higher speeds.

Conclusions

Dependence of gait parameters on gait speed could be concluded for a group of patients and for control subjects. Use of a force-instrumented treadmill is necessary for the setting of a standard gait speed, which should be set as high as achievable by patients without inducing pain and problems of coordination or balance. With the usage of standardised speeds, clinical gait analysis becomes easier to perform. Furthermore, one can assess the expected biomechanical advantages of newer prostheses, thus providing the surgeon with a basis for further decisions.

In a prospective experimental study the level gait activity scores of the iliocostalis lumborum, glutaeus medius, tensor fasciae latae, vastus lateralis and peronaeus longus muscles of both body sides were examined by computerized electromyography in 23 patients with idiopathic scoliosis before and after CD instrumentation. The pre- and postoperative findings were examined as to asymmetric patterns in muscle requisition during gait and the respective changes induced by the spinal correction. These results were compared with the corresponding results obtained in healthy subjects in two independent sessions with identical experimental conditions. A muscle activity asymmetry coefficient was defined to quantify the degree of left/right muscle activation asymmetry observed. Postoperatively a statistically significant reduction (P < 0.05) of a preoperatively strongly increased activity was found in the lumbar muscles of the convex side of double major scolioses as well as in the glutaeus medius and tensor fascia lata muscles of the concave side of thoracic curvatures. Both the casuistic and statistical analysis of the results of our study support the hypothesis that activity asymmetries observed in the paravertebral musculature in idiopathic scoliosis patients are the result of the scoliotic body deformities, with consequent asymmetries in the biomechanical force patterns of body postures and body motions, rather than an aetiological factor of scoliotic curvatures.

The aim of the research was to evaluate the results of NDT-Bobath method in gait re-education of adult patients after ischemic stroke using normalized parameters of gait. The investigation group consisted of 60 patients, all sufferers of an ischemic stroke, and participated in a rehabilitation program: 10 sessions of NDT-Bobath therapy through 2 weeks (ten days of the therapy). Normalized parameters of gait were calculated based on anthropometric measures of patients and their gait parameters (gait velocity, cadence and stride length) measured in every patient on admission (before the therapy) and after the last session of the therapy to assess rehabilitation effects. Results among patients involved in the research were as follows:

in normalized gait velocity: recovery in 42 cases (70 %), relapse in 10 cases (16,67 %), no measurable changes in 8 cases (13.33 %)

in normalized cadence: recovery in 39 cases (65 %), relapse in 16 cases (26.67 %), no measurable changes in 5 cases (8.33 %)

in normalized stride length: recovery in 50 cases (83.33 %), relapse in 4 cases (6.67 %), no measurable changes in 6 cases (10 %).

Observed statistically significant and favourable changes in health status of patients, described by normalized gait parameters, confirm effectiveness of the NDT-Bobath method.

In subcortical vascular encephalopathy (SVE) gait disturbance is a common and early clinical sign which might be used to monitor disease progression. In the absence of reliable scales and with regard to the equivocal results of highly complex gait imaging devices we assessed the natural course of SVE in a prospective study, using a new straight forward technique to quantify and compare sequential gait studies. We report the results of 300 computerized gait analyses in 119 patients with SVE and 63 age-matched controls. Thirty-nine SVE patients were re-evaluated to monitor the natural course of the disease and to study the correlation of gait disturbances with MRI changes and neuropsychological findings. The system consists of a set of shoes containing 16 load sensors and a measuring-unit reading each sensor at 20-ms intervals. By off-line analysis we graded each recording on a Gait Disorder Score (GDS) with six variables indicating gait steadiness: step frequency, length of gait lines (which represent the movement of the centre of gravity during heel to toe movement), length of single support lines, variability of single and of double support lines, and double support time. In cross-sectional analysis, patients with SVE showed cadence (steps/min) to be reduced at 87.3±19.5 (96.4±7.8 in controls, P < 0.05). Length of gait lines was significantly less: 0.70±0.13 vs. 0.80±0.05 in controls, with length of single support gait lines reduced at 0.42±0.14 in SVE (0.58±0.06 in controls, P < 0.05). Variability of both single support lines (5.69±1.90%; 4.24±1.07% in controls, P < 0.05) and double support lines was elevated (3.59±1.62% vs. 2.54±0.59%), while duration of double support phases was increased (0.19±0.10 s vs. 0.13±0.02 s in controls, P < 0.05). The progressive character of the disease was demonstrated by increasing GDS values in 39 SVE patients with a frontal gait disorder who were re-investigated after a mean interval of 26 months (5.4±4.5 vs. 8.4±5.5, P < 0.05). This study shows the value of a new and practicable gait analysis system for the evaluation of gait disorders and it quantifies the deterioration of gait in SVE patients.

Purpose

The aim of this study was to evaluate weight-bearing distribution in patients with bilateral end-stage knee osteoarthritis (OA) and to clarify the gait parameters affecting the weight-bearing distribution during both standing and walking using gait analysis.

Methods

Twenty-five patients (averaged 71 years) with symptomatic bilateral end-stage medial knee OA participated in this study. They performed relaxed standing, placing one foot on a force plate and thereafter, level walking. First, knee resultant force was calculated on bilateral knees during standing. The knees in each patient were divided into Higher and Lower force side for the definition of dominant side limb. Second, gait parameters in each subject were compared between both sides.

Results

Each patient had large weight-bearing asymmetry, though passive range of motion, subjective pain level, femorotibial angle and radiographic disease severities were not significantly different between both sides. In standing, knees on Higher force side were significantly extended (11.2 ± 6.5°) than on Lower force side (14.4 ± 7.3°, P = 0.0086). Similarly, knees on Higher force side were also significantly extended at heel strike during gait. Besides, peak values of extension moment, knee adduction moment, knee adduction moment impulse and vertical force during gait were significantly greater on Higher force side.

Conclusions

Ability to extend the knee in standing was considered to be an essential factor to decide loading condition. It is clinically important to examine the ability to extend the knee in standing when considering loading asymmetry during gait in patients with bilateral knee OA.

Level of evidence

III.

The hypothesis that Pygmies may differ from Caucasians in some aspects of the mechanics of locomotion was tested. A total of 13 Pygmies and 7 Caucasians were asked to walk and run on a treadmill at 4–12 km · h⁻¹. Simultaneous metabolic measurements and three-dimensional motion analysis were performed allowing the energy expenditure and the mechanical external and internal work to be calculated. In Pygmies the metabolic energy cost was higher during walking at all speeds (P < 0.05), but tended to be lower during running (NS). The stride frequency and the internal mechanical work were higher for Pygmies at all walking (P < 0.05) and running (NS) speeds although the external mechanical work was similar. The total mechanical work for Pygmies was higher during walking (P < 0.05), but not during running and the efficiency of locomotion was similar in all subjects and speeds. The higher cost of walking in Pygmies is consistent with the allometric prediction for smaller subjects. The major determinants of the higher cost of walking was the difference in stride frequency (+9.45, SD 0.44% for Pygmies), which affected the mechanical internal work. This explains the observed higher total mechanical work of walking in Pygmies, even when the external component was the same. Most of the differences between Pygmies and Caucasians, observed during walking, tended to disappear when the speed was normalized as the Fronde number. However, this was not the case for running. Thus, whereas the tested hypothesis must be rejected for walking, the data from running, do indeed suggest that Pygmies may differ in some aspects of the mechanics of locomotion.

A method has been introduced in this paper to measure the kinematics of a knee joint and to use it as a boundary condition to model the knee’s mechanical behaviour. A mobile C-Arm fluoroscopy system (Ziehm Vision R) and a CCD camera were used for the measurement of a patient’s knee kinematics. The fluoroscopic images were recorded with 12 fps and then sent to Matlab software (Mathworks, Natick, MA, USA) for image processing. In parallel, CT scan images of the knee bones were used to create the 3D anatomical geometry of the knee by aid of Mimics software (Materialise NV). However, the geometrical model of the two medial and lateral menisci was generated from MRI data. The 3D geometrical model of the knee was then sent to Abaqus finite element software (Simulia Dassault Systems) to analyse the knee joint contact loads by introducing the boundary condition which was obtained from fluoroscopic images. The finite element model was used to evaluate the stress distribution on the cartilages during the gait. The result was then compared with the experimental data of gait analysis. The comparison between the results showed a close agreement between the two outcomes.

In this paper, a new approach is proposed for extracting human gait features from a walking human based on the silhouette images. The approach consists of six stages: clearing the background noise of image by morphological opening; measuring of the width and height of the human silhouette; dividing the enhanced human silhouette into six body segments based on anatomical knowledge; applying morphological skeleton to obtain the body skeleton; applying Hough transform to obtain the joint angles from the body segment skeletons; and measuring the distance between the bottom of right leg and left leg from the body segment skeletons. The angles of joints, step-size together with the height and width of the human silhouette are collected and used for gait analysis. The experimental results have demonstrated that the proposed system is feasible and achieved satisfactory results.

We present the case of a patient who, after undergoing unilateral total hip arthroplasty (THA), achieved pain reduction in the contralateral hip accompanied by restoration of the radiographic joint space. We conducted gait analysis to clarify the dynamic factors affecting the natural course of osteoarthritis (OA). Our findings revealed that the patient walked with exaggerated adduction of the hip following the contralateral THA, causing substantial regeneration of joint loading.

Gait analysis using 3D motion capture systems provides joint kinematic and kinetic analysis results such as joint relative angles and moments that can be use used to evaluate the degrees of pathological gait patterns. However, the complex data produced using these 3D motion capture systems can only analyzed by experts, because the gait analysis is highly coupled to the kinematics of each joint. Therefore, several Several previous studies using gait analysis have relied on the data compression technique to represent gait deviation from the average normal profiles as a single value. Even though it is important to evaluate gait pathologies at the joint level, all these previous studies have just used a single value to evaluate the pathological gait pattern. Using just one variable for evaluation of a gait is limited in terms of determining which joint movement patterns are getting better during rehabilitation. Therefore, in this study, a method suitable for evaluating gait deviation during a gait was developed to provide three indices for the hip, knee and ankle joints. In addition, to validate the proposed method in clinical cases, experimental tests were conducted on thirty thirty-six normal walkers and six patients with cerebral palsy. Furthermore, to validate the proposed method in regards to rehabilitation, experimental tests were conducted on three classified walking groups with imposed ankle equinus constraints. The JNI for the hip joint, knee joint and ankle were 8.78 (±3.70), 2.92 (±3.25) and 8.79 (±4.38), respectively, in the normal walking group. However, these values were significantly different for the pathological walking group with cerebral palsy. The JNI of the hip joint, knee joint and ankle joint were 203.73 (±171.59), 81.23 (±52.13) and 248.39 (±149.99), respectively, for this group. There were also differences between any two of the three classified groups with imposed ankle equinus constraints. In particular, the JNI of the ankle joint was statistically different at the p<0.01 level, and this parameter clearly increased as the degree of the imposed ankle equinus was increased. These results demonstrate that the proposed JNI can be used as a scalar factor to evaluate the angular deviation of each joint in normal and patient groups. In addition, this approach can be adapted to evaluate rehabilitation and pre/post surgery.

With the increasing interest of using inertial measurement units (IMU) in human biomechanics studies, methods dealing with inertial sensor measurement errors become more and more important. Pre-test calibration and in-test error compensation are commonly used to minimize the sensor errors and improve the accuracy of the walking speed estimation results. However, the performance of a given sensor error compensation method does not only depend on the accuracy of the calibration or the sensor error evaluation, but also strongly relies on the selected sensor error model. The best performance could be achieved only when the essential components of sensor errors are included and compensated. Two new sensor error models, with the concerns about sensor acceleration measurement biases and sensor attachment misalignment, have been developed. The performance of these two error models were evaluated in the shank-mounted IMU-based walking speed/inclination estimation algorithm with a comparison of an existing error model. The treadmill walking experiment, conducted at both level and incline conditions, demonstrated the importance of sensor error model selection on the spatio-temporal gait parameter estimation performance. Accurate walking inclination estimation was made possible with a newly developed sensor error model.

Walking with the knee joint locked increases the amplitude of pelvic tilt and results in an unnatural gait. This paper introduces a powered gait orthosis with a moveable knee joint designed to improve the gait speed of patients with spinal cord injury (SCI). The unlockable knee joint powered gait orthosis (UKJ-PGO) uses a gas spring cylinder and a solenoid locking device to enable flexion of the joint, while the rigidity of the hip-joint device is enhanced using air muscles. A gait analysis was conducted to evaluate the performance of the UKJ-PGO, and the kinematic parameters obtained were compared with those of a standard PGO. In the gait of SCI patients using the UKJ-PGO, the new knee-joint device enabled flexion during the swing phase and showed a decrease in pelvic tilt compared with the standard PGO gait. As greater flexion was possible at the knee joint, the duration of the stance phase substantially decreased to near to the normal value, and the duration of the swing phase increased accordingly. In addition, the gait using the UKJ-PGO was faster than that with the standard PGO.

Gait alterations after ACL reconstruction have been reported in the literature. The current study examined a group of 14 patients who all had an ACL reconstruction with a patellar tendon autograft. Kinetic and kinematic data were obtained from the knee during walking. The flexion-extension deficit (FED) calculated from the angular difference between maximal flexion and maximal extension during the stance phase in the ACL-reconstructed and the normal knee was measured. We investigated whether these alterations in gait are related to quadriceps strength and residual laxity of the knee. It may be that patients modify their gait patterns to protect the knee from excessive anterior translation of the tibia by reducing the amount of extension during stance. On the other hand, persistent quadriceps weakness may also cause changes in gait patterns as the quadriceps is functioning as an important dynamic stabilizer of the knee during stance. Results showed that patients had a significantly higher FED value (4.9±4.0) than a healthy control group in a previous study (1.3±0.9). This is caused mainly by an extension deficit during midstance. External extension moments of the knee (T_ZMAX were significantly lower in the current patients group than in a healthy control group (T_ZMAX −0.27±0.19 Nm/kg in patients vs. −0.08±0.06 Nm/kg in controls). There were no significant correlations between quadriceps strength and gait analysis parameters. Furthermore no correlation was found between the amount of laxity of the knee and gait. The relevance of this study lies in the fact that apparently the measured gait alterations cannot be explained solely by often used biomechanical indicators such as laxity and strength. The measured gait alterations may be a result of the surgical procedure with subsequent modified motor programming.

A protocol named Outwalk was developed to easily measure the thorax–pelvis and lower-limb 3D kinematics on children with cerebral palsy (CP) and amputees during gait in free-living conditions, by means of an Inertial and Magnetic Measurement System (IMMS). Outwalk defines the anatomical/functional coordinate systems (CS) for each body segment through three steps: (1) positioning the sensing units (SUs) of the IMMS on the subjects’ thorax, pelvis, thighs, shanks and feet, following simple rules; (2) computing the orientation of the mean flexion–extension axis of the knees; (3) measuring the SUs’ orientation while the subject’s body is oriented in a predefined posture, either upright or supine. If the supine posture is chosen, e.g. when spasticity does not allow to maintain the upright posture, hips and knees static flexion angles must be measured through a standard goniometer and input into the equations that define Outwalk anatomical CSs. In order to test for the inter-rater measurement reliability of these angles, a study was carried out involving nine healthy children (7.9 ± 2 years old) and two physical therapists as raters. Results showed RMS error of 1.4° and 1.8° and a negligible worst-case standard error of measurement of 2.0° and 2.5° for hip and knee angles, respectively. Results were thus smaller than those reported for the same measures when performed through an optoelectronic system with the CAST protocol and support the beginning of clinical trials of Outwalk with children with CP.

Although there has been much previous research on which bodily features are most important in gait analysis, the questions of which features should be extracted from gait, and why these features in particular should be extracted, have not been convincingly answered. The primary goal of the study reported here was to take an analytical approach to answering these questions, in the context of identifying the features that are most important for gait recognition and gait attractiveness evaluation. Using precise 3D gait motion data obtained from motion capture, we analyzed the relative motions from different body segments to a root marker (located on the lower back) of 30 males by the fixed root method, and compared them with the original motions without fixing root. Some particular features were obtained by principal component analysis (PCA). The left lower arm, lower legs and hips were identified as important features for gait recognition. For gait attractiveness evaluation, the lower legs were recognized as important features.

Chronic musculoskeletal pain affects a large percentage of the general population. Traditional therapies focus on treating the symptoms of pain, yet sometimes fail to address the root of the problem. The purpose of the following case study was to determine whether visual and verbal cues could improve walking gait kinematics and subsequently decrease pain. Ground reaction forces were used as visual feedback for each participant as these represent forces acting on the body during stance phase of walking. Two volunteer participants were chosen to participate in the study; Participant 1 being a 23 year old male experiencing pain due to ankylosing spondylitis for 4.5 years, and Participant 2 being a 36 year old female experiencing 1 year of back pain due to a past ligamentous strain injury. The participants were interviewed, given a Lower Extremity Functionality Scale questionnaire and a Numeric Pain Scale. A gait analysis was performed using a four camera system, AMTI force plate and Vicon Peak Motus 8.2 analysis software to determine gait deviations and develop verbal cues used during gait training sessions to modify gait pattern. Sessions were held twice a week over a four-week period using feedback to achieve a smoother and more natural gait pattern. Following the treatment, significant improvements were found in the Lower Extremity Functionality Scale scores for Participant 1 which increased from 68 to 78 points out of 80, and 53 to 63 points for Participant 2. The Numeric Pain Scale score decreased from 5 to 1 for Participant 1, with Participant 2 following the same trend of a 4.5 to 0.5. The participants reported the intervention was beneficial in creating awareness to correct bad walking habits and contributed toward pain reduction.

The purpose of this study was to select the appropriate input variables for the development of an expert system to analyze the gait asymmetry of patients with idiopathic scoliosis. Gait experiments were performed with 12 healthy female adolescents and 16 female adolescents with untreated adolescent idiopathic scoliosis. The experimental equipment included six infrared cameras and two ground reaction force platforms. By using a 3D human model, gait elements, kinematic and kinetic data were extracted. Self-organizing map and genetic algorithm were used for proper selection of input variables, and these methods were validated by using auto regression models, which were described in previous studies. Sixty gait variables based on a literature review were selected, and Self-organizing map was used to maintain the independency between the input variables, and the 39 independent retaining variables were chosen. Also, in order to identify the inputs exhibiting a significant relationship with the output, a genetic algorithm-general regression neural network was applied; and the frequency of the solution set was measured by genetic algorithm iteration. A stepwise method was applied based on the variables with high frequency, and final 11 input variables were selected. Furthermore, a back propagation artificial neural network with high accuracy 96.3(3.2)%, which can discriminate patients from the normal subjects, was developed with selected 11 input variables. Therefore, the results of this study can be used as input variables for the development of a gait asymmetry expert system.

Human gait is a procedure of learning and maturation; the steady, normal, adult gait pattern is considered to be established after the age of 11 years. This study presents the results accumulated for a group of 20 able-bodied children (10 male) aged 9–10 (mean age 9.5, SD=0.5), who were tested with a portable system using telemetry for temporal factors. These results can serve as reference for the assessment of possible orthopedic disorders in children with similar ages. For the parameter of single support, a systematic difference between the two legs was found for runs with normal speed, which opposes to the symmetric gait pattern of a mature able-bodied population; this difference seemed to disappear in fast gait. However, for the double support, insignificant differences between the two legs were observed in both normal and fast gaits, which opposes to other findings for a similar group of children. Last, the single step duration was significantly different between the two feet only in normal gait.

Recent years there is an extremely growing interest in the study of human motion. A large amount of scientific research projects deal with problems like monitoring human motion, gesture and posture recognition, fall detection etc. Wearable computers and electronic textiles have been successfully used for the study of human physiology, rehabilitation and ergonomics. We present a platform and a methodology for rapid prototype development of e-textile applications for human activity monitoring.

Summary

A comprehensive method of evaluating the feet of patients with adolescent hallux valgus both before and after surgical correction is described. Serial clinical, photographic and radiological studies were made and a dynamic assessment of gait was carried out using a load-sensitive walkway. Observations were made on 36 feet in which hallux valgus was treated by a modification of the Wilson oblique metatarsal osteotomy, with removal of a wedge of bone and screw fixation. In the first six months after operation, there was a lateral shift of the weight-bearing pattern in the forefoot and less weight was taken on the toes, but there was a tendency to return to the pre-operative distribution of weight during the next four years. Persistence of the lateral shift of weight-bearing appeared to result from elevation of the first metatarsal head secondary to shortening of the first metatarsal during the osteotomy. This can be avoided by deliberate depression of the first metatarsal head at the time of operation and fixation of the fragments in the required position with a screw.

A method of joint angle measurement during gait using wearable sensors for rehabilitation was studied in this paper. The method corrected joint angles measured by gyroscopes using joint angles measured by accelerometers with Kalman filter. Although gyroscopes could measure joint angles, their offset drift caused error in measurement of joint angles. At first, we made up small sensor units consist of a gyroscope and an accelerometer. Then, the method was validated with the developed sensor units in measurement of ankle and knee joint angles of three healthy subjects under walking on short distance pathway and on treadmill for long time. The measured joint angles were compared with reference joint angles measured with optical motion measurement system simultaneously. The result for short distance walking showed low RMS errors and high correlation coefficients (3.19deg and 0.918 for the ankle joint, 2.98deg and 0.993 for the knee joint in average). The result for treadmill walking also showed low RMS errors and high correlation coefficients (3.04deg and 0.960 for the ankle, 4.19deg and 0.994 for the knee in average). Although the measurement accuracy decreased in some of trials of a specific subject because of sensor attachment position, the experimental results suggested that joint angle could be measured with good accuracy independent of measurement period of time, walking speeds and subjects.

A portable and wireless activity monitoring system was developed for the estimation of temporal gait parameters. The new system was built using three-axis accelerometers to automatically detect walking steps with various walking speeds. The accuracy of walking step-peak detection algorithm was assessed by using a running machine with variable speeds. To assess the consistency of gait parameter analysis system, estimated parameters, such as heel-contact and toe-off time based on accelerometers and footswitches were compared for consecutive 20 steps from 19 individual healthy subjects. Accelerometers and footswitches had high consistency in the temporal gait parameters. The stance, swing, single-limb support, and double-limb support time of gait cycle revealed ICCs values of 0.95, 0.93, 0.86, and 0.75 on the right and 0.96, 0.86, 0.93, 0.84 on the left, respectively. And the walking step-peak detection accuracy was 99.15% (±0.007) for the proposed method compared to 87.48% (±0.033) for a pedometer. Therefore, the proposed activity monitoring system proved to be a reliable and useful tool for identification of temporal gait parameters and walking pattern classification.

Summary

Gait analysis utilizing foot switches and electromyography of antigravity muscles was performed on 31 patients with vertigo. Twenty-one cases had peripheral vestibular lesions (such as vestibular neuronitis, Meniere's disease, traumatic labyrinthitis, small acoustic neuroma), and 10 cases had central lesions (such as spinocerebellar degeneration, pontine glioma, cerebellar tumor and giant acoustic neuroma). Parameters employed for analysis included time from heel strike to forefoot strike (HA-I), time from heel off to forefoot off (HA-II) as well as durations of stance, swing and (initial) double supports (DS). Fourteen healthy adults served as controls. The overall incidence of abnormality was highest in HA-1, followed by stance and swing. The occurrence of abnormalities in stance, swing and DS was higher in the central lesion when compared with the group having peripheral lesions. The significance and usefulness of gait analysis for dizzy patients are discussed.

Summary

Distal elongation of the hamstrings was performed for contracture due to neurogenic disorders in 66 patients. A follow-up study on 34 of the patients with cerebral palsy is reported here. The success of the operation was judged by functional evaluation including joint measurement and gait analysis. The advantages of this operation and the need for prolonged aftercare are discussed.

We propose a hybrid dynamical model of human motion and develop a classification algorithm for the purpose of analysis and recognition. We assume that some temporal statistics are extracted from the images, and use them to infer a dynamical model that explicitly represents ground contact events. Such events correspond to “switches” between symmetric sets of hidden parameters in an auto-regressive model. We propose novel algorithms to estimate switches and model parameters, and develop a distance between such models that explicitly factors out exogenous inputs that are not unique to an individual or his/her gait. We show that such a distance is more discriminative than the distance between simple linear systems for the task of gait recognition.

Femoral rotational waveforms sampled at 15 Hz for a duration 20 s satisfy the sampling rate and frequency resolution requirements of such waveforms during walking. Spectral analysis provides a unique signature of the frequency composition of such signals. This identity may prove useful in characterising human gait and could be of value in future studies of walking in health and disease.

Cerebral palsy (CP) results from an injury to the developing brain and commonly results in an abnormal gait pattern. Crouch gait is a common gait abnormality associated with CP. The aim of the presented study was to compare kinematics, kinetics and EMG data of CP children walking with a crouched gait with those of aged-matched healthy children and young healthy adults. Gait experiments were performed on two CP children. The main difference in the gait patterns of healthy children and young healthy adults appeared to be in late stance, just before toe off. Children exerted lower torques about the knee and ankle, and they also exerted lower forces on the ground. In crouch gait, the net extensor moment exerted about the hip increased during early stance, which may be due to an increase in the passive force exerted by the hamstrings. Prolonged activity of the biceps femoris and co-contraction with rectus femoris, together with activation of gastrocnemius in late swing, may explain the excessive knee flexion observed in these patients. Early onset of tibialis anterior in the CP patients may also contribute to the reduced amount of ankle plantarflexion observed in these patients.

This paper proposes a system for the early automatic recognition of health problems that manifest themselves in distinctive form of gait. Purpose of the system is to prolong the autonomous living of the elderly at home. When the system identifies a health problem, it automatically notifies a physician and provides an explanation of the automatic diagnosis. The gait of the elderly user is captured using a motion-capture system, which consists of body-worn tags and wall-mounted sensors. The positions of the tags are acquired by the sensors and the resulting time series of position coordinates are analyzed with machine-learning algorithms in order to recognize a specific health problem. Novel semantic features based on medical knowledge for training a machine-learning classifier are proposed in this paper. The classifier classifies the user’s gait into: 1) normal, 2) with hemiplegia, 3) with Parkinson’s disease, 4) with pain in the back and 5) with pain in the leg. The studies of 1) the feasibility of automatic recognition and 2) the impact of tag placement and noise level on the accuracy of the recognition of health problems are presented. The experimental results of the first study (12 tags, no noise) showed that the k-nearest neighbors and neural network algorithms achieved classification accuracies of 100%. The experimental results of the second study showed that classification accuracy of over 99% is achievable using several machine-learning algorithms and 8 or more tags with up to 15 mm standard deviation of noise. The results show that the proposed approach achieves high classification accuracy and can be used as a guide for further studies in the increasingly important area of Ambient Assisted Living. Since the system uses semantic features and an artificial-intelligence approach to interpret the health state, provides a natural explanation of the hypothesis and is embedded in the domestic environment of the elderly person; it is an example of the semantic ambient media for Ambient Assisted Living.

Introduction

The most common implants for treating unstable femoral neck fractures are sliding constructs, which allow postoperative collapse. Successful healing, typically, is a malunion with a shortened femoral neck. Functional sequelae resulting from altered femoral neck biomechanics have been increasingly reported. Re-operation rate due to nonunion, avascular necrosis, hardware cut-out and prominence is high with this treatment modality. We evaluated the outcomes of patients with femoral neck fractures treated with stable calcar pivot reduction, intraoperative compression across the fracture, and stabilization with length-stable implants.

Materials and methods

Fifty-four patients with femoral neck fractures underwent open reduction and internal fixation. Average follow up duration was 23.6 months (range: 15–36 months). There were 23 Garden I, 2 Garden II, 14 Garden III and 15 Garden IV fractures. Reduction was achieved through a modified Smith-Petersen approach. Fractures were compressed initially, and subsequently stabilized with a length-stable device. Post-operative radiographs were assessed for change in fracture alignment. Variation in the femoral neck offset and abductor lever arm measurements was performed using the contralateral hip as control. Functional outcome was assessed using SF-36, Harris Hip Score (HHS) and a gait analysis device. The average patient age was 78 years. Fifty-one (94%) healed without complications. Surgical fixation failed in two patients and one patient developed avascular necrosis. The average femoral neck shortening was 1.7 mm.

Results

The average difference in femoral neck offset and the abductor lever arm measurement at the latest follow up was 3.5 and 1.5 mm respectively. The average score on physical, mental components of SF-36 and HHS was 42 and 47 and 87 respectively. By 6 months, patients on average recovered 94% of the single limb stance time, 98% of cadence, 90% of cycle duration, 96% in stride length compared to the uninjured side.

Conclusion

Reduction with a stable calcar pivot, intraoperative compression and length-stable fixation can achieve high union rates with minimal femoral neck shortening and improved functional outcomes.

Level of evidence

IV, retrospective with historical controls.

Background

Numerous recommendations have been made for treating idiopathic toe-walking (ITW), but the treatment results have been questioned. The purpose of this study was to investigate whether botulinum toxin A (BTX) improves the walking pattern in ITW as examined with 3-D gait analysis.

Participants and methods

A consecutive series of 15 children (aged 5–13 years) were enrolled in the study. The children underwent a 3-D gait analysis prior to treatment with a total of 6 units/kg bodyweight Botox^® in the calf muscles and an exercise program. The gait analysis was repeated 3 weeks and 3, 6, and 12 months after treatment. A classification of toe-walking severity was made before treatment and after 12 months. The parents rated the perceived amount of toe-walking prior to treatment and 6 and 12 months after treatment.

Results

Eleven children completed the 12-month follow-up. The gait analysis results displayed a significant improvement, indicating decreased plantarflexion angle at initial contact and during swing phase and increased dorsiflexion angle during midstance at all post-treatment testing instances. According to the parents’ perception of toe-walking, 3/11 children followed for 12 months had ceased toe-walking completely, 4/11 decreased toe-walking, and 4/11 continued toe-walking. After 6–12 months, the toe-walking severity classification improved in 9 of the 14 children for whom data could be assessed.

Conclusions

A single injection of BTX in combination with an exercise program can improve the walking pattern in children with ITW seen at gait analysis, but the obvious goal of ceasing toe-walking is only occasionally reached.

In this work, image segmentation is addressed as the starting point within a motion analysis methodology intended for rat biomechanics behavior characterization. First, we propose a general segmentation framework that uses interval valued fuzzy sets (IVFSs) to determine the optimal image threshold value. The amplitude values of the IVFSs are used for representing the unknowledge/ignorance of an expert on determining whether a pixel belongs to the background or to the object of the image. Then, we introduce an extension of this methodology that uses a heuristic-based multi-threshold approach to determine the optimal threshold. Experimental results are presented.

Geometric revision reconstruction of the hip joint of a female patient is presented. Because of extensive bone resorption and strong bone obstruction, we decided to employ a custom–made prosthesis not only in the pelvis but also in the femur. The custom prosthesis design and manufacturing processes were carried out with the aid of computed tomography (CT), a system of tomographic image processing, a computer–aided design (CAD) system and a computer–aided manufacturing (CAM) system. The process included tomographic measurements of the patient’s hip joint, conversion of the CT images, geometrical modelling of the femur and pelvis in the CAD system, prostheses design, virtual simulation of the reconstructed acetabulum, determination of prosthesis matching, and manufacturing on a CNC machine. The outcome of this engineering process was a total hip arthroplasty (THA) surgical operation.

Introduction

The goal of this study was to observe scoliotic subjects during level walking to identify asymmetries—which may be related to a neurological dysfunction or the spinal deformity itself—and to correlate these to the severity of the scoliotic curve.

Methods

We assessed the gait pattern of ten females (median age 14.4) with idiopathic scoliosis characterised by a left-lumbar and a right-thoracic curve component. Gait analysis consisted of 3D kinematic (VICON) and kinetic (Kistler force plates) measurements. The 3D-segment positions of the head, trunk and pelvis, as well as the individual joint angles of the upper and lower extremities, were computed during walking and static standing. Calculation of pertinent kinetic and kinematic parameters allowed statistical comparison.

Results

All subjects walked at a normal velocity (median: 1.22 m/s; range:1.08–1.30 m/s; height-adjusted velocity: 0.75 m/s; range: 0.62–0.88 m/s). The timing of the individual gait phases was normal and symmetrical for the whole group. Sagittal plane hip, knee and ankle motion followed a physiological pattern. Significant asymmetry was observed in the trunk’s rotational behaviour in the transverse plane. During gait, the pelvis and the head rotated symmetrically to the line of progression, whereas trunk rotation was asymmetric, with increased relative forward rotation of the right upper body in relation to the pelvis. This produced a torsional offset to the line of progression. Minimal torsion (at right heel strike) measured: median 1.0° (range: 5.1°–8.3°), and maximal torsion (at left heel strike) measured 11.4° (range 6.9°–17.9°). The magnitude of the torsional offset during gait correlated to the severity of the thoracic deformity and to the standing posture, whereas the range of the rotational movement was not affected by the severity of the deformity. The ground reaction forces revealed a significant asymmetry of [Msz], the free rotational moment around the vertical axis going through the point of equivalent force application. On the right side, the initial endo-rotational moment was lower, followed by a higher exo-rotational moment than on the left. All the other force parameters (vertical, medio–lateral, anterior–posterior), did not show a significant side difference for the whole group. The use of a brace stiffened torsional motion. However the torsional offset and the asymmetry of the free rotational moment remained unchanged.

Conclusion

The most significant and marked asymmetry was seen in the transverse plane, denoted as a torsional offset of the upper trunk in relation to the symmetrically rotating pelvis. This motion pattern was reflected by a ground-reaction-force asymmetry of the free rotational moment. Further studies are needed to investigate whether this behaviour is solely an expression of the structural deformity or whether it could enhance the progression of the torsional deformity.

Deterioration of motor neurons due to amyotrophic lateral sclerosis (ALS) would affect the strides from one gait cycle to the next. Computer-assisted techniques are useful for gait analysis, and also have high potential in quantitatively monitoring the pathological progression. In this paper, we applied the signal turns count method to measure the fluctuations in the swing-interval time series recorded from 16 healthy control subjects and 13 patients with ALS. The swing-interval turns count (SWITC) parameter derived with the threshold of 0.06 s presented a significant difference (p < 0.001) between the healthy control subjects and ALS patients. Besides the SWITC, we also computed the averaged stride interval (ASI), which is usually longer in the patient with ALS (p < 0.0001), to characterize the gait patterns of ALS patients. In the pattern classification experiments, the Fisher’s linear discriminant analysis (FLDA) and the least squares support vector machine (LS-SVM), both input with the SWITC and ASI features, were evaluated using the leave-one-out cross-validation method. The results showed that the LS-SVM with sigmoid kernels was able to provide a classification accurate rate of 89.66% and an area of 0.9629 under the receiver operating characteristic (ROC) curve, which were superior to those obtained with the linear classifier in the form of FLDA.