Edited by P Larking ACC Date report completed 18 January 2010

Transcription

1 Brief report Hart Walker Reviewer Adrian Purins AHTA Edited by P Larking ACC Date report completed 18 January Background Cerebral Palsy (CP) is a group of disorders that arise from brain damage sustained during development, either in utero or during early infancy. Worldwide the incidence of CP is approximately 1 in 400 births and increases in incidence with degree of prematurity, with CP being more predominant in low birth weight infants. CP is characterised by lack of movement control and/or poor posture. The primary disease is non progressive but secondary and associated conditions can be progressive and may increase disability (Murphy 2009; Turk 2009). Secondary conditions are largely related to changes in joint alignment due to the disordered muscle tone, control and balance in CP, which then leads to soft tissue contracture and deformity, and also bony deformity (commonly hips, spine and feet). In all but the mildest cases, CP usually manifests in infancy although a definitive diagnosis may only be able to be made in the second year of life. Symptoms of CP include poor motor control; lack of posture control; difficulties in cognition, perception or sensation; seizures, and behavioural disturbances. The condition is most likely a spectrum of disorders and as such is often heterogeneous in nature. Disability associated with CP is also highly variable depending on the regions of the body affected, with the disorder affecting all limbs in some individuals and only legs or one side of the body in other individuals. The most common impairments are spasticity or abnormal muscle control, with other common impairments being involuntary movements, poor muscle coordination, and diminished muscle tone. An individual may have a single or multiple impairments. Due to the heterogeneity of CP, classifying the severity of the disorder has only had Accident Compensation Corporation Page 1

2 limited success. No cure exists for CP and hence treatments for CP are aimed at improving or maintaining function for the affected individual. Current treatments for CP include physiotherapy, occupational therapy, speech pathology, psychology, and social work (AIHW 2006). Orthotic, medical and surgical interventions are also important, for example medications and interventions for spasticity, and surgical interventions for spasticity and secondary deformity. Some of these treatments as well as aiming at improving or maintaining function, are also aimed at reducing secondary complications. There is a variable evidence base for these interventions. 2. Health Technology The Hart walker is a series of extensible orthotic devices designed to aid the mobility of and encourage a normal gait pattern in CP affected and other mobility impaired children. The device was designed by David Hart, an English medical engineer and is a customised and adjustable orthotic walking support, allowing disabled children to walk hands free (David Hart Clinic 2008). The current model, the Hart Walker Mk II device, is shown in Figure 1. The device consists of over 1,000 parts and the primary sub systems are braces for the chest, pelvis and limbs; movable joints at the hips, knees and ankles; and a four wheeled base to allow supported, controlled, and hands free walking. The device is adjustable as the child grows. The minimum hip to foot sole measurement required to use the Hart Walker is 390 mm and the maximum accommodated hip to foot sole measurement is 860 mm. This equates to an approximate age range of 3 to 12 years. To date, no larger size walkers exist due to the prohibitive wheel base size required to support taller individuals. Additional base configurations are available if the child progresses enough to be able to use them. These bases can be supported by 2 or 3 wheels. Additionally, if the ability of the child allows the base unit can be completely removed leaving only the braces to support ambulation (David Hart Clinic 2008). Two videos of Hart Walkers in use can be seen here and here. Accident Compensation Corporation Page 2

3 Figure 1 Hart Walker Mk II in 4 wheel and 2 wheel configurations (Ortho Proactive 2009) 3. Investigation Several databases were searched for publications on the Hart Walker EMBASE An Embase.com (EMBASE and MEDLINE databases) search was conducted with the following search algorithm: 'hart walker' OR 'hart orthosis' OR 'hart walking aid' No time frame limit was selected for this search which identified two relevant studies Cochrane Library A search of the Cochrane Library was conducted with the following search terms: hart walker or hart orthosis or hart walking aid The time frame was not limited for this search. No relevant publications were identified. Accident Compensation Corporation Page 3

4 3.3. Included studies Two studies, a cohort and a case series, were identified and included in this brief that investigated the use of the Hart Walker in CP children. No randomised controlled trials were identified. Table 1 Literature search results Publication type Number of publications Cohort 1 Case reports/series 1 Case control studies 0 Meeting reports 0 Health technology assessments 0 Narrative reviews 0 Systematic reviews 0 Randomised controlled trials 0 4. Results 4.1. FDA Approval No documents were found related to the Hart Walker on the FDA database Clinical trials of the Hart Walker A search at Clinicaltrials.gov did not find any clinical trials involving the Hart Walker. A similar search was performed at and did not find any clinical trials of this device within Australia or New Zealand Effectiveness Two relevant studies investigated the effectiveness of the Hart Walker in populations of CP affected children. The cohort study investigated the effect of stepping, using a Hart Walker, versus passive standing, as techniques to reduce secondary conditions including constipation and loss of bone strength. The subjects were 22 children severely affected by CP. The study had two groups of 11 subjects in a non-crossover design 1. The first group used the Hart Walker and the second control group were treated with passive standing only. The results showed a significant difference 2 between the Hart Walker treated subjects and the controls with respect to 1 The study was not reported as being randomised. 2 Magnitude not reported. Accident Compensation Corporation Page 4

5 constipation, with walker treated subjects having improved bowel function (p = 0.02). Bone density did not differ between the two groups as determined by quantitative ultrasound (p = 0.12) (Eisenberg et al 2009). The second study was a three year longitudinal case series (Wright & Jutai 2006). Twenty children, aged between 4-12 years, (average age at 36 months follow-up was 10.7 years) were tested at baseline and after three years. The primary outcome was the assessment of ambulatory ability using the following tools administered by physical therapists blinded to baseline results: Gross Motor Function Measure (GMFM) 3 Stand and Walk/Run/Jump Dimensions, Directional Mobility Assessment (DMA) 4, a 30 metre timed walk test and a Quality of Gait assessment 5. The functional ability of the children was assessed by parent interview 6 and a parent satisfaction questionnaire. One child dropped out at 13 months due to outgrowing the device. At two years, 19 of the 20 children continued to use the device, however at three years follow-up this number had reduced to 13. Six of the seven children who discontinued use of the device at three years were over 12-years of age and had outgrown the device. Both first and second generation Hart Walkers were used in this study, with some subjects upgrading devices during the course of the study. Mean baseline values for any of the outcome measures were not reported for the 12 children who completed follow-up. Outcome measures for ambulatory abilities are summarised in Table 2. There was no clinically important improvement (> 3 percentage points) in the mean scores of GMFM Stand or Walk Dimensions from 12 to 36 months (p>0.16) for the 12 children who completed the 3-year follow-up. However, both of these measures at 36 months are characterised by large standard deviations. A clinically significant improvement was observed for mean DMA scores, increasing from 12.0 to 27.8 per cent (p=0.02), with the largest gain occurring between 24 and 36 months. Again these scores are characterised by high standard deviations indicating substantial variability in the data. There was no statistically significant difference in the time taken to walk 30 metres at any of the follow-up points ( p>0.4). The subjective Quality of Gait results were inconclusive. 3 The GMFM is an internationally accepted measure with demonstrated psychometric strength for motor function impaired children such as those with CP. The GMFM is usually performed unassisted by orthoses, however provision is made in the assessment for the evaluation of the Stand and Walk Dimensions using assistive technology. 4 The Directional Mobility Assessment is a non-validated tool, however scores correlated with GMFM scores, therefore DMA was deemed reliable. DMA assesses the child s skill at manoeuvring around a variety of obstacles, with each item rated out of 5 points. The sum of the item s tested is then expressed as a percentage. 5 A non-validated subjective tool developed for the purpose of this study by physical therapists. 6 Parents completed the validated Paediatric Evaluation of Disability Inventory evaluating functional skills and caregiver assistance. Accident Compensation Corporation Page 5

6 Table 2 GMFM stand (%) 12-months Ambulatory abilities outcome results Mean ± SD 18.4 ± ± ± 11.4 GMFM walk (%) 12-months DMA (%) 12-months Timed wa lk (seconds) 12-months 11.3 ± ± ± ± ± ± ± ± ± The Paediatric Evaluation of Disability Inventory (PEDI) questionnaire was only completed by less than 50 per cent of the children in the initial sample and therefore it was only possible to report on results from 24 to 36 months (Table 3). No significant improvements in any of the domains for functional skills were reported from 24 to 36 months. For the PEDI care assistance domains, there was no significant improvement (>2.0 points) on the mobility scale (p=0.79), however there was a significant improvement in the social function domain (a gain of 6.5 points, p=0.04). An increase of 4.0 points in the self care domain was also noted, however this increase was not significant (p=0.52). This may be due to the low numbers of children assessed but as noted in the ambulatory results, results for this domain had large standard deviations. Table 3 Paediatric Evaluation of Disability Inventory results Scores out of 100 Mean ± SD PEDI FS self care 42.9 ± ± 6.4 PEDI FS mobility 40.8 ± ± 5.6 PEDI FS social function 52.9 ± ± 10.8 PEDI CA self care 28.9 ± ± 16.5 PE DI CA mobility 27.1 ± ± 9.1 PE DI CA social function 52.8 ± ± 15.6 FS = functional skills CA = care assistance Accident Compensation Corporation Page 6

7 Parental satisfaction was measured using visual analogue scales 0-10, and although not explicitly stated it has been assumed that 10 represents total satisfaction and zero not satisfied at all. Again, baseline results were not reported. Results are summarised in Figure 2. Parents rated the overall clinical utility of the device as 8.2 out of 10. Although limitations were noted including the upper limit of child size able to use the device, all parents indicated that they thought the device was useful. Parents felt that improvements in mobility and improvements in psychosocial areas made even limited use of the device worthwhile. Figure 2 Results of the parental satisfaction questionnaire (Wright & Jutai 2006) Both studies identified that investigated the use of the Hart Walker in children with CP reported favourable results Safety Although the study by Eisenberg et al (2009) recorded adverse events none were reported. Three children in the Wright and Jutai (2006) study had surgical interventions related to CP including hip adductor and hamstring release procedures (n=2) and Botulinum injections (n=1). However, these interventions were unrelated to the use of the Hart Walker and the subjects, once they recovered, continued to use the Hart Walkers. Several parents reported incidents of tall children tipping over on uneven ground, however no injuries were sustained. One parent instigated the use of a helmet for the child after a tipping incident. Accident Compensation Corporation Page 7

8 4.5. Cost-effectiveness No studies on the cost-effectiveness of the Hart Walker were found during literature searches for this brief. The cost of the Hart Walker Mk II is reported to be $AU 6,175 ($NZ 7,748). This cost includes freight, one pair of boots, initial assessment and adjustments for 12 months. Purchases of additional parts, e.g. different wheel bases or boots, are in addition to this cost. Fitting and adjustment after 12 months is also an added cost that would vary with the practitioner performing the adjustments (The Spastic Centre 2009). 5. Summary Two small studies were identified which investigated the effectiveness of the Hart Walker in CP affected populations. The results show a mix of non-significant effects which contrast with high parent satisfaction rating reported in one study, an improved Directional Mobility Assessment score and improvements in social function. There were no safety issues reported by either study. No comparisons were made with other interventions regarding cost-effectiveness. 6. Conclusions The Hart Walker appears to have some positive effects on the lives of some children and parents report high overall satisfaction with the device. The main disadvantage of the device is that subjects out grow it and are forced to discontinue its use. The two studies reviewed here were small and hence definitive conclusions about the clinical effectiveness, cost effectiveness or safety cannot be drawn. Further, larger controlled studies are needed to assess this intervention against other standard CP treatment practices. If ACC was to consider funding a Hart Walker, the therapist would need to indicate why this was preferred/necessary over other models and for these to be considered on a case by case basis, on their merits. Accident Compensation Corporation Page 8

9 7. References AIHW (2006). Therapy and equipment needs of people with cerebral palsy and like disabilities in Australia, Australian Institute of Health and Welfare. David Hart Clinic (2008). A Brief History of the Equipment [Internet]. David Hart Clinic Limited. Available from: [Accessed 15th December]. Eisenberg, S., Zuk, L. et al (2009). 'Contribution of stepping while standing to function and secondary conditions among children with cerebral palsy', Pediatric Physical Therapy, 21 (1), Murphy, K. P. (2009). 'Cerebral palsy lifetime care - four musculoskeletal conditions', Dev Med Child Neurol, 51 Suppl 4, Ortho Proactive (2009). Mk II HartWalker [Internet]. Available from: [Accessed 7th December]. The Spastic Centre (2009). GOmobility: Hart Walker Program [Internet]. Available from: [Accessed 14th December]. Turk, M. A. (2009). 'Health, mortality, and wellness issues in adults with cerebral palsy', Dev Med Child Neurol, 51 Suppl 4, Wright, F. V. & Jutai, J. W. (2006). 'Evaluation of the longer-term use of the David Hart Walker Orthosis by children with cerebral palsy: a 3-year prospective evaluation', Disability and rehabilitation. Assistive technology, 1 (3), Accident Compensation Corporation Page 9