What the Editor is Reading
29 October 2017
Posted by: Kasia Duchna
There is a long-running debate in prosthetics and orthotics about the time required for a user to accommodate to a new orthotic or prosthetic device. Some researchers might fit a new or experimental device and test after an accommodation period of a few minutes or a few hours either because of constraints on time and resources or because the experimental devices are not suitable for everyday use. Other researchers are wary of such studies arguing that much more time is required for the user to adapt to the device and for new motor patterns to become fully established. These researchers allow weeks or even months between initial fitting and biomechanical testing. Clinicians, on the other hand, make adjustments to devices based on as little as one or two traverses of a walking race and will attempt to achieve an “optimal” fitting/alignment/adjustment within a single clinical session. Indeed, some prosthetists have commented to me that the first few steps are the most informative for dynamic alignment because they reveal the true underlying mechanics of the device. After that, the user might already have accommodated to a possibly sub-optimal device. In a paper published in the current (October) issue of Prosthetics and Orthotics International, Wanamaker, Andridge and Chaudhari (2017) conducted a systematic review of accommodation times reported in studies of lower limb amputees. Although the review does not resolve the question, it provides a very good overview of the range of accommodation times reported in the literature. The debate will no doubt continue.
Spina bifida is an uncommon but devastating congenital condition which results in neurological deficits and mobility problems for people with the disorder. If, in addition, people with spina bifida require an amputation, they present a complex clinical problem for the medical and rehabilitation team. In the current issue of POI, Graham (2017) reports a case series of people with spina bifida who also have a lower limb amputation. Skin ulceration as a result of sensory deficits and lymphedema is a common cause of amputation in this population. With prosthetic fitting and rehabilitation, most patients were able to maintain their pre-existing level of mobility after amputation.
In a paper recently published in OnlineFirst, Nicholas Hale and colleagues (2017) have demonstrated the feasibility of a small fingertip sensor to measure both pressure and shear in hand grasping, pressing and dragging movements. Until now, such shear measurements have not been possible except with large, bulky sensors which interfere with hand function. The ne sensors extend our capability for measuring normal hand biomechanics in everyday activities. Incorporating these sensors into a prosthetic hand could enable slip detection and improved control of grasping.
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Prosthetics and Orthotics International
- Graham, L. (2017). Spina bifida and lower limb amputation in Northern Ireland: A retrospective study of demographics and outcome. Prosthetics and Orthotics International, 41(5)
- Hale, N., Valero, M., Tang, J., Moser, D., & Jiang, L. (2017). A preliminary study on characterisation of finger interface kinetics using a pressure and shear sensor system. Prosthetics and Orthotics International, 0(0)
- Wanamaker, A. B., Andridge, R. R., & Chaudhari, A. M. (2017). When to biomechanically examine a lower-limb amputee: A systematic review of accommodation times. Prosthetics and Orthotics International, 41(5)