Biomedical subjects

D C Kerrigan

Publications and source records attributed to D C Kerrigan.

At least 19 recordsLinked to original sources

PubMed2001

Can toe-walking contribute to stiff-legged gait?

OBJECTIVE: Spastic paretic stiff-legged gait, defined as reduced knee flexion in swing, has previously been attributed solely to spastic quadriceps activity. In earlier work, the authors suggested that reduced knee flexion in swing can be attributed to other indirect factors, such as poor hip flexion and abnormal foot-ankle function during gait. The present study was undertaken to determine whether toe-walking, which often occurs in conjunction with stiff-legged gait, in and of itself, might explain some of the reduced knee flexion in swing. DESIGN: An analysis was performed of three-dimensional kinematic data collected from able-bodied subjects while walking on their toes vs. normal heel-toe walking. RESULTS: Peak knee flexion was reduced significantly compared with normal heel-toe walking (42.2+/-8.9 degrees toe-walking vs. 59.2+/-5.7 degrees heel-toe walking; P < 0.00001). CONCLUSIONS: This finding, which occurred when controlling for walking speed, may be clinically relevant for patients who have both a toe-walking and a stiff-legged gait pattern. Some of the reduced knee flexion in swing may be merely a consequence of toe-walking, rather than a result of other causes, such as intrinsic spasticity or abnormal muscle firing about the knee.

Adult↗

PubMed2000

Kinetic alterations independent of walking speed in elderly fallers.

OBJECTIVES: To determine if joint kinetic gait alterations in fallers persist when they attempt to walk at a faster speed that is more comparable with nonfallers' comfortable walking speed. DESIGN: Retrospective, case-control study. Stereophotogrammetric and force platform data were collected. SETTING: A gait laboratory. PARTICIPANTS: Sixteen elderly subjects who had at least 2 falls in the last 6 months from an unclear cause and 23 elderly subjects with no history of repeated falls. MAIN OUTCOME MEASURES: Differences in all major peak joint kinetic (moment and power) values during the gait cycle between elderly nonfallers walking at comfortable speed and elderly fallers walking at (1) comfortable and (2) fast speed. RESULTS: Statistically significant differences present at both comfortable and fast walking speeds were present in 4 sagittal plane parameters. There was an increase in peak external hip flexion moment in stance, a reduction in peak hip extension moment, a reduction in knee flexion moment in preswing, and a reduction in knee power absorption in preswing. CONCLUSION: The presence and persistence of 4 specific alterations in sagittal plane joint kinetics at both comfortable and fast walking speeds imply specific intrinsic pattern differences and allow for new insights into the mechanics of gait in elderly people who fall. The presence of these alterations also suggests they may serve as potential identifiable markers to detect those who may be at risk for falls.

Accidental Falls↗

PubMed2000

A refined view of the determinants of gait: significance of heel rise.

OBJECTIVES: Although the major determinants of gait described by Saunders and colleagues have been accepted for more than 40 years, recent investigations raise the question of whether the reduction in center of mass (COM) displacement compared with a compass gait model indeed results from the factors originally described. We tested the hypothesis that heel rise at the end of stance is a true determinant that can explain a considerable portion of the reduction in COM vertical displacement during walking. DESIGN: Stereophotogrammetric data during walking were collected. A modified compass gait model incorporating the effect of heel rise, as compared with predictions based on a standard compass model, were used to estimate the isolated effect of heel rise on reducing the vertical displacement of COM. SETTING: A gait laboratory. PARTICIPANTS: Thirty able-bodied subjects. MAIN OUTCOME MEASURE: The estimated reduction in COM displacement due to heel rise was compared with the actual reduction in displacement. RESULTS: The estimated effect of heel rise on reduction in COM displacement was 23.4+/-7.6mm, whereas the actual reduction in COM displacement was 21.2+/-6.5mm (difference not significant, paired p = .185). CONCLUSION: During normal walking, heel rise from foot flat has a considerable role in raising the height of the COM when it is at its lowest, thus reducing its overall displacement. Insofar as reduction of COM vertical displacement may have important energy implications, appreciating the specific gait parameter of heel rise is key in rehabilitative approaches to improve gait disability.

Adult↗

PubMed2000

Knee joint torques: a comparison between women and men during barefoot walking.

OBJECTIVE: To determine if knee joint torques, which are likely relevant to the development and, possibly, progression of knee osteoarthritis, are equivalent between genders during natural, barefoot walking. DESIGN: Collected stereophotogrammetric and force platform data during comfortable, barefoot walking. Knee joint torques were plotted and statistically compared between genders using both an unpaired t test (p < .05) and an equivalence test (20% delta). SETTING: A gait laboratory. PARTICIPANTS: One hundred ten healthy, nondisabled young women and men. MAIN OUTCOME MEASURES: Four knee joint torque parameters normalized for height and weight: (1) peak and (2) duration of sagittal flexor joint torque from early to midstance, and (3) first and (4) second peak coronal (frontal) varus torque values during the stance period. RESULTS: No statistically significant differences between genders were found, and the values were equivalent between genders for each of the 4 knee joint torque parameters. CONCLUSION: These findings support the hypothesis that under similar barefoot conditions women and men have a similar intrinsic biomechanic risk for knee osteoarthritis. Future research to assess the effects of other potential biomechanic factors, such as shoe-wear and activity type, may assist not only in preventing knee joint osteoarthritis, but also in developing new rehabilitative strategies to treat osteoarthritis of the knee.

Adult↗

PubMed2000

Compensatory advantages of toe walking.

OBJECTIVES: The study's hypothesis is that toe walking requires less peak muscle strength distally about the ankle and knee compared with normal heel-toe walking and thus may have compensatory advantages for patients with upper motor neuron injury and distal muscle weakness. DESIGN: Motion analysis and force platform data were collected in able-bodied subjects during toe walking and normal walking. Sagittal plane joint torques reflecting muscle force requirements and joint powers reflecting nonisometric muscle contraction were compared between the two conditions using paired t tests, applying a Bonferroni correction for multiple comparisons. SETTING: A gait laboratory. SUBJECTS: Seventeen able-bodied adults, 9 of whom were ballet dancers. MAIN OUTCOME MEASURES: Peak hip, knee, and ankle joint torque and power variables during walking. RESULTS: Peak ankle plantarflexor torque and ankle power generation during terminal stance and preswing were reduced (p<.001), as compared with normal heel-toe walking. The normal ankle dorsiflexor torque at initial contact-and the knee extensor torque and knee power generation during loading response were all essentially absent during toe walking. Hip extensor torque and hip power generation during the loading response phase were greater for toe walking (p<.001). CONCLUSION: Toe walking may require less ankle plantarflexor, ankle dorsiflexor, and knee extensor strength than normal heel-toe walking and thus may have compensatory advantages for patients with upper motor neuron injury and distal lower extremity weakness.

Adult↗

PubMed1999

Pelvis and lower limb anatomical landmark calibration precision and its propagation to bone geometry and joint angles.

Human movement analysis using stereophotogrammetry is based on the reconstruction of the instantaneous laboratory position of selected bony anatomical landmarks (AL). For this purpose, knowledge of an AL's position in relevant bone-embedded frames is required. Because ALs are not points but relatively large and curved areas, their identification by palpation or other means is subject to both intra- and inter-examiner variability. In addition, the local position of ALs, as reconstructed using an ad hoc experimental procedure (AL calibration), is affected by photogrammetric errors. The intra- and inter-examiner precision with which local positions of pelvis and lower limb palpable bony ALs can be identified and reconstructed were experimentally assessed. Six examiners and two subjects participated in the study. Intra- and inter-examiner precision (RMS distance from the mean position) resulted in the range 6-21 mm and 13-25 mm, respectively. Propagation of the imprecision of ALs to the orientation of bone-embedded anatomical frames and to hip, knee and ankle joint angles was assessed. Results showed that this imprecision may cause distortion in joint angle against time functions to the extent that information relative to angular movements in the range of 10 degrees or lower may be concealed. Bone geometry parameters estimated using the same data showed that the relevant precision does not allow for reliable bone geometry description. These findings, together with those relative to skin movement artefacts reported elsewhere, assist the human movement analyst's consciousness of the possible limitations involved in 3D movement analysis using stereophotogrammetry and call for improvements of the relevant experimental protocols.

Biomedical Engineering↗

PubMed1999

Rectus femoris: its role in normal gait.

OBJECTIVE: To analyze the role of the rectus femoris muscle in nondisabled gait at various walking velocities using fine-wire dynamic electromyography. DESIGN: Descriptive study. Fine-wire electromyography data were collected from the rectus femoris during level walking at four walking speeds. Rectus femoris activity patterns in the loading response phase and the pre- and initial-swing phase of the gait cycle were compared using paired t tests. SETTING: A gait laboratory. SUBJECTS: Ten nondisabled adult volunteers. MAIN OUTCOME MEASURES: Amplitude of rectus femoris activity in the loading response phase and the pre- and initial-swing phase during walking at four speeds. RESULTS: There was a bimodal pattern of rectus femoris activity in all subjects, at all speeds, in both phases, with high variability in the onsets, durations, and amplitudes of activity, and paired t tests revealed no significant differences (p > .05) between phases at any walking speed. CONCLUSION: Activity in the rectus femoris in the pre- and initial-swing phase in nondisabled individuals at all speeds suggests that similar activity detected in individuals with stiff-legged gait may not be inappropriate.

Adult↗

PubMed1999

An algorithm to assess stiff-legged gait in traumatic brain injury.

Spastic paretic stiff-legged gait is a frequently encountered gait problem in patients with traumatic brain injury, as well as in many other patients with upper motor neuron disease. Formerly, spasticity of the quadriceps was considered to be the sole cause of stiff-legged gait. Quantitative gait analysis, however, may implicate hip flexor weakness or poor ankle mechanics as the cause of stiff-legged gait. We discuss the use of an algorithm to evaluate stiff-legged gait in traumatic brain injury using a quantitative gait analysis system such that the specific etiology of stiff-legged gait can be identified and can serve as the basis of a treatment plan.

Algorithms↗

PubMed1999

Kinetics of stiff-legged gait: induced acceleration analysis.

Treating spastic paretic stiff-legged gait, defined as reduced knee flexion in swing, holds a high priority in the rehabilitation of patients with upper motor neuron lesions. We propose a method to determine the relative contributions of hip, knee, and ankle impairments to this disability. We analyzed the gait of ten patients with stiff-legged gait (SLG) due to a single stroke and ten healthy, able-bodied controls. Using subject specific models, we analyzed the induced accelerations (IA's) at the knee. Knee IA's throughout the gait cycle were calculated and the sum of the IA's was compared to the knee joint angular acceleration estimated from kinematic data. The preswing and early swing IA's were the focus of our examination as these largely determine knee kinematics in swing. Knee angular accelerations estimated from IA's and kinematic data agreed for both controls and patients. Gait cycle IA analysis of individual patients identified highly variable causes of SLG including ankle and hip joint impairments. Induced acceleration analysis (IAA) suggested that multiple impairments, not just about the knee, but also about the hip and ankle, lead to this disability. Individual subjects are likely to have individual reasons for their stiff-legged gait. Defining the link between the patients specific impairments and their gait disability should be a goal of clinical gait analysis. IAA is a useful tool for this purpose with a strong potential for clinical application.

Acceleration↗

PubMed1998

Knee osteoarthritis and high-heeled shoes.

BACKGROUND: Little is known about the effects of walking in high heels on joints in the legs. Since osteoarthritis of the knee is twice as common in women as in men, we investigated torques (forces applied about the leg joints) of women who wore high-heeled shoes. METHODS: We studied 20 healthy women who were comfortable wearing high-heeled shoes. The women walked with their own high-heeled shoes and barefoot. Data were plotted and qualitatively compared; major peak values for high-heeled and barefoot walking were statistically compared. Bonferroni adjustment was made for multiple comparisons. FINDINGS: Measurement showed increased force across the patellofemoral joint and a greater compressive force on the medial compartment of the knee (average 23% greater forces) during walking in high heels than barefoot. INTERPRETATION: The altered forces at the knee caused by walking in high heels may predispose to degenerative changes in the joint.

Adult↗

PubMed1998

Functionally oriented and clinically feasible quantitative gait analysis method.

A protocol for clinical gait analysis is described, and data from 30 normal adult female subjects are presented. Extensive application to pathologic subjects has proven to be feasible and sufficiently accurate. The method is based on a particular location and attachment of retro-reflective markers on the body and on a particular arrangement of four TV cameras. A motion analyser measures the 3D coordinates of each marker. A modelling approach, based on individual anthropometric measurements, and a functional approach, based on kinematical considerations, are used to estimate the location of hip, knee, and ankle joint centers and the orientation of the flexion-extension axis of the knee. 3D relative and absolute movements of pelvis and lower limbs are obtained and shown to be consistent with functional anatomy.

Adult↗

PubMed1998

Biomechanical gait alterations independent of speed in the healthy elderly: evidence for specific limiting impairments.

OBJECTIVES: It is not known whether changes in the biomechanics of elderly gait are related to aging per se, or to reduced walking speed in this population. The goals of the present study were to identify specific biomechanical changes, independent of speed, that might impair gait performance in healthy older people by identifying age-associated changes in the biomechanics of gait, and to determine which of these changes persist at increased walking speed. DESIGN: Stereophotogrammetric and force platform data were collected. Differences in peak joint motion (kinematic) and joint moment and power (kinetic) values between healthy young and elderly subjects at comfortable and increased walking speed were measured. SETTING: A gait laboratory. SUBJECTS: Thirty-one healthy elderly (age 65 to 84 years) and 31 healthy young adult subjects (age 18 to 36 years), all without known neurologic, musculoskeletal, cardiac, or pulmonary problems. MAIN OUTCOME MEASURES: All major peak kinematic and kinetic variables during the gait cycle. RESULTS: Several kinematic and kinetic differences between young and elderly adults were found that did not persist when walking speed was increased. Differences that persisted at both comfortable and fast walking speeds were reduced peak hip extension, increased anterior pelvic tilt, and reduced ankle plantarflexion and ankle power generation. CONCLUSION: Gait performance in the elderly may be limited by both subtle hip flexion contracture and ankle plantarflexor concentric weakness. Results of the current study should motivate future experimental trials of specific hip flexor stretching and ankle plantarflexor concentric strengthening exercises to preserve and potentially improve walking performance in the elderly.

Adolescent↗

PubMed1998

Age-related changes in the initiation of gait: degradation of central mechanisms for momentum generation.

OBJECTIVE: To investigate cross-sectionally age-related changes in the expression and biomechanical efficiency of the gait-initiation motor program. DESIGN: Case-control study. PARTICIPANTS AND SETTING: Twenty healthy young research subjects and 20 healthy elderly subjects who volunteered from the community participated in this study at a university research laboratory. MAIN OUTCOME MEASURES: Participants performed gait-initiation trials at three speeds from a starting position on a force platform while ground reaction force data, 3-D motion analysis data, and electromyographic data were collected. Measures included: latency of tibialis anterior (TA) activation and soleus (SOL) and gastrocnemius (GA) inhibition, magnitude of center of pressure (COP) displacement, magnitude of momentum generated, and final walking velocity. RESULTS: The expression of the central motor program governing gait initiation, as evidenced by the invariant timing between TA activation and SOL/GA inhibition, was seen in both the young and elderly populations, but the frequency was diminished in the latter group. The momentum-generating capacity of the COP shift mechanism was present but significantly diminished in the elderly population. CONCLUSIONS: These findings suggest that the central nervous system uses stable, efficient mechanisms for dealing with the inherent instability of upright bipedalism and that the integrity of these mechanisms degrades with aging.

Adolescent↗

PubMed1998

Torque action of two-joint muscles in the swing period of stiff-legged gait: a forward dynamic model analysis.

Stiff-legged gait, characterized by limited knee flexion during the swing period, is a common consequence of upper motor neuron injury. The purpose of this investigation was to determine whether the rectus femoris and hamstrings muscles (which act at both the hip and knee) contribute to stiff-legged gait if active during the swing period of the gait cycle. Ten subjects with unilateral stiff-legged gait due to stroke were evaluated. Swing period free gait data were obtained. A biomechanical model of the affected limb was developed for each subject. Muscle and tendon lengths were scaled to individual subjects while constant nominal values for maximum muscle forces were used for all subjects. Torque driven forward dynamic simulations were employed to determine the sensitivity of swing period maximum knee flexion angle to changes in hip and knee torques. Combined torque and muscle driven simulations were used to access the action of specific two-joint muscles. Both hip flexion torque and knee extension torque were found to influence knee angle, but knee angle was more sensitive to changes in torque at the knee joint. The actions of the rectus femoris and long hamstrings are most marked at the knee, although their action at the hip opposes their action at the knee. Rectus femoris activity during early swing acts to limit knee flexion and contributes to stiff-legged gait. Long hamstring activity in early swing contributes to knee flexion.

Adult↗

PubMed1998

The vertical displacement of the center of mass during walking: a comparison of four measurement methods.

Measuring the vertical displacement of the center of mass (COM) of the body during walking may provide useful information about the energy required to walk. Four methods of varying complexity to estimate the vertical displacement of the COM were compared in 25 able-bodied, female subjects. The first method, the sacral marker method, utilized an external marker on the sacrum as representative of the COM of the body. The second method, the reconstructed pelvis method, which also utilized a marker over the sacrum, theoretically controlled for pelvic tilt motion. The third method, the segmental analysis method, involved measuring motion of the trunk and limb segments. The fourth method, the forceplate method, involved estimating the COM displacement from ground reaction force measurements. A two-tailed paired t-test within an ANOVA showed no statistically significant difference between the sacral marker and the reconstructed pelvis methods (p = 0.839). There was also no statistically significant difference between the sacral marker and the segmental analysis method (p = 0.119) or between the reconstructed pelvis and the segmental analysis method (p = 0.174). It follows that the first method, which is the most simple, can provide essentially the same estimate of the vertical displacement of the COM as the more complicated second and third measures. The forceplate method produced data with a lower range and a different distribution than the other three methods. There was a statistically significant difference between the forceplate method and the other methods (p < 0.01 for each of the three comparisons). The forceplate method provides information that is statistically significantly different from the results of the kinematic methods. The magnitude of the difference is large enough to be physiologically significant and further studies to define the sources of the differences and the relative validity of the two approaches are warranted.

Adult↗

PubMed1997

Biomechanic effects of a contralateral shoe-lift on walking with an immobilized knee.

OBJECTIVES: A previous study demonstrated that when one knee is artificially immobilized, a contralateral shoe-lift improves the oxygen cost of walking. This study was undertaken to evaluate the kinematic and kinetic effects associated with this shoe-lift. DESIGN: Motion analysis and force platform data were collected in subjects walking (1) normally, (2) with one knee immobilized, (3) with one knee immobilized and with a one-half-inch shoe-lift applied to the contralateral, nonimmobilized shoe, and (4) with a one-inch shoe-lift similarly applied. Kinematic and kinetic data from three trials of each condition were compared graphically and statistically using a repeated measures analysis of variance. SETTING: A gait laboratory. SUBJECTS: Eight able-bodied subjects without known neurologic or musculoskeletal problems. MAIN OUTCOME MEASURES: Fifty-two peak kinematic and kinetic variables during various phases of the gait cycle. RESULTS: Statistically significant differences (p < .05) between the normal and immobilized knee conditions were noted in 22 variables; however, significant differences between the immobilized knee conditions were found in only 4 variables. There were small improvements with the shoe-lifts toward normal in peak hip abduction, hip abduction at 20% to 30% of the gait cycle, and in peak knee extension moment on the nonimmobilized side. There was a small change away from normal in peak knee extension moment on the immobilized-side for the 1" shoe-lift. CONCLUSION: Wearing a contralateral shoe-lift when one knee is immobilized is associated with only small changes in kinematic and kinetic parameters. The shoe-lift may slightly reduce the need for compensatory hip abduction and vaulting on the nonimmobilized side. Importantly, no adverse biomechanic effect from the shoe-lift was noted except for a slightly increased peak knee extension moment on the immobilized side found for the 1" but not the 1"/2 shoe-lift.

Adult↗

PubMed1996

Knee recurvatum in gait: a study of associated knee biomechanics.

OBJECTIVES: To quantitatively evaluate peak knee extensor torque values imparted to the posterior knee structures during gait in patients with knee recurvatum compared with torque values observed in control subjects, and to assess the predictive value of the degree of knee hyperextension and other clinical factors in estimating peak knee extensor torque. DESIGN: A retrospective analysis of clinical and quantitative gait data obtained from patients and control subjects. SETTINGS: A gait laboratory. SUBJECTS: Forty-one consecutive patients with neurologically based impairments presenting with knee hyperextension during gait (52 limbs) and 46 able-bodied control subjects. MAIN OUTCOME MEASURE: Peak knee extensor torque during the stance period of the gait cycle. RESULTS: Although overall, the patient average peak extensor torque was significantly greater (p < .001) than the control subjects' average value, knee extensor torques were within or below a +/- 1 standard deviation range for control subjects in 25% (13) of limbs tested. Peak knee hyperextension angle was a poor predictor of peak extensor torque; there was statistical significance (coefficient .061,p < .001) only for hyperextension angles of < or = 4 degrees. Multiple regression incorporating hyperextension angle and other clinical variables to predict peak knee extensor torque resulted in an adjusted r2 of .53. CONCLUSION: Patients with knee recurvatum have variable peak extensor torque values associated with their knee hyperextension. Knowledge of knee hyperextension angle and other clinical factors are only partially useful in predicting a patient's peak knee extensor torque imparted to the posterior knee structures during walking.

Adult↗

PubMed1996

Contralateral shoe-lift: effect on oxygen cost of walking with an immobilized knee.

OBJECTIVE: Evaluate the effect of a contralateral shoe-lift on the oxygen cost of walking with an artificially immobilized knee. DESIGN: A prospective quantitative evaluation of oxygen cost of walking under varying conditions. Subjects walked (1) normally (N), (2) with one knee immobilized (1), (3) with one knee immobilized and with a one-half-inch shoe-lift applied to the contralateral shoe (I1/2"L), and (4) with one knee immobilized and with a one-inch shoe-lift (I1"L). SETTING: Exercise physiology laboratory. SUBJECTS: Ten able-bodied subjects without known cardiopolmonary or musculoskeletal problems. MAIN OUTCOME MEASURE: Breath-by-breath oxygen consumption measurements in mL/kg/m. RESULTS: Oxygen cost on average was 20% more with the knee immobilized (I) compared to normal (N) (mean difference = .0298 +/- .0245mL/kg/m, p = .002). Oxygen cost was significantly less (11% versus 20% above that of normal walking) with the half-inch shoe-lift (mean difference between I1/2" and I = .0167 +/- .0138mL/kg/m, p = .002). Similarly, oxygen cost was significantly less (12% versus 20% above that of normal walking) with the one-inch shoe-lift (mean difference between I1"L and I = .0142 +/- .0116, p = .002). CONCLUSION: This study demonstrates that a subject with an immobilized knee requires less energy to walk with a contralateral shoe-lift and provides scientific evidence for prescribing a shoe-lift in patients with an immobilized knee as a result of knee joint fusion, knee immobilization as a result of casting or orthotics, or spastic paretic stiff-legged gait associated with upper motor neuron disease.

Adult↗