The slump test: the effects of head and lower extremity position on knee extension

Maitland's slump test is a widely used neural tissue tension test. During slump testing, terminal knee extension is assessed for signs of restricted range of motion (ROM), which may indicate impaired neural tissue mobility. A number of refinements that modify hip and ankle position has been added to the basic slump test procedure, but no research to date has measured the effects of ankle and hip position on knee extension ROM during testing. The purpose of this study was to examine the effect of neural tension-producing movements of the cervical spine and lower extremity on knee extension ROM during the slump test. Thirty-four males with no significant history of low back pain were tested in the slump position with the cervical spine flexed and extended in each of three lower extremity test positions: neutral hip rotation with the ankle in a position of subject comfort (neutral), neutral hip rotation with ankle dorsiflexion (ankle dorsiflexion), and medial hip rotation with ankle dorsiflexion. Results showed significant decreases in active knee extension ROM (F1,198 = 29.53, p < 0.0001) in the cervical flexion compared with the cervical extension conditions. Subjects also exhibited significant decreases in active knee extension ROM (F2,198 = 56.76, p < 0.0001) as they were progressed from neutral to the ankle dorsiflexion to the medial hip rotation with ankle dorsiflexion positions of the lower extremity. The results of our study indicate that limitations in terminal knee extension ROM may be considered a normal response to the inclusion of cervical flexion, ankle dorsiflexion, or medial hip rotation in the slump test in young, healthy, adult males. In addition, the presence of a cumulative effect on knee extension ROM with the simultaneous application of these motions is noted. These findings may assist clinicians when assessing knee extension ROM during slump testing.     

Effects of resistive and balance exercises on isokinetic strength in older persons

OBJECTIVE: To determine the safety and efficacy of 3 months of resistive training of multiple lower extremity muscle groups compared with balance training in persons over 75 years. DESIGN: Randomized 3-month clinical trial. Subjects (n = 110, mean age 80) were randomized to 4 groups in a 2 x 2 design (control, resistive, balance, combined resistive/balance). INTERVENTIONS: Resistive training involved knee extension and flexion, hip abduction and extension, and plantar and dorsiflexion using simple resistive machines and sandbags. Balance training consisted of exercises to improve postural control. The control group attended 5 health-related discussion sessions. MEASUREMENTS: Summed isokinetic moments (N m) of 8 leg movements: hip, knee and ankle flexion/extension, and hip abduction/adduction. Secondary outcomes were gait velocity and chair rise time. MAIN RESULTS: Summed peak moment increased in both resistive exercise-trained groups (13% increase in the resistive group and 21% in the combined training group, P < 0.001). The effect of resistance training was significant (MANOVA F = 21.1, P < 0.001), but balance training did not improve strength, and there was no interaction (positive or negative) between balance and resistive training. Maximal gait velocity and chair rise time did not improve. Eleven subjects (20%) had musculoskeletal complaints related to resistive training, but all were able to complete the program with modifications. CONCLUSION: Resistive training using simple equipment is an effective and acceptable method to increase overall leg strength in older persons. Resistive or balance training did not improve maximal gait velocity or chair rise time in this sample of relatively healthy older persons.     

Gait analysis of adult patients with complete congenital dislocation of the hip

Comprehensive gait analysis is valuable in understanding the performance of patients with lower limb disorders. The gait pattern of adult patients with untreated congenital dislocation of the hip (CDH) has not yet been reported. We studied the gait pattern in nine women (mean age 31.4 years) with Crows group IV CDH. Six had unilateral and three had bilateral involvement. They were not treated during childhood and had no pain at the time of study. A control group comprised 15 normal female subjects of the same age group. Gait was studied using a motion-analysis system, force plateforms, and computer calculation during level walking. Common abnormal gait patterns seen in patients with both unilateral and bilateral CDH were slower walking velocity, which was due to a shorter stride length, less forward tilting of the pelvis, insufficient flexion, and excessive internal rotation of the hips. The patients with unilateral CDH had a shorter step length, lower pelvis, a lateral shift of the ground reaction force, decreased maximum adduction moments of the hip and knee on the diseased side, and increased maximum adduction moments of the hip and knee on the unaffected side. This asymmetry may have been due to leg length inequality. Thus, correlation of the leg length discrepancy may be important for unilateral CDH patients in improving their gait.     

Biomechanics of walking, running, and sprinting

A biomechanical study of 13 runners which consisted of 2 male sprinters, 5 experienced joggers, and 6 elite long-distance runners were studied. We obtained hip, knee, and ankle joints motions in the sagittal plane and electromyographic data from specific muscle groups. As the speed of gait increased, the length of stance phase progressively decreased from 62% for walking to 31% for running and to 22% for sprinting. The sagittal plane motion increased as the speed of gait increased. Generally speaking, the body lowers its center of gravity with the increased speed by increasing flexion of the hips and knees and magnifying dorsiflexion at the ankle joint. Electromyographic activity about the knee demonstrated increased activity in the quadricep muscle group and hamstring group with increased speed. Muscle function about the ankle joint demonstrated that the posterior calf musculature which normally functions during the midstance phase in walking became a late swing phase muscle and was active through the first 80% of stance phase, as compared to 15% in walking. Beside the changes in the electromyographic activity of the muscles, the anterior compartment muscles of the calf undergo a concentric contracture at the time of initial floor contact during running and sprinting but undergo an eccentric contraction during walking.     

Effect of N-acylethanolamines with different acyl-chains on DPPC multilamellar liposomes

Relationships between lower extremity strength and stride characteristics were studied in 24 patients with post-polio syndrome. Maximum isometric torques were measured in the ankle plantar flexors, hip and knee extensors, and hip abductors. Gait velocity, stride length, and cadence were recorded during free and fast walking. Step-wise regression analysis was performed to determine which muscle groups best predicted ambulatory function. Plantar flexion torque was the best predictor of velocity (r = .55 free walking and r = .76 fast) and cadence (r = .46 free and r = .58 fast). The combination of plantar flexion and hip abduction torques was the best predictor of fast stride length (r = .78). These findings emphasize the important role of the plantar flexor muscles in gait. Knee extension torque was the poorest predictor for each of the gait parameters. Several patients demonstrated gait deviations that minimized the penalty of quadriceps weakness. Without a contracture or an orthosis, however, no adequate substitution exists for weak plantar flexion.     

Chronic nitric oxide inhibition model six years on

The gait pattern in 10 patients with cerebellar degenerations was studied and the results were compared with 10 matched normal subjects, seeking the principal patterns in this disorder. Gait at natural speed was studied in a biomechanics laboratory using a video-based kinematic data acquisition system for measuring body movements. Patients showed a reduced step and stride length with a trend to reduced cadence. Heel off time, toe off time, and time of peak flexion of the knee in swing were all delayed. Range of motion of ankle, knee, and hip were all reduced, but only ankle range of motion reached significance. Multijoint coordination was impaired, as indicated by a relatively greater delay of plantar flexion of the ankle compared with flexion of the knee and a relatively late knee flexion compared with hip flexion at the onset of swing. The patients also showed increased variability of almost all measures. Although some of the deviations from normal were simply the result of slowness of walking, the gait pattern of patients with cerebellar degeneration shows incoordination similar to that previously described for their multijoint limb motion.     

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.     

Cabin 1, a negative regulator for calcineurin signaling in T lymphocytes

Rectus femoris surgery was performed on 70 patients with cerebral palsy and stiff-knee gait. Fifty-three patients underwent distal rectus transfer, and 17 patients had distal rectus release with complete muscle mobilization. Gait analysis was performed preoperatively and postoperatively at a minimum of 1 year. Swing-phase peak knee flexion (PKF) was improved in the transfer group, allowing improved foot clearance and more efficient gait (p = 0.04). PKF in swing deteriorated slightly in the release group (p = 0.04). The presence of abnormal swing-phase electromyogram (EMG) activity in the rectus alone or abnormal combined rectus and vastus lateralis activity did not influence the PKF results in either surgery (p < 0.05). The Ely test had no predictive value in identifying patients with abnormal EMG activity (p > 0.05). Preoperative knee range of motion was not a significant variable in determining relative success of rectus surgery. No deleterious effects were observed in stance phase in either group (p > 0.05).     

Stereotypic muscle-torque patterns are systematically adopted during acquisition of a multi-articular kicking task

Motor-control mechanisms used to learn multi-joint (kinematically indeterminate) movements, which involve the control of intersegmental dynamics, are poorly understood, because the few kinetic studies which examined them studied only a few trials performed early and late in learning. Therefore, we examined changes in movement kinematics and kinetics accompanying multi-joint movement acquisition to address the following questions: Once subjects can produce accurate movements, do motor patterns (i.e. net muscle torques) change with further learning? Are motor patterns learned using a systematic strategy? Following learning, are the same motor patterns consistently used for movement production? Subjects performed 16 blocks of 16 trials of a discrete weighted (mass = 1.674 kg) kicking movement, involving hip, knee, and ankle motion. They attempted to perform 400 ms spatially accurate movements. Kinematics were recorded for the hip, knee, ankle, and toe of the kicking leg, and inverse dynamics were used to obtain net-muscle-torque profiles. Subjects did not adopt the motor patterns initially used to produce accurate movements. With further learning, net muscle torques became less variable both within and between blocks; inter-joint dependency of muscle torques increased, as evidenced by decreased variability in the pair of muscle torques which directly affect a segment's motion (i.e. hip-knee and knee ankle muscle torques); and inter-joint relationships of muscle torques became more phase-locked, with hip and knee torques being produced simultaneously, as were knee and ankle torques. As there was a progression across blocks until the preferred motor patterns were adopted, the learned stereotypic motor patterns were systematically selected.     

Long-term efficacy of low-density lipoprotein apheresis on coronary heart disease in familial hypercholesterolemia. Hokuriku-FH-LDL-Apheresis Study Group

BACKGROUND: Decreased muscle strength impedes elders' functional performance in daily activities such as gait. The mechanisms whereby increased strength improves gait are unknown. METHODS: A prospective, blinded, randomized trial of moderate intensity strength exercise was conducted and its impact was measured on functional mobility during gait in 132 functionally limited elders. Lower extremity strength was measured, including hip abductor, hip extensor, and knee extensor strength. Of the 132 subjects, 120 subjects (mean age, 75.1 yrs) completed 6 months of elastic band resistance training at least 3 times a week or served as no-exercise controls. RESULTS: Subjects increased their lower extremity strength in the exercise and control groups, by 17.6% and 7.3% (p < .01), respectively. Gait stability improved significantly more in the exercise group than in the control group (p < .05). Increases in forward gait velocity were not significantly different between groups. Peak mediolateral velocity and base of support improved in the exercise group, but not in the control group. Change in lower extremity strength correlated significantly but weakly with many of the gait variables. CONCLUSIONS: Gait stability, especially mediolateral steadiness, improved in the exercise group but not in the control group. These results show that even moderate strength gains benefit gait performance in elders and thus provide a sound basis for encouraging low-intensity strength training for elders with functional limitations.     

Early complications in the operative treatment of patella fractures

In this study two aspects of hybrid functional electrical stimulation (FES) orthoses were investigated: joint motion constraints and FES control strategies. First, the effects of joint motion constraints on the gait of normal subjects were investigated using modern motion analysis systems, including electromyogram (EMG) and heart rate measurements. An orthosis was developed to impose joint motion constraints; the knee and ankle could be fixed or free, and the hip joint could rotate independently or coupled, according to a preset flexion-extension coupling ratio (FECR). Compared with a 1:1 hip FECR, a 2:1 hip FECR was associated with a reduced energy cost and increased speed and step length. The knee flexion during swing significantly reduced energy cost and increased walking speed. Ankle plantar flexion reduced the knee flexing moment during the early stance phase. Second, trials on 3 paraplegic subjects were conducted to implement some of these findings. It appeared that the 2:1 FECR encouraged hip flexion and made leg swing easier. A simple FES strategy increased walking speed and step length and reduced crutch force impulse using fixed orthotic joints.     

Quantitative gait analysis after bilateral total knee arthroplasty with two different systems within each subject

The functional behavior of two kinematically different knee arthroplasty systems within each subject was studied by gait analysis (three-dimensional kinematics, kinetics, dynamic electromyography) in five elderly patients, 2 to 5 years after bilateral surgery. Clinical results were good, yet gait velocity was reduced (range, 0.57-1.1 m/s), with a shortened stride length and a decreased duration of single-limb stance in all subjects. Force plate recordings revealed an undynamic gait with slow loading, reduced modulation of the vertical forces, and poor fore/aft shears. Sagittal plane knee motion during gait was reduced in all subjects, with trunk and pelvic compensation patterns for foot clearance. Muscle activity around the knee was prolonged bilaterally, with activity modulation related to the motion pattern. Although the stride parameters were quite symmetric, there was a marked asymmetry of the motion pattern, with a side-to-side difference of peak knee flexion during stance and swing phase of up to 15 degrees. This finding, however, was not clearly related to the type of prosthesis. Even within one subject, significant side-to-side variability may persist, which leads to asymmetry of the motion pattern, unrelated to the kinematic design of the implant. Other factors, such as the patella-extensor mechanism, ligament balancing, leg-length discrepancy, proprioception, continuation of a preoperative habit, or a contralateral influence, may explain part of the asymmetry seen in these subjects.     

Skeletal muscle contraction: analysis with use of velocity distributions from phase-contrast MR imaging

PURPOSE: Velocity gradient data from phase-contrast magnetic resonance (MR) imaging were tested for the ability to calculate tensile strain and shear strain (deformation) during cyclical motion of skeletal muscle. MATERIALS AND METHODS: Strain data were derived from in vitro and in vivo phase-contrast MR velocity maps. A motion phantom designed to cyclically compress and expand a specimen of skeletal muscle provided a standard of reference to validate deformation, translation, and rotation measurements. The authors studied anterior and posterior muscle compartments of the lower extremity in three healthy volunteers during ankle dorsiflexion and plantar flexion against various resistances and the forearms of five healthy volunteers during flexion and extension of the fingers. RESULTS: The mean in vitro tracking error was 0.5 mm. The gastrocnemius muscle area in vivo changed 20% for both the minimum and maximum force conditions and therefore did not appear to be a good predictor of force. CONCLUSION: Phase-contrast MR imaging provides quantitative data on muscle contraction and demonstrates that shear and tensile strain can be measured and separated from translation and rotation of muscle.     

Functional evaluation of normal and pathologic knees during gait

The functional performance of the knee joints of 29 normal volunteers, 65 patients with degenerative joint disease and 30 patients with rheumatoid arthritis was studied according to clinical (historical, physical and roentgenographic) and biomechanical gait parameters. Temporal and distance gait factors (velocity, cadence and stride length) were significantly reduced in patients with diseased knees. Sagittal plane knee motion was markedly reduced, as was stance phase flexion, indicating poor tolerance of loading the flexed knee in the patient groups. There was no correlation between passive motion of the diseased knee and the amount of motion used during gait. Patients with rheumatoid arthritis generally showed more compromise of knee joint function than did patients with degenerative joint disease. Statistically, significant correlations between various clinical and biomechanical gait parameters suggest that the techniques used are an objective measurement of knee joint function and may be employed as a means of evaluating various treatment modalities for the diseased knee.     

Three-dimensional gait analysis in spina bifida

This study was designed to determine gait patterns in children with lumbar and sacral neurologic level spina bifida. We studied a group of 28 children: 10 had L4-level lesions and a mean age of 11 years; eight had L5-level lesions and a mean age of 8 years; and 10 had S1-level lesions with a mean age of 12 years. A group of 15 normal children, mean age 10 years, was used for comparison. Each child underwent three-dimensional gait analysis using the Vicon system. We found that there were recognisable gait patterns for each level of spina bifida and that the abnormalities accurately reflected the muscle deficiencies present. The gait patterns approximated more closely to those of the normal group as the neurological level descended. The most important findings were of increased pelvic obliquity and rotation with hip abduction in stance (reflecting the gross Trendelenburg-type gait seen in these children) and persistent knee flexion throughout stance as a result of the absence of the plantar flexion-knee extension couple. We found that gait was not improved by tendon transfers performed either at the hip (posterolateral psoas transfer) or at the ankle (tibialis anterior transfer).     

Kinematic gait analysis in dogs with hip dysplasia

OBJECTIVE: To define alterations of movement in dogs with hip dysplasia by use of noninvasive, 3-dimensional, computer-assisted kinematic gait analysis. DESIGN: Kinematic and force plate data were collected at the trot from clinically normal dogs and from dogs with hip dysplasia. ANIMALS: 12 large adult dogs of various breeds with clinical and radiographic evidence of hip dysplasia, and 12 clinically normal adult large dogs of various breeds with body weight similar to that of the dogs with hip dysplasia. PROCEDURE: Dynamic flexion and extension angles and angular velocities were calculated for the coxofemoral, femorotibial, and tarsal joints. Temporal and distance variables were also computed. Essential Fourier coefficients were determined and used to reconstruct mean dynamic flexion and extension curves for all joints, and to compare differences in movement between dogs with hip dysplasia and clinically normal dogs. RESULTS: Dogs with hip dysplasia had subtle characteristic changes in dynamic flexion and extension angles and angular velocities of each joint, verified by significant differences in essential Fourier coefficients between the 2 study groups. Stride length was increased and peak vertical force was decreased in dogs with hip dysplasia. Subject velocity, maximal foot velocity, stance duration, stride frequency, and impulse area did not differ between the 2 groups. CONCLUSIONS: Kinematic gait analysis indicated that hip dysplasia is associated with alterations in movement of the coxofemoral, femorotibial, and tarsal joints. Computer-assisted kinematic gait analysis provided a noninvasive, objective tool with which to evaluate these complex motion alterations. CLINICAL RELEVANCE: The information obtained may be useful in future evaluations of various modes of treatment for hip dysplasia.     

Effects of varying acceleration of platform translation and toes-up rotations on the pattern and magnitude of balance reactions in humans

Different movement synergies used to restore balance in response to sudden support surface displacements have been described, which include the ankle movement synergy and a number of multisegmental movement synergies. The purpose of this study was to extend the analysis of the effects of stimulus magnitude on the pattern and scaling of balance reactions to larger magnitudes of balance disturbances, and to other types of balance disturbances, in particular, forward translations (FT), backward translations (BT), and toes-up rotations (RT). In addition, we examined whether the timing and magnitude of center of body mass (CM) displacement is an invariant feature of corrective responses to varying magnitudes of balance disturbances. Thirteen healthy adults were subjected to FT, BT, and RT of varying acceleration/velocity. The balance disturbance induced by FT and BT was fundamentally different from that induced by RT. The balance requirement during FT and BT was to rapidly translate the CM forward/backward to the new position within the displaced base of support. For RT, the requirement was to minimize the backward displacement of the CM. As evidenced from the initial phase of ankle, knee, and hip angular displacements and anterior-posterior (A-P) center of foot pressure displacement, the magnitude of the balance disturbance increased with increasing platform acceleration/velocity. For FT and BT, the present findings are consistent with the view that trajectory of CM is a control variable, as the timing, peak magnitude, and time to peak CM displacement did not vary as a function of platform acceleration/velocity. However, for RT, the peak magnitude and time to peak CM displacement did increase with increasing platform acceleration/velocity. The results demonstrate that in response to FT, BT, and RT, stability was restored by distinct multisegmental movement synergies. The corrective response to FT consisted of early knee flexion then ankle dorsiflexion and hip extension. The corrective response to BT consisted of hip flexion and ankle plantar flexion. For RT early hip flexion and knee flexion was observed. All muscles recorded (tibialis anterior, soleus, gastrocnemius, hamstrings, and quadriceps) were activated within a range of 60 to 170 ms from onset of platform displacement. For FT, BT, and RT, the pattern and timing of angular displacements and muscle responses did not vary as a function of platform acceleration/velocity, while there was a significant effect of platform acceleration/velocity on the magnitude of the corrective response, that is, peak magnitude of corrective hip, knee, and ankle angular displacements and magnitude of muscle responses. The present findings indicate that multiple sources of spatial information are necessary for the selection and initiation of the appropriate corrective response to meet the requirements of the different balance tasks. The present results strongly endorse the concept of a postural control network for recovery of standing balance, as opposed to positive feedback through local segmental or long loop reflex circuits.     

A dynamic model for simulating movements of the elbow, forearm, an wrist

We developed a dynamic model of the upper extremity to simulate forearm and wrist movements. The model is based on the skeletal structure of the arm and is capable of elbow flexion/extension, forearm pronosupination, and wrist flexion/extension and radial/ulnar deviation movements. Movements are produced by activation of a Hill-type model of muscle, and limits on joint motion are imposed by passive moments modeled after experimental results. We investigated the muscle output force sensitivity, as well as wrist flexion/extension motion sensitivity to parameter variations. The tendon slack length and muscle fiber length were found to have the greatest influence on muscle output and flexion/extension wrist motion. The model captured the direction of the moment vectors at the wrist well, but predicted much higher moments than were measured by stimulating the paralyzed muscles of one tetraplegic subject.     

Doctors'' attitudes towards empirical data--a comparative study

PROBLEM: The interdependencies between movements of the thighs and the lumbar vertebral shape are of high practical interest. Which are the normals of this phenomenon? METHOD: In an experiment on 107 volunteers without before known spinal disorders and complaints of back pain (47 f, 60 m, 17 a-30 a), the interdependencies between movements of the thighs in the sagittal and the lumbar back profile were analysed. Hip joint movements were provoked by a lift jack, elevating the feet to the volunteers, which sat on a bicycle chair. The hip joint flexion was measured by a Zebris CMS 50. The sagittal profile of the lower back was sensed by a comb of steel needles with low friction support. RESULTS: At 30 degrees of hip flexion, 68% of the volunteers demonstrated a kyphotic, 17% a straight and 15% a lordotic lumbar shape. Starting at 90 degrees of hip flexion, "definitively kyphosating movements" of the lumbar motion segments occur. At the end of the motion, 89% of the volunteers had a kyphotic, 3% a straight and 8% a lordotic lumbar configuration. Each 2 degrees of additional hip joint flexion caudo-cranially one more lumbar motion segment is recruited for the definitive kyphosation of the lumbar spine. CONCLUSIONS: Instead of a "physiological shape of the lumbar spine" its "physiological function" or its "physiological interaction between shape und function" should be in the focus of future discussions. In the sitting, hip joint flexion leads to a coupled motion of the thighs, the pelvic girdle and the lumbar vertebral column with the consequence of a kyphosation of the lumbar back shape.     

Motor patterns for human gait: backward versus forward locomotion

Seven healthy subjects walked forward (FW) and backward (BW) at different freely chosen speeds, while their motion, ground reaction forces, and electromyographic (EMG) activity from lower limb muscles were recorded. We considered the time course of the elevation angles of the thigh, shank, and foot segments in the sagittal plane, the anatomic angles of the hip, knee, and ankle joints, the vertical and longitudinal ground reaction forces, and the rectified EMGs. The elevation angles were the most reproducible variables across trials in each walking direction. After normalizing the time course of each variable over the gait cycle duration, the waveforms of all elevation angles in BW gait were essentially time reversed relative to the corresponding waveforms in FW gait. Moreover, the changes of the thigh, shank, and foot elevation covaried along a plane during the whole gait cycle in both FW and BW directions. Cross-correlation analysis revealed that the phase coupling among these elevation angles is maintained with a simple reversal of the delay on the reversal of walking direction. The extent of FW-BW correspondence also was good for the hip angle, but it was smaller for the knee and ankle angles and for the ground reaction forces. The EMG patterns were drastically different in the two movement directions as was the organization of the muscular synergies measured by cross-correlation analysis. Moreover, at any given speed, the mean EMG activity over the gait cycle was generally higher in BW than in FW gait, suggesting a greater level of energy expenditure in the former task. We argue that conservation of kinematic templates across gait reversal at the expense of a complete reorganization of muscle synergies does not arise from biomechanical constraints but may reflect a behavioral goal achieved by the central networks involved in the control of locomotion.