Present Status of the Amoll (Active Modular Orthosis for Lower Limb) Project

Summary

Restoration of lower limb locomotion presents complex biomechanical considerations. Each lower limb contains a minimum of 27 degrees of freedom controlled by 44 muscular actuators. Moreover, the role of feedback systems from the skin, muscles, tendons and ligaments are of the utmost importance. Lower limb paralysis is not necessarily accompanied by loss of sensitivity, for example in acute anterior poliomyelitis, but can be associated with a loss of communication between the spinal cord and the superior centres, for example, paraplegia due to complete section of the spinal cord. In the latter instance restoring locomotor function becomes particularly difficult since sensation is affected which results in loss of ‘consciousness’, of position and displacement of the lower limbs. The condition can be further complicated by tonic muscular spasms opposing segment mobilisation; this constitutes the spasticity. Therefore, the goal of the AMOLL project is to create a system or device which could make locomotion, although paranormal, possible for these patients.

The project is now at the stage of laboratory prototype. This has demonstrated that it is possible for a patient to use a walking machine equipped with four motors. The necessary stabilisation is provided through the patient’s use of crutches. The next stage will be the production of ten machines for evaluation in a number of rehabilitation centres, particularly in the United States. The price of the device will also be explored in order to make its supply possible within the budgetary framework of the present day health and social services.