Open articles

The Paralympic Games in Rio De Janeiro have once again captured world-wide attention and once again focused attention on the ability of people with disabilities. In many sports represented in the Games, performance of athletes depends on the interface between the athlete and the assistive technology. This interface in paracycling is examined in a systematic review published as the lead article in the current issue of Prosthetics and Orthotics International (October 2016).  In the article, Bruce Dyer (2015)examines the biomechanics and physiology of amputee cycling and the development of technology to maximise performance for amputee cyclists.

Although cerebral palsy is a static neurological disorder, it leads to progressive musculoskeletal pathology as a result of normal growth and abnormal muscular control. Surgical, pharmacological, physiotherapeutic and orthotic treatments are aimed at ameliorating the physical effects of the neural damage and in particular at maintaining or increasing muscle length to prevent muscle shortening and joint contracture. Ankle-foot orthoses for children with CP are prescribed to maintain ankle and foot posture to improve gait and other activities of daily living. A recent paper by Choi, Wren and Steele (2016)published in OnlineFirst demonstrates that AFOs also have potential to extend therapy into everyday life and promote gastrocnemius muscle stretching during normal activity. The authors investigated the effects of two commercial AFOs in children with CP. Using motion analysis and muscle modelling software, they demonstrated that during walking, one of the orthoses tested stretched the gastrocnemius beyond its passive threshold length in the majority of children tested. Although restoring optimal function is the primary goal of orthotic management, it may be that orthoses can at the same time contribute to stretching tight muscles.

Increasingly sophisticated myoeletric prostheses require increasingly sophisticated control systems. Direct control systems, however, are limited by the number of separate EMG signals that can be accessed. Targeted reinnervation techniques have made possible more sites and more intuitive control but the degrees-of-freedom available in state-of-the-art myoelectric hands still greatly exceeds the control signals available. A paper by Edwards and co-workers (2015)in the current issue of POI describes the use of machine intelligence and real-time learning to predict user intent in order to reduce the number of possible grip patterns available for the hand. The authors showed, in a single amputee and a number of able-bodied subjects, that real-time learning algorithms made control of a robotic arm easier and faster.

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Tim Bach
Prosthetics and Orthotics International (POI)