RESTORATION OF GAIT USING A NEW HYBRID-FES ORTHOSIS
(PRIMEWALK)
IN A COMPLETE PARAPLEGIC PATIENT
T. Matsunaga, Y. Shimada, K. Sato, A. Misawa,
M. Sato, K. Hatakeyama, S. Chida, K. Iizuka
Department of Orthopedic Surgery,
ABSTRACT
The purpose of this study was to evaluate the restoration of
Key words: hybrid-FES, medially linked knee ankle foot orthosis,
Primewalk, paraplegia
INTRODUCTION
Functional electrical stimulation (FES) and orthotics can be combined as
a hybrid orthosis to overcome the limitations of either approach when used
alone. “Walkabout” is one of several medially linked knee ankle foot orthosis
(MLKAFO) [1]. The Walkabout can be used as a hybrid-FES orthosis to restore
ambulatory function in paraplegic patients. The step length of the
Walkabout/FES gait is restricted because the medial joint is placed under the
hip, and accordingly the walking speed becomes slow. During the Walkabout/FES
gait, the paraplegic patient sometimes rotated their pelvis to gain a longer
step length. Therefore, further improvement is needed for the MLKAFO’s FES
gait. Recently, a new MLKAFO named “Primewalk” was developed by Saitoh and
colleagues [2]. The purpose of this study was to compare the Walkabout/FES gait
and the Primewalk/FES gait.
METHODS
Subject A 30-year-old
man with T8 complete paraplegia volunteered for this study. His informed
consent was obtained. He had already started an FES program for his lower limbs
using implanted parcutaneous intramuscular electrodes. The time since injury
was 5 years and the follow-up time since starting the FES program was 4 years.
He was previously able to perform standing-up, standing, and sitting-down using
only FES. He was also able to walk using both FES and ankle-foot orthosis.
The FES system We developed
a stimulator having 2 hand switches for both right and left legs (AKITA
STIMULATOR II). The rectangular pulse trains that were used consisted of a
pulse with of 0.2 msec, a pulse interval of 50 msec, and an output voltage
modulated from 0 to -15V. When the patient pressed the hand switch, the hip
flexors and the contra-lateral hip extensors were electrically stimulated
simultaneously. The iliopsoas muscle and the femoral nerve were stimulated for
the hip flexion. The gluteus maximus and long head of the biceps femoris were
stimulated for the hip extension. Reciprocal gait was obtained by the
repetition of switch-on and switch-off with the 2 hand switches.
The hybrid-FES gait analysis The walking
speeds, the step cadence and the step length during the FES assisted gait of
the subject, wearing Walkabout and Primewalk, were measured. The L-walker was
used to support the gait.
RESULTS
The walking speeds were 5.23 ± 0.97 m/min (Mean ± SD) at Walkabout/FES gait and 9.27 ± 0.65 m/min at Primewalk/FES gait. The step cadences
were 24 ± 2 steps/min at Walkabout/FES gait and 27 ± 1 steps at Primewalk/FES gait. The step lengths were
0.22 ± 0.03 m at Walkabout/FES gait and 0.43 ± 0.07 m
at Primewalk/FES gait. All parameters were significantly greater at
Primewalk/FES gait than at Walkabout/FES gait (p < 0.05).
DISCUSSION
The medial hip joint of the Primewalk is positioned under the hip in the
same way as the Walkabout. However, the physiological axis of the Primewalk is
higher than that of the Walkabout. This is due to the sliding mechanisms of the
Primewalk system [2]. The two mechanisms of the hip joint are quite different
between the Primewalk and Walkabout. During Primewalk/FES walking, the patients
can swing their legs more easily and walking speeds, step cadence and step
length are improved. Future studies could include: the stability of the
Primewalk/FES gait and the energy cost of using the Primewalk system.
REFERENCES
[1] Kirtley C, Mckay SK: A medially-mounted orthotic hip joint for
paraplegic walking systems preliminary report on the “polymedic walker” device.
Polymedic technical note, Australia, 1992.
[2] Saitoh E, Baba M, Sonoda S, Tomita Y, Suzuki M, Hayashi M: A new
medial single hip joint for paraplegic walkers. The 8th World Congress of the
International Rehabilitation Medicine Association (IRMA VIII); Kyoto, Japan;
1997, 1299-1305.