A Neuro-Mechanical Model Comparing Traditional and Pseudoelastic Splinting of Spastic Joints

Neuromuscular rehabilitation of patients with upper motor neuron syndromes (traumatic brain injury - TBI, stroke, cerebral palsy…) is based on multidisciplinary approaches aiming at preventing or contrasting the detrimental sequelae of paresis, contracture and spasticity. Due to the large individual variability of patients’ conditions and impairments it is generally difficult to have a quantitative grasp of the appropriate line of action to prescribe bracing in the most effective manner. This is an even more complex task when testing new therapeutic principles and using non-standardized devices. To this end, it is important to evaluate both instantaneous interaction (orthosis compliance to patient’s movement, localized pressure on the skin, reflex responses, etc.) and mid-long term evolution of the ill-posture (resting angle, reflex adaptation, range of motion, etc.). Accordingly, the current paper presents a model devised to investigate the interaction between the human body and two main types of othotic devices: traditional and pseudoelastic Ni-Ti based orthoses. The two devices represent different approaches to repositioning: traditional braces impose a joint angle and expect plastic relaxation, while pseudoelastic splints promote a plastic creep of tissues towards a more physiological posture without forcing the joints into any particular position. This idea has already been described in previous work [1] and ad-hoc devices have been constructed [2]. The focus here is on possible application scenarios.