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Principles underlying the organization of gait initiation and stepping
Abstracts
I Gait & Posture
7 (1998)
173
144~190
DhCl&Od’ Tbs indices describedby Ftmg 0 Bsrbeau mm obtsincd while sobjccb walked on P motorized treadmill. Possibledixrepswies betwem the two studies may be the u&dybtg assumptionsof the index that a) the whtdo~ wxdd mmdn consistenttbtwgbottt the mngesof slower speeds;b) the s&e andmlatively quiet phsses of the EMG represent 50% escb of tb+ g&t cyck ; and c) the EMG amplitude within the “oft” window falls close to zem. Om possibility for our bigber indicesttt nstoml speedsis that our “off window mrely madted zero in spite of similer EMG processing betweenths two labs. Finally, it was assumedthat indicesdevelopedfrom treadmill wdkiog would bethe semeas during overgmut~I walking. Results from the lsrger study will address both the extremely slow speed of wdkbtg in addition to comparisons with overground and treadmill trials. Past normative resesrch has shown that slower walking speeds reveal alterations in the amplitude of EMG raordbtgs (Yang & Winter, 1985). However, our prelimii data,collectedst substantiallyslower walking speeds,suggesta shift in muscle timing ss well, likely in psrt dueto maintenanceof balance. Concluaioa Quantificationof muscle actwation patternswould assist in comparisonswithin andbetweensubjectsand labs. The inflwnce of speedneedstc~be consideredin the detectionand isolationof alteredmotor control due to “MN pathologies to guide and evaluate treatments. Analyses are in progress to develop a normative de6 bssc ofphasic muscle timing in combination with kinematic and kinetic analyses. It is suggestedthat the mtktticuk, and bisrticular muscles, in their mle m deceleratorsandaccelerators, need to be further exam&d in order to sssist clinical decision-making. This research direction is aimed at mcms.singthe mmms ofclinical gait analysisusing dynamic stice EMG. kinematic and kinetic analyses to identify hypertomcity and weakness in neumrehabilitation.
Figure I. Force plate data for obstie clcarana at sdfvdcaty. verttcal lutes mdtcate light signal. peak tmlceding. swing toe-off. stana bed F I, swtttg heel-strtke.
References Fung J , BarbeauH Electroencepholoaophy & Clmcol Neurophysiology, 73, 233-244. ,989. Richards C, Olney S PosrureondGorl, 4: 149-162, 1996. Yang JF Winter DA. Electrorncepholagrophy & Clmcal Neurophysrologv, 60: 485-491.1985
Acktmwledgements The financial support of the Labatts Relay Fund, Royal Ottawa HealthCare Group and assistance of the rehabilitation engineermg sewices of J Tomes and L.Goudreau are gratefully acknowledged.
Cock, T.. and Cmzcns. B. 1976. Human solutions fw loccmoii on: the mi!iattcmof gmt. In: Hammt R.. Grilbtcr S.. Stein PSG, Stuart Do. cd. Neural Control of Lccomotimt. New Yarkz Plenum Press, pp. 6576. Cremtq P.. and Frtgo. C. 1991. A mmor pmgmmme for tbz imttatton of forward-oriented movementsin humans. Jottmd cd Phniolo& 437, pp. 635653.
Prtnciplcs
Underlying the Organization of Gait initiatlon and Stepping. Shene-Mm Lu. Dems Brunt. Jeff Bauer, DcpirtmenLFof physical Therapy and Exercw and Sports Science, Unl”enlty or Ronda, Oamesv1lle,FL.
Using inmumented gait aoatyris for idcotlcstioo and treatment phnning of a Yunctiosat” gait impairment fotimviag tnunu and knee artbropt~ty Ids A Kramende Oucrvain MD-*,
U Mundn&?r MD’, E Stuss~PhD*
“Laboratory for Biomechanics, ETH Zurich and * Schulthess Klinik, Zurich, Switzerland Crenna and Fngo (1991) repo,ted that the m,tml or postural component of gmt mmatlon began with soleus (S) mhtbmon followed by the onset 01 tibiahs Anterior (TA) and that the mtetamm of thesemusda could be comidered a motor program to the extent that they exerted control over thecenter of pressure. However, that same burst of TA aconty also covartes wtb S act~ty during the mowstte”, companent of gatt tnmatta~ (Bttmt et al., 1991; Cook and Caz.ens.l975). It ts mdeed bkely t&t& initial S inhibition and TA onset is not a smgk motor program but rather a compcmm, of a larger motor program thatmrttrds the complete process of gait tmsatlmt. Given that them are some executwe stmtlarius between diffemtt motor tasks tt has been suggested that we access the same program, wth some ternpad and spatial mcdtfwtxits of thm program. for ezh task. Comparison of gait mitmtton to stmilar motor tasks. such as stePping, may further cbtrify how gmt tmtmtxm IS programmed. The pttrpox of thrs study, tberefom, was to detmmtne common principles tmderlymg the organimtion of gait l”m*m and stepping.
Methodolgy Ten healthy su+& @dpated in the study. Surface clectrod~ wue applied to the TA and S of the left stemx limb. A ground elecbuie ~88 sttxbed to the medial aspect of the tibk. Two farce pktiorms t”ca5”d gromtd rcactio” foroes of the left stance leg and heel co”Urt d the right win leg. EJcctriCa switches &temtinai the hmc of smtta heel-df and swtttg &e-off. Rmcss.d& andamPifKdfcroeplslrawsi~swemssmplsdon-lloeataratcol1.000 Hz for2semndn.Subjec(sw~aslcEdto~nwalkin&stcpwerarulw,or~stepo”eral0an hlgb otetlcle at D self-@ s@ lad ss fast &? possible. Analysis of vpriance wss used b &termtm mm and intemchoneffects. The tndcpcttdentvariables were axditiott (gmt mtttatimt, rulerand oixtwle) and initiation velocity (self-paced and as fast as possible). EMG dependent mcasutta were the latexy hetweet,sdcus offset andTA ottset, TA and S duration. Force plate measuresare illwtmted in Figure I.
rnbodtK!tioo - Cue EbtorY: A 5 I year old woman ruptured her right smerior c&ate ligament and me&l co4latad ligament during L ski accidem Following several rmxntstructi~e wrgmia she cotttimtai to experience an insmbility. After II fall doriog yard work she started to complain about knee pain on the comrsls.temJleft kttce. A pmtisl tupture oftbe mttmim cruciltc ligament was diagnosedby MBI She developeds severe limping gait p~ttertt, which wes considued to be a ‘?imUicmd” gait sbttmmsiity. Four yem-stdkrthe initial accident s saniunstrained total knee sr!hroplssty was oerformed on the right side due to contimmtion of severe pain. However, at\er surgery the wo&t oomimmd to c&plain about s persistent feeling of instability She also cotthnued to feel an instabilitv on the I& side One year after surgery she wore long leg braces on both sides which she could lock in extension No ~eurdo$icd G &chattical reasonwss found to explain her gait sbnormality and the need fw the long leg brwcs She consulted one specialtst after sttother Treatment by revision srthmplasty usmg B fully constrained system or even arthrodesn had been proposed
Gait analysis consisting of kinematic analysts (VICON), kmetic analysis (Kistler force plates) and dynamic electromyogmphy wss performed for documentation of the problem and for further treatment planning one year after the implantatmn of the knee arthroplasty Pbvsiul eslm tindings:
That was no mmndfectfortbe mfnval from the inbtbttmnof S to the onset of TA. There.was ametndfectfavekxityf~ the dttmtionof tatbTA (F (1, 9)=53X4, P-zO.001) and S (F (I, 9)x52.34, P-Xt.001) of tbc smtce limb. The duration of TA mcrcased and the duration of t tnumtiat the otlset stance S deamsed wiUt an iin tk velocity of initiation. For fast 01 s aivity ~-CC&S the dfset of TA activity. hencea mmntmction of tc two musclea (F (I, 9)=34.aS. P
13&pwGb$;
tbc writ vdables for the ground reactioo forces. For the fimt @ Fxl -bBlueen v&&y and rmditiats (F (2. 18)=3.59. p&OS). Tbe peaks of Fxl forallcomliticwwem a’rsilr~tkadf-pwxd velocity (rpO.05). all i&at the fmt velocityk*mepaLforobasckrcbcfsavdocitywas~gi8~lylessthntbeotha~o conditimts(P4.001 for ail sigtdfmt cuttpwianr). The slops to peal; Fxl itweased with an imtraac in tbs vebdty of i&i&m (F(I. 9)=6!I68, ILo.001). Thcrr wm en intim betweatvelocitymtdandition(F(2.18)=3.59~ pcO.05) forFeakFx2. Rak Fx? was less for gait ittiiimion (P&O01 for both ruler and obstlcle). Fa the fast velocity, the peak value fc8 oh%& ~3s signdi~tty hlgber lhnn the other two cc4twns (P-9X05 for bc& 01 and ruler). The slope ws grwter for fastest trials dtut sdf-lmwd trmls (F (I 9)=33. IO. Pd.00 I ). Them was also a signNkmt main d&t for cmtdittons (F (2, IS)= 10.36. P&.001) wbem the slope was gmter for smppmg over a l&cm otelaclc (P-=001) and steppmg over a ruler (P
The semnntstrained arthroplarty on the right side showed s Socd ali&wmentwith correct positioninn of the imdent and with wad stability The knee was tender with slight effusmn The rangeof motion was normal forfhe type of implant (Flexion - Extension I25 0 - 0) The Left knee had no effusion Anterior translation was slightly increased The pivot shift slgtt was negative The range of motion wss normal (Flexian - Extension 140- 0 - 5) Both hips and ankles were normal
Time- distance p.wameters The free gait velocity wthouf braces or cane WIP reduced to 0 56 m/s (45% norm), with a proportional reduction ofthe stride length (0.85 m, 66% notm) and the cadence (77 step /min. 66% norm) Asymmeuy of step length (right 0 46 m, I& 0 38) and simde limb stanceduration (r&t 24% of cycle, left 44% of cycle) indicatedI limpmg behaviouyof the right side _ Kmatmtic mtalvsis and dvtmmic EMG. Excessive kneeflexion wes seenduring wagbt scceptame on the right side coupled with increased dorsiflexicm st the ankle DyMmic EMG revealed a failure of sccur& timing ofthe knet smbiliing muscles No quadricepsor hamstrings activity was present doting the end of swing phsse and ewly weight acc@att=. A delayed onset of qosdriceps activity was seen ss s reaction to the buckling knee motion driven by gravity Gtt the l&l side kna flexion wss also excessive to B lesser de. No adequte compensationwlu seenfor *n emerior crudate ligament insoflicimcy Despite the ant&x laxity knee flexion wss mcressed with prolonged quadriceps activity and insuflicient hemsmngs
I Gait & Posture
7 (1998)
173
144~190
DhCl&Od’ Tbs indices describedby Ftmg 0 Bsrbeau mm obtsincd while sobjccb walked on P motorized treadmill. Possibledixrepswies betwem the two studies may be the u&dybtg assumptionsof the index that a) the whtdo~ wxdd mmdn consistenttbtwgbottt the mngesof slower speeds;b) the s&e andmlatively quiet phsses of the EMG represent 50% escb of tb+ g&t cyck ; and c) the EMG amplitude within the “oft” window falls close to zem. Om possibility for our bigber indicesttt nstoml speedsis that our “off window mrely madted zero in spite of similer EMG processing betweenths two labs. Finally, it was assumedthat indicesdevelopedfrom treadmill wdkiog would bethe semeas during overgmut~I walking. Results from the lsrger study will address both the extremely slow speed of wdkbtg in addition to comparisons with overground and treadmill trials. Past normative resesrch has shown that slower walking speeds reveal alterations in the amplitude of EMG raordbtgs (Yang & Winter, 1985). However, our prelimii data,collectedst substantiallyslower walking speeds,suggesta shift in muscle timing ss well, likely in psrt dueto maintenanceof balance. Concluaioa Quantificationof muscle actwation patternswould assist in comparisonswithin andbetweensubjectsand labs. The inflwnce of speedneedstc~be consideredin the detectionand isolationof alteredmotor control due to “MN pathologies to guide and evaluate treatments. Analyses are in progress to develop a normative de6 bssc ofphasic muscle timing in combination with kinematic and kinetic analyses. It is suggestedthat the mtktticuk, and bisrticular muscles, in their mle m deceleratorsandaccelerators, need to be further exam&d in order to sssist clinical decision-making. This research direction is aimed at mcms.singthe mmms ofclinical gait analysisusing dynamic stice EMG. kinematic and kinetic analyses to identify hypertomcity and weakness in neumrehabilitation.
Figure I. Force plate data for obstie clcarana at sdfvdcaty. verttcal lutes mdtcate light signal. peak tmlceding. swing toe-off. stana bed F I, swtttg heel-strtke.
References Fung J , BarbeauH Electroencepholoaophy & Clmcol Neurophysiology, 73, 233-244. ,989. Richards C, Olney S PosrureondGorl, 4: 149-162, 1996. Yang JF Winter DA. Electrorncepholagrophy & Clmcal Neurophysrologv, 60: 485-491.1985
Acktmwledgements The financial support of the Labatts Relay Fund, Royal Ottawa HealthCare Group and assistance of the rehabilitation engineermg sewices of J Tomes and L.Goudreau are gratefully acknowledged.
Cock, T.. and Cmzcns. B. 1976. Human solutions fw loccmoii on: the mi!iattcmof gmt. In: Hammt R.. Grilbtcr S.. Stein PSG, Stuart Do. cd. Neural Control of Lccomotimt. New Yarkz Plenum Press, pp. 6576. Cremtq P.. and Frtgo. C. 1991. A mmor pmgmmme for tbz imttatton of forward-oriented movementsin humans. Jottmd cd Phniolo& 437, pp. 635653.
Prtnciplcs
Underlying the Organization of Gait initiatlon and Stepping. Shene-Mm Lu. Dems Brunt. Jeff Bauer, DcpirtmenLFof physical Therapy and Exercw and Sports Science, Unl”enlty or Ronda, Oamesv1lle,FL.
Using inmumented gait aoatyris for idcotlcstioo and treatment phnning of a Yunctiosat” gait impairment fotimviag tnunu and knee artbropt~ty Ids A Kramende Oucrvain MD-*,
U Mundn&?r MD’, E Stuss~PhD*
“Laboratory for Biomechanics, ETH Zurich and * Schulthess Klinik, Zurich, Switzerland Crenna and Fngo (1991) repo,ted that the m,tml or postural component of gmt mmatlon began with soleus (S) mhtbmon followed by the onset 01 tibiahs Anterior (TA) and that the mtetamm of thesemusda could be comidered a motor program to the extent that they exerted control over thecenter of pressure. However, that same burst of TA aconty also covartes wtb S act~ty during the mowstte”, companent of gatt tnmatta~ (Bttmt et al., 1991; Cook and Caz.ens.l975). It ts mdeed bkely t&t& initial S inhibition and TA onset is not a smgk motor program but rather a compcmm, of a larger motor program thatmrttrds the complete process of gait tmsatlmt. Given that them are some executwe stmtlarius between diffemtt motor tasks tt has been suggested that we access the same program, wth some ternpad and spatial mcdtfwtxits of thm program. for ezh task. Comparison of gait mitmtton to stmilar motor tasks. such as stePping, may further cbtrify how gmt tmtmtxm IS programmed. The pttrpox of thrs study, tberefom, was to detmmtne common principles tmderlymg the organimtion of gait l”m*m and stepping.
Methodolgy Ten healthy su+& @dpated in the study. Surface clectrod~ wue applied to the TA and S of the left stemx limb. A ground elecbuie ~88 sttxbed to the medial aspect of the tibk. Two farce pktiorms t”ca5”d gromtd rcactio” foroes of the left stance leg and heel co”Urt d the right win leg. EJcctriCa switches &temtinai the hmc of smtta heel-df and swtttg &e-off. Rmcss.d& andamPifKdfcroeplslrawsi~swemssmplsdon-lloeataratcol1.000 Hz for2semndn.Subjec(sw~aslcEdto~nwalkin&stcpwerarulw,or~stepo”eral0an hlgb otetlcle at D self-@ s@ lad ss fast &? possible. Analysis of vpriance wss used b &termtm mm and intemchoneffects. The tndcpcttdentvariables were axditiott (gmt mtttatimt, rulerand oixtwle) and initiation velocity (self-paced and as fast as possible). EMG dependent mcasutta were the latexy hetweet,sdcus offset andTA ottset, TA and S duration. Force plate measuresare illwtmted in Figure I.
rnbodtK!tioo - Cue EbtorY: A 5 I year old woman ruptured her right smerior c&ate ligament and me&l co4latad ligament during L ski accidem Following several rmxntstructi~e wrgmia she cotttimtai to experience an insmbility. After II fall doriog yard work she started to complain about knee pain on the comrsls.temJleft kttce. A pmtisl tupture oftbe mttmim cruciltc ligament was diagnosedby MBI She developeds severe limping gait p~ttertt, which wes considued to be a ‘?imUicmd” gait sbttmmsiity. Four yem-stdkrthe initial accident s saniunstrained total knee sr!hroplssty was oerformed on the right side due to contimmtion of severe pain. However, at\er surgery the wo&t oomimmd to c&plain about s persistent feeling of instability She also cotthnued to feel an instabilitv on the I& side One year after surgery she wore long leg braces on both sides which she could lock in extension No ~eurdo$icd G &chattical reasonwss found to explain her gait sbnormality and the need fw the long leg brwcs She consulted one specialtst after sttother Treatment by revision srthmplasty usmg B fully constrained system or even arthrodesn had been proposed
Gait analysis consisting of kinematic analysts (VICON), kmetic analysis (Kistler force plates) and dynamic electromyogmphy wss performed for documentation of the problem and for further treatment planning one year after the implantatmn of the knee arthroplasty Pbvsiul eslm tindings:
That was no mmndfectfortbe mfnval from the inbtbttmnof S to the onset of TA. There.was ametndfectfavekxityf~ the dttmtionof tatbTA (F (1, 9)=53X4, P-zO.001) and S (F (I, 9)x52.34, P-Xt.001) of tbc smtce limb. The duration of TA mcrcased and the duration of t tnumtiat the otlset stance S deamsed wiUt an iin tk velocity of initiation. For fast 01 s aivity ~-CC&S the dfset of TA activity. hencea mmntmction of tc two musclea (F (I, 9)=34.aS. P
13&pwGb$;
tbc writ vdables for the ground reactioo forces. For the fimt @ Fxl -bBlueen v&&y and rmditiats (F (2. 18)=3.59. p&OS). Tbe peaks of Fxl forallcomliticwwem a’rsilr~tkadf-pwxd velocity (rpO.05). all i&at the fmt velocityk*mepaLforobasckrcbcfsavdocitywas~gi8~lylessthntbeotha~o conditimts(P4.001 for ail sigtdfmt cuttpwianr). The slops to peal; Fxl itweased with an imtraac in tbs vebdty of i&i&m (F(I. 9)=6!I68, ILo.001). Thcrr wm en intim betweatvelocitymtdandition(F(2.18)=3.59~ pcO.05) forFeakFx2. Rak Fx? was less for gait ittiiimion (P&O01 for both ruler and obstlcle). Fa the fast velocity, the peak value fc8 oh%& ~3s signdi~tty hlgber lhnn the other two cc4twns (P-9X05 for bc& 01 and ruler). The slope ws grwter for fastest trials dtut sdf-lmwd trmls (F (I 9)=33. IO. Pd.00 I ). Them was also a signNkmt main d&t for cmtdittons (F (2, IS)= 10.36. P&.001) wbem the slope was gmter for smppmg over a l&cm otelaclc (P-=001) and steppmg over a ruler (P
The semnntstrained arthroplarty on the right side showed s Socd ali&wmentwith correct positioninn of the imdent and with wad stability The knee was tender with slight effusmn The rangeof motion was normal forfhe type of implant (Flexion - Extension I25 0 - 0) The Left knee had no effusion Anterior translation was slightly increased The pivot shift slgtt was negative The range of motion wss normal (Flexian - Extension 140- 0 - 5) Both hips and ankles were normal
Time- distance p.wameters The free gait velocity wthouf braces or cane WIP reduced to 0 56 m/s (45% norm), with a proportional reduction ofthe stride length (0.85 m, 66% notm) and the cadence (77 step /min. 66% norm) Asymmeuy of step length (right 0 46 m, I& 0 38) and simde limb stanceduration (r&t 24% of cycle, left 44% of cycle) indicatedI limpmg behaviouyof the right side _ Kmatmtic mtalvsis and dvtmmic EMG. Excessive kneeflexion wes seenduring wagbt scceptame on the right side coupled with increased dorsiflexicm st the ankle DyMmic EMG revealed a failure of sccur& timing ofthe knet smbiliing muscles No quadricepsor hamstrings activity was present doting the end of swing phsse and ewly weight acc@att=. A delayed onset of qosdriceps activity was seen ss s reaction to the buckling knee motion driven by gravity Gtt the l&l side kna flexion wss also excessive to B lesser de. No adequte compensationwlu seenfor *n emerior crudate ligament insoflicimcy Despite the ant&x laxity knee flexion wss mcressed with prolonged quadriceps activity and insuflicient hemsmngs