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D C Kerrigan

Publications and source records attributed to D C Kerrigan.

47 records · Page 3Linked to original sources
PubMedDate not supplied

A tool to assess biomechanical gait efficiency; a preliminary clinical study.

A goal of many physiatric interventions is to improve biomechanical walking efficiency. Thus, a tool that helps assess this efficiency, independent of cardiac, pulmonary, psychologic, or other nonbiomechanical factors, would be useful. Currently used methods to measure efficiency, including comfortable walking speed, are not specific to biomechanical variables. A potential tool, the biomechanical efficiency quotient (BEQ), which uses three variables--average stride length, vertical displacement of the trunk during walking, and sacral height during standing--is proposed and preliminarily tested. This quotient is based on Saunders, Inman, and Eberhart's theories and on a prior study in able-bodied subjects. The BEQ was computed in 20 consecutive patients with neurologically based gait disability referred for gait laboratory evaluation who subjectively reported that one or two ankle-foot-orthoses (AFOs) reduced the effort necessary to walk. The quotient was calculated with and without the AFO(s) by dividing the average vertical displacement of the sacrum, which was measured with an optoelectronic system, and by a predicted displacement, which was based on the patient's sacral height and average stride length. The mean BEQ with the AFO(s) (6.3 +/- 4.4) was significantly less than the mean BEQ without the AFO(s) (9.7 +/- 7.1); P = 0.005. Furthermore, the BEQ was less with the AFO(s) compared with trials without the AFO(s) in all subjects. Percent change in BEQ with the AFO(s) (26.8 +/- 19.6) correlated with percent change in comfortable walking velocity (24.8 +/- 31.8), r = 0.73, P<0.001, across all subjects. The BEQ may be useful in specifically assessing the effect on biomechanical efficiency of physiatric interventions, despite variable nonbiomechnical factors. An instrument to measure vertical trunk displacement during walking outside of the gait laboratory would be extremely useful for further necessary longitudinal studies.

Adult↗
PubMedDate not supplied

Camptocormia: a biomechanical analysis. A case report.

Although camptocormia, a conversion disorder associated with the disability of severely forward-bent posture, has been reported in the literature, to date there has been no report of a detailed kinematic or biomechanical analysis of this disability. Presented is a 47-yr-old male engineer with severely forward-bent posture during walking. One year ago, after playing tennis, he developed low back pain followed by a sensation that to walk comfortably he had to assume a forward-bent posture. Two months later, although the low back pain had resolved, he maintained the same unusual walking pattern. Although he could walk a few steps in the upright position, he would spontaneously revert to the forward-bent posture. Physical examination was normal except for bilateral 10 degree hip flexion contractures. Gait laboratory analysis, including kinematics, kinetics, and dynamic electromyography, revealed exaggerated anterior pelvic tilt during terminal stance when he walked in an upright posture. In the forward-bent posture, however, this anterior pelvic tilt was significantly less. It is possible that his unusual forward-bent posture was a compensatory mechanism to reduce excessive pelvic tilt. Although this rare disability has been previously attributed to a conversion disorder, there may be, in some instances, a biomechanical component.

Biomechanical Phenomena↗
PubMedDate not supplied

The proportional work of lifting the center of mass during walking.

The present study determined the proportion of energy consumption used to lift the center of mass vertically during walking. By assuming that the vertical oscillations of the trunk were identical to those of the center of mass, the complexity of studying the human gait was simplified. The work performed on the center of mass, defined as lift work, was calculated using the subject's mass and the vertical displacement of the trunk. Compensating for the fact that human muscles are approximately 25% efficient in performing external work, the mechanical work was compared with the total energy expenditure, determined using an expired air analysis. At 1.34 and 1.79 m/s, 53.2 +/- 9.3% and 62.8 +/- 8.6%, respectively, of the total energy can be explained by lift work. At 0.45 and 0.90 m/s, the proportions are considerably less, 21.6 +/- 6.6% and 37.6 +/- 8.2%, respectively. These findings provide a rationale for why the metabolic energy cost per unit distance is greater at slower speeds than comfortable or fast speeds of walking. The total energy consumption can be accounted for by changes in the potential and kinetic energies and internal muscular work, defined as the less readily observable work probably needed for balance. The present study demonstrated that the metabolic energy cost of changing the potential energy of the center of mass during walking is significantly less relative to the total energy consumption at slower speeds than at higher speeds. Because kinetic energy is proportional to the square of the velocity, the metabolic energy cost of changing this energy is relatively small at slower speeds. Internal muscular work must therefore play a large role in total energy consumption at slow speeds of walking.

Adult↗
PubMedDate not supplied

Dynamic implications of hip flexion contractures.

Hip flexion contractures are a common complication in disabled patients. However, no previous study has examined reduced hip motion during gait. This retrospective analysis evaluates the relationship between the degree of hip flexion contracture found on static testing and the degree found during gait and also assesses the strength of the association between hip flexion contractures and compensatory mechanisms such as anterior pelvic tilting, increased knee flexion, and decreased contralateral step length. Clinical and quantitative gait laboratory data were obtained from 41 consecutive patients with mostly neurologically based impairments who presented with bilateral hip flexion contractures on Thomas testing (82 limbs). Correlation studies demonstrated a relatively weak association between the degree of peak hip extension during gait and hip flexion contracture by Thomas testing (r = 0.41, P < 0.0001). Limited hip extension was most closely associated with anterior pelvic tilting (r = 0.60, P < 0.0001), whereas Thomas test measurements yielded a correlation with anterior pelvic tilt of only r = 0.36 (P < 0.001) and were insignificant predictor variables of anterior pelvic tilting in regression analysis. Thus, peak hip extension and anterior pelvic tilting assessed during gait were poorly associated with the static Thomas test measurements, and anterior pelvic tilt was most strongly correlated with reduced hip extension during gait compared with the other compensatory mechanisms.

Adolescent↗
PubMedDate not supplied

Gender differences in joint biomechanics during walking: normative study in young adults.

The effect of gender on specific joint biomechanics during gait has been largely unexplored. Given the perceived, subjective, and temporal differences in walking between genders, we hypothesized that quantitative analysis would reveal specific gender differences in joint biomechanics as well. Sagittal kinematic (joint motion) and kinetic (joint torque and power) data from the lower limbs during walking were collected and analyzed in 99 young adult subjects (49 females), aged 20 to 40 years, using an optoelectronic motion analysis and force platform system. Kinetic data were normalized for both height and weight. Female and male data were compared graphically and statistically to assess differences in all major peak joint kinematic and kinetic values. Females had significantly greater hip flexion and less knee extension before initial contact, greater knee flexion moment in pre-swing, and greater peak mechanical joint power absorption at the knee in pre-swing (P < 0.0019 for each parameter). Other differences were noted (P < 0.05) that were not statistically significant when accounting for multiple comparisons. These gender differences may provide new insights into walking dynamics and may be important for both clinical and research studies in motivating the development of separate biomechanical reference databases for males and females.

Absorption↗
PubMedDate not supplied

Identification of kinetic differences between fallers and nonfallers in the elderly.

Falls are a major cause of decreased mobility and disability in the elderly. Multiple factors are believed to contribute to falling. Among these, gait abnormalities have drawn attention as a possible risk factor. Although previous studies have revealed few differences in gait parameters compared with similar aged controls, it was hypothesized that because of intrinsic differences in balance and motor control, we would observe differences in joint kinetics. In this study, 15 subjects (mean age, 77 +/- 9 yr), who had at least 2 mo of repeated falls from an unclear cause, were evaluated in a gait laboratory and were compared with a control group of 15 subjects (mean age, 75 +/- 5 yr) with no history of falls. Analysis of data demonstrated a significantly greater peak torque in the falls group for the following: hip flexion, hip adduction, knee extension, knee varum, ankle dorsiflexion, and ankle eversion (P < 0.003 in each comparison). Also, ankle plantarflexion torque was significantly decreased in the falls group (P = 0.001). Joint powers showed different absorption at the knee and ankle in the falls group. The discovery of these kinetic differences may provide further insight into the mechanism of falls in the elderly and, more importantly, lead to identifiable markers to detect those who may be susceptible to falls.

Accidental Falls↗
PubMedDate not supplied

Gait analysis in rehabilitation medicine: a brief report.

Gait analysis can be a powerful tool for rehabilitation research and clinical practice. However, there has been little coordinated effort to set goals for the application of gait analysis in rehabilitation. Therefore, a priority setting process was engaged to obtain the opinions of a diverse pool of experts related to human motion analysis. The primary goal of this process was to develop priorities for future research, development, and standardization in gait analysis. A multistep approach was used that included expert testimony, group discussions, individually developed priorities, and a ranking process. Several important priorities emerged from this activity. The highest priority was assigned to research on the efficacy, outcomes, and cost-effectiveness of gait analysis.

Cost-Benefit Analysis↗
PubMedDate not supplied

Spastic paretic stiff-legged gait: biomechanics of the unaffected limb.

A concern for individuals with hemiparesis affecting their gait, which heretofore has never been studied, is the possibility that various compensations occurring in the unaffected limb may strain or fatigue the muscles or ligaments and/or predispose to joint injury in that limb. We studied the biomechanics of the unaffected limb during walking in 20 subjects with hemiparesis who had stiff-legged gait as a result of stroke. An optoelectronic motion analysis and force platform system was used to estimate torques in all three planes about the hip, knee, and ankle. Sagittal plane joint motion and power about the unaffected hip, knee, and ankle were also studied. Data were compared with control walking data collected from 20 able-bodied controls. On average, peak torques and powers were all either reduced or the same compared with controls, even though in some instances values were >2 standard deviations (SD) above the control means. Our findings suggest that on average the probability of excessive muscular-tendon effort and the risk for biomechanical injury in the unaffected limb are minimal compared with able-bodied, walking controls. However, given individual variability, we recommend routine clinical gait analysis for all people with stiff-legged gait to eliminate excessive values in certain biomechanical parameters, which could, if not addressed, predispose to muscle-tendon strain or joint or ligamentous injury.

Ankle Joint↗
PubMedDate not supplied

Hip hiking and circumduction: quantitative definitions.

OBJECTIVE: To define and propose clinically useful quantitative measurements of hip hiking and circumduction using standard three-dimensional motion analysis techniques. DESIGN: We studied pelvic, hip, and thigh motions in 23 subjects with hemiparetic, stiff-legged gait as a result of stroke and compared these motions with those obtained from 23 able-bodied controls. RESULTS: We observed significantly increased hip abduction on the unaffected limb during stance, with simultaneous elevation of the affected side of the pelvis during swing. We define these differences as hip hiking and, thus, can quantify the degree to which hip hiking occurs by measuring the unaffected coronal hip angle and/or the coronal pelvic angle when the affected limb is in midswing. We also observed a greater than normal coronal thigh angle during midswing of the affected limb that we can use to quantitatively define circumduction. Of note, hip abduction during swing was not increased on the affected swing limb, compared with the control. CONCLUSIONS: Hip hiking can be defined precisely as unaffected coronal hip and/or pelvic angle when the affected limb is in midswing and circumduction can be defined as greater than normal coronal thigh angle during midswing of the affected limb. These precise definitions should allow us to better communicate and understand the implications of these gait patterns, and can serve as the basis for clinically meaningful quantitative assessment and outcome measurement tools.

Adult↗