Gait In Children With Cerebral Palsy

ORIGINAL ARTICLE

Gait in Children With Cerebral Palsy Observer Reliability of Physician Rating Scale and Edinburgh Visual Gait Analysis Interval Testing Scale Karel 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 intraobserver reliability of the Physician Rating Scale (PRS) and the Edinburgh Visual Gait Analysis Interval Testing (GAIT) scale for use in children with cerebral palsy (CP). Both assessment scales are quantitative observational scales, evaluating gait. The study involved 24 patients ages 3 to 10 years (mean age 6.7 years) with an abnormal gait caused by CP. They were all able to walk independently with or without walking aids. Of the children 15 had spastic diplegia and 9 had spastic hemiplegia. With a minimum time interval of 6 weeks, video recordings of the gait of these 24 patients were scored twice by three independent observers using the PRS and the GAIT scale. The study showed that both the GAIT scale and the PRS had excellent intraobserver reliability but poor interobserver reliability for children with CP. In the total scores of the GAIT scale and the PRS, the three observers showed systematic differences. Consequently, the authors recommend that longitudinal assessments of a patient should be done by one observer only. Key Words: cerebral palsy, video gait assessment, gait analysis, visual gait assessment (J Pediatr Orthop 2005;25:268–272)

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bnormal gait is a common problem in children with cerebral palsy (CP). These children are at great risk of deterioration in their walking ability as they grow up. Many treatment modalities have been developed in the past decade, depending on the age of the child and the nature and severity of the restricted walking ability. Because of the importance of planning in the timing of interventions and the difficulty in predicting the outcome of different interventions, monitoring the patient, including gait analysis, before and after an intervention is essential.1–6 Instrumented gait analysis, in-

From the *Centre for Rehabilitation University Hospital, Groningen, The Netherlands; †Northern Centre for Health Care Research, University Groningen, The Netherlands; and ‡University for Professional Education, Hanzehogeschool, Groningen, The Netherlands. Study conducted at the Department of Rehabilitation, University Hospital Groningen, 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: [email protected]). Copyright Ó 2005 by Lippincott Williams & Wilkins

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cluding computerized kinematics and kinetics, electromyography, and videotaping, is increasingly used in the evaluation of gait pattern of CP patients and is considered the gold standard for gait assessment.7–9 However, because this assessment is complex, expensive, and time-consuming and is not generally available, it is impractical for routine use. In the past decade simplified methods have been developed to quantify walking in children with a spastic gait by using a standardized observation scoring system with videotaping only,10–14 but existing measures are either not easily accessed or untested. One of these instruments is the Physician Rating Scale (PRS), an observational clinical evaluation of gait originally reported by Koman et al in 199315 and modified by others.16–18 This simple scale records gait in the sagittal plane only. A more systematic and extended gait-evaluating instrument is the Edinburgh Visual Gait Analysis Interval Testing (GAIT) scale, developed by Read et al in 1998.19,20 In 2002 the GAIT scale was refined and renamed the Edinburgh Visual Gait Score.21 It was developed to give a quantitative assessment of gait where instrumented gait analysis is not available. The PRS and the GAIT scale were used for this study because, to our knowledge in 2002, a good validation study for observer reliability in CP for these instruments had not been carried out before. The aim of this study was to test the inter- and intraobserver reliability of the PRS and the GAIT scale for use in children with CP.

MATERIALS AND METHODS The study population consisted of 24 children with CP with 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 and 9 had spastic hemiplegia (right, n = 8; left, n = 1). All children had an abnormal gait caused by CP but were able to walk independently with or without walking aids. All patients were assessed in the University Hospital of Groningen, the Netherlands, between 1999 and 2001. Frontal and sagittal video recordings were used, taped on a split-screen video. The observers were three physicians in rehabilitation medicine (A.van I., C.M., J.R.); two of them were experienced in the field (C.M., J.R.). They all scored the video recordings independently. Guidelines for the PRS and the GAIT scale were provided to the observers, and they received a short training (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. J Pediatr Orthop  Volume 25, Number 3, May/June 2005

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TABLE 1. Physician Rating Scale15 Definition

Right

Crouch Severe (.20° hip, knee, ankle) Moderate (5–20° hip, knee, ankle) Mild (,5° hip, knee, ankle) None Knee Recurvatum .5° Recurvatum 0–5° Neutral (no recurvatum) Foot contact Toe Toe-heel Flat Occasional heel-toe Heel-toe Change Worse None Better

Left

0 1 2 3

0 1 2 3

0 1 2

0 1 2

0 1 2 3 4

0 1 2 3 4

21 0 1

21 0 1

GAIT scale variables are given in Table 2. It contains 17 variables of observation during gait at six anatomic levels (foot, ankle, knee, hip, pelvis, and trunk), including sagittal22 and frontal23 observations. Recordings are made using a threepoint ordinal scale: 0 (normal), 1 (moderate deviation), and 2 (marked deviation). Both sides of the patients were scored separately. Observers were recommended to use slow-motion facilities, to stop or repeat the video if necessary, and to take their time. They were instructed not to measure degrees directly from the video screen but to give their best visual estimate. For all patients, either with hemiplegia or diplegia, both sides were scored. All video recordings were scored twice using both the PRS and GAIT scale with a minimal time interval of 6 weeks to avoid any effects of memory; this also corresponds with clinical practice.

Statistical Analysis All 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 intraobserver reliability of the total scores and in the sources of

TABLE 2. Edinburgh Visual Gait Analysis Interval Testing Scale25 Movement Sagittal

2

1

0

1

2

FOOT 1 foot clearance

none

reduced

full

n.a

n.a

2 initial contact

toe

flat foot

heel

n.a

n.a

3 heel lift none early normal 4 max dorsiflexion .10 10–0–9 10–20 hind foot in stance plan plan/dor dor KNEE 7 terminal swing .30 15–30 0–15 flex flex flex 8 peak stance knee extension 9 peak knee flexion in swing HIP 11 peak hip extension in stance 12 peak hip flexion in swing PELVIS 14 pelvic rotation midstance TRUNK 16 peak sagittal position in stance TOTAL

2

1

0

1

2

FOOT 5 stance position .15 6–15 5–0–5 6–15 .15 hind foot in load valgus valgus neutral varus varus 6 foot progression .15 ir 6–15 ir 5–0–5 6–15 er .15 er angle neutral

delayed n.a 21–30 dor .30 dor .0 hyperext

n.a

.30 16–30 flex flex .80 65–80 flex flex

0–15 flex 60–64 flex

.30 16–30 flex flex .75 51–75 flex flex

15–0–15 n.a flex/ext 30–50 15–29 flex flex

,15 flex

.15 6–15 fwd fwd

5–0–5 6–15 neutral bwd

.15 bwd

.15 6–15 fwd fwd

Movement Frontal

KNEE 10 knee part all cap ir neutral progression cap ir angle mid-stance

all part cap er cap er

1–10 .10 hyperext hyperext 30–59 .30 flex flex

5–0–5 6–15 neutral bwd

n.a

.15 bwd

HIP 13 position in swing

PELVIS 15 contra lateral drop in stance TRUNK 17 max lateral shift in stance TOTAL

.15 add

5–15 add

4–0–9 10–20 add/abd abd

.20 abd

marked mod

normal

n.a

n.a

marked mod

neutral

n.a

n.a

Score 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, external rotation; 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.

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variance (child, observer, and repetition), for each total score we chose this method, not kappa statistics of the separate items. Total GAIT scale and PRS and subscores of both scales for the right and left side were taken as independent factors. For each independent factor the estimated variances were calculated. Post hoc comparison of differences between the three observers was done using the Friedman test. P , 0.05 was considered statistically significant.

RESULTS

TABLE 4. Total Scores of GAIT Scale and PRS of All Three Observers Observer 1 (AvI) Mean (sd) GAIT scale right GAIT scale left PRS right PRS left

9.1 7.8 5.5 6.1

(5) (6.8) (1.9) (2.4)

Observer 2 (CM) Mean (sd) 10.3 8.5 4.4 5.4

(5.2) (6.9) (2.1) (2.7)

Observer 3 (JR) Mean (sd) 13.5 11.1 4.4 5.5

(6.7) (9.4) (2.2) (3.0)

P Values* ,0.001 0.003 ,0.001 0.004

*Friedman test.

Two subjects were excluded from analysis: in one patient the frontal video imaging failed; in the other the sagittal one failed. The 22 patients who remained for the reliability analysis were assessed at random by the observers. On the right as well as the left side, both observer and child proved to be significant sources of variance in the GAIT scale and in the PRS. Repetition was not a significant source of variance (Table 3); in most cases it even approached P = 1. In fact, both the GAIT scale and the PRS showed excellent intraobserver reliability. The interobserver reliability of both assessment scales, the GAIT scale and the PRS, was considered poor. Post hoc analysis showed considerable differences between the three observers. The mean (SD) scores for each observer are given in Table 4; box plots are shown in Figure 1. In Table 5, the GAIT scale is subdivided into seven subscales: the first five subscales correspond to the different anatomic levels, and the last two correspond to the different directions of observing gait (frontal and sagittal views). Only with the ankle subscale on the left side did the observer appear not to be a significant factor in the source of variation. In all other GAIT subscales the observer appeared to be a significant source of variance.

relevant because the differences in the outcome of 1.1 in the PRS and 4.4 in the GAIT scale (Table 4) for the same person should be clearly visible when observing gait. Besides, if the same difference in the PRS and GAIT scale could be measured as a result of an intervention in CP patients, it would be considered a clinically relevant difference. The total scores of the GAIT scale and the PRS, between the three observers, also showed systematic differences. The reason is not clear. Probably, angle estimation of the different anatomic levels from a video screen was done systematically different between the observers. Although the PRS is used often in research, we only found one study in the literature23 that reported interobserver reliability; we found no study that reported intraobserver reliability data. Corry et al23 studied the interobserver reliability of the PRS in a group of 20 CP children with a dynamic component in spastic equinus, treated by serial casting or

DISCUSSION The differences in mean total scores of the three observers were considerable and were considered clinically TABLE 3. Sources of Variation in the GAIT Scale and PRS GAIT scale right Observer Repetition Child GAIT scale left Observer Repetition Child PRS right Observer Repetition Child PRS left Observer Repetition Child

SS

MS

P Value

Variance Estimates

240 0.2 3904

120 0.2 186

,0.001 0.846 ,0.001

2.6 0 30.1

162 0.1 7571

81 0.1 361

,0.001 0.941 ,0.001

1.7 0 59.2

21 0.4 509

10.5 0.4 24

,0.001 0.395 ,0.001

0.2 0 4.0

14.6 0 872

7.3 0 42

,0.001 1 ,0.001

0.1 0 6.8

SS, sum of squares; MS, mean square.

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FIGURE 1. Box plots of GAIT scale and PRS. The ends of the rectangle reflect the interquartile range; the horizontal line in the rectangle reflects the median value; the whiskers indicate the minimum and maximum values. q 2005 Lippincott Williams & Wilkins

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TABLE 5. Observer Variance of Subscores of the GAIT Scale

GAIT subscore Ankle (6) Right Left Knee (4) Right Left Hip (3) Right Left Pelvis (2) Right Left Trunk (2) Right Left Frontal (6) Right Left Sagittal (11) Right Left

Variance Estimates

SS

MS

P Value

13.2 3.0

6.6 1.5

0.002 0.254

0.1 0

17.5 16.1

8.7 8.0

,0.001 ,0.001

0.2 0.2

13.5 9.5

6.7 4.7

,0.001 ,0.001

0.1 0

13.9 14.7

6.9 7.3

,0.001 ,0.001

0.1 0.2

11.2 8.4

5.6 4.2

,0.001 ,0.001

0.1 0.1

68.0 53.8

34.0 26.9

,0.001 ,0.001

0.7 0.6

109.1 43.7

54.6 21.8

,0.001 ,0.001

1.2 0.4

SS, 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 in crouch assessment and in the overall impression in gait change in 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 discriminating difference. Unfortunately, no information was given about the interobserver variation of the total PRS. Moreover, only two observers were used in Corry et al’s study. Post hoc analysis of the results of our two most experienced observers (observers 2 and 3) showed no differences between these observers for the PRS. In other words, the information concerning the interobserver reliability for this scale may have been influenced by the number of observers used in the study and the degree of experience in observing gait. This may explain the different results between the Corry et al study, which included only two observers, and ours, in which three observers took part. In 1999 Read et al20 presented data about the inter- and intraobserver reliability of the GAIT scale in a study population of four patients with CP and one ‘‘normal’’ person. Because of the very small group, these data are of limited value, however. In 2003 Read et al24 reported a good intra- and interobserver reliability for the Edinburgh Visual Gait Score system. They used kappa statistics for their calculations; we, however, were more interested in the source of variance. In our population the child and the observer proved to be a significant factor in this respect for the source of variation. We are aware of some limitations in our study. First, we used a fixed video camera framing for recording the sagittal q 2005 Lippincott Williams & Wilkins

Observer Reliability of Two Gait Scales

gait. This means that only a small part of the gait is available for evaluation of gait in the sagittal direction. We tried to approach daily practice as much as possible. With the technique used, it is possible to reproduce the study in any consulting room in a hospital. Second, the children did not wear standardized clothing at the time of the measurement. In some video recordings, children wore a T-shirt or sweater, which might have influenced the ability to estimate the amount of flexion and extension in the hip, pelvis, and trunk in the GAIT scale. To exclude such possible failures we calculated the interobserver reliability of each anatomic level itself and the subscores of the frontal and sagittal plane. Our hypothesis was that the reliability of the assessments of the foot, ankle, and knee level would have been better compared with the hip, pelvis, and trunk level (see Table 5). It appeared that only the subscore of the left ankle was not a significant factor for the source of variation. Of the 22 left sides we tested, 8 sides were not affected sides and were scored almost equally by all observers, compared with only 1 unaffected right side. This might explain the difference in interobserver reliability between the subscores at ankle level, respectively, on the right and left side. All other subscores of the GAIT scale, including the frontal and sagittal plane, showed poor interobserver reliability data. Post hoc analysis of the more affected side only of all patients showed similar results (data not presented). Noonan et al6 reported a interobserver reliability study of patients with CP evaluated with instrumented gait analysis at four different centers. The results were poor. In 2003 editorials in the Journal of Pediatric Orthopaedics, Gage22 and Wright25 made contrasting comments about interobserver variability in gait analysis. They agreed that we need a careful assessment of the analysis of the pathology of the CP child. The importance of instrumented gait analysis is clear for this assessment, but it is only one of the methods of examination and should be seen as complementary to the generation of the problem list, the physical examination, and radiographs. Further research into the different sources that contribute to the variability in gait analysis will be necessary. To evaluate the gait of a CP patient in the consulting room by means of video recording is very useful. To score gait with PRS took about 5 minutes; the GAIT scale took 25 minutes per patient on average. We also recommend that longitudinal assessments of a patient should be done by the same observer. REFERENCES 1. 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 decisionmaking in 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 of children with walking difficulties. Disabil Rehabil. 2000;6:275–280. 5. Molenaers G, Desloovere K, Eyssen M, et al. Botulinum toxin A treatment of cerebral palsy: an integrated approach. Eur J Neurol. 1999;6:S1–S7. 6. Noonan KJ, Halliday S, Brown R, et al. Interobserver variability of gait analysis on patients with cerebral palsy. J Pediatr Orthop. 2003;23:279– 287. 7. Drouin LM, Malouin F, Richards CL, et al. Correlation between the gross motor function measure and gait spatiotemporal measures in children with neurological impairments. Dev Med Child Neurol. 1996;38:1007–1019.

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8. Kirkpatrick M, Wytch R, Cole G, et al. Is the objective assessment of cerebral palsy gait reproducible? J Pediatr Orthop. 1994;14:705–708. 9. Sutherland DH, Kaufman KR, Wyatt MP, et al. Injections of botulinum A toxin into the gastrocnemius muscle of patients with cerebral palsy: a 3-dimensional motion analysis study. Gait Posture. 1996;4:269–279. 10. Boyd NR, Graham HK. Objective measurement of clinical findings in the use of botulinum toxin type A for the management of children with cerebral palsy. Eur J Neurol. 1999;6:523–535. 11. Boyd NR, Graham JEA, Nattrass GR, et al. Medium term outcomeresponse characterisation and risk factor analysis of Botulinum toxin type A in the management of spasticity in children with cerebral palsy. Eur J Neurol. 1999;6:S37–S45. 12. Eastlack ME, Arvidson J, Snyder-Mackler L, et al. Interrater reliability of videotaped observational gait-analysis assessments. Phys Ther. 1991;71: 465–472. 13. Flett PJ, Stern LM, Waddy H, et al. Botulinum toxin A versus fixed cast stretching for dynamic calf tightness in cerebral palsy. J Paediatr Child Health. 1999;35:71–77. 14. Ubhi T, Bhakta BB, Ives HL, et al. Randomised double-blind placebocontrolled trial of the effect of botulinum toxin on walking in cerebral palsy. Arch Dis Child. 2000;83:481–487. 15. Koman LA, Mooney JF, Smith B, et al. Management of cerebral palsy with botulinum-A toxin: preliminary investigation. J Pediatr Orthop. 1993;4: 489–495.

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16. Chutorion AM, Root L. Management of spasticity in children with botulinum-A toxin. Int Pediatr. 1994;9:35–42. 17. Denislic M, Meh D. Botulinum toxin in the treatment of cerebral palsy. Neuropediatrics. 1995;26:249–252. 18. Graham HK, Aoki KR, Autti-Ra¨mo¨, et al. Recommendations for the use of botulinum toxin type A in the management of cerebral palsy. Gait Posture. 2000;11:67–79. 19. Kerr AM, Hazlewood ME, Linden van der Ml, et al. The Edinburgh Visual Gait Score as an outcome measure after surgical intervention cerebral palsy. Gait Posture. 2002;16:S116. 20. Read HS, Hillmann SJ, Hazlewood ME, et al. The Edinburgh Visual Gait Analysis Interval Testing (GAIT) scale. Gait Posture. 1999;10:63. 21. Read HS, Hazlewood ME, Hillmann SJ, et al. A visual gait analysis score for use in cerebral palsy: the Edinburgh Visual Gait Score. Gait Posture. 2002;16:S115–S116. 22. Gage JR. Con: interobserver variability of gait analysis [editorial]. J Pediatr Orthop. 2003;23:290–291. 23. Corry IS, Graham HK. Botulinum toxin A compared with stretching casts in the treatment of spastic equines: a randomised prospective trial. J Pediatr Orthop. 1998;18:304–311. 24. Read HS, Hazlewood ME, Hillman SJ, et al. Edinburgh Visual Gait Score. J Pediatr Orthop. 2003;23:296–301. 25. Wright JG. Pro: interobserver variability of gait analysis [editorial]. J Pediatr Orthop. 2003;23:288–289.

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