Intrasubject repeatability of gait analysis data in normal and spastic children

Inter-trial and test-retest reliability of kinematic and kinetic gait parameters among subjects with adolescent idiopathic scoliosis

Gait analysis is actually used in subjects with scoliosis to determine the change in lower limb parameters after surgery, but the reliability of these parameters still remained unknown. The purpose of this study was to assess the repeatability of traditional gait parameters in subjects with adolescent idiopathic scoliosis (AIS) and to estimate the associated standard error of measurement (SEM). A test-retest design was used to assess the reliability of gait parameters at self-selected and fast speeds. A convenience sample of 20 girls aged from 12 to 17 years, with an idiopathic scoliosis (King classification: types I, II or III; Cobb angle 17-50 degrees) participated in the study. Five good trials were recorded on two occasions. The time-distance, kinematic, and kinetic gait parameters were recorded using foot-switches in combination with a three-dimensional motion analysis system (Optotrak) and Advanced Mechanical Technologies Inc., (AMTI) Watertown, MA, USA; force plates. The coefficients of dependability and SEM derived from the generalizability theory were used to assess the reliability. Inter-trial reliability was good for time-distance, kinematic, and kinetic (absolute and normalized) gait parameters except for the medio-lateral ground reaction force (GRF) component and the ankle dorsiflexor moment (phi = 0.60-0.77). Test-retest reliability was higher for the kinetic than for the kinematic parameters. These coefficients ranged from 0.42 to 0.58 for the time-distance parameters; from 0.55 to 0.88 for the angular displacements and from 0.25 to 0.99 for the kinetic parameters. The SEMs were lower than 3.3 degrees for the angular displacements and lower than 8 Nm (0.15 Nm/kg) and 36 W (0.54 W/Kg) for the joint moments and powers regardless of the speed. Several gait parameters are reliable among subjects with AIS and can be used to assess the evolution of the spinal modifications and the impact of treatment on their lower limb gait pattern.

Lower extremity kinetics for balance control in children with cerebral palsy

The authors examined and compared the effect of support-surface perturbations of various magnitudes on lower extremity kinetics of 7 children with cerebral palsy (CP) and 8 typically developing (TD) children. Results showed that the highest velocity tolerated without stepping was slower in children with CP than in either age-matched TD or younger TD children. Multimodal torque profiles were more frequent in children with CP than in TD controls. TD groups temporally and spatially organized torque activation, whereas children with CP activated all joints simultaneously and showed altered torque contribution patterns among joints. Those results suggest that impairments in reactive postural control in children with CP result not only from developmental delay but also from pathology. Evidence for pathology included increased numbers of torque bursts required to regain stability and less efficient temporal and spatial organization of torque activation patterns.

Preliminary Evaluation of an Automatically Stance-Phase Controlled Pediatric Prosthetic Knee Joint Using Quantitative Gait Analysis

OBJECTIVES

To evaluate the effects on gait of a new pediatric prosthetic knee joint using an automatic stance-phase lock (ASPL), shown previously to help prevent falls, and to propose future design considerations and prosthetic alignments.

DESIGN

Case series and crossover trial.

SETTING

Human movement laboratory.

PARTICIPANTS

Three children with unilateral above-knee amputations and 3 children with bilateral above-knee or below-knee amputations.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Spatiotemporal, kinematic, and kinetic gait parameters.

RESULTS

Spatiotemporal parameters indicated higher gait velocities with the ASPL knee joint for the children with unilateral amputations. The increased speed, as expected, was associated with increased temporal interlimb asymmetry, joint moments and powers, and excessive prosthetic knee range of motion in swing. A trend toward increased pelvic motions was observed with ASPL knee when compared with conventional knees.

CONCLUSIONS

The biomechanic performance of the single-axis ASPL knee joint was shown to be comparable with more complex polycentric pediatric prosthetic knee joint technologies worn by the children in this study.

The role of gait analysis in the orthopaedic management of ambulatory cerebral palsy

PURPOSE OF REVIEW

The literature was reviewed to describe the role of gait analysis in the orthopaedic management of ambulatory children with cerebral palsy and examine the current best evidence to support these roles.

RECENT FINDINGS

Gait laboratory analysis is superior to visual or observational analysis of gait because it provides an objective record of gait that is able to quantify the magnitude of deviations of pathologic gait from normal and also explain these abnormalities. Recognizable gait patterns can be classified and used for making treatment decisions, the effectiveness of which can be assessed using gait analysis as a measure of gait outcomes. There are many sources of variability, however, including patients themselves, the gait laboratories and testing processes, interpretation of data and surgeons' surgical recommendations.

SUMMARY

Although gait analysis has been shown to alter decision making, there is little evidence that the decisions based on gait analysis lead to better outcomes. Consequently, clinical gait analysis remains controversial, with wide variation in the rates of utilization of gait analysis in the management of children with ambulatory cerebral palsy. The time is ripe for clinical trials and cohort studies to provide the evidence to establish the appropriate utilization of this technology.

Froude number fractions to increase walking pattern dynamic similarities: application to plantar pressure study in healthy subjects

The purpose of this study was to determine if using similar walking velocities obtained from fractions of the Froude number (N(Fr)) and leg length can lead to kinematic and kinetic similarities and lower variability. Fifteen male subjects walked on a treadmill at 0.83 (VS(1)) and 1.16ms(-1) (VS(2)) and then at two similar velocities (V(Sim27) and V(Sim37)) determined from two fractions of the N(Fr) (0.27 and 0.37) so that the average group velocity remained unchanged in both conditions (VS(1)=V (Sim27)andVS(2)=V (Sim37)). N(Fr) can theoretically be used to determine walking velocities proportional to leg lengths and to establish dynamic similarities between subjects. This study represents the first attempt at using this approach to examine plantar pressure. The ankle and knee joint angles were studied in the sagittal plane and the plantar pressure distribution was assessed with an in-shoe measurement device. The similarity ratios were computed from anthropometric parameters and plantar pressure peaks. Dynamically similar conditions caused a 25% reduction in leg joint angles variation and a 10% significant decrease in dimensionless pressure peak variability on average of five footprint locations. It also lead to heel and under-midfoot pressure peaks proportional to body mass and to an increase in the number of under-forefoot plantar pressure peaks proportional to body mass and/or leg length. The use of walking velocities derived from N(Fr) allows kinematic and plantar pressure similarities between subjects to be observed and leads to a lower inter-subject variability. In-shoe pressure measurements have proven to be valuable for the understanding of lower extremity function. Set walking velocities used for clinical assessment mask the effects of body size and individual gait mechanics. The anthropometric scaling of walking velocities (fraction of N(Fr)) should improve identification of unique walking strategies and pathological foot functions.

Psychometric properties of measurement tools for quantifying knee joint position and movement: a systematic review

This systematic review critically evaluates literature on the reliability and validity of measurement tools for quantifying knee joint angles and knee movement. A search was conducted of seven medical databases and one biomedical engineering database, yielding 43 articles that reported reliability or validity. Tools for quantifying knee joint angles included standard handheld goniometers, fluid-based goniometers, gravity-based goniometers, photographs and two dimensional (2-D) motion analysis. Knee movement was measured with electrogoniometers, 2-D and three dimensional (3-D) motion analysis. Intraclass correlation coefficients for testing knee angles ranged from 0.51-1.00 for intratester reliability and 0.43-0.99 for intertester reliability. For quantifying knee position, sequential MRI and 2-D had the least error of measurement, followed by hand held goniometers and photographs. For dynamic measurements, electrogoniometers and 3-D motion analysis were most reliable and had low error of measurement. Strong concurrent validity was found between hand held goniometers and radiographs, as well as between hand held goniometers and 3-D motion analysis.

The repeatablity of spinal motion of normal and scoliotic adolescents during walking

The main aim of this study was to assess the within-day repeatability of measuring trunk and spinal motion during walking using external markers and a motion analysis system. A secondary aim was to compare the repeatability of motion between the scoliotic and normal spine. The sagittal and coronal plane trunk and spinal motion, three-dimensional pelvic and shoulder motion of 9 normal and 19 scoliotic adolescents was assessed. Intra-subject within-day repeatability was evaluated using waveform similarity statistics. Trunk sagittal and coronal plane motion was fairly repeatable. Repeatability of spinal frontal plane motion was fair, but that of sagittal plane motion is poor. Pelvic coronal and transverse plane motion was very reproducible but pelvic sagittal plane motion was very variable. Shoulder motion in all three planes was found to have a poor level of repeatability. A relationship possibly exists between the range of motion and repeatability values. Although the scoliotic adolescents had less variable spinal motion, differences from the normal subjects were not statistically significant. However, the scoliotic subjects had significantly more repeatable sagittal and coronal plane pelvic motion and coronal plane shoulder motion. The results of this study suggest that trunk sagittal and coronal plane motion and spinal coronal plane motion of normal and scoliotic adolescents can be reliably measured within a single test session.

Leg lengthening as part of gait improvement surgery in cerebral palsy: an evaluation using gait analysis

Eleven children with hemiplegic or an asymmetric diplegic cerebral palsy who had a preoperative leg length discrepancy of more than 2.5 cm underwent gait improvement surgery which included leg length equalisation. Sagittal plane kinematics and kinetics before and about 3 years after surgery for the lengthened limb and contralateral limb were evaluated. Preoperatively the unaffected limb had excessive stance phase flexion at the hip and knee, and dorsal flexion at the ankle joint. These changes could be partially reversed to produce a kinematic gait pattern comparable to age matched normal controls on the uninvolved side after equalisation of leg length.

Validation of a visual gait assessment scale for children with hemiplegic cerebral palsy

This study reports the experience of reliability testing and validation of a visual assessment of gait based on the Physician Rating Scale in children with hemiplegic cerebral palsy. Comparison with three-dimensional gait analysis showed excellent correlation between observers and full gait analysis for sagittal plane motion at the knee in stance. Inter and intra-rater reliability showed moderate to almost perfect agreement for foot contact characteristics and ankle in stance. Use of this scale may be helpful in assessment of children where frequent analysis of these characteristics is needed.

The Reliability and Validity of Assessment of Sagittal Plane Deviations in Children Who Have Spastic Diplegia

OBJECTIVE

To assess the reliability and validity of a newly described classification of sagittal plane alignment in spastic diplegic gait.

DESIGN

Twenty split-screen videos of children with spastic diplegia, Gross Motor Function Classification System levels I to III, were viewed on 2 occasions, 6 weeks apart, by 5 raters. The sagittal plane alignments of the right and left lower limbs in gait were classified separately as true equinus, jump knee, apparent equinus, or crouch, based on the published classification. A fifth category, nonclassifiable, was used if classification was not possible. We then used sagittal plane kinematic data to confirm the classification for each subject and these were compared with rater classification scores, which used the video information only.

SETTING

Tertiary-level children's hospital.

PARTICIPANTS

Three pediatric orthopedic surgeons and 2 pediatric orthopedic residents.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Gait classification scores derived from visual observation were compared among and within raters. The gait classification scores derived from visual observation were compared with the scores derived from sagittal plane kinematic data to assess validity.

RESULTS

A moderate correlation was found among the 5 raters within each session, with an interrater weighted kappa score of .45 in session 1 and .49 in session 2. The intrarater, weighted kappa scores showed a moderate to substantial level of agreement between sessions, ranging from .50 to .68. The classification scores of individual raters had moderate validity when compared with classifications derived from the sagittal plane kinematic data. However, there was a substantial level of agreement between the consensus opinion and the classification obtained using the kinematic data as well as the video recordings (weighted kappa=0.8).

CONCLUSIONS

This classification has only moderate reliability and validity when a single experienced rater views the 2-dimensional gait videos. However, the consensus opinion derived from the scores of 5 raters considerably improves the validity of the assessment.

Within- and between-day stability of treadmill walking VO2 in children with hemiplegic cerebral palsy. Stability of walking VO2 in children with CP

Within- and between-day stability in locomotor energy use was quantified in 13 children with hemiplegic CP. During testing, subjects were familiarized with the laboratory environment (Session 1), performed three 5-min level treadmill walks (Trials 1, 2, and 3) at 0.67 m x s-1 (Session 2), and completed a single 5-min walk (Trial 4) at 0.67 m x s-1 (Session 3). In Sessions 2 and 3, HR was assessed and expired air was collected and analyzed to determine VO2. Data analyses revealed no significant difference (P > 0.05) in either net VO2 (ml x kg-1 x min-1) or EEIHR (b x m-1) across the three trials performed in Session 2 and between average measures of net VO2 and EEIHR quantified in Session 2 and those obtained in Session 3. Mean within-day coefficient of variation (CV) values for net VO2 and EEIHR were 8.6% +/- 8.5% and 13.9% +/- 7.8%, respectively. Analysis of between-day variability and energy expenditure revealed a between-day CV value of 13.1% for net VO2 and 24.0% for EEIHR. In addition, significant inverse relationships between GMFM scores and within-day (r = -0.61) and between-day (r = -0.58) CV values for net VO2 were detected. Viewed in concert, these data suggest that fairly stable within- and between-day measures of locomotor energy expenditure during level treadmill walking can be achieved in subjects with hemiplegic CP if testing is preceded by a short period of treadmill accommodation. However, children with greater motor dysfunction may require an extended period of treadmill accommodation to reduce trial-to-trial variability in walking energy use.

Reliability of upper and lower limb three-dimensional kinematics in children with hemiplegia

The repeatability of both 3D kinematic measurements of arm movement during simple upper limb tasks and lower limb movement during gait analysis was evaluated in 10 children with hemiplegic cerebral palsy. All tasks were completed on two separate occasions, 1 week apart. The 3D lower limb gait analysis showed high levels of repeatability in the sagittal plane measures, with mean coefficient of multiple correlations (CMCs) greater than 0.92 between sessions. Transverse and frontal plane measures had mean CMCs greater than 0.7 between sessions. A 3D analysis of shoulder and elbow flexion/extension during the two functional tasks (hand to head and hand to mouth) was highly repeatable between sessions (mean CMCs, 0.87 to 0.95). Rotational measures at the shoulder and the elbow during the same tasks demonstrated moderate levels of inter-sessional repeatability (mean CMCs shoulder 0.49 to 0.63; elbow 0.63 to 0.74). Overall, the lower limb 3D kinematic analysis had similar levels of repeatability in both the hemiplegic limb and the limb with normal tone. The 3D kinematic analysis of movement of the hemiplegic upper limb during simple upper limb tasks also had moderate to good repeatability, suggesting it may be able to be used as an outcome measure in the hemiplegic upper limb.

Managing variability in the summary and comparison of gait data

Variability in quantitative gait data arises from many potential sources, including natural temporal dynamics of neuromotor control, pathologies of the neurological or musculoskeletal systems, the effects of aging, as well as variations in the external environment, assistive devices, instrumentation or data collection methodologies. In light of this variability, unidimensional, cycle-based gait variables such as stride period should be viewed as random variables and prototypical single-cycle kinematic or kinetic curves ought to be considered as random functions of time. Within this framework, we exemplify some practical solutions to a number of commonly encountered analytical challenges in dealing with gait variability. On the topic of univariate gait variables, robust estimation is proposed as a means of coping with contaminated gait data, and the summary of non-normally distributed gait data is demonstrated by way of empirical examples. On the summary of gait curves, we discuss methods to manage undesirable phase variation and non-robust spread estimates. To overcome the limitations of conventional comparisons among curve landmarks or parameters, we propose as a viable alternative, the combination of curve registration, robust estimation, and formal statistical testing of curves as coherent units. On the basis of these discussions, we provide heuristic guidelines for the summary of gait variables and the comparison of gait curves.

A cerebral palsy assessment tool using anatomically based geometries and free-form deformation

A geometrical analysis tool for investigating muscle length change in cerebral palsy (CP) patients is presented. A subset of anatomically based geometries from the International Union of Physiological Sciences (IUPS) Physiome Project is used, which is derived from the visible human (VH) data set with muscle attachment information, and customised using volume-preserving free-form deformation (FFD), the 'host-mesh' technique. The model's intended use is to provide pre- and post-surgery assessment for muscle lengthening, a surgery performed to help slacken tight muscles and improve gait. The model is illustrated using healthy patient data from motion capture as a validation followed by three CP case studies to highlight its use. The methodology is presented in three stages, (1) a FFD of the complete lower limb, (2) a focused geometric study on the semimembranosus (SM) and gastrocnemius (GT) muscles, and (3) an improved hybrid mechanics-FFD approach as an improvement for future analysis, with differentiation between muscle and tendon lengthening, and contact detection between sliding muscles. Finally, the issues, limitations, in particular with the marker system, and model improvements are discussed.

Within- and between-day stability of treadmill walking VO2 in children with hemiplegic cerebral palsy, stability of walking VO2 in children with CP

Within- and between-day stability in locomotor energy use was quantified in 13 children with hemiplegic cerebral palsy (CP). During testing, subjects were familiarized with the laboratory environment (Session 1), performed three 5 min level treadmill walks (Trials 1-3) at 0.67 m*s(-1) (Session 2), and completed a single 5 min walk (Trial 4) at 0.67 m*s(-1) (Session 3). In Sessions 2 and 3, heart rate (HR) was assessed and expired air was collected and analyzed to determine VO2. Data analyses revealed no significant difference (P > 0.05) in either net VO2 (ml kg(-1)*min(-1)) or EEI(HR) (b*m(-1)) across the three trials performed in Session 2 and between average measures of net VO2 and EEI(HR) quantified in Session 2 and those obtained in Session 3. Mean within-day coefficient of variation (CV) values for net VO2 and EEI(HR) were 8.6% +/- 8.5% and 13.9% +/- 7.8%, respectively. Analysis of between-day variability and energy expenditure revealed a between-day CV value of 13.1% for net VO2 and 24.0% for EEI(HR). In addition, significant inverse relationships between Gross Motor Function Measure (GMFM) scores and within- (r = -0.61) and between-day (r = -0.58) CV values for net VO2 were detected. Viewed in concert, these data suggest that fairly stable within- and between-day measures of locomotor energy expenditure during level treadmill walking can be achieved in subjects with hemiplegic CP if testing is preceded by a short period of treadmill accommodation. However, children with greater motor dysfunction may require an extended period of treadmill accommodation to reduce trial-to-trial variability in walking energy use.

Classification of equinus in ambulatory children with cerebral palsy-discrimination between dynamic tightness and fixed contracture

In this study a generalised dynamic neural network (GDNN) was designed to process gait analysis parameters to evaluate equinus deformity in ambulatory children with cerebral palsy. The aim was to differentiate dynamic calf muscle tightness from fixed muscle contracture. Patients underwent clinical examination and had instrumented gait analysis before evaluating their equinus under anaesthesia and muscle relaxation at the time of surgery to improve gait. The performance of the clinical examination, the subjective interpretation of gait analysis results, and the application of the neural network to assess ankle function were compared to the examination under anaesthesia. Evaluation of equinus by a Neural Network showed high sensitivity and specificity values with a likelihood ratio of +14.63. The results indicate that dynamic calf muscle tightness can be differentiated from fixed calf muscle contracture with considerable precision that might facilitate clinical decision-making.

Quantification of human motion: gait analysis-benefits and limitations to its application to clinical problems

The technology supporting the analysis of human motion has advanced dramatically. Past decades of locomotion research have provided us with significant knowledge about the accuracy of tests performed, the understanding of the process of human locomotion, and how clinical testing can be used to evaluate medical disorders and affect their treatment. Gait analysis is now recognized as clinically useful and financially reimbursable for some medical conditions. Yet, the routine clinical use of gait analysis has seen very limited growth. The issue of its clinical value is related to many factors, including the applicability of existing technology to addressing clinical problems; the limited use of such tests to address a wide variety of medical disorders; the manner in which gait laboratories are organized, tests are performed, and reports generated; and the clinical understanding and expectations of laboratory results. Clinical use is most hampered by the length of time and costs required for performing a study and interpreting it. A "gait" report is lengthy, its data are not well understood, and it includes a clinical interpretation, all of which do not occur with other clinical tests. Current biotechnology research is seeking to address these problems by creating techniques to capture data rapidly, accurately, and efficiently, and to interpret such data by an assortment of modeling, statistical, wave interpretation, and artificial intelligence methodologies. The success of such efforts rests on both our technical abilities and communication between engineers and clinicians.

Comparison of percutaneous and surface functional electrical stimulation during gait in a child with hemiplegic cerebral palsy

The purpose of this brief report was to compare the immediate effects of surface functional electrical stimulation (S-FES) and percutaneous functional electrical stimulation (P-FES) of the tibialis anterior applied during gait in a child with hemiplegic cerebral palsy. A three-dimensional gait analysis was conducted while an 11-yr-old girl with right hemiplegia walked with S-FES, P-FES, and no stimulation. The results indicated that both P-FES and S-FES increased dorsiflexion at initial contact, peak dorsiflexion in swing, and mean dorsiflexion in swing compared with walking without stimulation. The increase in dorsiflexion was greater with P-FES as compared with S-FES. Ankle absorption work was improved with both types of stimulation, whereas ankle generation work increased only with P-FES. This report suggests that S-FES and P-FES may have different immediate effects on gait due to issues such as muscle contraction strength, sensory feedback, and control systems for stimulation.

On the Robustness of Stride Frequency Estimation

The robustness of stride frequency estimation (location and spread) from stride period data is investigated using influence functions. Theoretical analysis reveals that stride frequency estimates by Stokes et al. and by direct calculation have unbounded influence functions and zero breakdown points, implying a lack of both local and global robustness. Comparison of estimates obtained from an ensemble of pathological gait stride time series shows that on average, differences among estimators are not statistically significant (p > or = 0.59) for long time series (hundreds of strides). Specific circumstances under which nonrobust estimates depart from robust estimates are investigated in terms of outlier influence. We recommend some heuristic rules-of-thumb for prudent selection of nonrobust stride frequency estimators for a given stride time series. The theoretical and empirical estimator comparisons suggest that in general, more research on estimator robustness in quantitative gait analysis is warranted.

Intrathecal baclofen in subjects with spastic hemiplegia: assessment of the antispastic effect during gait

OBJECTIVE

To determine whether leg muscle stiffness is measurably reduced after intrathecal baclofen (ITB) in subjects with spastic hemiplegia.

DESIGN

Nonrandomized trial.

SETTING

Inpatient multidisciplinary rehabilitation unit in France.

PARTICIPANTS

Seven consecutive subjects with spastic hemiplegia having Ashworth Scale scores for their quadriceps and triceps greater than 2.

INTERVENTION

Subjects were given ITB by lumbar puncture after a dose-selecting test period.

MAIN OUTCOME MEASURES

Triceps and quadriceps Ashworth scores, gait analysis at preferred and maximal speed measured by a motion analysis system with 2 forceplates, and electromyographic recording of leg muscles before and 4 hours after ITB. The slopes of the moment-angle curves were measured on the hemiplegic side at the onset of ankle and knee flexion to assess muscle stiffness during walking. Pre- and post-ITB spatiotemporal, kinetic, and kinematic data were compared by using a nonparametric test (Wilcoxon signed-rank test).

RESULTS

Ashworth scores of the quadriceps and triceps of all subjects decreased significantly after ITB. Maximal walking speed increased significantly, with a significant increase in stride length, but the preferred walking speed was unchanged. Minimal knee extension and maximal ankle flexion were the only kinematic data significantly different (increased) after ITB. The slope of the ankle moment-angle curve decreased significantly after ITB at preferred gait speed; it also decreased at maximal gait speed in all but 1 subject. Of the 4 available moment-angle curves, 3 showed decreased knee extensor muscle stiffness. The duration of the bursts of spastic muscles decreased after ITB.

CONCLUSION

Acute ITB improved walking and reduced muscle stiffness at both the ankles and knees on the spastic hemiplegic side of our subjects. Electromyographic findings suggest that some of the post-ITB reduction in muscle stiffness might be attributed to decreased spasticity.

Intra-rater and inter-rater reliability of gait measurements with CODA mpx30 motion analysis system

Variations between measurements of clinical outcomes sometimes result from observer errors and are not due to the therapeutic intervention. For the correct interpretation of clinical data it is, therefore, important to ascertain the reliability of the measurement methods used. In the present study we evaluated the test-retest and between observer reliability of gait measurements with the Cartesian Optoelectronic Dynamic Anthropometer (CODA mpx30) motion analysis system. Our findings suggest a better intra-rater and inter-rater reliability of kinetic than kinematic data. Disagreements between the investigators were most marked for the kinematic data, especially the hip angle, and disagreements were least for the spatio-temporal gait parameters. The poor reproducibility of kinematic variables may be due to problems with the accurate placement of markers on the surface anatomical landmarks.

Medial hamstring lengthening in the presence of hip flexor tightness in spastic diplegia

This study evaluated the effects of medial hamstring lengthening on gait in patients with diplegic cerebral palsy. A group of patients who underwent medial hamstring lengthening and distal rectus transfer was compared to a group of patients who underwent intramuscular psoas lengthening as well. Patients who underwent a psoas lengthening showed an increased anterior pelvic tilt and a tendency towards genu recurvatum, features that could indicate postoperative hamstring weakness. These results underline the importance of medial hamstrings for pelvis and knee motion in the sagittal plane during walking. In additional the limitations of the popliteal angle as a clinical measure to evaluate hamstring length in the presence of hip flexor tightness are discussed.

A comparison of within- and between-day reliability of discrete 3D lower extremity variables in runners

It is important to understand the day-to-day variability that is attributed to repositioning of markers especially when assessing a treatment effect or response over time. While previous studies have reported reliability of waveform patterns, none have assessed the repeatability of discrete points such as peak angles, velocities and angular excursions which are often used when making statistical and clinical comparisons. The purpose of this study was to compare the within- and between-day variability of discrete kinematic, kinetic, and ground reaction force (GRF) data collected during running. Comparisons for 20 recreational runners were evaluated for within- and between-day reliability of discrete 3D kinematic, kinetic, and GRF variables. The results indicated that within-day comparisons were more reliable than between-day. Joint angular velocity and angular excursion values were more reliable between-days as compared to absolute peak angle measures and may be more useful in interpreting changes in treatment over time. Between-day kinematic and kinetic sagittal plane values were more reliable than secondary plane values. Reliability of GRF data was greater than kinematic and kinetic data for between-day comparisons.

Intra-subject repeatability of the three dimensional angular kinematics within the lumbo-pelvic-hip complex during running

The intra-subject repeatability of measuring the three dimensional (3D) angular kinematics of the lumbo-pelvic-hip complex during running was evaluated. Spatio-temporal parameters were found to be repeatable. All angular kinematic parameters displayed high within-day repeatability despite numerous potential sources of variability in the data. Most angular kinematic parameters also displayed high between-day and overall repeatability, except for trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior-posterior tilt, hip axial rotation and thigh axial rotation. These angular parameters were highly susceptible to marker reapplication errors that produced static daily offsets in the data. Overall, the results of this study suggest that the 3D angular kinematic patterns of the lumbo-pelvic-hip complex during running can be measured with sufficient repeatability to justify the implementation of the method as an evaluation tool in future investigations. However, caution must be exerted when interpreting the absolute magnitudes of trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior-posterior tilt, hip axial rotation and thigh axial rotation, given the poor level of repeatability found for these measures.

Effect of derotation osteotomy of the femur on hip and pelvis rotations in hemiplegic and diplegic children

The purpose of this study was to evaluate hip and pelvis rotations in groups of hemiplegic and diplegic children before and after surgical correction of fixed internal rotation deformity of the hip. Twenty-two children with cerebral palsy (eight diplegia, 14 hemiplegia) having fixed internal rotation deformity at the hip were treated by multilevel surgery which included derotation osteotomy of the femur. Evaluation was done before and at a mean of 3.1 years after surgery using three-dimensional computerized gait analysis. Preoperatively, the patients in the hemiplegia group had a significantly greater compensatory external rotation of the pelvis than those in the diplegic group. Post-operatively there were no significant differences between the two groups. In the hemiplegia group the external rotation of the pelvis was corrected after correction of hip rotation by derotation osteotomy. Patients in the diplegia group showed significant improvements in the hip rotation with no significant change in the pelvis rotation after multilevel surgery.

Movement Variability as a Clinical Measure for Locomotion

The purpose of this paper is to discuss the role of variability in human movement, with emphasis on locomotion variability. Based on the assessment of stride characteristics, movement variability has been associated with reduced gait stability and unsteadiness. However, based on the measure of joint coordination during locomotion, variability has been suggested to provide a source of adaptation. Therefore, it would appear that the assessment of movement coordination from either the task outcome (i.e., stride characteristics) or the joint coordination patterns provide distinctly opposing views of variability. This paper will discuss the use of the variability measures, specifically joint coordination variability, from a clinical perspective. Investigations will be presented in which a reduction in joint coordination variability has been associated with pathology. Finally, the clinical implications of these measures as well as treatment suggestions are discussed.