Ossur Scientific E-letter
22 July 2009
Ossur Academy's scientific E-letter Issue 2#2009
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Dear readers,
Welcome to the second issue of our Scientific E-letter of 2009. We are happy to share pertinent and interesting scientific news with you!
This E-letter includes ten different scientific papers. The articles cover the subjects of amputation/rehabilitation, prosthetics/biomechanics, orthotics/biomechanics and clinical management.
Eight of the selected papers have been published in 2009 and two in 2008.
Enjoy the reading!
Amputation/Rehabilitation
Lower extremity leg amputation: an advantage in running?
Sports Technol. 2008, No. 4-5, 229-234
This article is a contribution to the discussion about weather the use of prosthetic feet are an advantage in running or not. This discussion has been brought up after the bilateral tibial-amputee runner Oscar Pistonius have had sprinting results close to able bodied sprinters' results.
Lechler and Lilja mean that the discussion focus on the use of prosthetic feet and doesn't have a holistic view of the amputees, prostheses and the rehabilitation and training amputees have gone through.
The authors described the challenges amputees have had before he/she will be able to run, such as selection, fitting, alignment, adapt to the prosthesis and compensatory strategies. Further the disadvantages of amputees compared to able bodied sprinters where assessed. Lechler and Lilja found that relatively few methods where used to generate objective data. That made it difficult to conclude that the prosthetic application gives advantage in performance to the amputee athlete over the able-bodied athlete. “Measurements of amputee performance look at a fraction of the values in defined speed on a straight lane, whereas the athlete performs the race with varying demands on the prosthetic application from getting out of the starting blocks to accelerating straight away to running through the bend. In addition, the unknown variables in the socket with their effects on performance and the discomfort and additional challenges an amputee has to overcome have not been considered. Considering the time differences in performance between amputee athletes and able-bodied athletes there is still a big gap that is difficult to close without utilizing a similar power generator like the human muscle.”
Lechler and Lilja meant that it is hard to imagine that bilateral amputees have advantages compared to able bodied athletes that are related to the prosthesis.
Motor control over the phantom limb in above-elbow amputees and its relationship with phantom limb pain.
Neuroscience (2009), doi: 10.1016/j.neuroscience.2009.04.061
Recent evidence showed that the primary motor cortex continued to send motor commands when amputees executed phantom movements. These commands were retargeted toward the remaining stump muscles as a result of motor system reorganization. As amputation-induced reorganization in the primary motor cortex has been associated with phantom limb pain Gagné and his study group hypothesized that the motor control of the phantom limb would differ between amputees with and without phantom limb pain.
To perform this study eight above-elbow amputees with or without pain, were asked to produce cyclic movements with their phantom limb (hand, wrist, and elbow movements) while simultaneously reproducing the same movement with the intact limb. The time needed to complete a movement cycle and its amplitude was derived from the kinematics of the intact limb. Electromyographic (EMG) activity from different stump muscles and from the homologous muscles on the intact side was recorded. Different EMG patterns were recorded in the stump muscles depending on the movement produced. The EMG patterns showed that different phantom movements were associated with distinct motor commands.
Further it was found that phantom limb pain was associated with some aspects of phantom limb motor control. The time needed to complete a full cycle of a phantom movement was systematically shorter in subjects without phantom limb pain. Also, the amount of EMG modulation recorded in a stump muscle during a phantom hand movement was positively correlated with the intensity of phantom limb pain.
The authors meant that since phantom hand movement– related EMG patterns in above-elbow stump muscles can be considered as a marker of motor system reorganization, this result indirectly supports the hypothesis that amputation-induced plasticity is associated with the severity of phantom limb pain. The discordance between the (amputated) hand motor command and the feedback from above-elbow muscles might partially explain why subjects exhibiting large EMG modulation during phantom hand movement have more phantom limb pain.
Prosthetics/biomechanics
Wu, Yeongchi, Casanova, Hector R. and Ikeda, Andrea J.(2009).
Plastic soda bottles: A reusable material for making transradial sockets.
Prosthetics and Orthotics International,2009 33:2,100 — 106
Wu and colleagues describe in this paper a new fabrication process for making low-cost transradial sockets using recyclable plastic soda bottles. The process has been developed as a potential cost-effective assistive technology that is appropriate for individuals with transradial amputation in resource limited countries.
The authors mean they are easy, fast, and inexpensive to fabricate and the resulting socket can be used as a temporary device for stump care. Multiple sockets can be made and individually incorporated with various terminal devices for light-duty self-care or functional activities, such as feeding, showering, typing, swimming, or gardening. The formed socket is lightweight and also suitable for use with cosmetic passive hand prosthesis.
The paper explains the step in manufacturing the soda bottle in to a socket with easy step by step advices and pictures.
- Make the plaster modell
- Prepare the plastic soda bottle socket
- Prepare the distal end of the formed socket for connection of a terminal device
- Affix terminal devices
- Suspension of light-duty transradial prosthesis
The procedure described utilizes a commonly available 2-litre plastic soda bottle to form a transradial prosthetic socket.
The authors concluded that since many areas of the developing world lack resources required for prosthetic fabrication the reuse of recyclable, durable and abundant plastic soda bottles provides an alternative solution for making light-duty prosthetic devices to meet the functional need of many trans-radial amputees. They believe that creative clinicians can use the unique features of the plastic soda bottle to develop other applications and variations of this technique to improve patients' function.
Houdijk H. Pollmann E. Groenewold M.Wiggerts H. Polomski W.
The energy cost for the step-to-step transition in amputee walking
Gait & Posture 30 (2009) 35–40
The energy cost for amputees is higher than for able bodied during walking. It is not clearly investigated which factor or factors that give increased energy consumption.
Houdijk and his study group wanted to investigate whether the mechanical work required for the step-to-step transition could be the explanation.
To assess this, the investigators included eleven trans-tibial amputees (AMP) and 11 age-matched controls (CO) in their study. The subjects walked at comfortable (CWS) and fixed (FWS, 1.3 m/s) walking speed, while external mechanical work of each separate leg and metabolic energy consumption were measured.
At FWS the metabolic energy consumption (E˙met) was significantly higher in AMP compared to CO At CWS, no difference in energy consumption was found but CWS was significantly lower in AMP compared to CO. In conjunction with the higher E˙met at FWS, the negative work generated by the intact leading leg for the step-to-step transition in double support was significantly higher for AMP than CO at FWS. A moderate though significant correlation was found between negative mechanical power generated during the step-to-step transition and metabolic power.
Despite the difference in negative work during the step-to-step transition, the total absolute mechanical work over a stride did not differ between groups. Houdijk et al mean that this could possibly be attributed to exchange of internal positive and negative work during single support, which remains unnoticed in the external work calculations.
The authors could conclude that the increased mechanical work for the step-to-step transition from prosthetic to intact limb contributed to the increased metabolic energy cost of amputee walking.
Orthotics /biomechanics
Does the use of orthoses improve self-reported pain and function measures in patients with plantar fasciitis? A meta-analysis
Phys Ther Sport. 2009 Feb;10(1):12-8. Epub 2008 Nov 20.
Lee and collegues objectives for their study were to examine the effects of foot orthoses on self-reported pain and function in patients with plantar fasciitis. They performed a meta analysis, which is a statistical method to combine results of several studies that address a set of related research hypotheses.
The study group included research studies that met following criteria
- randomised controlled trials or prospective cohort designs
- the patients had to be suffering from plantar fasciitis at the time of recruitment
- evaluated the efficacy of foot orthoses with self-reported pain and/or function
- means, standard deviations, and sample size of each group had to be reported
The result of the meta analysis showed significant reductions in pain after orthotic intervention. One study showed significant reduction in pain after night splint treatment. Further the results also showed significant increases in function after orthotic use.
The authors concluded that the use of foot orthoses in patients with plantar fasciitis appears to be associated with reduced pain and increased function.
Murley G S: Landorf K B. Menz H B. Bird A R.
Effect of foot posture, foot orthoses and footwear on lower limb muscle activity during walking and running: A systematic review
Gait & Posture 29 (2009) 172–187
Murley et al aimed for assessing the effect of foot orthoses and foot wear on lower limb muscle activity during walking and running by reviewing the literature in the area.
Of the selected studies six studies investigated the effect of foot posture, 12 the effect of foot orthoses and 20 the effect of footwear on lower limb muscle activity during walking or running. Meta analysis was not conducted due to heterogeneity between studies.
The review showed that some evidence exists that:
- pronated feet demonstrate greater electromyographic activation of invertor musculature and decreased activation of evertor musculature
- foot orthoses increase activation of tibialis anterior and peroneus longus, and may alter low back muscle activity
- shoes with elevated heels alter lower limb and back muscle activation
Most studies reported statistically significant changes in electromyographic activation, although these findings were often not well supported when confidence intervals were calculated.
The authors mean that there is a need for further research of more rigorous methodological quality, including greater consensus regarding standards for reporting of electromyographic parameters.
Bus S A. van Deursen R W M. Kanade R V. Wissink M. Manning E A. van Baal J G. Harding K G
Plantar pressure relief in the diabetic foot using forefoot offloading shoes
Gait & Posture 29 (2009) 618–622
Forefoot offloading shoes (FOS) are commonly used in clinical practice for treatment of plantar forefoot ulcers in the diabetic foot.
Bus and collegues aimed for assessing the efficacy in treating plantar forefoot ulcers of four different FOS models in comparison with a cast shoe and control shoe.
The study were performed by in-shoe plantar pressures were measured when 24 neuropathic diabetic patients at high risk for plantar foot ulceration walked in each of the six footwear conditions. For each of six foot regions, peak pressure, pressure–time integral, and force–time integral were calculated. They developed load transfer diagrams to assess the footwear mechanisms of action. Finally perceived walking comfort was measured by using a visual analogue scale (VAS). All comparisons between conditions were tested.
The result showed that peak pressures and pressure–time integrals at the metatarsal heads and hallux regions were significantly reduced (by 38–58%) in all FOSmodels when compared with the control shoe. The FOS also relieved metatarsal head peak pressure to a significantly larger extent than the cast shoe (20%). The load transfer diagrams showed a major transfer of 40% of forefoot load to the midfoot, that explained the offloading efficacy of the FOS. Perceived walking comfort was significantly lower in the FOS (VAS score 2.7–5.9) when compared with the control shoe (VAS 8.2) and cast shoe (VAS 6.8).
The study group concluded that the data showed that all FOS models were effective in their primary goal, relieving forefoot pressure in at-risk neuropathic diabetic patients. Therefore, these shoes may be effective in offloading and healing plantar forefoot ulcers, although the low comfort scores should be considered as this may potentially affect adherence to treatment.
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Ramstrand N. Björk Andersson C. Rusaw D. (2008)
Effects of an unstable shoe construction on standing balance in children with developmental disabilities: A pilot studyProsthetics and Orthotics International 2008,32:4,422 — 433
Ramstrand and her study group aimed to investigate whether prolonged use of shoes incorporating an unstable sole construction could facilitate improvements of various aspects of balance in a sample of developmentally disabled children.
Ten children (six male and four female) aged between 10 and 17 years were included in this study. The children were fitted with shoes incorporating an unstable sole and instructed to wear them for a minimum of two hours per day for eight weeks. A within subjects repeated measures design was used. The subjects were tested prior to receiving the shoes, four weeks after receiving the shoes and eight weeks after receiving the shoes.
Intentionally the study group selected tests that measure both static and dynamic aspects of balance since they both have been identified as integral to motor performance. A force plate capable of rotating about a single axis was used to test static balance, reactive balance and directional control.
The analysis of the result showed that static balance was not found to be influenced by prolonged use of the footwear; however, significant improvements were noted in children’s reactive balance both with the shoes and barefoot.
The authors concluded that their results suggest that reactive balance can be improved by prolonged and regular use of shoes incorporating an unstable sole construction.
Quality management
Agrawal, Vibhor, Gailey, Robert, O’Toole, Christopher, Gaunaurd, Ignacio and Dowell, Tomas (2009)
Symmetry in External Work (SEW): A novel method of quantifying gait differences between prosthetic feetProsthetics and Orthotics International 2009, 33:2,148 — 156
Unilateral transtibial amputees (TTAs) show subtle gait variations while using different prosthetic feet. These variations have not been detected consistently with previous experimental measures.
To address this problem Agrawal and colleagues introduced a novel measure called Symmetry in External Work (SEW) for quantifying kinetic gait differences between prosthetic feet.
External work is the result of changes in kinetic and potential energy of body center of mass (CoM). SEW is computed by integrating vertical ground reaction forces obtained using F-scan in-sole sensors. Since various prosthetic feet have different designs, the study group hypothesized that SEW will vary with the type of foot used. To test this hypothesis a single unilateral TTA used four prosthetic feet (Proprio, Triasþ, Seattle Lite and SACH) while the external work was measured.
The result showed that the Proprio (mean symmetry 94.5%+1.1%) and the Triasþ (92.1%+2.5%) feet exhibited higher symmetry between the intact and prosthetic limbs, as compared to the Seattle (67.8%+19.3%) and SACH (35.7%+11.1%) feet. There was also a good agreement in vertical CoM excursion between the intact foot and prosthetic feet with heel-toe foot plate designs.
The authors concluded that since the results indicate that SEW measure may be a viable method to detect kinetic differences between prosthetic feet and could have clinical applications because of its relatively low cost instrumentation and minimal subject intervention.
Kohler F. Cieza A. Stucki G. Geertzen J. Burger H. Dillon M P. Schiappacasse C. Esquenazi A. Kistenberg R S and Kostanjsek N. (2009)
Developing Core Sets for persons following amputation based on the International Classification of Functioning, Disability and Health as a way to specify functioning.Prosthetics and Orthotics International 2009,33:2,117 — 129
Amputation is a common late stage sequel of peripheral vascular disease and diabetes or a sequel of accidental trauma, civil unrest and landmines. The functional impairments affect many facets of life including but not limited to: Mobility; activities of daily living; body image and sexuality.
Classification, measurement and comparison of the consequences of amputations have been hold back by the limited availability of internationally, multi culturally standardized instruments in the amputee setting.
The introduction of the International Classification of Functioning, Disability and Health (ICF) by the World Health Assembly in May 2001 provides a globally accepted framework and classification system to describe, assess and compare function and disability.
The ICF defines components of health and some components of well-being. It was developed by the WHO to provide a unified and standard language and framework for the description of health and health related states. The ICF is used increasingly in various settings within health and in the wider community. It is one of a ‘family’ of international classifications developed by the WHO for application to various aspects of health as a framework for coding a wide range of information about health. It uses standardized common language permitting communication about health and healthcare across the world in various disciplines and sciences.
The classification is divided into two main subdivisions: Functioning and Disability as well as Contextual Factors.
In order to facilitate the use of the ICF in everyday clinical practice and research, ICF core sets have been developed that focus on specific aspects of function typically associated with a particular disability.
The authors objective of this paper was to outline the development process for the ICF core sets for persons following amputation. The ICF core sets are designed to translate the benefits of the ICF into clinical routine. The ICF core sets will be defined at a Consensus conference which will integrate evidence from preparatory studies, namely:
- a systematic literature review regarding the outcome measures of clinical trails and observational studies
- semi-structured patient interviews
- international experts participating in an internet-based survey
- cross-sectional, multi-center studies for clinical applicability.
To validate the ICF core sets field-testing will follow.
Kohler and colleagues wanted to invite for participation: The development of ICF Core Sets is an inclusive and open process. Therefore, the authors of this paper encourage clinical and consumer experts to actively participate in the process. Anyone who wishes to actively participate in contributing to any of the phases as delineated in the methods section is invited to contact Dr Friedbert Kohler at F.Kohler@unsw.edu.au. Individuals, institutions and associations can be formally associated as partners of the project.
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Ossur Academy is looking forward to providing you with more interesting scientific news in September!
Thank you for reading,
Ossur Academy.
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