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Military Health System

EACE Journal Publications: Fiscal Year 2014

Following is a summary of published results in FY14 for several key research initiatives and focused research efforts.

Advanced Rehabilitation Sciences

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Can an Integrated Orthotic and Rehabilitation Program Decrease Pain and Improve Function After Lower Extremity Trauma?

Bedigrew KM, Patzkowski JC, Wilken JM, Owens JG, Blanck RV, Stinner D,  Kirk K, Hsu JR. Can an Integrated Orthotic and Rehabilitation Program Decrease Pain and Improve Function After Lower Extremity Trauma? (2014) Clin Orthop Relat Res. (472)10. 3017-3025.

Patients with severe lower extremity trauma have significant disability 2 years after injury that worsens by 7 years. Up to 15% seek late amputation. Recently, an energy-storing orthosis (Intrepid Dynamic Exoskeletal Orthosis (IDEO ) demonstrated improved function compared with standard orthoses; however, the effect when integrated with rehabilitation over time is unknown.   A study was undertaken to analyze the effects of an 8-week integrated orthotic and rehabilitation program on  physical performance, pain, and outcomes in patients with lower extremity functional deficits and if this was different for patients enrolled more than 2 years after their injury.    Results showed the integrated orthotic and rehabilitation initiative improved physical performance, pain, and patient-reported outcomes in patients with severe, traumatic lower extremity deficits and that these improvements were sustained for > 2 years after injury.  

Mitigating Falls Risk

Margins of stability in young adults with traumatic transtibial amputation walking in destabilizing environments

Beltran EJ, Dingwell JB, Wilken JM. Margins of stability in young adults with traumatic transtibial amputation walking in destabilizing environments. (2014)  J Biomech. 47(5):1138-43.

Understanding how lower-limb amputation affects walking stability, specifically in destabilizing environments, is essential for developing effective interventions to prevent falls. This study quantified mediolateral margins of stability (MOS) and MOS sub-components in young individuals with traumatic unilateral transtibial amputation (TTA) and young able-bodied individuals (AB).   Young and otherwise healthy individuals with transtibial amputation achieved lateral stability similar to that of their able-bodied counterparts during unperturbed and visually-perturbed walking. However, unilateral transtibial amputation was shown to have affected lateral walking stability during platform perturbations when compared to able-bodied controls.  These findings begin to validate and quantify the lack of proprioception and subsequent reaction to contact perturbation of individuals with unilateral transtibial amputation. 

Dynamic stability of individuals with trans-tibial amputation walking in destabilizing environments

Beurskens R,  Wilken JM, Dingwell JB. Dynamic stability of individuals with trans-tibial amputation walking in destabilizing environments. (2014). J Biomech. 47(7):1675-81

Lower limb amputation substantially disrupts motor and proprioceptive function. People with lower limb amputation experience considerable impairments in walking ability, including increased fall risk. Understanding the biomechanical aspects of the gait of these patients is crucial in improving their gait function and their quality of life.  In the present study, a Computer Assisted Rehabilitation Environment (CAREN) was used to compare gait variances of unilateral transtibial amputation and healthy individuals.   While walking, subjects were either not perturbed, or were perturbed either by continuous mediolateral platform movements or by continuous mediolateral movements of the visual scene.  Patients with amputation exhibited greater step width variability and greater trunk movement variability  during platform perturbations, but did not exhibit greater local or orbital instability than healthy controls for either perturbation conditions.  These findings suggest that, in the absence of other co-morbidities, patients with unilateral transtibial amputation appear to retain sufficient sensory and motor function to maintain overall upper body stability during walking, even when substantially challenged. 

Task-specific fall prevention training is effective for warfighters with transtibial amputations

Kaufman, K. R., Wyatt, M. P., Sessoms, P. H., & Grabiner, M. D. (2014). Task-specific fall prevention training is effective for warfighters with transtibial amputations. Clinical Orthopaedics and Related Research, 472(10), 3076-3084.

Key factors limiting patients with lower extremity amputations to achieve maximal functional capabilities are falls and fear of falling.  A task-specific fall prevention training program has successfully reduced prospectively recorded trip-related falls that occur in the community by the elderly.  This study was undertaken to test this program in unilateral transtibial amputees. Subjects prospectively reported decreased stumbles, semi-controlled falls, and uncontrolled falls. These results indicate that task-specific fall prevention training is an effective rehabilitation method to reduce falls in persons with lower extremity transtibial amputations.

Optimizing Gait Efficiency

Does intact limb loading differ in service members with traumatic lower limb loss?

Pruziner, A. L., Werner, K. M., Copple, T. J., Hendershot, B. D., & Wolf, E. J. (2014). Does intact limb loading differ in servicemembers with traumatic lower limb loss?. Clinical Orthopaedics and Related Research, 472(10), 3068-3075.

The initiation and progression of knee and hip arthritis have been related to limb loading during ambulation.  Although altered gait mechanics, with unilateral lower limb loss, often result in larger and more prolonged forces through the intact limb, how these forces differ with traumatic limb loss and duration of ambulation have not been well described.  A retrospective review of all clinical and research gait evaluations performed in the biomechanics laboratory at Walter Reed Army Medical Center and Walter Reed National Military Medical Center between January 2008 and December 2012.   Results showed that greater intact limb loading, in individuals with traumatic transtibial loss, were only noted early in the rehabilitation process, but these variables were present early and late in the rehabilitation process for those with transfemoral limb loss.  These findings suggest an increased risk for early onset and progression of arthritis in the intact limb, especially in those with transfemoral limb loss.

Use of a powered versus a passive prosthetic system for a person with bilateral amputations during level-ground walking

Wolf, E. J., & Pruziner, A. L. (2014). Use of a powered versus a passive prosthetic system for a person with bilateral amputations during level-ground walking. JPO: Journal of Prosthetics and Orthotics, 26(3), 166-170.

Persons who have had bilateral lower-limb amputations, especially transfemoral amputation, must use biomechanical compensations to ambulate. Compensations during gait produce abnormal loads on the body and may reduce efficiency. Recent prosthetic advances have attempted to mimic the lost musculature by adding power to knee and ankle systems. A patient with bilateral amputations (right transtibial, left transfemoral) was evaluated 10 months after injury using a passive prosthetic system and then a powered prosthetic system.  Kinematic and kinetic data were collected while the patient walked overground wearing both systems.  The patient showed greater symmetry of step length, decreased vertical ground reaction force, and increased limb transition work using the powered system. Biomechanical variables showed some improvements when using a powered prosthetic system, which may indicate increased mechanical efficiency and decreased lower-limb loading.

Mediolateral joint powers at the low back among persons with unilateral transfemoral amputation

Hendershot, B. D., & Wolf, E. J. (2015). Mediolateral joint powers at the low back among persons with unilateral transfemoral amputation. Archives of physical medicine and rehabilitation, 96(1), 154-157.

A retrospective analysis of the biomechanical gait data  unilateral transfemoral amputation showed larger positive phases of mediolateral joint power at L5/S1 in the frontal plane.  These findings support prior suggestions that persons with transfemoral amputation use a more active mediolateral trunk movement strategy.  Such an active trunk movement strategy with transfemoral amputation may contribute to higher metabolic energy expenditures and low back pain risk.

Mitigating Secondary Health Effects

Knee extension and stiffness in osteoarthritic and normal knees: a videofluoroscopic analysis of the effect of a single session of manual therapy

Taylor, A. L., Wilken, J. M., Deyle, G. D., & Gill, N. W. (2014). Knee extension and stiffness in osteoarthritic and normal knees: a videofluoroscopic analysis of the effect of a single session of manual therapy. journal of orthopaedic & sports physical therapy, 44(4), 273-282.

While manual therapy benefits patients with knee OA, there is limited research quantifying the effects of a manual therapy treatment session on either motion or stiffness of osteoarthritic and normal knees. This study sought to quantify the response of participants with and without knee osteoarthritis (OA) to a single session of manual physical therapy. The intervention consisted primarily of joint mobilization techniques, supplemented by exercises, aiming to improve knee extension.  Results were inconclusive showing there was a significant increase in knee motion in participants with knee OA (P = .004) but not in those with normal knees who had full knee extension at baseline.  Video fluoroscopy of the knee appears reliable and relevant for future studies attempting to quantify the underlying mechanisms of manual therapy.

Kinematic analysis of males with transtibial amputation carrying military loads

Schnall, B. L., Hendershot, B. D., Bell, J. C., & Wolf, E. J. (2014). Kinematic analysis of males with transtibial amputation carrying military loads. J. Rehabil. Res. Dev, 51(10), 1505-1514.

The biomechanical responses to load carriage, a common task for dismounted troops, have been well studied in able-bodied individuals. However, with recent shifts in the rehabilitation and retention process of injured service members, there remains a substantial need for understanding these responses in persons with lower-limb amputations.  This study sought to analyze the kinematic differences between persons with transtibial amputation (TTA) and uninjured control subjects.   Unilateral transtibial amputation (TTA)  exhibited several distinct gait changes; Increased dorsiflexion (deformation) of the prosthetic foot/ankle, less stance knee flexion on the prosthetic limb, and altered trunk forward lean/excursion.  Such evidence supports the need for future work to assess the risk for overuse injuries with carried loads in this population, in addition to guiding the development of adaptive prosthetic feet/components to meet the needs of redeployed service members or veterans/civilians in physically-demanding occupations.

Three-dimensional joint reaction forces and moments at the low back during over-ground walking in persons with unilateral lower-extremity amputation

Hendershot, B. D., & Wolf, E. J. (2014). Three-dimensional joint reaction forces and moments at the low back during over-ground walking in persons with unilateral lower-extremity amputation. Clinical Biomechanics, 29(3), 235-242.

Abnormal mechanics of locomotion following lower-extremity amputation are associated with increases in trunk motion, which in turn may alter loads at the low back due to changes in inertial and gravitational demands on the spine and surrounding trunk musculature. A series of studies were undertaken to better understand the forces and stress on the low back of unilateral lower extremity amputation.  Analysis showed increased and asymmetric peak reaction forces and moments at the low back among persons with unilateral lower-extremity amputation, particularly in the frontal plane.  These findings  suggest potential mechanistic pathways through which repeated exposure to altered trunk motion and spinal loading may contribute to low-back injury risk among persons with lower-extremity amputation.

Advanced Prosthetics and Orthotics

How does ankle-foot orthosis stiffness affect gait in patients with lower limb salvage?

Esposito, E. R., Blanck, R. V., Harper, N. G., Hsu, J. R., & Wilken, J. M. (2014). How does ankle-foot orthosis stiffness affect gait in patients with lower limb salvage?. Clinical Orthopaedics and Related Research, 472(10), 3026-3035.

Ankle-foot orthoses (AFOs) are commonly prescribed during rehabilitation after limb salvage. AFO stiffness is selected to help mitigate gait deficiencies. The Intrepid Dynamic Exoskeletal Orthosis (IDEO), is new custom dynamic AFO, and is available to injured service members but prescription guidelines are limited.  This study found that patients with limb salvage readily adapted to different dynamic AFO stiffnesses and demonstrated few biomechanical differences among conditions during walking.  A general lack of differences across a 40% range of strut stiffness suggests that orthotists do not need to invest large amounts of time identifying optimal device stiffness for patients who use dynamic AFOs for low-impact activities such as walking. However, choosing a stiffer strut may more readily translate to higher-impact activities and offer less chance of mechanical failure.

Does a microprocessor-controlled prosthetic knee affect stair ascent strategies in persons with transfemoral amputation?

Whitehead, J. M. A., Wolf, E. J., Scoville, C. R., & Wilken, J. M. (2014). Does a microprocessor-controlled prosthetic knee affect stair ascent strategies in persons with transfemoral amputation?. Clinical Orthopaedics and Related Research, 472(10), 3093-3101.

Stair ascent can be difficult for individuals with transfemoral amputation because of the loss of knee function. A new microprocessor-controlled knee (Ottobock X2®) uses flexion/extension resistance to allow step-over-step stair ascent.  This study compared self-selected stair ascent strategies between conventional and X2® prosthetic knees, examined between-limb differences, and differentiated stair ascent mechanics between X2® users and individuals without amputation.   The results of this study showed participants with transfemoral amputation were more likely to self-select a step-over-step strategy similar to individuals without amputation while using X2® knees than conventional prostheses.  However, the increased prosthetic knee flexion used with X2® knees placed large power demands on the hip during pull-up and push-up/early swing. These results suggest the X2 allows for a more normal stair accent; however a modified strategy that uses less knee flexion may be needed to allow step-over-step ascent in individuals with less hip strength.

Medical/Surgical Interventions

Transfemoral amputations: is there an effect of residual limb length and orientation on energy expenditure?

Bell, J. C., Wolf, E. J., Schnall, B. L., Tis, J. E., & Potter, B. K. (2014). Transfemoral amputations: is there an effect of residual limb length and orientation on energy expenditure?. Clinical Orthopaedics and Related Research®, 472(10), 3055-3061.

Ambulation with prosthetics may lead to asymmetric and aberrant motions resulting from compensatory strategies.  Persons with transfemoral amputations generally exhibit a larger center of mass excursion and an increased energy cost. However, few studies have analyzed the effect of residual femur length and orientation or energy cost of ambulation.  The purpose of this study was to compare residual limb length and orientation with energy efficiency in patients with transfemoral amputation.  Results showed that those with longer residual limbs chose a faster self-selected walking velocity (confirming previous studies).  However, there were no differences found to O2 cost or other metabolic variables regardless of limb length or orientation, including the center of mass motion.  These findings suggest that length of residual limb in transfemoral amputations may have less effect on gait efficiency and energy requirements than previously thought.

Do patients with bone bridge amputations have improved gait compared with patients with traditional amputations?

Kingsbury, T., Thesing, N., Collins, J. D., Carney, J., & Wyatt, M. (2014). Do patients with bone bridge amputations have improved gait compared with patients with traditional amputations?. Clinical Orthopaedics and Related Research®, 472(10), 3036-3043.

Two surgical techniques for performing a transtibial amputation include a traditional approach and a bone bridge approach .  To date, there is no conclusive evidence of superiority of either technique in terms of temporal-spatial, kinetic, and mechanical work parameters.  This study sought to compare three-dimensional gait parameters and mechanical work measurements of patients who had undergone a traditional or bone bridge amputation at the Transtibial level.  Although some evidence indicated that patients with a bone bridge have improved loading at higher speeds, a regression of all patients walking at self-selected speed indicates that as residual limb length increases, loading increases regardless of amputation type.  The results  of this study suggest it is important to preserve the residual limb length to allow for improved loading in terminal stance.

Last Updated: January 28, 2022
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