Gait in Children With Cerebral Palsy - share

ORIGINAL ARTICLEGait in Children With Cerebral PalsyObserver Reliability of Physician Rating Scale and EdinburghVisual Gait Analysis Interval Testing ScaleKarel G. B. Maathuis, MD, PhD,*† Cees P. van der Schans, PhD,‡ Andries van Iperen, MD,*Hans S. Rietman, MD,*† and Jan H. B. Geertzen, MD, PhD*†Abstract: The aim of this study was to test the inter- and intraobserverreliability of the Physician Rating Scale (PRS) and theEdinburgh Visual Gait Analysis Interval Testing (GAIT) scale for usein children with cerebral palsy (CP). Both assessment scales arequantitative observational scales, evaluating gait. The study involved24 patients ages 3 to 10 years (mean age 6.7 years) with an abnormalgait caused by CP. They were all able to walk independently with orwithout walking aids. Of the children 15 had spastic diplegia and 9had spastic hemiplegia. With a minimum time interval of 6 weeks,video recordings of the gait of these 24 patients were scored twice bythree independent observers using the PRS and the GAIT scale. Thestudy showed that both the GAIT scale and the PRS had excellentintraobserver reliability but poor interobserver reliability for childrenwith CP. In the total scores of the GAIT scale and the PRS, the threeobservers showed systematic differences. Consequently, the authorsrecommend that longitudinal assessments of a patient should be doneby one observer only.Key Words: cerebral palsy, video gait assessment, gait analysis, visualgait assessment(J Pediatr Orthop 2005;25:268–272)From the *Centre for Rehabilitation University Hospital, Groningen, TheNetherlands; †Northern Centre for Health Care Research, UniversityGroningen, The Netherlands; and ‡University for Professional Education,Hanzehogeschool, Groningen, The Netherlands.Study conducted at the Department of Rehabilitation, University HospitalGroningen, Groningen, The Netherlands.None of the authors received financial support for this study.Reprints: Karel G. B. Maathuis, MD, PhD, Department of Rehabilitation,University Hospital Groningen, Hanzeplein 1, P. O. Box 30.001, 9700 RB,Groningen, the Netherlands (e-mail: c.g.b.maathuis@rev.umcg.nl).Copyright Ó 2005 by Lippincott Williams & WilkinsAbnormal gait is a common problem in children with cerebralpalsy (CP). These children are at great risk of deteriorationin their walking ability as they grow up. Manytreatment modalities have been developed in the past decade,depending on the age of the child and the nature and severity ofthe restricted walking ability. Because of the importance ofplanning in the timing of interventions and the difficulty inpredicting the outcome of different interventions, monitoringthe patient, including gait analysis, before and after anintervention is essential. 1–6 Instrumented gait analysis, includingcomputerized kinematics and kinetics, electromyography,and videotaping, is increasingly used in the evaluationof gait pattern of CP patients and is considered the goldstandard for gait assessment. 7–9 However, because thisassessment is complex, expensive, and time-consuming andis not generally available, it is impractical for routine use. Inthe past decade simplified methods have been developed toquantify walking in children with a spastic gait by usinga standardized observation scoring system with videotapingonly, 10–14 but existing measures are either not easily accessedor untested.One of these instruments is the Physician Rating Scale(PRS), an observational clinical evaluation of gait originallyreported by Koman et al in 1993 15 and modified by others. 16–18This simple scale records gait in the sagittal plane only. A moresystematic and extended gait-evaluating instrument is theEdinburgh Visual Gait Analysis Interval Testing (GAIT) scale,developed by Read et al in 1998. 19,20 In 2002 the GAIT scalewas refined and renamed the Edinburgh Visual Gait Score. 21 Itwas developed to give a quantitative assessment of gait whereinstrumented gait analysis is not available. The PRS and theGAIT scale were used for this study because, to our knowledgein 2002, a good validation study for observer reliability in CPfor these instruments had not been carried out before. The aimof this study was to test the inter- and intraobserver reliabilityof the PRS and the GAIT scale for use in children with CP.MATERIALS AND METHODSThe study population consisted of 24 children with CPwith a mean age of 6.7 years (range 3.3–9.9 years); 18 (75%)of them were boys. Of the children, 15 had spastic diplegia and9 had spastic hemiplegia (right, n = 8; left, n = 1). All childrenhad an abnormal gait caused by CP but were able to walkindependently with or without walking aids. All patients wereassessed in the University Hospital of Groningen, theNetherlands, between 1999 and 2001. Frontal and sagittalvideo recordings were used, taped on a split-screen video. Theobservers were three physicians in rehabilitation medicine(A.van I., C.M., J.R.); two of them were experienced in thefield (C.M., J.R.). They all scored the video recordingsindependently. Guidelines for the PRS and the GAIT scalewere provided to the observers, and they received a shorttraining (1 hour) in scoring using the PRS and GAIT scale.PRS variables are given in Table 1. The last subscale (change)was not used for the purpose of this cross-sectional study.268 J Pediatr Orthop Volume 25, Number 3, May/June 2005

J Pediatr Orthop Volume 25, Number 3, May/June 2005Observer Reliability of Two Gait ScalesTABLE 1. Physician Rating Scale 15Definition Right LeftCrouchSevere (.20° hip, knee, ankle) 0 0Moderate (5–20° hip, knee, ankle) 1 1Mild (,5° hip, knee, ankle) 2 2None 3 3KneeRecurvatum .5° 0 0Recurvatum 0–5° 1 1Neutral (no recurvatum) 2 2Foot contactToe 0 0Toe-heel 1 1Flat 2 2Occasional heel-toe 3 3Heel-toe 4 4ChangeWorse 21 21None 0 0Better 1 1GAIT scale variables are given in Table 2. It contains 17variables of observation during gait at six anatomic levels(foot, ankle, knee, hip, pelvis, and trunk), including sagittal 22and frontal 23 observations. Recordings are made using a threepointordinal scale: 0 (normal), 1 (moderate deviation), and 2(marked deviation). Both sides of the patients were scoredseparately.Observers were recommended to use slow-motion facilities,to stop or repeat the video if necessary, and to take theirtime. They were instructed not to measure degrees directlyfrom the video screen but to give their best visual estimate. Forall patients, either with hemiplegia or diplegia, both sides werescored. All video recordings were scored twice using both thePRS and GAIT scale with a minimal time interval of 6 weeksto avoid any effects of memory; this also corresponds withclinical practice.Statistical AnalysisAll statistical analyses were performed using SPSS 11.0.Reliability analysis was done using analysis of variance(ANOVA). As we were interested in the inter- and intraobserverreliability of the total scores and in the sources ofTABLE 2. Edinburgh Visual Gait Analysis Interval Testing Scale 25MovementSagittal 2 1 0 1 2FOOTMovementFrontal 2 1 0 1 2FOOT1 foot clearance none reduced full n.a n.a 5 stance positionhind foot in load.15valgus6–15valgus5–0–5neutral6–15varus.15varus2 initial contact toe flat foot heel n.a n.a 6 foot progression .15 ir 6–15 ir 5–0–5 6–15 er .15 erangleneutral3 heel lift none early normal delayed n.a4 max dorsiflexionhind foot in stance.10plan10–0–9plan/dor10–20dor21–30 dor .30dorKNEEKNEE7 terminal swing .30flex15–30flex0–15flex.0hyperextn.apartcap irall cap ir neutral allcap erpartcap er8 peak stance kneeextension.30flex16–30flex9 peak knee flexion .80 65–80in swingflex flexHIP11 peak hip .30 16–30extension in stance flex flex12 peak hip flexion .75 51–75in swingflex flexPELVIS14 pelvic rotation .15 6–15midstancefwd fwdTRUNK16 peak sagittalposition in stanceTOTAL.15fwd6–15fwd10 kneeprogressionangle mid-stance0–15flex1–10hyperext.10hyperext60–64 30–59 .30flex flex flexHIP15–0–15 n.a n.a 13 positionflex/extin swing30–50 15–29 ,15flex flex flexPELVIS5–0–5 6–15neutral bwd5–0–5 6–15neutral bwd.15bwd.15bwd.15add5–15add4–0–9 10–20add/abd abd.20abd15 contralateral dropin stance marked mod normal n.a n.aTRUNK17 max lateralshift in stance marked mod neutral n.a n.aTOTALScore 2 means marked deviation, score 1 is moderate deviation, score 0 is normal range.n.a, not available; plan, plantarflexion; dor, dorsiflexion; flex, flexion; hyperext, hyperextension; fwd, forward rotation; bwd, backward rotation; ir, internal rotation; er, externalrotation; part cap, only a part of the knee cap is visible; all cap, whole knee cap is visible; add, adduction; abd, abduction; lat, lateral; mod, moderate.q 2005 Lippincott Williams & Wilkins 269

Maathuis et al J Pediatr Orthop Volume 25, Number 3, May/June 2005variance (child, observer, and repetition), for each total scorewe chose this method, not kappa statistics of the separateitems. Total GAIT scale and PRS and subscores of both scalesfor the right and left side were taken as independent factors.For each independent factor the estimated variances werecalculated. Post hoc comparison of differences between thethree observers was done using the Friedman test. P , 0.05was considered statistically significant.RESULTSTwo subjects were excluded from analysis: in one patientthe frontal video imaging failed; in the other the sagittal onefailed. The 22 patients who remained for the reliabilityanalysis were assessed at random by the observers. On theright as well as the left side, both observer and child proved tobe significant sources of variance in the GAIT scale and in thePRS. Repetition was not a significant source of variance (Table3); in most cases it even approached P = 1. In fact, both theGAIT scale and the PRS showed excellent intraobserverreliability. The interobserver reliability of both assessmentscales, the GAIT scale and the PRS, was considered poor.Post hoc analysis showed considerable differencesbetween the three observers. The mean (SD) scores for eachobserver are given in Table 4; box plots are shown in Figure 1.In Table 5, the GAIT scale is subdivided into sevensubscales: the first five subscales correspond to the differentanatomic levels, and the last two correspond to the differentdirections of observing gait (frontal and sagittal views). Onlywith the ankle subscale on the left side did the observer appearnot to be a significant factor in the source of variation. In allother GAIT subscales the observer appeared to be a significantsource of variance.TABLE 4. Total Scores of GAIT Scale and PRS of All ThreeObserversObserver 1(AvI)Mean (sd)Observer 2(CM)Mean (sd)Observer 3(JR)Mean (sd)P Values*GAIT scale right 9.1 (5) 10.3 (5.2) 13.5 (6.7) ,0.001GAIT scale left 7.8 (6.8) 8.5 (6.9) 11.1 (9.4) 0.003PRS right 5.5 (1.9) 4.4 (2.1) 4.4 (2.2) ,0.001PRS left 6.1 (2.4) 5.4 (2.7) 5.5 (3.0) 0.004*Friedman test.relevant because the differences in the outcome of 1.1 in thePRS and 4.4 in the GAIT scale (Table 4) for the same personshould be clearly visible when observing gait. Besides, if thesame difference in the PRS and GAIT scale could be measuredas a result of an intervention in CP patients, it would beconsidered a clinically relevant difference.The total scores of the GAIT scale and the PRS, betweenthe three observers, also showed systematic differences. Thereason is not clear. Probably, angle estimation of the differentanatomic levels from a video screen was done systematicallydifferent between the observers.Although the PRS is used often in research, we onlyfound one study in the literature 23 that reported interobserverreliability; we found no study that reported intraobserverreliability data. Corry et al 23 studied the interobserver reliabilityof the PRS in a group of 20 CP children with a dynamiccomponent in spastic equinus, treated by serial casting orDISCUSSIONThe differences in mean total scores of the threeobservers were considerable and were considered clinicallyTABLE 3. Sources of Variation in the GAIT Scale and PRSSS MS P Value Variance EstimatesGAIT scale rightObserver 240 120 ,0.001 2.6Repetition 0.2 0.2 0.846 0Child 3904 186 ,0.001 30.1GAIT scale leftObserver 162 81 ,0.001 1.7Repetition 0.1 0.1 0.941 0Child 7571 361 ,0.001 59.2PRS rightObserver 21 10.5 ,0.001 0.2Repetition 0.4 0.4 0.395 0Child 509 24 ,0.001 4.0PRS leftObserver 14.6 7.3 ,0.001 0.1Repetition 0 0 1 0Child 872 42 ,0.001 6.8SS, sum of squares; MS, mean square.FIGURE 1. Box plots of GAIT scale and PRS. The ends of therectangle reflect the interquartile range; the horizontal line inthe rectangle reflects the median value; the whiskers indicatethe minimum and maximum values.270 q 2005 Lippincott Williams & Wilkins

J Pediatr Orthop Volume 25, Number 3, May/June 2005Observer Reliability of Two Gait ScalesTABLE 5. Observer Variance of Subscores of the GAIT ScaleSS MS P ValueVarianceEstimatesGAIT subscoreAnkle (6)Right 13.2 6.6 0.002 0.1Left 3.0 1.5 0.254 0Knee (4)Right 17.5 8.7 ,0.001 0.2Left 16.1 8.0 ,0.001 0.2Hip (3)Right 13.5 6.7 ,0.001 0.1Left 9.5 4.7 ,0.001 0Pelvis (2)Right 13.9 6.9 ,0.001 0.1Left 14.7 7.3 ,0.001 0.2Trunk (2)Right 11.2 5.6 ,0.001 0.1Left 8.4 4.2 ,0.001 0.1Frontal (6)Right 68.0 34.0 ,0.001 0.7Left 53.8 26.9 ,0.001 0.6Sagittal (11)Right 109.1 54.6 ,0.001 1.2Left 43.7 21.8 ,0.001 0.4SS, sum of squares; MS, mean square.Values in parentheses represent the number of items on the GAIT scale.Botulinum toxin A. They found a moderate agreement incrouch assessment and in the overall impression in gait changein the affected side using the PRS (weighted kappa test 0.55–0.67). The agreement in the knee assessment was poor. The‘‘change’’ section was added to provide a more discriminatingdifference. Unfortunately, no information was given about theinterobserver variation of the total PRS. Moreover, only twoobservers were used in Corry et al’s study.Post hoc analysis of the results of our two mostexperienced observers (observers 2 and 3) showed no differencesbetween these observers for the PRS. In other words,the information concerning the interobserver reliability for thisscale may have been influenced by the number of observersused in the study and the degree of experience in observinggait. This may explain the different results between the Corryet al study, which included only two observers, and ours, inwhich three observers took part.In 1999 Read et al 20 presented data about the inter- andintraobserver reliability of the GAIT scale in a studypopulation of four patients with CP and one ‘‘normal’’ person.Because of the very small group, these data are of limitedvalue, however. In 2003 Read et al 24 reported a good intra- andinterobserver reliability for the Edinburgh Visual Gait Scoresystem. They used kappa statistics for their calculations; we,however, were more interested in the source of variance. In ourpopulation the child and the observer proved to be a significantfactor in this respect for the source of variation.We are aware of some limitations in our study. First, weused a fixed video camera framing for recording the sagittalgait. This means that only a small part of the gait is availablefor evaluation of gait in the sagittal direction. We tried toapproach daily practice as much as possible. With the techniqueused, it is possible to reproduce the study in any consultingroom in a hospital. Second, the children did not wearstandardized clothing at the time of the measurement. In somevideo recordings, children wore a T-shirt or sweater, whichmight have influenced the ability to estimate the amount offlexion and extension in the hip, pelvis, and trunk in the GAITscale. To exclude such possible failures we calculated theinterobserver reliability of each anatomic level itself and thesubscores of the frontal and sagittal plane. Our hypothesis wasthat the reliability of the assessments of the foot, ankle, andknee level would have been better compared with the hip,pelvis, and trunk level (see Table 5). It appeared that onlythe subscore of the left ankle was not a significant factor forthe source of variation. Of the 22 left sides we tested, 8 sideswere not affected sides and were scored almost equally by allobservers, compared with only 1 unaffected right side. Thismight explain the difference in interobserver reliability betweenthe subscores at ankle level, respectively, on the rightand left side. All other subscores of the GAIT scale, includingthe frontal and sagittal plane, showed poor interobserver reliabilitydata. Post hoc analysis of the more affected side only ofall patients showed similar results (data not presented).Noonan et al 6 reported a interobserver reliability studyof patients with CP evaluated with instrumented gait analysisat four different centers. The results were poor.In 2003 editorials in the Journal of Pediatric Orthopaedics,Gage22 and Wright 25 made contrasting comments aboutinterobserver variability in gait analysis. They agreed that weneed a careful assessment of the analysis of the pathology ofthe CP child. The importance of instrumented gait analysis isclear for this assessment, but it is only one of the methods ofexamination and should be seen as complementary to thegeneration of the problem list, the physical examination, andradiographs. Further research into the different sources thatcontribute to the variability in gait analysis will be necessary.To evaluate the gait of a CP patient in the consulting room bymeans of video recording is very useful. To score gait withPRS took about 5 minutes; the GAIT scale took 25 minutes perpatient on average. We also recommend that longitudinalassessments of a patient should be done by the same observer.REFERENCES1. Calderon-Gonzalez R, Calderon-Sepulveda R, Rincon-Reyes M, et al.Botulinum toxin A in management of cerebral palsy. Pediatr Neurol.1994;4:284–288.2. Cook RE, Schneider I, Hazlewood ME, et al. Gait analysis alters decisionmakingin cerebral palsy. J Pediatr Orthop. 2003;23:292–295.3. Gage JR. The role of gait analysis in the treatment of cerebral palsy[editorial]. J Pediatr Orthop. 1994;14:701–702.4. Hailey D, Tomie J. An assessment of gait analysis in the rehabilitation ofchildren with walking difficulties. Disabil Rehabil. 2000;6:275–280.5. 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