The evolution of clinical gait analysis part III--kinetics and energy assessment.

Historically, clinical applications of measurements of force and energy followed electromyography and kinematics in temporal sequence. This sequence is mirrored by the order of topics included in this trilogy on the Evolution of Clinical Gait Analysis, with part I [Sutherland DH. The evolution of clinical gait analysis part I: kinesiological EMG. Gait Posture 2001;14:61-70.] devoted to Kinesiological EMG and part II [Sutherland DH. The evolution of clinical gait analysis part II - kinematics. Gait Posture 2002;16(2):159-179.] to Kinematics. This final review in the series will focus on kinetics as it relates to gait applications. Kinematic measurements give the movements of the body segments, which can be compared with normal controls to identify pathological gait patterns, but they do not deal with the forces controlling the movements. As a major goal of scientifically minded clinicians is to understand the biomechanical forces producing movements, the objective measurement of ground reaction forces is essential. The force plate (platform) is now an indispensable tool in a state-of-the-art motion analysis laboratory. Nonetheless, it is not a stand-alone instrument as both kinematic and EMG measurements are needed for maximum clinical implementation and interpretation of force plate measurements. The subject of energy assessment is also given mention, as there is a compelling interest in whether walking has been made easier with intervention. The goals of this manuscript are to provide a historical background, recognize some of the important contributors, and describe the current multiple uses of the force plate in gait analysis. The widespread use of force plates for postural analyses is an important and more recent application of this technology, but this review will be restricted to measurements of gait rather than balance activities. Finally, this manuscript presents my personal perspective and discusses the developments and contributors that have shaped my thoughts and actions, and which I have found to be particularly noteworthy or intriguing. Just as in parts I and II, emphasis has been placed on the early development. All subtopics and important contributors, in this third and certainly most challenging of the review papers, have not been included. Some may find that my perceptions are incomplete. I accept responsibility for all deficiencies, as none were intended. Letters to selected contributors and their responses reveal how each contributor built on the work of others. The level of cooperation and sharing by these early investigators is extraordinary. Had they wished to withhold information about their own work, clinical gait analysis would have been severely delayed.

Clinical utility of the Duncan-Ely test for rectus femoris dysfunction during the swing phase of gait.

The Ely Test (or Duncan-Ely test) has been accepted as a clinical tool to assess rectus femoris spasticity by passively flexing the knee rapidly while the patient lies prone in a relaxed state. In this retrospective review, patients' dynamic knee range of motion (ROM) during gait and an electromyogram (EMG) were compared with the results of the Ely test. Data for 70 patients (44 males, 26 females; 104 limbs) were included. Mean age of patients was 13 years, SD 9 years, range 4 years 5 months to 54 years. All patients were diagnosed with cerebral palsy (spastic diplegia, n = 42; spastic quadriplegia, n = 15, and hemiplegia, n = 13). All patients were ambulatory (50 independent, 20 with assistive devices). A standard matrix was used to calculate sensitivity and specificity of the Ely test as well as its positive and negative predictive value. For the gait variables examined (decreased dynamic knee ROM, timing of peak knee flexion, and abnormal EMG in swing) the sensitivity of the Ely test ranged from 56 to 59% and the specificity ranged from 64 to 85%. For the same variables the positive predictive value ranged from 91 to 98% and the negative predictive value ranged from 4 to 19%. The Ely test was shown to have a good positive predictive value (i.e. the certainty about the presence of rectus spasticity in patients with a positive Ely test result) for rectus femoris dysfunction during gait.

The evolution of clinical gait analysis. Part II kinematics.

Kinematics is treated as a single topic in this manuscript and the emphasis is on early history, just as it was in Part I, Electromyography. Needless to say, neither kinematics nor electromyography, nor kinetics and energy (the latter to be included in Part III) are stand-alone components of clinical gait analysis. The only reason for this selective format is that it lessens my task to be able to write about one subject at a time. One of the consequences of this arbitrary separation is that some contributors, who have enriched more than one portion of clinical gait analysis, are highlighted only in the area in which they have contributed the most. I began with Kinesiological Electromyography in Part I because the earliest stirrings of the dream of clinical gait analysis were expressed in the development of KEMG (kinesiological electromyography). The early investigators realized that very little could be said about the dynamic action of muscles without KEMG. Next, in chronological order, came kinematics. I have been an active participant and eyewitness, and take full responsibility for attempting to write an early history at a time when most of the contributors are still alive. Ordinarily, history is written much later, in order to fully grasp the significance of individual contributions in the tapestry of the whole. As stated in Part I, Electromyography, the emphasis has been placed on the early history. The application of motion analysis to sports medicine, and sports medicine functional analysis, is covered only lightly here, and this should not be interpreted as minimizing its importance. The literature on this subject is now quite voluminous and it would not be possible to cover it adequately in this manuscript. Later historical writings may differ significantly and will hopefully give more recognition to pioneers in later generations: those physicians, engineers, physical therapists and kinesiologists who are lifting the level of clinical gait analysis and directing their energies in expanding clinical directions. It is hoped that this manuscript will prompt additional manuscripts, as well as letters to the editor of Gait and Posture on the content of this review paper.

The evolution of clinical gait analysis part l: kinesiological EMG.

In 1996, I was asked by Roy Davis, President of the Gait and Clinical Movement Analysis Society, to be the presidential guest speaker at the Birmingham, AL, annual society meeting and present a talk on the development of clinical gait analysis. Following my presentation, James Gage, Editor-in-Chief for Gait and Posture, and David Winter, Associate Editor for review articles requested a manuscript for publication. To address this task I have the advantage of being a participant throughout this exciting era and of personally knowing most of the people mentioned in this manuscript. To prepare for this assignment, I wrote letters and/or made phone calls to them. Their replies to my inquiries, plus their publications, provide documentation for this review paper. The opinions expressed, for better or worse, are my own. Due to space limitations, only a partial list of the many that have contributed is presented and I regret that not all of the important contributors have been included. In some instances they will be found in Part II and Part III. Hopefully, later publications on this subject will correct the omissions. Emphasis has been given to the earliest years and to walking gait. The subject of upper extremity analysis has not been included, though studies of subjects with upper extremity motion problems are carried out in many motion laboratories including our own. A further disclaimer is that the flood of more recent publications does not receive equal coverage. History is being written daily as clinical gait analysis gains momentum. We have barely scratched the surface of the development and potential contributions of clinical gait analysis.

Double-blind study of botulinum A toxin injections into the gastrocnemius muscle in patients with cerebral palsy.

The purpose of this study was to quantify the gait of subjects receiving two injections of either botulinum A toxin or saline vehicle into the gastrocnemius muscle(s). The study group consisted of cerebral palsy patients who walked with an equinus gait pattern. This study was a randomized, double-blinded, parallel clinical trial of 20 subjects. All were studied by gait analysis before and after the injections. There were no adverse effects. Peak ankle dorsiflexion in stance and swing significantly improved in subjects who received the drug and not in controls. Results of this double blind study give support to the short term efficacy of botulinum toxin A to improve gait in selected patients with cerebral palsy.

Femoral anteversion and neck-shaft angle in children with cerebral palsy.

A database of femoral anteversion and neck-shaft angle was compiled of measurements made by the trigonometric fluoroscopic method of 147 patients (267 hips) with cerebral palsy. The angles of femoral anteversion were similar at early ages between healthy children and children with cerebral palsy. However, as the age of the children increased, those with cerebral palsy showed little change in anteversion angle, whereas the healthy children had progressively decreasing angles of femoral anteversion as they approached adulthood. The neck-shaft angle was increased significantly in children with cerebral palsy compared with the angles of healthy children. Patients who were ambulatory were shown to have an increased angle of femoral anteversion and a decreased neck-shaft angle compared with nonambulatory patients. There was no significant difference in angles among the various distributions of involvement, including patients with diplegia, hemiplegia, and quadriplegia.

Automatic control design for a dynamic knee-brace system.

A self-contained electronically controlled dynamic knee-brace system (DKBS) has been designed and tested which allows knee flexion during swing phase, but restricts flexion during the stance phase of gait. Cardiovascular energy measurements indicate that DKBS use allowed a more energy efficient gait.

Optimization and application of a wrap-spring clutch to a dynamic knee-ankle-foot orthosis.

A dynamic knee-brace system (DKBS) has been designed which provides stance phase stability and swing phase freedom. A wrap-spring clutch controls knee flexion. Clutch optimization was performed minimizing clutch length. Kinematic tests on a normal subject using the DKBS document nearly normal dynamic knee flexion during swing (38 degrees versus 53 degrees for normal).

Kinematic and kinetic analysis of distal derotational osteotomy of the leg in children with cerebral palsy.

Patients with cerebral palsy often develop rotational deformities of the lower extremities. These deformities may be caused by abnormal muscle tone, soft-tissue contractures, or bony malalignment. When rotational deformity persists after correction of the soft-tissue components, bony-realignment procedures are warranted to improve gait in ambulatory patients. We performed a retrospective review of 10 ambulatory children with cerebral palsy and tibial torsion who underwent 13 distal tibial and fibular derotation osteotomies. Preoperative and postoperative three-dimensional gait analysis were used to determine the effect of distal tibial and fibular derotation osteotomy on tibial rotation, foot-progression angle, gait velocity, and moments about the ankle. Mean tibial rotation and foot-progression angle were significantly improved by the procedure. Gait velocity improved but not significantly. Moment data demonstrated a trend toward normal. This study demonstrates that the derotational distal tibial and fibular osteotomy stabilized with percutaneous crossed Kirschner wires is a safe, reliable, and effective procedure for correcting rotational deformities of the leg in patients with cerebral palsy.

Three-dimensional characteristics of cartilaginous and bony components of dysplastic hips in children: three-dimensional computed tomography quantitative analysis.

A cartilage-viewing technique was developed to overcome the shortcoming of not seeing the cartilaginous components, believed to play more important role than the osseous components in children's hips, with computed tomography. This technique was applied to 25 dysplastic hips in children younger than 10 years to evaluate their global and local deficiencies. The findings helped us to understand more about their individual problems. To quantify the three-dimensional (3-D) parameters of acetabular anatomy and femoral head coverage, a measuring technique was developed based on digitization of the 3-D coordinates and fitting of every component of the hip. The improved images and the quantified parameters were expected to aid the planning, formulation, and even simulation of individualized surgical treatment for children with developmental dysplasia of the hip.

Psoas release at the pelvic brim in ambulatory patients with cerebral palsy: operative technique and functional outcome.

Seventeen patients with cerebral palsy (29 hips) underwent psoas recession at the pelvic brim. The operative technique was a direct anterior approach, lateral to the femoral sheath. There were no infections or nerve or arterial injuries. After surgery, clinical examination revealed that fixed hip-flexion contractures decreased significantly in all patients. All of the subjects retained the ability to flex the hip against gravity and against manual resistance. All of the subjects underwent pre- and postoperative gait analysis. Stance-phase dynamic minimum hip flexion decreased significantly. Dynamic pelvic tilt improved to a statistically significant level for the younger children but did not for the group as a whole. There was less improvement with increasing age. Step length was significantly increased and cadence significantly decreased in all patients. We conclude that psoas recession at the pelvic brim, by using the anterior approach, lateral to the femoral sheath, is a safe, reliable, and effective procedure for children with cerebral palsy who have excessive anterior pelvic tilt and excessive dynamic hip flexion or hip-flexion contracture.

Clinical use of prediction regions for motion analysis.

This study assesses the diagnostic capability of statistically defined prediction regions, developed by a 'bootstrap' method, for assessing the curves of angular rotation of joints in children as they walk. The prediction regions had been previously developed in the authors' laboratory from a study of 309 normal children. The goal of the present study was to determine whether these computer-generated prediction regions could be used as a screen in clinical gait analysis, to determine whether a movement falls outside the normal range of variability. Kinematic analysis of 38 consecutive children referred to the motion analysis laboratory for clinical gait assessment provided 912 curves of lower-extremity joint angle dynamics. An experienced observer first inspected the patients' curves with mean normal curves superimposed and designated the curves as normal or abnormal. The performance of the computer-generated prediction regions was judged by comparison with the experienced observer's designations. The prediction regions were found to have a high sensitivity (81%), indicating that they can be used as an initial screen to identify deficits in lower limb function.

Gait asymmetry in patients with limb-length inequality.

One of the problems facing the clinician is the differentiation between functional and structural limb-length inequality. This study investigated 20 subjects (mean age, 9.0 +/- 3.9 years) with documented limb-length inequalities to determine the magnitude of discrepancies that result in gait abnormalities. The subjects were asked to walk on an 8-m walkway at a self-selected free pace. The contact time, first and second force peaks, and loading and unloading rates of the vertical ground-reaction force were measured for both limbs. These parameters were predictive for quantification of gait asymmetry. The asymmetry of these parameters increased as the limb-length inequality increased. In general, a limb-length inequality > 2.0 cm (3.7%) resulted in gait asymmetry that was greater than that observed in the normal population. However, the amount of asymmetry varied for each individual. A static examination can document an anatomic deformity, but this deformity may be compensated for by functional adaptations. An analysis of the patient's gait should be performed to identify asymmetries during ambulation. Dynamic gait findings, such as demonstrated in this study, are needed to support static measurements.

Quantitative analysis of hip dysplasia in cerebral palsy: a study of radiographs and 3-D reformatted images.

Cerebral palsy patients (31 hips) were evaluated using radiographic and three-dimensional (3-D) images to quantify hip anatomy. The 3-D images overcome distortions caused by joint contractures. Changes were more pronounced in the non-ambulators and characterized by shallow sockets with increased neck-shaft angles. These hips tended to subluxate in a posterior-superior direction and most had defects in the femoral heads. Ambulators had increased femoral anterversion but other hip parameters tended to improve with age. The 3-D measures of roof steepness and socket depth were found to correlate strongly with radiographic parameters of subluxation.

Evaluation of CT scans and 3-D reformatted images for quantitative assessment of the hip.

Hip measurements using three-dimensional (3-D) images and computed tomography (CT) scans were evaluated. The 3-D measurements proved more accurate than CT measurements of femoral and acetabular anteversion. Additionally, accurate 3-D measurements (> 99%) of the femoral neck-shaft angle were provided. Acetabular anteversion determinations by CT scans were systematically decreased as pelvic flexion increased, whereas accuracy was > 96% with 3-D images. The 3-D software allows image rotation in all three reference planes, which minimizes positional errors. A case study is provided to exemplify the shortcomings of conventional imaging techniques and the utility of the quantitative 3-D protocol.

Significance of the confusion test in cerebral palsy.

The confusion test examines ankle dorsiflexion in patients with cerebral palsy. Orthopedists have related this test to swing-phase activity of the tibialis anterior, and have used it as a prerequisite for tendon transfer. To determine the validity of this assumption, ankle dorsiflexion was tested in 47 normal children. Forty-seven percent had a positive, unresisted confusion test, and 97% had a positive, resisted confusion test. Twenty-three patients with cerebral palsy who had a positive confusion test underwent gait analysis. Tibialis anterior electromyographs showed wide variability. Sagittal-plane ankle-movement curves revealed five patterns. Thirty-three percent of the patients showed abnormal swing-phase dorsiflexion, and 61% had abnormal swing-phase plantar-flexion. We conclude that the confusion test evaluates a normal, patterned response, and is positive in most children with cerebral palsy. Although a positive confusion test shows that active ankle dorsiflexion is possible, it is not predictive of swing-phase ankle kinematics.

Energy cost of ambulation with different methods of foot and ankle immobilization.

In order to measure the energy cost of immobilization of the foot and ankle during ambulation, 14 healthy male volunteers exercised while wearing various immobilization devices. Oxygen consumption, oxygen cost, cardiac output, minute ventilation, heart rate, stroke volume, stride length, and stride frequency were determined at a steady state of exercise as the subjects walked on a treadmill at 80 m/min (equivalent to the comfortable walking speed of approximately 3 mi/h). Each subject was tested with three different types of immobilization devices: a short leg walking cast, a prefabricated lower leg orthosis, and a rigid-soled surgical shoe. The results were compared with those for the same men ambulating without an immobilization device. Ambulation with the short leg walking cast and the prefabricated lower leg orthosis required significantly more energy in comparison with control values (all p values < 0.006) in terms of oxygen cost, cardiac index, oxygen consumption, and minute ventilation. However, when the rigid-soled surgical shoe was worn, energy consumption as measured by all parameters was not significantly increased compared with control values. Comparison of the findings for the short leg walking cast and the prefabricated lower leg orthosis showed no significant differences in any parameter of energy consumption. Stride length, however, was significantly shorter in the short leg walking cast compared with all immobilizers tested.

Common gait abnormalities of the knee in cerebral palsy.

Gait abnormalities in children with cerebral palsy are the consequence of contractures across joints, muscle spasticity, and phasically inappropriate muscle action. Though abnormalities involving one of the major joints of the lower extremity will usually have consequences on the function of the other joints, it is possible to recognize certain primary disorders at each joint. The most common gait abnormalities of the knee in patients with cerebral palsy occur in the sagittal plane. Based on the experience gained from performing gait analysis on more than 588 patients with cerebral palsy, four primary gait abnormalities of the knee have been identified: jump knee, crouch knee, stiff knee, and recurvatum knee. In this review, each abnormality is described by its motion analysis laboratory profile (physical examination, motion parameters, electromyography [EMG] data, and force plate data). The most common etiologies and the consequences for gait of each disorder are also considered. Appreciation of the most common pathologic patterns of gait should facilitate accurate and detailed analysis of the individual patient with gait abnormalities.

Varus foot in cerebral palsy: an overview.

In cerebral palsy, imbalance of the invertor and evertor muscles can result in varus alignment of the foot. The primary functional problems of varus foot are weightbearing instability and/or difficulty in foot clearance in swing phase. Additional problems include difficulties in shoe fitting, abnormal shoe wear, and unacceptable cosmesis. Gait studies have shed some light on the alterations of the muscle activity that can cause this problem but have fallen short of providing clear guidelines for treatment of this common problem. Confusion exists because dynamic electromyography does not give definitive information about the quantity of muscle tension and because the analyses have not included movement measurements that distinguish between the movements that occur in the hind foot and forefoot. Technical limitations that have made it impossible to obtain this information are rapidly disappearing, and the way is opening up for biomechanical studies of foot and ankle function that will allow greater precision in the selection of surgical treatment for varus foot.

Proximal hamstring lengthening in the sitting cerebral palsy patient.

We retrospectively studied 62 nonambulatory children with spastic quadriplegic cerebral palsy who underwent proximal hamstring lengthening to improve hip and spine positioning. Preoperatively, all had hamstring contracture, with difficulty sitting due to hip extensor thrust and increased kyphosis. Thirty-five patients with follow-up greater than or equal to 2 years were studied using a modified Reimer scale to assess sitting ability. Sitting ability improved significantly (p less than 0.01) postoperatively, along with popliteal angle (p less than 0.001) and straight leg raising (p less than 0.001). Proximal hamstring lengthening is effective in treating severe hamstring contractures in the wheelchair-bound child with cerebral palsy.