Abstract
We have developed a motion analyzing
system with eight force plates for upper extremities in standing
.
Introduction/Background
We have
developed a functional electrical stimulation (FES) system using percutaneous
electrodes , applied to spinal cord injury(SCI) patients, and restored standing
function[1][2][3]. Stability of
standing with
By the way, we
developed a motion analyzing system for upper extremities in FES standing and
gait of paraplegics, using eight force plates and three dimensional motion
analyzer.
So, in this
study, we measured motion and reaction force of shoulder and elbow from
complete paraplegics in quite standing FES and analyzed their roles.
Methods
a) Subjects:
Three complete paraplegic patients (3
men) participated in this study (Table 1). Their average age was 44.3 years
old. The average time since spinal cord
injury was 68.6 months and the average time of treatment with FES was 40 months
.
Table 1
Patients information
|
Case |
Age (y.o.) |
Level of injury |
Time since Injury (month) |
Treatment with FES (month) |
|
A |
39 |
T3 |
20 |
6 |
|
B |
51 |
C7 |
96 |
42 |
|
C |
43 |
T5 |
90 |
72 |
b) Electrical
stimulation: The stimulation data for
stimulated Gluteus Maximus muscles, Gluteus Medius muscles, Adductor maximus
muscles, and Femoral nerves were given by a portable multi-channel FES system (
NEC Co. Ltd. ) using about thirty percutaneous electrodes. The pulse trains consisted of a pulse width
of 0.2 milliseconds, and a pulse interval of 50 msec. Each pulse amplitude was from 0 to -15 volt. These were fixed in standing.
c)
Analysis: A motion analyzing
system was consisted of eight force plates (Kistler Co. Ltd. ) , eight
infrared-cameras and a computer (VICON). Figure 1 shows its apparatus. Patients
were standing on two force plates
and parallel bars were on four one used for measuring of reaction
force of patient’s upper extremities. Sampling frequency was 60 Hz, and
10Hz-low pass filtered.
Reflective markers were placed over the lateral
malleoulous, on the lateral side of knee joint line midway between the patella
and the popliteal fold, over the greater trochanter of the femur , over the
acromion of the shoulder, over the orecranon and over the wrist.
Patients
were quit standing with FES in parallel bars and measured with a motion
analyzer in 2 seconds.
Figure 1 a
motion analyzing system
Results
Three patients could stand over 5 minutes with FES, and make one hand left off the parallel bars within several seconds.
Figure 2 shows reaction forces of Case A in FES standing , (a) vertical (b) lateral (c) anterior and posterior. Reaction forces of upper extremities were smaller than those of lower extremities at vertical direction. But at anterior and posterior direction reaction forces of bilateral lower extremities were negative and that of left upper extremities was positive. This was thought to be the effort for correction of body balance.
Figure 3 shows Average reaction forces of three cases in 2 seconds with FES standing. In three cases, average reaction forces of upper extremities at vertical direction were smaller than those of lower extremities, but at other two directions there were difference between upper and lower. In case B at anterior and posterior direction, same as case A, the effort for correction of body balance by right upper extremities.
Figure 2 Reaction forces of Case A in FES standing
within 2 seconds. Rt. UE: Right upper extremities , Lt. UE: Left upper
extremities, Rt. LE: Right lower extremities, Lt. L: Left lower extremities. (a)
vertical direction, (b) lateral direction, right positive (c) anterior and
posterior direction, anterior positive.
Figure 3 Average reaction forces of three cases in FES standing within 2 seconds. Rt. UE: Right upper extremities , Lt. UE: Left upper extremities, Rt. LE: Right lower extremities, Lt. L: Left lower extremities. (a) vertical direction, (b) lateral direction, right positive (c) anterior and posterior direction, anterior positive.
Discussion/Conclusions
In two of three cases, there were efforts for correction of body balance by upper extremities at anterior and posterior direction, otherwise little effort at vertical direction. So Main effort of upper extremities in FES quit standing is thought to be horizontal force balancer. The reason why vertical reaction forces were small is that there is knee locking system and small knee torque with FES is enough when their knee joints are complete extension position.
If a patient want to leave their hands off the parallel bar in FES quit standing at long time, we must develop two technique. The first one is the searching system of body balance for feedback control. The other one is a stimulation system for small change of muscle contraction, because the upper extremities efforts were very little. The latter one is more difficult.
Finally, we are developing a new FES system which can make patient’s hand free in standing and gait. And in our recent study the main problem is how the weight shift can be done without upper extremities efforts. At the next step, using this analyzing system, a weight shift control system only with FES will be developed.
References
[1] K. Fujita, Y. Handa, N.
Hoshimiya & M. Ichie: Preliminary Study for Feedback Trunk Stabilization in
FES-Induced Paraplegic Standing. IEEE/ 16th Annual Conference of
Engineering in Medicine & Biology Society, pp 408-409 (1994)
[2] Y. Handa: Current topics
in clinical functional electrical stimulation in japan. Journal of Electromyography and Kinesiology 7(4) pp267-274 (1997)
[3] Y. HANDA, R.YAGI, N.
HOSHIMIYA: Application of Functional Electrical Stimulation to the Paralysed
Extremities. Neurologia medico-chirurgica
38(11) pp784-788(1998)
Acknowledgments: This study was supported by Miyagi
Organization for Industry Promotion.