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Prosthetic Gait Training Using the Concept of Biofeedback and Instrumented Gait Analysis
Copvrighl © I FAC Control AspeclS of Proslhelics and Orthol ics Ohio . USA. 1982
PROSTHETIC GAIT TRAINING USING THE CONCEPT OF BIOFEEDBACK AND INSTRUMENTED GAIT ANALYSIS R . K. Laughman, E. Schneider, S. Bogard and E. Y. Chao Biomechanics Laboratory, Department of Orthopedics, Mayo Chnic l Mayo Foundation, Roch ester, Minnesota 55905, USA Abstract. The purpose of this paper is to present a gait analysis (Chao, 1 980) which is routinely used in the clinical evaluation of to report the preliminary results from a new gait training device, describe one additional training device, both of which utilize the back concept . Keywords.
system amputees, and to biofeed -
Amputee; gait training devices; objective gait analysis.
INTRODUCTION
data indicates that gai t deviations are common, even among young amputees, and that additional methods of training may prove helpful . For yo un g , potentially long, prosth esis users, it would be desirable to correct residual gai t faults early, before they become uncorrectable gai t habits, which may later cause additional problems (Batz dorff, 1978) .
The use of gait analysis for the objective documentat i on of amputee function is not a new idea . However, the majority of work in this area has been directed toward prosthetic design rather than the ga it training process. A number of authors (Radcliff, 1974; Lewis, 1970; Drillis, 1958; Ganguli, 1973) have discussed a lack of information regarding gait training methods. To date, the objective clinical gait evaluation of amputees has been limited, with the patient ' s gait training being accomplished largely by subjective methods. This makes it difficu l t for the patient, and therapist alike, to perform optimally.
Admittedly, cancer amputees make up a small percentage of the amputations performed nationally . Coleman (1979) stated that approximately 85% of all peacetime amputations involve older individuals with peripheral vascu l ar disease. This g roup of patients presents a difficult rehabilitation problem, in that their vascular disease is systemic, involving the heart and cent r al nervous system, as well as the vasculature of t he unamputated extremity . For this reason, it i s especially important that these patients receive training which will develop the most efficient gait pattern , while minimizing the time and effor t required.
It is an obvious fact that following an ampu tation, a patient's gait function will be le ss efficient than a normal individual, even under the best of conditions. However , a faulty gait pattern should not be accepted by assuming tha t an amputee fit t ed with a welldesigned prosthesis will automatically walk in the most efficient manner, and that further rehabilitation need not be a t tempted. We feel that with new and innovative methods of ga it training, a number of previousl y accepted poor gait habits can be cor r ected , resulting in a more efficient gait pattern .
GAIT LABORATORY The gait laborator y (Fig. 1) consists of t"o walkways. One is instrumented with two force plates, step length and step width grids, and two infrared light switches . The second walkway is u sed to simulate various walking surfaces, including a sideslope, ramp, and stairs . Goniometers and foot switches, attached to the patient, are used to measure three - dimensional joint motion (Fig . 2), and such temporal and distance gait factors as the patient's percent stance phase, his individual step length, as well as cadence and velocity . All of the gai t lab information is monitored in a control room and transferred to the lab's PDP 11/34 computer, which provides a means of rapid data analysis and storage. Once the ampu tee ' s data are reduced, a computerized
The need for additional training techniques is illustra t ed by a group of 31 ampu t ees , who were evaluated before and after their gait training . Because of our clinical set ting, the p r edominant diagnosis in t his g roup of amputees was osteogenic sarcoma, and the average age was 28 years. Of the 38 gait parameters measured on the amputated side, 55% were found to be abnorma l (p < .05) compared to the data from the uninvo l ved ex tremit y . Out of these 21 abnorma l pa r ameters, only three were found to be significantly improved (p < . 05) at the end of their gait training . This pre - and post-gait training C AP e - E O
129
130
R. K. Laughman et al . GAIT TRAINING DEVICES The first training device deals with a gait fault which consists of a lon g interval between knee extension and ipsilateral heelstrike, creating a halting and awkward gait (Fig. 3).
flU.
i
1:11
30·:
I r '- I
\
Fig . 1
Gait lab Hith instrumented Ha lkways , including infrared light sHit ches , fo r ce p l ate , and instrumented stainless s t eel mats.
E;--;J; .--1 \-JI
I
I
I I _ .____.1
I I I
I I I
ElT.
h'\- - l !rl ..., ,- ••1 ,hike -r lr" t.o. -- t ••• ff
Fig. 3
[
F-r: 1
-
Excessive knee extension-heelstrike interval (note arrows) equal to 15% of the gait cycle.
According to Winter (1979), it is important to correct this type of gait pattern to minimize the metabolic cost of ambulation. This prolonged interval was identified in a number of amputees, and was found to persist throughout gait trainin g . In an attempt to correct this fault, a training aid was designed (Fig. 4) which consists of two
Fig . 2
Three-dimensional e l ect ro go niometer Hi t h attachment and footswitches .
r epo rt fo rm is completed and sent to the patient ' s r efe rring c linician . Based on this objective cance r amputee data, a num ber of r es idual ga it problems have been ident i f i ed . Two devices , which have been desig n ed to co rr ec t specific ga it fau lt s , Hill be presented in thi s paper.
Fig. 4
Training device used for the excessive knee extension-hee1strike interval show ing both knee and heel swi tch es.
131
Prosthetic Gait Training switches, one that closes as the knee extends, and a second switch which closes as the heel contacts the ground. These switches are then connected to a small signal generator, worn on the patient's belt. An audio output is produced as each switch closes. The objective of the device is to allow the amputee to hear his/her gait problem, and thereby, facilitate its correction. Since the device's development, 19 patients displaying this gait fault have been evaluated, both pre- and post-formal gait training. These patients were divided into two groups, both receiving the usual gait training, with the experimental group receiving the additional aid of the audio feedback device. When the data from the two groups were compared (Table 1), a statistically significant difference (p < .05) was found. All of the subjects receiving training with the new device showed a reduction in this time interval. The control group demonstrated mixed results, with the majority displaying an actual increase in the studied interval. Similar results were obtained when the data were normalized to a percent of the gait cycle. Continued anal y sis of our data has identified various other gait problems, one of which is the familiar positive Trendelenburg or compensated gluteus medius limp. This gait proble~ (Fig. 5) consists of excessive
liD.
10·
1
I
/\ ~i /\ : ",
,
V "'--'I
\{
1
1
I
i /\
~
V
1
Grade 3 Grade 2
"
.2
i«
-5
Fig. 6
20
"
40
60
100% /
% of Stance phose "
Patient data
\
/
I
: Normal data \
, ..... - - - - -
-............
-_
..... ....
I /
I
I
Grading sy s tem developed to document a patient's coronal pla n e hip motion . This figure shows the normal patt e rn (dotted line) and a patient' s data obtained 20 months postop. (upper solid line), and 34 month s po s top. (lower solid line) .
following surger y . The gradin g sy stem provides a very convenient method o f monitoring a patient's pro gress. For inst a n ce , this patient's progression from a grade 2 t o a grade 1 gait fault during the intervening 14 months, is easily visualized and reported using these methods. We have thu s f a r studied 24 patients with this deviation both pre- and post-phy s i c al therap y . S ~v en teen subjects exhibited a pre-the rap y positive Trendelenburg toward the amputated s ide, none of which were c orrected by g ait trainin g . The average amount of stanc e phase abduction equaled 6 degrees, resulting in a total deviation of 11 degrees, based on avera g e normal values.
lOO.
\V-'h]cV~T'l1j (
".s. - heel strike t.o. - toe off
Fig. 5
Abnormal hip motion post gait training, showing 8 degrees of hip abduction during stance in place of the normal hip adduction.
lateral motion of the upper torso toward the involved extremity. This movement is reflected in the patieftt's coronal plane hip motion, where the normal 5 degrees of stance phase hip adduction (Saunders, 1953) is replaced by hip abduction of varying degrees. Figure 6 illustrates a grading system, which we have developed, to categorize this gait fault. The solid lines represent the stance phase coronal plane hip motion, obtained from a 69-year-old man who underwent custom total hip arthroplasty in 1978 secondar y to chondrosarcoma. The uppermost line represents his coronal plane motion 20"months postop., while the lower line was obtained 34 months
The persistence of this dev iation and its potential adverse effects on the iow back and gait efficiency, has lead to the desi gn of another training device. Thi s d ev ic e shown in concept in Figure 7, consi s ts of a rotating disk in a bearing, with co ntr o lled friction and an eccentric adju s table we i g ht, forming a pendulum. The circumference of th e plexiglass disk contains markers whic h are read by a pair of optical s witches. Th es e switches can be adjusted to ac commodat e a pre-determined range of lat e ral trunk motion. The light switches are conne c ted to a belt box, containing a battery and e lec troni cs f or the accoustical feedback, which s o und s a s lon g as the disk is outside the rang e s et b y th e therapist. The unit is s ensitiv e to d e fl ec tions of the trunk relative to a v ertical reference. This dev ice is currentl y und e r clinical trial for further impr ov ement s and mod if ica t ions. DISCUSSION With these training conc e pts, we a r e a tt emp ting to make further improvement on a pa ti e nt' s gait quality, once he or s h e i s pr operl y fitted with a well-desig ned pro s th es i s. We are encouraged by our prelimin a r y fun c tio n a l
R. K. Laughman et al .
132
Table 1
Change in Knee Extension-Heelstrike Interval
Subjects with Biofeedback
Il 1 2 3 4 5 6 7 8 9 10
PreTraining .32 .34 .23 .09 .40 .07 .26 .20 .14 .35
PostTraining .24+ .l3-1.19-1.03 -1.2H .03-1.23 4 .19-1.08-1.28-1-
Subjects without Biofeedback
If 1 2 3 4 5 6 7 8 9
PreTraining .21 .18 .30 .20 .07 .27 .l3 .16 .37
PastTraining .25 t .20t .2H .25t .10t .32t .1H .28t .28 -1-
REFERENCES Fig. 7
Artist's conception of the pendulumcontrolled training device for the abducted gait pattern.
results regarding the biofeedback concept. Our results appear to be in agreement with others' who have used various types of instruments. These other training techniques include audio output to aid with stance phase knee control (Fernie, 1978), load sensing equipment to either restrict (Kegel, 1977) or promote (Fernie) weight transfer to the prosthesis, depending on the patient's stage of rehabilitation, and video equipment to assist with the overall gait appearance (Alexander, 1978). It is also hoped that by using these modes of training, patients will be more easily able to understand their gait problems, and that the immediate feedback features will provide increased patient motivation during the training process. Follow-up studies are currently needed to determine if the gait skills observed immediately post-training are carried over into the patient's daily life, or whether the patient's gait deteriorates once the formal training period is over. SUMMARY The unnecessary acceptance of an inefficient and tiring gait could cause the amputees to become disillusioned with the prosthesis, and even cause him to revert to a \o]heelchair and crutch existance. New training methods may assist in avoiding this sort of outcome. If these methods survive scientific scrutiny, their use, as well as the further development of new devices and methodology, could provide a positive impact on the amputee's functional life.
Alexander, J., Goodrich, R., (1978). Videotape immediate playback: A tool in Rehabilitation of persons with amputations. Arch. Phys. Med. Rehabil., ~, 141-144. Batzdorff, J. an~rankel, B., (1978). Initial gait training of the patient with an above knee amputation. Phys. Therap., 58, No. 5, 575-578, May. Chao~E.Y., Laughman, R.K., et al., (1980). Biomechanical gait evaluation of pre and postoperative total knee replacement patients. Arch. Orthop. Traumat., 22, 309-317. Coleman, A., (1979). Rehabilitation of the elderly amputee: A review of the literature. The ONA ~., ~, No. 7, 281-285, July. Drillis, R., (1958). Objective recording and biomechanics of pathological gait. Ann. of N.Y. Acad. Sci., 74, 86-109, September. Fernie,-G~, Halden:-J., al., (1978). Biofeedback training or knee control in the above knee amputee. Am.~. Phys. Med., 57, No. 4, 161-166. Fernie, G. Personal communication. Ganguli, S. and Mukhirjie, P., (1973). A gait recording technique suitable for clinical use. Biomed. ~., ~, 60-63, February. Lewis, E.A. and Storos, A., (1970). Research in lower-extremity prostheses. Bull. Prosth. Res., 184, Spring. Kege~an~oore, A.J., (1977). Load. cell, a device to monitor weight bearlng for lower extremity amputees. Phys. Therap., 57, No. 5, 652-654, June. Radcliff, C.W~ (1974). Locomotion and lower limb prostheses. Bull. Prosth. Res., 167, Fall. Saunders, J.B., Inman, V.T., et al., (1953). The major determinants in normal and pathological gait. ~. Bone Joint Surg., 35-A, No. 3, 543-558, July. Winter,-D.A., (1979). Biomechanics of Human Movement. John IHley & Sons. Chap. 5.
et
ACKNOWLEDGMENT This study supported in parts by NIH Grant AN 18029, and NCI Grant CA 23751.
PROSTHETIC GAIT TRAINING USING THE CONCEPT OF BIOFEEDBACK AND INSTRUMENTED GAIT ANALYSIS R . K. Laughman, E. Schneider, S. Bogard and E. Y. Chao Biomechanics Laboratory, Department of Orthopedics, Mayo Chnic l Mayo Foundation, Roch ester, Minnesota 55905, USA Abstract. The purpose of this paper is to present a gait analysis (Chao, 1 980) which is routinely used in the clinical evaluation of to report the preliminary results from a new gait training device, describe one additional training device, both of which utilize the back concept . Keywords.
system amputees, and to biofeed -
Amputee; gait training devices; objective gait analysis.
INTRODUCTION
data indicates that gai t deviations are common, even among young amputees, and that additional methods of training may prove helpful . For yo un g , potentially long, prosth esis users, it would be desirable to correct residual gai t faults early, before they become uncorrectable gai t habits, which may later cause additional problems (Batz dorff, 1978) .
The use of gait analysis for the objective documentat i on of amputee function is not a new idea . However, the majority of work in this area has been directed toward prosthetic design rather than the ga it training process. A number of authors (Radcliff, 1974; Lewis, 1970; Drillis, 1958; Ganguli, 1973) have discussed a lack of information regarding gait training methods. To date, the objective clinical gait evaluation of amputees has been limited, with the patient ' s gait training being accomplished largely by subjective methods. This makes it difficu l t for the patient, and therapist alike, to perform optimally.
Admittedly, cancer amputees make up a small percentage of the amputations performed nationally . Coleman (1979) stated that approximately 85% of all peacetime amputations involve older individuals with peripheral vascu l ar disease. This g roup of patients presents a difficult rehabilitation problem, in that their vascular disease is systemic, involving the heart and cent r al nervous system, as well as the vasculature of t he unamputated extremity . For this reason, it i s especially important that these patients receive training which will develop the most efficient gait pattern , while minimizing the time and effor t required.
It is an obvious fact that following an ampu tation, a patient's gait function will be le ss efficient than a normal individual, even under the best of conditions. However , a faulty gait pattern should not be accepted by assuming tha t an amputee fit t ed with a welldesigned prosthesis will automatically walk in the most efficient manner, and that further rehabilitation need not be a t tempted. We feel that with new and innovative methods of ga it training, a number of previousl y accepted poor gait habits can be cor r ected , resulting in a more efficient gait pattern .
GAIT LABORATORY The gait laborator y (Fig. 1) consists of t"o walkways. One is instrumented with two force plates, step length and step width grids, and two infrared light switches . The second walkway is u sed to simulate various walking surfaces, including a sideslope, ramp, and stairs . Goniometers and foot switches, attached to the patient, are used to measure three - dimensional joint motion (Fig . 2), and such temporal and distance gait factors as the patient's percent stance phase, his individual step length, as well as cadence and velocity . All of the gai t lab information is monitored in a control room and transferred to the lab's PDP 11/34 computer, which provides a means of rapid data analysis and storage. Once the ampu tee ' s data are reduced, a computerized
The need for additional training techniques is illustra t ed by a group of 31 ampu t ees , who were evaluated before and after their gait training . Because of our clinical set ting, the p r edominant diagnosis in t his g roup of amputees was osteogenic sarcoma, and the average age was 28 years. Of the 38 gait parameters measured on the amputated side, 55% were found to be abnorma l (p < .05) compared to the data from the uninvo l ved ex tremit y . Out of these 21 abnorma l pa r ameters, only three were found to be significantly improved (p < . 05) at the end of their gait training . This pre - and post-gait training C AP e - E O
129
130
R. K. Laughman et al . GAIT TRAINING DEVICES The first training device deals with a gait fault which consists of a lon g interval between knee extension and ipsilateral heelstrike, creating a halting and awkward gait (Fig. 3).
flU.
i
1:11
30·:
I r '- I
\
Fig . 1
Gait lab Hith instrumented Ha lkways , including infrared light sHit ches , fo r ce p l ate , and instrumented stainless s t eel mats.
E;--;J; .--1 \-JI
I
I
I I _ .____.1
I I I
I I I
ElT.
h'\- - l !rl ..., ,- ••1 ,hike -r lr" t.o. -- t ••• ff
Fig. 3
[
F-r: 1
-
Excessive knee extension-heelstrike interval (note arrows) equal to 15% of the gait cycle.
According to Winter (1979), it is important to correct this type of gait pattern to minimize the metabolic cost of ambulation. This prolonged interval was identified in a number of amputees, and was found to persist throughout gait trainin g . In an attempt to correct this fault, a training aid was designed (Fig. 4) which consists of two
Fig . 2
Three-dimensional e l ect ro go niometer Hi t h attachment and footswitches .
r epo rt fo rm is completed and sent to the patient ' s r efe rring c linician . Based on this objective cance r amputee data, a num ber of r es idual ga it problems have been ident i f i ed . Two devices , which have been desig n ed to co rr ec t specific ga it fau lt s , Hill be presented in thi s paper.
Fig. 4
Training device used for the excessive knee extension-hee1strike interval show ing both knee and heel swi tch es.
131
Prosthetic Gait Training switches, one that closes as the knee extends, and a second switch which closes as the heel contacts the ground. These switches are then connected to a small signal generator, worn on the patient's belt. An audio output is produced as each switch closes. The objective of the device is to allow the amputee to hear his/her gait problem, and thereby, facilitate its correction. Since the device's development, 19 patients displaying this gait fault have been evaluated, both pre- and post-formal gait training. These patients were divided into two groups, both receiving the usual gait training, with the experimental group receiving the additional aid of the audio feedback device. When the data from the two groups were compared (Table 1), a statistically significant difference (p < .05) was found. All of the subjects receiving training with the new device showed a reduction in this time interval. The control group demonstrated mixed results, with the majority displaying an actual increase in the studied interval. Similar results were obtained when the data were normalized to a percent of the gait cycle. Continued anal y sis of our data has identified various other gait problems, one of which is the familiar positive Trendelenburg or compensated gluteus medius limp. This gait proble~ (Fig. 5) consists of excessive
liD.
10·
1
I
/\ ~i /\ : ",
,
V "'--'I
\{
1
1
I
i /\
~
V
1
Grade 3 Grade 2
"
.2
i«
-5
Fig. 6
20
"
40
60
100% /
% of Stance phose "
Patient data
\
/
I
: Normal data \
, ..... - - - - -
-............
-_
..... ....
I /
I
I
Grading sy s tem developed to document a patient's coronal pla n e hip motion . This figure shows the normal patt e rn (dotted line) and a patient' s data obtained 20 months postop. (upper solid line), and 34 month s po s top. (lower solid line) .
following surger y . The gradin g sy stem provides a very convenient method o f monitoring a patient's pro gress. For inst a n ce , this patient's progression from a grade 2 t o a grade 1 gait fault during the intervening 14 months, is easily visualized and reported using these methods. We have thu s f a r studied 24 patients with this deviation both pre- and post-phy s i c al therap y . S ~v en teen subjects exhibited a pre-the rap y positive Trendelenburg toward the amputated s ide, none of which were c orrected by g ait trainin g . The average amount of stanc e phase abduction equaled 6 degrees, resulting in a total deviation of 11 degrees, based on avera g e normal values.
lOO.
\V-'h]cV~T'l1j (
".s. - heel strike t.o. - toe off
Fig. 5
Abnormal hip motion post gait training, showing 8 degrees of hip abduction during stance in place of the normal hip adduction.
lateral motion of the upper torso toward the involved extremity. This movement is reflected in the patieftt's coronal plane hip motion, where the normal 5 degrees of stance phase hip adduction (Saunders, 1953) is replaced by hip abduction of varying degrees. Figure 6 illustrates a grading system, which we have developed, to categorize this gait fault. The solid lines represent the stance phase coronal plane hip motion, obtained from a 69-year-old man who underwent custom total hip arthroplasty in 1978 secondar y to chondrosarcoma. The uppermost line represents his coronal plane motion 20"months postop., while the lower line was obtained 34 months
The persistence of this dev iation and its potential adverse effects on the iow back and gait efficiency, has lead to the desi gn of another training device. Thi s d ev ic e shown in concept in Figure 7, consi s ts of a rotating disk in a bearing, with co ntr o lled friction and an eccentric adju s table we i g ht, forming a pendulum. The circumference of th e plexiglass disk contains markers whic h are read by a pair of optical s witches. Th es e switches can be adjusted to ac commodat e a pre-determined range of lat e ral trunk motion. The light switches are conne c ted to a belt box, containing a battery and e lec troni cs f or the accoustical feedback, which s o und s a s lon g as the disk is outside the rang e s et b y th e therapist. The unit is s ensitiv e to d e fl ec tions of the trunk relative to a v ertical reference. This dev ice is currentl y und e r clinical trial for further impr ov ement s and mod if ica t ions. DISCUSSION With these training conc e pts, we a r e a tt emp ting to make further improvement on a pa ti e nt' s gait quality, once he or s h e i s pr operl y fitted with a well-desig ned pro s th es i s. We are encouraged by our prelimin a r y fun c tio n a l
R. K. Laughman et al .
132
Table 1
Change in Knee Extension-Heelstrike Interval
Subjects with Biofeedback
Il 1 2 3 4 5 6 7 8 9 10
PreTraining .32 .34 .23 .09 .40 .07 .26 .20 .14 .35
PostTraining .24+ .l3-1.19-1.03 -1.2H .03-1.23 4 .19-1.08-1.28-1-
Subjects without Biofeedback
If 1 2 3 4 5 6 7 8 9
PreTraining .21 .18 .30 .20 .07 .27 .l3 .16 .37
PastTraining .25 t .20t .2H .25t .10t .32t .1H .28t .28 -1-
REFERENCES Fig. 7
Artist's conception of the pendulumcontrolled training device for the abducted gait pattern.
results regarding the biofeedback concept. Our results appear to be in agreement with others' who have used various types of instruments. These other training techniques include audio output to aid with stance phase knee control (Fernie, 1978), load sensing equipment to either restrict (Kegel, 1977) or promote (Fernie) weight transfer to the prosthesis, depending on the patient's stage of rehabilitation, and video equipment to assist with the overall gait appearance (Alexander, 1978). It is also hoped that by using these modes of training, patients will be more easily able to understand their gait problems, and that the immediate feedback features will provide increased patient motivation during the training process. Follow-up studies are currently needed to determine if the gait skills observed immediately post-training are carried over into the patient's daily life, or whether the patient's gait deteriorates once the formal training period is over. SUMMARY The unnecessary acceptance of an inefficient and tiring gait could cause the amputees to become disillusioned with the prosthesis, and even cause him to revert to a \o]heelchair and crutch existance. New training methods may assist in avoiding this sort of outcome. If these methods survive scientific scrutiny, their use, as well as the further development of new devices and methodology, could provide a positive impact on the amputee's functional life.
Alexander, J., Goodrich, R., (1978). Videotape immediate playback: A tool in Rehabilitation of persons with amputations. Arch. Phys. Med. Rehabil., ~, 141-144. Batzdorff, J. an~rankel, B., (1978). Initial gait training of the patient with an above knee amputation. Phys. Therap., 58, No. 5, 575-578, May. Chao~E.Y., Laughman, R.K., et al., (1980). Biomechanical gait evaluation of pre and postoperative total knee replacement patients. Arch. Orthop. Traumat., 22, 309-317. Coleman, A., (1979). Rehabilitation of the elderly amputee: A review of the literature. The ONA ~., ~, No. 7, 281-285, July. Drillis, R., (1958). Objective recording and biomechanics of pathological gait. Ann. of N.Y. Acad. Sci., 74, 86-109, September. Fernie,-G~, Halden:-J., al., (1978). Biofeedback training or knee control in the above knee amputee. Am.~. Phys. Med., 57, No. 4, 161-166. Fernie, G. Personal communication. Ganguli, S. and Mukhirjie, P., (1973). A gait recording technique suitable for clinical use. Biomed. ~., ~, 60-63, February. Lewis, E.A. and Storos, A., (1970). Research in lower-extremity prostheses. Bull. Prosth. Res., 184, Spring. Kege~an~oore, A.J., (1977). Load. cell, a device to monitor weight bearlng for lower extremity amputees. Phys. Therap., 57, No. 5, 652-654, June. Radcliff, C.W~ (1974). Locomotion and lower limb prostheses. Bull. Prosth. Res., 167, Fall. Saunders, J.B., Inman, V.T., et al., (1953). The major determinants in normal and pathological gait. ~. Bone Joint Surg., 35-A, No. 3, 543-558, July. Winter,-D.A., (1979). Biomechanics of Human Movement. John IHley & Sons. Chap. 5.
et
ACKNOWLEDGMENT This study supported in parts by NIH Grant AN 18029, and NCI Grant CA 23751.