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A method to extend the applicability of hip center estimates in gait analysis
66
Gait & Posture 1994; 2: No 1
Effectiveness ily Spaslicily
of Inlrathecal Baclofcn
on Reducing Lower
Extrem-
l ~GregoryRash*.EdD.. KarenBloom+*. M.D., JohnShaw+. M.D., l Gait& Biomechanics Laboratory, FrazierRehabCenter, Louisville. KY. l*KetttuckianaRehabilitationMedicine, PSC, Louisville.KY.
Anindividualsuffetittgfromlowerextremityspasticityofunkttowttetiology resultinginimpairedgaitwas~atedbyimplantationofaBaclofenin~thecal pump. Cerebral palsy, a&a. multiple sclerosis and musculardystmphy had all been tuled out A gaitanalysis was performed before the implantationof the pump collecting standard kinematic, kinetic and EMG data. Before implantationof the Baclofenpump. the patient could not ambulate without the assist of a single lofstrand crutch Additionally, he rated the equivalent of a 3 block ambulationas 9, on a 0 to 10 Rate of Perceived Exertion scale. AnadjustmentperiodoftwomontIuafterimplatttationoftheBaclofen pump was given prior to conducting a second gait analysis. The patient now rated the equivalent of a 3 block ambulationas a 4. on a 0 to 10 Rate of Perceived Exertionscale. Althoughhe continues to use a lofswand crutchwhile ambulating in the community. he ambulates without his lofstrandcmtchat home and was able to ambulate for the gaitanalysis without his assistive device. Althoughnodramatic changes wereseeninthesubjectskinematicor kinetic data. several small differences were noted His abnormally long left double support time decreased by 15%. His stride length improved by an average of 5% and his resultant velocity increased anaverage of 10%. Other kinematic impmvements included decreases in pelvic rotationand an &teased ability to abduct& left lower extremity. The greatestchange among the kinetic measures was his ability to generate greater amounts of power in hip, knee and ankle. However. the timing of the powergenerationwas noteffective. There also seems to be a attenuationof the EMG data reducing many of the large EMG spikes whichoccurred in thefiratanalysis. however. itis hardtocompare EMGdatabetweengaitevaluatiOll.3. The timing and amounts of the subjects Baclofenittjectiotu are still being adjusted in an effort to obtain the best results for this individual. It is hoped that continued refinement of the injection protocol and physical therapy will improve his gait parameters more over time.
A PREOPERATIVE PLANNING STRATEGY FOR TRANSFER OF THE LONG HEAD OF THE TRICEP IN PEDIATRIC PATIENTS WITH ARTI-IROGRYPOSIS
.
.
Randy Robbins, M.D., Nasreen Sachin Rae, M.E., Cecilia Concha, B.S.
Marybeth Ezaki, M.D..
Texas Scottish Rite Hospital for Children, Dallas, TX. The purpose of this investigation was to establish a method for objective examination of the tricep muscles in patients with arthrogryposis. It has been proposed that if different muscles within the same group can be electrically isolated, that there exists sufficiently independent neurological innervation to allow for separate firing and independent function. With this in mind, we devised an objective test utilizing surface EMG to test the electrical isolation of the lateral and long heads of the triceps in patients with arthrogryposis. If the muscles were isolated, a transfer of the distal end of the long head of the tricep milscle was performed to allow the patient elbow flexion capability. Testing was performed on two normals to verify the comparability of surface electrodes and tine wire electrodes in the two heads of the tricep. Motion Control preamplifiers were used for both the surface and fine wire electrodes. Electrical stimulation of the fine wires was performed to ensure appropriate placement. With the electrodes in place, the subjects performed several movements in an attempt to isolate each of the muscles. The signals were collected on a DATAQ data acquisition system and analyzed utilizing Codas and AdvPost Codas software (Dataq Instruments, Inc.). The raw EMG signals were calibrated for amplification, rectified and integrated over the period of each contraction. The integrated value of the signal at the completion of a movement was quantified as the EMG activity index. Equivalent activity indexes were demonstrated for the wire and surface electrodes on the same muscle. The ratio of the EMG activity indices for each muscle was used to determine isolation for given motions. Both surface and wire electrodes demonstrated isolation of the two tricep heads comparably. Preoperative testing has been conducted on four patients with arthrogryposis. For three of the four, electrical isolation of the two tricep heads was demonstrated utilizing the EMG activity index. Two of the four have undergone surgety and been tested postoperatively in the Lab. During the postoperative testing, isolation of the long and lateral tricep heads has been demonstrated for several motions including elbow flexion and extension.
THE EFFECT OF SURFACE AND INTRAMUSCULAR EMG ELECTRODES ON THE TEMPORAL DISTANCE MEASURES OF GAIT PatriciaWinchester. PhD. PT. James 1. Carollo, MS, PE, and John M. Wrobbel, BSEE Mobility Research and Assessment Laboratory I Department of Orthopaedic Surgery University of Texas Southwestern Medical Center at Dallas Most gait investigators presume that the existence of body attached instmmentation does not alter a subject’s walking pattern, and any changes observed in temporal distance measurements retlect bona tide alterations in the subject’s gait. This assumes that temporal distance measurements are reliable between passes and between days, and arc not adversely affected by devices such as EMG recording systems. This study examined the reliabilitv of temooral distance measures in 10 normal subiects and determined if surface or int&uscuiar tine wire (IM) electrodes affected the& parameters. Methods: Ten healthy subjects (6 men I4 women) with an average age of 25.2 f 4.0 years volunteered for this study. Thin flexible footswitches were attached to the heel, 5th, 1st metatarsal, and great toe of both feet. Data were transmitted to a computerized recording system via a custom interface and fiber optic telemetry. Each subject was asked to walk at a normal, comfortable velocity down a 12 m walkway while collecting foot/floor contact events over the central 9 m portion. No attempts were made to control the subject’s velocity or cadence. Six temporal distance measures (see table) were recordid on two separate days within a five day period. On day 1 temporal distance measures were recorded, fust without EMG electrodes, and then immediately following surface electrode application. Electrodes were arranged in bipolar pairs along the long axis of 4 muscles; anterior tibialis. soleus. vastus medialis, and biceps fernotis. Wireless telemetrv transmitters for each electrode oair were also attached in the customarv wav. The samk procedures were followed on bay 2, except EMelectrodes were used h pla& of surface electrodes; all other aspects of the EMG recording system were identical. Intraclass correlation coefficients type. 1 (ICC 1.1) were used to estimate the reliability of temporal distance measures betwedn passes. A’&tivariate ANOVA was used to test for differences in temwral distance measures for two factors: dav and tvce of electrode. Results: ICC’s fo; the 6 temporal distance measures under th 3 cobbitions follow. i3lectrodes velocity cadence stnde 1. cycle time DLS tnne SLS ratlo None 9 0.97 1 0. 21 ,953 0.65 1 Surface 0.980 0.849 0.939 0.86 I 0.948 0.764 Ih4 Wire I 0.991 0.923 Or912 0.930 0.930 0.518 The high ICC values demonstrate that temporal distance measures (with the exception of SLS ratio) are very repeatable from pass to pass for normal subjects ‘Electrode Day (1 velocity cadence stnde 1. cycle t. DLS t. SLS ratio 1 (m/min) (step/min) (m) (set) (% cycle) (dom/nd) 1 77.9t7.24 111.7+7.1 1.40+0.10 1.08+0.07 30.6i1.23 1.01+0.03 None Surface 1 77.9k77.12 111.8i7.7 1.40~0.10 1.089.08 29.9i22.13 0.98*0,04 None 2 78.4k8.11 112.N7.1 1.4Oj$.ll 1.08iO.07 30.3k2.45 0.99+0.03 IM Wire 2 78.7k8.60 112.0&6.3 1.41+0.11 1.08+0.06 3OQ2.43 l.Oi&O.OS ( distance measures between days or electrode type. Based on these findings. temtmral distance measures have high i&a-subject reli&ility. In addition, the appiicationof surface or IM electrodes did not alter the gait pattern of normal adult subjects. as demonstrated by highly consistent temporal distance measurements.
A METHOD TO EXTEND THE APPLICABILITY OF HIP CENTER ESTIMATES IN GAIT ANALYSIS. Mu&U&&& Daniel Antonelli. Ph.D., George Bassett, M.D. Childrens Hospital Los Angeles John C. Wilson Jr. Motion Analysis Laboratory Los Angeles, CA. 90027 Introduction: A biomechanical model used to estimate the hip center is described by Davis et al.‘. The hip center estimate is useful for normally proportioned subjects. The model is inaccurate for subjects who fall outside this profile (i.e. dwarfs or congenital leg length deficits) resulting in misleading embedded joint angles. This method describes the analytical process to calculate parameters for Ihis model that will produce an accurate hip center estimate for a subject who is not normally proportioned. Method: 1) The input parameters for a normal subject were measoredl. 2) Kinematic data for a normal subject was processed iteratively, decreasing the leg length measure in IO cm intervals until an angular change greater than the standard deviation of the normal kinematics was observed. This condition was observed at 66% of the measured leg length. 3) Hip center estimates were calculated at normal leg length using equations from Davis et al.1 and obtained from AP and lateral X-rays following established conventions. 4) New input parameters were calculated from the X-ray measures and the following equations: Xd,n = -rmarker-Xn
L,, z-8.696
co@)-ZH
sin(P)
ZH -co’@) + 8.6957 XH fl+ cos(8) code)
0.13304
5) The estimates obtained in step 4 were compared to the clinical measures. Results: X-rays for one normal subject were obtained to test this method. The X-ray estimate of leg length was 3.7 cm less than the clinically measured leg length. The Xray estimate of ASlS to ASlS distance was 1.6 cm greater than the clinical measures. and the X-ray estimate of the Xdist measure was .9 cm less than clinically measured. These X-ray estimates will force the model to generate the hip center measured from the X-rays. This method is useful when the ratio of lee leneth to asis distance. falls below apprbximately 2.5. In these cases, input parameters m&red off an xray will result in more accurate output data. References Davis. R.B.. 111.S. i)unpuu. D. Tyburski and 1.R. Gage, IYYI. A gait analysis data collection and reduction technique. Human Movement Science IO. 575-587.
Gait & Posture 1994; 2: No 1
Effectiveness ily Spaslicily
of Inlrathecal Baclofcn
on Reducing Lower
Extrem-
l ~GregoryRash*.EdD.. KarenBloom+*. M.D., JohnShaw+. M.D., l Gait& Biomechanics Laboratory, FrazierRehabCenter, Louisville. KY. l*KetttuckianaRehabilitationMedicine, PSC, Louisville.KY.
Anindividualsuffetittgfromlowerextremityspasticityofunkttowttetiology resultinginimpairedgaitwas~atedbyimplantationofaBaclofenin~thecal pump. Cerebral palsy, a&a. multiple sclerosis and musculardystmphy had all been tuled out A gaitanalysis was performed before the implantationof the pump collecting standard kinematic, kinetic and EMG data. Before implantationof the Baclofenpump. the patient could not ambulate without the assist of a single lofstrand crutch Additionally, he rated the equivalent of a 3 block ambulationas 9, on a 0 to 10 Rate of Perceived Exertion scale. AnadjustmentperiodoftwomontIuafterimplatttationoftheBaclofen pump was given prior to conducting a second gait analysis. The patient now rated the equivalent of a 3 block ambulationas a 4. on a 0 to 10 Rate of Perceived Exertionscale. Althoughhe continues to use a lofswand crutchwhile ambulating in the community. he ambulates without his lofstrandcmtchat home and was able to ambulate for the gaitanalysis without his assistive device. Althoughnodramatic changes wereseeninthesubjectskinematicor kinetic data. several small differences were noted His abnormally long left double support time decreased by 15%. His stride length improved by an average of 5% and his resultant velocity increased anaverage of 10%. Other kinematic impmvements included decreases in pelvic rotationand an &teased ability to abduct& left lower extremity. The greatestchange among the kinetic measures was his ability to generate greater amounts of power in hip, knee and ankle. However. the timing of the powergenerationwas noteffective. There also seems to be a attenuationof the EMG data reducing many of the large EMG spikes whichoccurred in thefiratanalysis. however. itis hardtocompare EMGdatabetweengaitevaluatiOll.3. The timing and amounts of the subjects Baclofenittjectiotu are still being adjusted in an effort to obtain the best results for this individual. It is hoped that continued refinement of the injection protocol and physical therapy will improve his gait parameters more over time.
A PREOPERATIVE PLANNING STRATEGY FOR TRANSFER OF THE LONG HEAD OF THE TRICEP IN PEDIATRIC PATIENTS WITH ARTI-IROGRYPOSIS
.
.
Randy Robbins, M.D., Nasreen Sachin Rae, M.E., Cecilia Concha, B.S.
Marybeth Ezaki, M.D..
Texas Scottish Rite Hospital for Children, Dallas, TX. The purpose of this investigation was to establish a method for objective examination of the tricep muscles in patients with arthrogryposis. It has been proposed that if different muscles within the same group can be electrically isolated, that there exists sufficiently independent neurological innervation to allow for separate firing and independent function. With this in mind, we devised an objective test utilizing surface EMG to test the electrical isolation of the lateral and long heads of the triceps in patients with arthrogryposis. If the muscles were isolated, a transfer of the distal end of the long head of the tricep milscle was performed to allow the patient elbow flexion capability. Testing was performed on two normals to verify the comparability of surface electrodes and tine wire electrodes in the two heads of the tricep. Motion Control preamplifiers were used for both the surface and fine wire electrodes. Electrical stimulation of the fine wires was performed to ensure appropriate placement. With the electrodes in place, the subjects performed several movements in an attempt to isolate each of the muscles. The signals were collected on a DATAQ data acquisition system and analyzed utilizing Codas and AdvPost Codas software (Dataq Instruments, Inc.). The raw EMG signals were calibrated for amplification, rectified and integrated over the period of each contraction. The integrated value of the signal at the completion of a movement was quantified as the EMG activity index. Equivalent activity indexes were demonstrated for the wire and surface electrodes on the same muscle. The ratio of the EMG activity indices for each muscle was used to determine isolation for given motions. Both surface and wire electrodes demonstrated isolation of the two tricep heads comparably. Preoperative testing has been conducted on four patients with arthrogryposis. For three of the four, electrical isolation of the two tricep heads was demonstrated utilizing the EMG activity index. Two of the four have undergone surgety and been tested postoperatively in the Lab. During the postoperative testing, isolation of the long and lateral tricep heads has been demonstrated for several motions including elbow flexion and extension.
THE EFFECT OF SURFACE AND INTRAMUSCULAR EMG ELECTRODES ON THE TEMPORAL DISTANCE MEASURES OF GAIT PatriciaWinchester. PhD. PT. James 1. Carollo, MS, PE, and John M. Wrobbel, BSEE Mobility Research and Assessment Laboratory I Department of Orthopaedic Surgery University of Texas Southwestern Medical Center at Dallas Most gait investigators presume that the existence of body attached instmmentation does not alter a subject’s walking pattern, and any changes observed in temporal distance measurements retlect bona tide alterations in the subject’s gait. This assumes that temporal distance measurements are reliable between passes and between days, and arc not adversely affected by devices such as EMG recording systems. This study examined the reliabilitv of temooral distance measures in 10 normal subiects and determined if surface or int&uscuiar tine wire (IM) electrodes affected the& parameters. Methods: Ten healthy subjects (6 men I4 women) with an average age of 25.2 f 4.0 years volunteered for this study. Thin flexible footswitches were attached to the heel, 5th, 1st metatarsal, and great toe of both feet. Data were transmitted to a computerized recording system via a custom interface and fiber optic telemetry. Each subject was asked to walk at a normal, comfortable velocity down a 12 m walkway while collecting foot/floor contact events over the central 9 m portion. No attempts were made to control the subject’s velocity or cadence. Six temporal distance measures (see table) were recordid on two separate days within a five day period. On day 1 temporal distance measures were recorded, fust without EMG electrodes, and then immediately following surface electrode application. Electrodes were arranged in bipolar pairs along the long axis of 4 muscles; anterior tibialis. soleus. vastus medialis, and biceps fernotis. Wireless telemetrv transmitters for each electrode oair were also attached in the customarv wav. The samk procedures were followed on bay 2, except EMelectrodes were used h pla& of surface electrodes; all other aspects of the EMG recording system were identical. Intraclass correlation coefficients type. 1 (ICC 1.1) were used to estimate the reliability of temporal distance measures betwedn passes. A’&tivariate ANOVA was used to test for differences in temwral distance measures for two factors: dav and tvce of electrode. Results: ICC’s fo; the 6 temporal distance measures under th 3 cobbitions follow. i3lectrodes velocity cadence stnde 1. cycle time DLS tnne SLS ratlo None 9 0.97 1 0. 21 ,953 0.65 1 Surface 0.980 0.849 0.939 0.86 I 0.948 0.764 Ih4 Wire I 0.991 0.923 Or912 0.930 0.930 0.518 The high ICC values demonstrate that temporal distance measures (with the exception of SLS ratio) are very repeatable from pass to pass for normal subjects ‘Electrode Day (1 velocity cadence stnde 1. cycle t. DLS t. SLS ratio 1 (m/min) (step/min) (m) (set) (% cycle) (dom/nd) 1 77.9t7.24 111.7+7.1 1.40+0.10 1.08+0.07 30.6i1.23 1.01+0.03 None Surface 1 77.9k77.12 111.8i7.7 1.40~0.10 1.089.08 29.9i22.13 0.98*0,04 None 2 78.4k8.11 112.N7.1 1.4Oj$.ll 1.08iO.07 30.3k2.45 0.99+0.03 IM Wire 2 78.7k8.60 112.0&6.3 1.41+0.11 1.08+0.06 3OQ2.43 l.Oi&O.OS ( distance measures between days or electrode type. Based on these findings. temtmral distance measures have high i&a-subject reli&ility. In addition, the appiicationof surface or IM electrodes did not alter the gait pattern of normal adult subjects. as demonstrated by highly consistent temporal distance measurements.
A METHOD TO EXTEND THE APPLICABILITY OF HIP CENTER ESTIMATES IN GAIT ANALYSIS. Mu&U&&& Daniel Antonelli. Ph.D., George Bassett, M.D. Childrens Hospital Los Angeles John C. Wilson Jr. Motion Analysis Laboratory Los Angeles, CA. 90027 Introduction: A biomechanical model used to estimate the hip center is described by Davis et al.‘. The hip center estimate is useful for normally proportioned subjects. The model is inaccurate for subjects who fall outside this profile (i.e. dwarfs or congenital leg length deficits) resulting in misleading embedded joint angles. This method describes the analytical process to calculate parameters for Ihis model that will produce an accurate hip center estimate for a subject who is not normally proportioned. Method: 1) The input parameters for a normal subject were measoredl. 2) Kinematic data for a normal subject was processed iteratively, decreasing the leg length measure in IO cm intervals until an angular change greater than the standard deviation of the normal kinematics was observed. This condition was observed at 66% of the measured leg length. 3) Hip center estimates were calculated at normal leg length using equations from Davis et al.1 and obtained from AP and lateral X-rays following established conventions. 4) New input parameters were calculated from the X-ray measures and the following equations: Xd,n = -rmarker-Xn
L,, z-8.696
co@)-ZH
sin(P)
ZH -co’@) + 8.6957 XH fl+ cos(8) code)
0.13304
5) The estimates obtained in step 4 were compared to the clinical measures. Results: X-rays for one normal subject were obtained to test this method. The X-ray estimate of leg length was 3.7 cm less than the clinically measured leg length. The Xray estimate of ASlS to ASlS distance was 1.6 cm greater than the clinical measures. and the X-ray estimate of the Xdist measure was .9 cm less than clinically measured. These X-ray estimates will force the model to generate the hip center measured from the X-rays. This method is useful when the ratio of lee leneth to asis distance. falls below apprbximately 2.5. In these cases, input parameters m&red off an xray will result in more accurate output data. References Davis. R.B.. 111.S. i)unpuu. D. Tyburski and 1.R. Gage, IYYI. A gait analysis data collection and reduction technique. Human Movement Science IO. 575-587.