The restoration of lost motor functions after upper motor neuron lesio
ns by functional electrical stimulation (FES) is not a new technique.
Early feasibility demonstrations of FES assisted standing and stepping
in paraplegics between 1960 and 1980 showed great promise that FES ma
y soon become an effective method to regain upright mobility after spi
nal cord injury. However, the difficulties encountered have been under
estimated. Today, there is a wide gap between FES related research and
the clinical application of FES in paraplegic patients. In this paper
the scientific literature about FES and its clinical applications is
carefully reviewed. The possible reasons for the low clinical relevanc
e of FES and possible solutions for the development of enhanced FES sy
stems are analyzed. Although the functional gain with present FES syst
ems for mobility restoration in paraplegics is relatively low, FES may
be beneficial to prevent secondary complications which occur after sp
inal cord injuries. The development of distributed systems and selecti
ve peripheral nerve stimulation techniques, the progress in microelect
ronics and sensor technology, and the development of nonlinear and clo
sed-loop control strategies give promise for the development of practi
cal and enhanced FES systems that will offer paraplegic patients some
additional degrees of freedom. (C) 1998 Elsevier Science Ireland Ltd.