What the Editor is reading
For years clinicians have debated the most effective transfemoral socket brim shape to enable tolerable load transfer while maintaining prosthesis control and range of motion. The debate has largely centred on the quadrilateral socket developed in the 1950s and various permutations of ischial containment sockets dating for the 1980s. The development of vacuum suspension technology has proved to be a “game changer” with recent reports of successful fitting of “brimless” sockets. A series of articles by Stefania Fatone and her co-workers at Northwestern University Prosthetics-Orthotics Centre describes the work they have done to develop a new brimless socket and to teach clinicians to fit the new socket to patients. A paper by Fatone and Caldwell (2017)in the current issue of Prosthetics and Orthotics International (Vol 41, Issue 3) describes gait biomechanics in two subjects using this socket and demonstrates excellent gait function for the brimless socket.
Increasingly, hospitals and health funding agencies are expecting evidence of the quality of outcomes but health practitioners are often reluctant to introduce or to routinely use outcome measure in everyday practice. In part this may be due to time pressures but it may also be related to a lack of confidence in administering tests due to a lack of knowledge and experience. In the current issue of POI, Brian Hafner and colleagues (2017)describe a study in which they provided a continuing education program on outcome measures to experienced prosthetists and surveyed the effects of the program on confidence and use of outcome measures. They demonstrated that the continuing education program increased both clinician confidence and usage of outcome measures.
It is common experience that any task which requires muscular exertion for long duration or high intensity will result in muscular fatigue which limits the capacity to continue performing the task. High forces can be maintained for short periods and lower forces for longer periods. Forces below 20% of maximum strength can be maintained indefinitely. In ergonomic task analysis, the force requirements of the task and the strength norms for the population are taken into consideration to estimate the proportion of workers who could perform a particular task. It is somewhat surprising that strength norms applied to the design of upper extremity prostheses are based on data published in 1954 based on a sample of able bodied subjects. Mona Hichert, Alistair Vardy and Dick Plettenberg (2017)have attempted to redress this problem by measuring maximum cable forces in a sample of sample of trans-radial amputees and comparing the strength of the amputees to the operating forces required for a range of prosthetic hands. About half of the sample were not strong enough to operate the range prosthetic hands for prolonged periods. The information is important for clinicians in selecting an appropriate terminal device.
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Prosthetics and Orthotics International (POI)
Prosthetists’ perceptions and use of outcome measures in clinical practice: Long-term effects of focused continuing education. Hafner, B. J., Spaulding, S. E., Salem, R., Morgan, S. J., Gaunaurd, I., & Gailey, R.
Fatigue-free operation of most body-powered prostheses not feasible for majority of users with trans-radial deficiency. Hichert, M., Vardy, A. N., & Plettenburg, D. (2017)