Abstract
The purpose of this study was to compare the effect of knee unlocked medially linked Knee-Ankle-Foot Orthoses (MLKAFO) to the conventional knee locked MLKAFO during walking by means of Functional Electrical Stimulation (FES). A 33-year-old male with complete T8 paraplegia participated in this study. The stimulator has two hand switches to change the stimulation pattern. When the switch was turned on, the femoral nerve and paravertebral muscles were stimulated. When the switch was turned off, the femoral nerve stimulation was stopped. Two different types of MLKAFO were prepared for that study namely the knee locked MLKAFO and the knee unlocked MLKAFO. The gaits were measured by three-dimensional analysis system. Trunk anterior tilt and swing leg time in initial swing phase and lateral aspect of gait were evaluated. The results revealed that trunk anterior tilt with knee unlocked MLKAFO was smaller than that of knee locked MLKAFO. Swing leg time in initial swing with knee unlocked MLKAFO was faster than that of knee locked MLKAFO. We concluded that the knee unlocked MLKAFO was provided better performances. The stance leg with knee flexed produced the weight bearing shift forward and the swing leg with knee flexed enabled to start swinging leg faster.
1.
Introduction
MLKAFO
was enabled the paraplegic patients to keep standing and walking than that of
medially unlinked both Knee-Ankle-Foot Orthoses (KAFOs) [1]. MLKAFO stabilize
both knee and ankle joints bilaterally by fixing both hip joints so as not to
abduct and adduct by medial linkage which connected to both KAFOs.
Functional
Electrical Stimulation (FES) utilizes several muscle groups for muscle power
generation. For swinging leg action in terms of stimulation it utilizes the
iliopsoas muscle, sartorius muscle, tensor fasciae latae. The stimulation of
quadriceps, gluteus maximus and the hamstrings cause hip extension so as to
stabilize the stance leg [2].
In
our institution, when the reconstruction of gait was performed in paraplegics
using FES with MLKAFO and L-walker, FES provided muscle power of swinging leg
by stimulating hip flexor muscles. However, paraplegics achieved weight shift
forward by bending over their trunk anteriorly and loading their weight to
their upper extremity muscles. However, the paraplegics complain that the most
principal factor of limitation of walking distance was fatigue of upper
extremity muscles or wrist pain caused by overloading of their weight.
In
general, the MLKAFO of knee joint were kept in a locked extension position. If
paraplegics were able to reconstruct walking with a knee unlocked MLKAFO with
FES which providing knee extension. Thus it was possible to assist weight shift
and to reduce the loading of upper extremities.
The
purpose of this study is to compare the effect of knee unlocked MLKAFO during
walking by FES to that of the conventional knee locked MLKAFO.
2.
Methods
A 33-year-old male with complete T8 paraplegia participated in this study. The patient’s gait has been reconstructed with MLKAFO by FES since 8 year ago.
The
stimulator of FES named Akita stimulator III (BIOTEC Ltd., Japan) was used and
this stimulator has two hand switches to control the stimulation pattern by
turning on and off. When the stimulation was turned on, the femoral nerve and
paravertebral muscles were being stimulated. When it was turned off, the
femoral nerve stimulation was stopped and remained the stimulation of
paravertebral muscles. Controlling this hand switches, the subject achieves
reciprocal gait.
The
MLKAFO was consisted of Walkabout device which connected medially to both of
KAFOs below the perineum. This MLKAFO provides better medio-lateral stability
to both hip joints. Two different types of MLKAFO were prepared for this study:
one was a knee locked MLKAFO and the other was a knee unlocked MLKAFO (Fig. 1a,
b). L-walker was used to reconstruct gait. The gaits were
measured by three-dimensional analysis system (PEAK Motus, USA). The trial
condition was set up as below: 5m walking distance with free walking which was
performed and measured at least 5 times.
Trunk
anterior tilt and swing leg time in initial swing phase were statistically
compared by Student t-test. Each condition of gait were evaluated by the stick
picture which was provided by three-dimensional analysis system.
3.
Results
Trunk anterior tilt of knee unlocked MLKAFO was smaller than that of knee locked MLKAFO (Table. 1). Swing leg time in initial swing phase with knee unlocked MLKAFO was faster than that of knee locked MLKAFO (Table. 2).
Stick picture indicated that the knee flexion was
occurred during the gait cycle. Especially, at the point of toe off most knee
and trunk flexion were obtained (Fig. 2a, b). It indicated that most loading
point to upper extremities was at the point of toe off. The stick picture of
knee locked MLKAFO showed the bigger trunk anterior tilt of weight shifting to
the forward limb. However, the trunk anterior tilt of knee unlocked MLKAFO was
smaller than that of knee locked one. Knee joint was gradually extended from
toe off to mid stance phase.
4.
Discussion/Conclusions
Knee locked
MLKAFO was provided the stability of knee joint during standing and waking in
paraplegics. However, healthy subjects were performs knee flexion in both swing
phase and stance phase. In case of extension contracture of the knee joint, the
energy cost of walking was increased by the additional body maneuvers which
required for floor clearance during swing [3]. We predicted that the gait in
paraplegic patient with knee locked MLKAFO using FES were also performed
additional body maneuvers which obtained for floor clearance. Thus we assumed
that the knee flexion was available in paraplegic’s gait.
With knee
unlocked MLKAFO the knee joint was flexed a little due to weight shifts to the
forward limb. The anterior weight shifts was occurred after the extension of
knee joint at the point of toe off. Progressed body weight forward, the
activation of quadriceps muscle were occurred which played a positive role of
shifting the body more forward. As a result, the weight shift to forward limb
was achieved regardless of small trunk anterior tilt.
In initial swing
phase, the hand switch was turned off for swing leg was observed in both
orthotic conditions. Swing leg time indicated that turning off in this phase
was effective to start faster swinging leg.
These results
suggested that knee flexion provide better performances in stance phase and in
swing phase respectively. Thus in stance phase, knee flexion of stance leg
assisted weight shift forward and it predicted that the load of upper
extremities was more decreased. In swing phase, knee unlocked MAFO enabled to
start swinging leg faster than that of knee locked one.
Controlling the
knee joint using FES has the problem of muscle fatigue and knee buckling [4]
[5]. However, in this study, muscle fatigue and knee buckling was not occurred
even though the gait was reconstructed sequentially using FES for 2 hours, on
contrary the muscle fatigue of upper extremities were observed [6].
References
[1] Middleton JW, Sinclair PJ, Smith RM,
Davis GM, Postural control during stance in paraplegia: effects of medially
linked versus unlinked knee-ankle-foot orthoses, Arch Phys Med Rehabil Vol 80,
pp. 1558-1565, 1999
[2] Kobetic R,
Triolo RJ, Meaolia EB, Muscle selection and walking performance of multichannel
FES systems for ambulation in paraplegia, IEEE transactions on rehabilitation
engineering, Vol 5, No 1, pp 23-29, 1997
[3] Jacquelin
Perry, Gait analysis, SLACK Incorporated, pp 172-173, 1992
[4] Kagaya H,
Shimada Y, Sato K, Sato M, Iizuka K, Obinata G, An electrical knee lock system
for functional electrical stimulation, Arch Phys Med Rehabil Vol 77, pp.
870-873,1996
[5] Kralj A,
Bajd T, Turk R, Electrical Stimulation providing functional use of paraplegic
patient muscles, Med. Progr. Technol., Vol 7, pp. 3-9, 1980
[6] Minato T, et al., Standing
stability of the medial linkage KAFOs using functional electrical stimulation
in complete paraplegia