Lofstrand Crutch-assisted Gait Research Articles

Point-Mass Biomechanical Model of the Upper Extremity During Lofstrand Crutch-Assisted Gait.

We propose a point-mass biomechanical model to estimate the forces and moments supported by the upper extremity during Lofstrand crutch-assisted gait. This model is based on the Newtonian classical mechanics and the angular momentum theorem. The system arm-crutch is divided into three segments: 1) crutch, 2) wrist-elbow, and 3) elbow-shoulder. The theoretical model was experimentally validated with a disabled person with spinal cord injury. Two crutch-assisted gait patterns have been chosen to carry out the experimental validation: two-point reciprocal gait and swing-through gait. Six position markers (three placed on the arm and three placed on the crutch) and two force sensors (placed on the crutch) were used in experiments for testing the model. The results were compared with a distributed-mass model based on studies previously published, concluding that the relative mean difference between models is less than 3% Body Weight and 1% Body Weight times Height when forces and moments are estimated, respectively. Some advantages of using a point-mass model are summarized: simple formulation, easy to understand; require less numerical calculation reducing the computational cost; requires less position markers placed on the subject, increasing therefore the comfort of the subject.

Evaluation of a wrist orthosis on lofstrand crutch-assisted gait.

Lofstrand, or forearm, crutches are a common assistive mobility device for those with functional impairments. However, repeated loading of the wrist and palmar region and continual hyperextension of the wrist during Lofstrand crutch usage may cause wrist strain, pain, and secondary injuries such as carpal tunnel syndrome. In order to reduce risk of injury, a novel wrist orthosis was developed with the intent of improving wrist posture and reducing/redirecting palmar loads from the carpal tunnel region to the adductor pollicis area. Dominant-hand palmar loads and wrist extension angles of 10 healthy, able-bodied subjects were measured during swing-through Lofstrand crutch-assisted gait to demonstrate the orthosis effectiveness. Each subject performed 10 trials each with and without the orthosis. An enhanced understanding of the effects of the wrist orthosis on kinematics and palmar loading was gained through this study. Results indicated a significant decrease in maximum palmar force, contact area, and wrist extension when using the orthosis. Palmar loads were observed to be redirected toward the adductor pollicis when using an orthosis during Lofstrand crutch-assisted gait. Ultimately, this device was effective in redistributing palmar loads with the potential to reduce pain and risk of carpal tunnel syndrome in long-term Lofstrand crutch users.

Motion Analysis of the Upper Extremities During Lofstrand Crutch-Assisted Gait in Children with Orthopaedic Disabilities

Background This paper presents a review of current state-of-the-art dynamic systems for quantifying the kinematics and kinetics of the joints of the upper extremities during Lofstrand crutch-assisted gait. The reviewed systems focus on the rehabilitation of children and adults with myelomeningocele (MM), cerebral palsy (CP), spinal cord injury (SCI), and osteogenesis imperfecta (OI). Forearm crutch systems have evolved from models with single- to multi-sensor hardware systems that can incorporate an increasing number of segments that are in compliance with the standards of the International Society of Biomechanics (ISB). Methods The initial system developed by our group was a single, six-axis, sensor-crutch design with an accompanying ISB-compliant, inverse dynamics model. The model consisted of seven upper body segments and two crutch segments. After thorough validation of the software and hardware, it was tested using nine children with MM. The join dynamics of the shoulder, elbow, and wrist were assessed during reciprocal and swing-through gait. Results The dynamic metrics of the upper extremeties, including the mean, range, and maximum force and moment, were found to be significantly different depending on the gait pattern. Joint forces were found to be the greatest during swing-through gait, with inferior forces reaching 50% of body weight. In order to improve upon the initial system, our group developed a four-sensor crutch system that measures the contributions of the crutch-cuff kinetics. The inverse dynamics model was enhanced by including crutch-cuff and sensor segments that also follow the ISB modeling standards. This system was used to model subjects with CP, SCI, and OI. Maximum joint forces were measured in the subject with CP, while maximum moments were measured in the subject with SCI. The subject with OI presented the smallest joint forces and moments. Discussion These novel model systems may be used to improve the quantification of joint dynamics during Lofstrand crutch-assisted gait. These methods may ultimately improve the identification of the risk factors for joint pathology and subsequent therapeutic planning and rehabilitation paradigms.

Upper extremity inverse dynamics model for crutch-assisted gait assessment

Current inverse dynamics models of the upper extremity (UE) are limited for the measurement of Lofstrand crutch-assisted gait. The objective of this study is to develop, validate, and demonstrate a three-dimensional (3-D) UE motion assessment system to quantify crutch-assisted gait in children. We propose a novel 3-D dynamic model of the UEs and crutches for quantification of joint motions, forces, and moments during Lofstrand crutch-assisted gait. The model is composed of the upper body (i.e., thorax, upper arms, forearms, and hands) and Lofstrand crutches to determine joint dynamics of the thorax, shoulders, elbows, wrists, and crutches. The model was evaluated and applied to a pediatric subject with myelomeningocele (MM) to demonstrate its effectiveness in the characterization of crutch gait during multiple walking patterns. The model quantified UE dynamics during reciprocal and swing-through crutch-assisted gait patterns. Joint motions and forces were greater during swing-through gait than reciprocal gait. The model is suitable for further application to pediatric crutch-user populations. This study has potential for improving the understanding of the biomechanics of crutch-assisted gait and may impact clinical intervention strategies and therapeutic planning of ambulation.

Upper extremity dynamics during Lofstrand crutch-assisted gait in children with myelomeningocele

The use of quantitative models for evaluating upper extremity (UE) dynamics in children with myelomeningocele (MM) is limited. A biomechanical model for assessment of UE dynamics during Lofstrand crutch-assisted gait in children with MM is presented. This pediatric model may be a valuable tool for clinicians to characterize crutch-assisted gait, which may advance treatment monitoring, crutch prescription, and rehabilitation planning for children with MM. Nine subjects with L3 or L4 level myelodysplasia (mean ± S.D. age: 11.1 ± 3.8 years) were analyzed during forearm crutch-assisted gait: (1) reciprocal gait and (2) swing-through gait. Three-dimensional (3D) dynamics of the UE were acquired and the Pediatric Outcomes Data Collection Instrument (PODCI) was administered. The goal of this study was to determine if meaningful differences occur between gait patterns in UE kinematics and kinetics, and if correlations exist between dynamics and functional outcomes. Temporal-distance parameters showed significant differences between reciprocal and swing-through gait in stride length, and stance duration. All joint ranges of motion were greater during swing-through gait. Thorax, elbow and crutch ranges of motion were found to be significantly different between gait patterns. Kinetic results demonstrated significant differences between reciprocal and swing-through gait, bilaterally, at all joints for the force variables of mean superior/inferior force, range of force, and maximum inferior force. Functional outcomes were strongly correlated with joint dynamics. Accurate quantitative assessment is essential for preventing injury in long-term crutch users. This study has potential for improving clinical intervention strategies and therapeutic planning of ambulation for children with MM.

Upper Extremity Dynamics During Lofstrand Crutch-Assisted Gait in Children With Myelomeningocele

Background/Objective: We present a 3-dimensional biomechanical model of the upper extremities to characterize joint dynamics during 2 patterns of Lofstrand crutch-assisted gait in children with myelomeningocele. The upper extremity model incorporates recommendations by the International Society of Biomechanics.Methods: A Vicon motion analysis system (14 cameras) captured the marker patterns. Instrumented crutches measured reaction forces. Five subjects with L3 or L4 level myelodysplasia (aged 9.8 ± 1.6 years) were analyzed during reciprocal and swing-through Lofstrand crutch-assisted gait.Results: The mean walking speed, cadence, and stride length were greatest during swing-through gait. Although the gait patterns had different morphologies, the thorax and elbows remained in flexion, the wrists remained in extension, and the shoulders demonstrated both flexion and extension throughout the gait cycles. Swing-through gait showed larger ranges of motion for all joints than reciprocal gait. Peak crutch forces were highest during swing-through gait. The model was effective in detecting significant differences in upper extremity joint dynamics between reciprocal and swing-through crutch-assisted gait in children with myelomeningocele.Conclusions: Results support continued testing. Future work should include clinical and functionalassessment in a correlated study of dynamics and function. Knowledge from the study may be useful in treatment planning and intervention.

Upper extremity kinetics during Lofstrand crutch-assisted gait

A three-dimensional (3D) biomechanical model was developed to determine upper extremity kinematics and kinetics of persons walking with forearm crutches. Six-component load cells and strain gauges were installed in the crutches to determine crutch forces. A six-camera VICON motion system was used to acquire coordinate data from 24 reflective markers attached to the upper extremities and crutches. Joint axes for the wrist, elbow, and glenohumeral joints were defined and joint forces and moments were determined using inverse dynamics. Accuracy of the crutch instrumentation was established by simultaneously collecting force data from a Kistler forceplate and each crutch during crutch-assisted gait with the respective crutch tip contacting the forceplate. In order to demonstrate the application of this biomechanical model, upper extremity weight bearing forces, joint motion, and stride characteristics were recorded from a subject with T-12 incomplete spinal cord injury (SCI), using a crutch-assisted reciprocal four-point gait pattern. The peak net joint forces and moments were greater for the right arm opposite the weaker left lower extremity. The largest joint forces were directed superiorly ( F z ) and the asymmetrical pattern of crutch use was consistent with lower extremity strength differences. During left leg weight acceptance, increased right wrist extension motion and moment were recorded, which may contribute to wrist pathology.