 CHILDREN’S ORTHOPAEDICS

Prevention of dislocation of the hip in children with cerebral palsy 20-YEAR RESULTS OF A POPULATION-BASED PREVENTION PROGRAMME G. Hägglund, A. Alriksson-Schmidt, H. Lauge-Pedersen, E. Rodby-Bousquet, P. Wagner, L. Westbom From Lund University, Lund, Sweden

In 1994 a cerebral palsy (CP) register and healthcare programme was established in southern Sweden with the primary aim of preventing dislocation of the hip in these children. The results from the first ten years were published in 2005 and showed a decrease in the incidence of dislocation of the hip, from 8% in a historical control group of 103 children born between 1990 and 1991 to 0.5% in a group of 258 children born between 1992 and 1997. These two cohorts have now been re-evaluated and an additional group of 431 children born between 1998 and 2007 has been added. By 1 January 2014, nine children in the control group, two in the first study group and none in the second study group had developed a dislocated hip (p < 0.001). The two children in the first study group who developed a dislocated hip were too unwell to undergo preventive surgery. Every child with a dislocated hip reported severe pain, at least periodically, and four underwent salvage surgery. Of the 689 children in the study groups, 91 (13%) underwent preventive surgery. A population-based hip surveillance programme enables the early identification and preventive treatment, which can result in a significantly lower incidence of dislocation of the hip in children with CP. Cite this article: Bone Joint J 2014; 96-B:1546–52.

 G. Hägglund, MD, PhD, Paediatric Orthopaedic Surgeon, Professor  A. Alriksson-Schmidt, PhD, MSPH, Research Manager  H. Lauge-Pedersen, MD, PhD, Paediatric Orthopaedic Surgeon, Ass Prof Division of Orthopaedics  L. Westbom, MD, PhD, Neuropaediatrician, Assistant Professor Division of Paediatrics Lund University, Department of Clinical Sciences, Lund, 22185, Sweden.  E. Rodby-Bousquet, PT, PhD, Research Physiotherapist  P. Wagner, MSc, Statistician Uppsala University, Centre for Clinical Research Västerås, Sweden. Correspondence should be sent to Prof G. Hägglund; e-mail: [email protected] ©2014 The British Editorial Society of Bone & Joint Surgery do:10.1302/0301-620X.96B11. 34385 $2.00 Bone Joint J 2014;96-B:1546–52. Received 7 May 2014; Accepted 1 August 2014

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In cerebral palsy (CP), dislocation of the hip is a major problem, but in many cases it is preventable. The risk of developing a dislocated hip in the whole population of children with CP has been estimated to be between 15% and 20%.1 The risk is highest between the ages of two and five years in children with severe limitation of gross motor function, and occurs predominantly in children with the spastic or dyskinetic subtypes.2 Repeated radiological examinations are required to detect displacement of the hip.2 The most frequently used measure of lateral displacement of the femoral head is the Reimer’s migration percentage (MP) (Fig. 1).3 Most authors classify hips with an MP > 30% to 33% as displaced, and hips with an MP > 90% to 100% as dislocated.1,4 The forms of conservative treatment which are available to prevent displacement of the hip involve positioning the hip in abduction and extension.5 It has also been suggested that weight-bearing in abduction and extension has a preventive effect.6 The effect of reducing muscle tone with botulinum toxin A, intrathecal baclofen or selective dorsal rhizotomy has been questioned.7,8 Most hips with an MP

> 40% need surgery to prevent them progressing to dislocation.9,10 Adductor–psoas lengthening, varus osteotomy of the proximal femur and pelvic reconstruction are generally considered to be the procedures of choice. In 1994, a surveillance programme for CP called the Cerebral Palsy Follow-Up Programme (CPUP) was established in southern Sweden. All children born after 1992 were eligible for inclusion, with those born between 1990 and 1991 forming a historical control group. After ten years (on 1 January 2003), the hip prevention programme was evaluated.1 Only one of the 258 children in the study group, who were then between five and ten years of age, had developed dislocation of the hip, compared with eight of the 103 children in the control group, who were aged between 11 and 12 years. The aim of this study was twofold: first, to perform a 20-year follow-up evaluation of the CPUP surveillance programme using the two cohorts that were analysed in 2003; and secondly, to analyse the hip surveillance results in all children with CP born between 1998 and 2007 who were living in the study area. THE BONE & JOINT JOURNAL

PREVENTION OF DISLOCATION OF THE HIP IN CHILDREN WITH CEREBRAL PALSY

Fig. 1 Diagram showing the measurement of migration percentage (MP): MP = a / b × 100.

Patients and Methods The programme started as a collaborative initiative between paediatric orthopaedic surgeons, neuropaediatricians and physiotherapists in southern Sweden, which has a population of 1.3 million. All children born since 1990 have been reviewed every four years to identify those in the designated catchment area with possible CP. In each case, the diagnosis of CP and its subtype were verified after the child’s fourth birthday. The prevalence of CP in the area was 2.7 per 1000 children.11 CP was initially defined according to Mutch et al,12 and after 2010 according to Rosenbaum et al.13 The Swedish classification of subtypes of CP by Hagberg, Hagberg and Olow14 was used, and also, since 2000, the Surveillance of Cerebral Palsy in Europe (SCPE) classification algorithm.15 Gross motor function was classified according to the Gross Motor Function Classification System (GMFCS)16 after 1995 and its revised version after 2010.17 The CPUP healthcare programme includes a standardised follow-up of gross and fine motor function, clinical findings and treatment. A local physiotherapist and occupational therapist examine the child and complete an assessment form twice a year until the age of six years, and once a year thereafter. The results are computerised, and the treatment team receives an online report summarising the child’s long-term development. The radiological follow-up programme in CPUP was initially based on the subtypes of CP. Children with diplegic, tetraplegic or dystonic CP are examined with an anteroposterior (AP) pelvic radiograph at the time of diagnosis, or suspicion, of CP, and then at least once a year until their eighth birthday. After this, radiographs are carried out on an individual basis. Children with spastic hemiplegia or pure ataxia are only examined at the age of four years. Since 2007, the radiological follow-up programme has been based on the GMFCS. Children in GMFCS levels III–V are examined VOL. 96-B, No. 11, NOVEMBER 2014

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radiologically once a year, and those in level II at two and six years of age. Children in level I are not examined radiologically, provided that they have a normal pain-free range of movement of the hip. After eight years of age the children are followed individually according to the results of their previous clinical and radiological findings. After fusion of the growth plate, those with an MP < 33% and without a progressive scoliosis are only followed clinically. Any decrease in the range of movement at the hip or onset of scoliosis is an indication for further radiological examination. Hip dislocation was defined as MP 100%. This study included children and young adults with CP born between 1990 and 2007 who lived in the catchment area between the start of the programme in 1994 and January 2014 (Fig. 2). The control group, born in 1990 and 1991, and the first study group, born between 1992 and 1997, do not include those who moved into the area after January 2003. In the second study group, born between 1998 and 2007, data on children who moved into the area were included but analysed separately. Data were censored on 1 January 2014, or when a child moved out of the area or died. Overall, four children born between 1992 and 1997 and 12 born between 1998 and 2007 did not participate in the programme. Information about dislocation of the hip and operations in these children was collected during the inventory. The children were treated at 13 centres in southern Sweden. Non-operative treatment to prevent contractures consisted of appropriate lying, sitting and standing positions and the use of orthoses. Most children in GMFCS levels III–V were treated with a customised standing brace. Preventive surgery consisted of adductor– psoas tenotomy, varus osteotomy of the proximal femur or pelvic reconstruction, usually by Dega osteotomy. The MPs were measured on all radiographs by one of the authors (GH). There are four orthopaedic departments in the area: decisions on preventive surgery were made locally. The proportion of CP subtypes, GMFCS levels and gender in the control group and study groups were similar in the three cohorts (Table I). Statistical analysis. The prevalence of dislocation of the hip was calculated for the control group and for the two study groups. Corresponding 95% confidence intervals (CIs) were calculated using the exact binomial method. For groups with zero prevalence, one-sided 97.5% CIs were used. The relative risk (RR) was calculated by comparing the second study group with the control group in order to evaluate the effect of the follow-up programme. The effect was further evaluated by calculating the preventive fraction, which is the fraction of dislocated hips that could potentially have been prevented by implementing the programme. Life table methods were used to illustrate the differences in the probability of surgery in terms of the age between individuals with different GMFCS levels. Differences in life

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G. HÄGGLUND, A. ALRIKSSON-SCHMIDT, H. LAUGE-PEDERSEN, E. RODBY-BOUSQUET, P. WAGNER, L. WESTBOM

Control group Born 1990 to 1991 Living in the area (1994) Moved into the area N = 103

87 16

Moved out of the area 1 Deceased 3

Born in the area Moved into the area N = 258

210 48

Born in the area Moved into the area N = 431

349 82

Moved out of the area Deceased

17 14

Moved out of the area 4 Deceased 3

1 Jan 2003 N = 99

Moved out of the area Deceased

Study group 2 Born 1998 to 2007

Study group 1 Born 1992 to1997

1 Jan 2003 N = 251

6 5

Moved out of the area Deceased

1 Jan 2014 N = 88

5 18

1 Jan 2014 N = 400

1 Jan 2014 N = 228 Fig. 2

Flow chart showing the number of children with cerebral palsy living in the area, moved into or out of the area, or deceased in the three study cohorts.

Table I. Number of patients (%) by gender, CP subtype and GMFCS level Patient demographic

Control group: born 1990 to 1991 Study group 1: born 1992 to 1997 Study group 2: born 1998 to 2007 (n = 103) (%) (n = 258) (%) (n = 431) (%) Total (n = 792) (%)

Male Female

54 (52) 49 (48)

155 (60) 103 (40)

243 (56) 188 (44)

452 (57) 340 (43)

CP subtype Unilateral spastic Bilateral spastic* Ataxic Dyskinetic Mixed

29 (28) 52 (50) 7 (7) 14 (14) 1 (1)

86 (33) 116 (45) 14 (6) 37 (14) 5 (2)

129 (30) 175 (40) 23 (5) 97 (23) 7 (2)

244 (31) 343 (43) 44 (5) 148 (19) 13 (2)

GMFCS level I II III IV V Unclassified

35 (34) 21 (20) 14 (14) 7 (7) 16 (15) 10 (10)

130 (51) 31 (12) 29 (11) 29 (11) 36 (14) 3 (1)

164 (38) 84 (19) 37 (9) 74 (17) 65 (15) 7 (2)

329 (42) 136 (17) 80 (10) 110 (14) 117 (15) 20 (2)

*Including 37 with ataxic diplegia (respectively three, 12 and 22 in the control and study groups 1 and 2)

table data were analysed using standard multiple logistic regression analysis, correcting for age groups zero to three, three to six, six to 11 and > 11 years by including indicator variables. Estimates of the odds ratio (OR) were presented with 95% CIs. As there were no operations in children with GMFCS level I, this group was excluded from the regression analyses.

Logistic regression was also used to estimate the difference in the frequency of surgery between those in the two more common CP subtypes: spastic bilateral and dyskinetic CP. Both crude and adjusted (for GMFCS level) analyses were performed. STATA version 12 (StataCorp Stata Statistical Software: Release 12. College Station, Texas) was used for all statistical analyses. The study had ethical approval. THE BONE & JOINT JOURNAL

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Table II. Hip operations and radiological outcomes Control group: born 1990 to First study group: born 1992 to Second study group: born 1998 1991 (n = 103) 1997 (n = 258) to 2008 (n = 431) Hip dislocation (MP 100%) at last examination Hip displacement (MP > 40%) at last examination† Total number of children operated n (%) Total number of operations n Primary surgery Adductor–psoas tenotomy Varus femoral osteotomy Salvage Repeat surgery Adductor–psoas tenotomy Varus femoral osteotomy Varus femoral osteotomy + Dega Salvage

9 2 14 (14) 23

2+2* 2 39 (15) 56

0 9 52 (12) 75

8 4 2

24 15 0

31 21 0

2 3 2 2

1 14+2‡ 0 0

0 18 + 3‡ 2 0

* One child with hip dislocation before moving into the area and one child not participating in CPUP † Dislocated hips not included ‡ Third operation n, number of children; MP, migration percentage

Results By the census date (1 January 2014), eight of the 103 children in the control group (born 1990 to 1991) had died at a median age of 11 years (IQR 11 to 13) and seven had moved out of the area at a median age of 16 years (IQR 11 to 16) (Fig. 2). Dislocation of the hip had occurred in nine patients, eight of which occurred in children between three and six years of age. One boy underwent bilateral adductor psoas tenotomy at the age of five, and bilateral varus osteotomy and Dega osteotomy at the age of 12. At 14 he had displacement of his left hip with an MP of 60%. Further surgery was recommended, but the family opted to wait. By the age of 16 the hip had dislocated; his symptoms continued and at the age of 22 he underwent resection of the femoral head. Of the nine children with a dislocation, four underwent resection of the femoral head, at the ages of nine, ten, 11 and 22 years. All children with a dislocated hip were in severe pain, at least periodically, and all had a scoliosis with a Cobb angle > 40°. A total of four children with a dislocated hip had died at the ages of eight, 11, 12 and 17 years respectively. Preventive surgery was carried out for 12 children in the control group (Table II). All those with a dislocated hip or who underwent preventive surgery were in GMFCS levels IV or V. At the time of evaluation, two 23year-old men in the control group had hips with an MP > 40%. Both have remained with a stable MP since they finished growing. Of the 258 children in study group 1 (born 1992 to 1997), 21 had died at a median age of 12.5 years (IQR 8 to 15) and nine had moved at a median age of nine years (IQR 6 to 13) (Fig. 2). Two of the 210 children born in the area and who participated in CPUP developed a dislocation of the hip. Both were diagnosed with a displaced hip before dislocation. However, these children were not considered well enough to undergo surgery. Of the four children in the area who did not participate in CPUP, one developed dislocation in both hips. Of the 48 children who moved into the VOL. 96-B, No. 11, NOVEMBER 2014

area, one had a dislocated hip before joining the programme. No child in study group 1 developed a dislocated hip since joining CPUP. Of the 431 children in study group 2 (born 1998 to 2007), 14 died at a median age of four years (IQR 3 to 8) and 17 had moved from the area at a median age of five years (IQR 4 to 6) (Fig. 2). None of the 349 children born in the area and none of the 82 children who moved to the area had developed a dislocated hip at the time of analysis. Several of the children who moved into the area had been followed in CPUP in other parts of Sweden. The RR of dislocation of the hip between the second study group and the control group was zero. The 95% CI for prevalence of dislocation in the second study group was 0% to 0.09% and the estimated preventive fraction was 1. Preventive surgery was undertaken in 15% (39/258) of the children in the first study group and 12% (52/431) of those in the second (Table II). No child in the study has needed salvage surgery. A total of 55 children underwent bilateral adductor psoas tenotomy as a first surgical intervention at a mean age of 4.8 years (1 to 10), and 36 underwent adductor psoas tenotomy and varus osteotomy of the proximal femur at a mean age of 4.9 years (2 to 14). Of the 55 children who were treated with adductor psoas tenotomy, one needed a revision of the tenotomy and 24 needed a varus femoral osteotomy a mean of 2.7 years (1 to 7) later: five needed a further osteotomy a mean of 4.6 years (2 to 10) after the second operation. Of the 36 children treated by varus femoral osteotomy as a primary intervention, ten needed a further osteotomy, in two in combination with a Dega osteotomy, a mean of 3.2 years (1 to 5) later. The percentage of children who underwent preventive surgery increased with GMFCS level (p < 0.001) from 0% in level I to 49% in level V (Table III) (Fig. 3). All had spastic bilateral, dyskinetic or mixed CP subtype; no child with spastic unilateral or pure ataxic CP had preventive surgery. The observed difference in surgery between children with

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G. HÄGGLUND, A. ALRIKSSON-SCHMIDT, H. LAUGE-PEDERSEN, E. RODBY-BOUSQUET, P. WAGNER, L. WESTBOM

Table III. Hip operations by CP subtype and GMFCS level. Number of children with hip surgery relative to the total number, percentage in brackets Control group: born 1990 to 1991 (n = 103)

First study group: born 1992 to 1997 (n = 258)

Second study group: born 1998 to 2007 (n = 431)

Total (n = 792)

CP subtype Unilateral spastic Bilateral spastic* Ataxic Dyskinetic Mixed

0/29 11/52 (21) 0/7 3/14 (21) 0/1

0/86 30/116 (26) 0/14 9/37 (24) 0/5

0/129 26/175 (15) 0/23 24/97 (25) 2/7 (29)

0/244 67/343 (20) 0/44 36/148 (24) 13

GMFCS level I II III IV V Unclassified

0/35 0/21 0/14 4/7 (57) 10/16 (63) 0/10

0/130 1/31 (3) 9/29 (31) 12/29 (41) 17/36 (47) 0/3

0/164 1/75 (1) 4/37 (11) 15/74 (20) 32/65 (49) 0/6

0/329 2/127 (2) 13/80 (16) 31/110 (28) 59/117 (50) 0/19

*Including ataxic diplegia

Table IV. Results of logistic regression analysis of the probability of preventive surgery. The left column shows two separate analyses, one in relation to having dyskinetic or bilateral CP and one in relation to GMFCS level. The right column shows the results adjusted for GMFCS level Crude OR Dyskinetic CP Spastic bilateral CP

ref. 0.90

GMFCS II GMFCS III GMFCS IV GMFCS V

ref 12.72 18.16 41.04

Adjusted

95% CI

p-value

OR

95% CI

p-value

0.58 to 1.39

0.63

ref. 1.98

1.24 to 3.18

0.004

2.86 to 56.59 4.30 to 76.64 9.94 to 169.46

0.001 < 0.001 < 0.001

OR, odds ratio; CI, confidence interval

bilateral and dyskinetic CP was small and not statistically significant (OR 0.9, p = 0.63, Table IV). However, when adjusting for GMFCS level, it was found that children with spastic bilateral CP had almost twice the risk of undergoing surgery as those with dyskinetic CP (Table IV). Risks corresponding to other sub-diagnoses could not be evaluated owing to the small number of children in these groups who had surgery. At the time of census, two children in study group 1 had an MP ≥ 40% (41% and 44%, respectively), in addition to the four with a dislocated hip. The degree of displacement had not increased during the preceding years and they continue to be followed radiologically according to the followup protocol. In study group 2, nine children had an MP ≥ 40% (40% to 51%) by the date of the census. This had recently been detected in five children who are scheduled for preventive surgery. The degree of displacement has not increased in the other four children, who are followed in the CPUP. Currently, there are no plans to operate on them.

Discussion The risk of dislocation of the hip in all children with CP has been estimated to be 15% to 20%.1 In the historical control

group, nine children (9%) developed a dislocation and seven others (7%) underwent preventive surgery. This corresponds to the natural risk and means that approximately one in three dislocations was prevented, even in the absence of a systematic prevention programme. Except for the two children who were considered to be too unwell to undergo preventive surgery, no child in the CPUP had a dislocated hip at census suggesting that it is eminently possible to prevent dislocation of the hip in children with CP. Preventive surgery was undertaken in 15% of the children in study group 1 and in 12% in study group 2. As children in the latter group were six to 15 years old at census there will probably be more displaced hips in this group that will need surgery. Furthermore, the estimated preventive fraction, which was 1.0, indicates that all dislocations could potentially be prevented by using the follow-up programme. This was further supported by the fact that the prevalence of dislocation of the hip in the second study group was 0 (95% CI 0 to 0.09). This means that the true prevalence, given the conditions in this group, is at most 9/10 000 with 95% certainty. The mean age at first operation was 4.8 years, but the youngest was only one year old. In a previous study18 children from the same catchment area in GMFCS levels THE BONE & JOINT JOURNAL

Cumulative probability of preventive surgery

PREVENTION OF DISLOCATION OF THE HIP IN CHILDREN WITH CEREBRAL PALSY

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● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● 15 5 10 20 Age at operation (yrs) Fig. 3

Graph showing the cumulative proportion of children with preventive surgery by GMFCS level and age.

III–V born between 1996 and 2003 were compared with children of the same age from Norway who were not in a hip surveillance programme. In the Norwegian group, 15% of children in GMFCS III–V developed a dislocated hip, despite there being a higher number of operations on the hip. These operations were performed a mean of two years later than in the Swedish group, suggesting that one key component of CPUP is the importance of early identification and timely treatment of a displaced hip. An important prerequisite is the standardised radiological screening of the hip even in children with no symptoms from the hip. Simply to wait until symptoms appear is unlikely to reduce the number of dislocated hips in children with CP. Basing the radiological follow-up on GMFCS rather than on CP subtype has resulted in a reduction of radiological examinations by about one-third. The main reason for this is that children with spastic bilateral CP are represented in all GMFCS levels. The proportion of children undergoing preventive surgery by age group was similar in the dyskinetic and bilateral subtypes (Table III). However, when children with the same GMFCS levels were compared in the adjusted analysis, those with spastic bilateral CP needed almost twice as many operations (Table IV). This shows that both subtype and GMFCS level are important predictors of the need for preventive surgery. However, unlike subtypes of CP, GMFCS levels can be classified from an early age by several professions, even parents, and have been shown to be highly reliable and stable over time.16,19 In 1997, another hip surveillance programme based on the child’s age and GMFCS level was established in Australia.20 This programme also uses the MP and their indications for surgery are similar to those of CPUP, that is, hips with an MP > 40% and hips with an increase in MP by > 10% in one year. This programme has also been shown to be effective in preventing dislocation of the hip. The Australian programme contains more frequent radiological VOL. 96-B, No. 11, NOVEMBER 2014

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examinations, but unlike the CPUP programme, it does not include annual clinical examinations by a physiotherapist. Of the 91 children in the groups studied who underwent preventive surgery, 35 (38%) required a second and five (5%) a third operation. In study group 2, more children will probably need repeated surgery until they are fully grown. The proportion of children who needed a second operation was higher after adductor–psoas tenotomy (45%) than after varus osteotomy (28%). Adductor–psoas tenotomy is more often performed in children with a lower degree of displacement, in the knowledge that an osteotomy might be required in the future. A second operation should not be regarded as a complication of treatment. The muscle imbalance and spasticity remain more or less unchanged post-operatively and may re-dislocate the hip. Therefore, patients should be followed throughout their entire growth period. Most children with an MP > 40% need operative treatment to prevent dislocation of the hip.2 When to operate and which operation to choose needs to be investigated in long-term follow-up studies. In this study, only four children underwent pelvic reconstruction. Acetabular dysplasia usually develops at a later stage than lateralisation of the femoral head.9 Early surgery may prevent the development of acetabular dysplasia and the need for pelvic reconstruction. There are no recommendations so far that address the type of surgery to be undertaken in the CPUP. The decision regarding the type of surgery to be carried out is made locally by the child’s orthopaedic surgeon. This makes evaluation of the methods more difficult and is a limitation of this study. Dislocation of the hip in CP is associated with pain, a ‘windswept’ deformity, pelvic obliquity and scoliosis, which impair lying, sitting and standing.21 This is also shown in this study by the clinical findings in children with a dislocated hip. In order to succeed with a hip dislocation prevention programme, the main challenge is to identify all children with CP, or suspected CP, at a young age and to perform a clinical and radiological examination as early as possible. It is also imperative to have prompt access to preventive surgery.22 However, the effectiveness of a preventive treatment programme such as CPUP also depends on the setting in which it is implemented. Contextual considerations, such as insurance cover in places where there is no universal healthcare cover; reimbursement schemes; long waiting lists; and lack of ‘buy-in’ from healthcare providers and policy makers are some factors that could hamper the programme. Nevertheless, many of these barriers could be circumvented, or the programme could be modified to fit the particular circumstances of a particular region. Since 2005, CPUP has been used throughout Sweden and is currently used in all or parts of Norway, Denmark, Iceland and Scotland. In conclusion, this 20-year evaluation of a hip surveillance programme shows that it is possible to prevent dislocation of the hip in children with CP.

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G. HÄGGLUND, A. ALRIKSSON-SCHMIDT, H. LAUGE-PEDERSEN, E. RODBY-BOUSQUET, P. WAGNER, L. WESTBOM

The study was supported by the Medical Faculty, Lund University, and Stiftelsen för bistånd åt rörelsehindrade i Skåne. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

11. Westbom L, Hagglund G, Nordmark E. Cerebral palsy in a total population of 4-11 year olds in southern Sweden. Prevalence and distribution according to different CP classification systems. BMC Pediatr 2007;7:41.

This article was primary edited by A. Ross and first proof edited by J. Scott.

12. Mutch L, Alberman E, Hagberg B, Kodama K, Perat MV. Cerebral palsy epidemiology: where are we now and where are we going? Dev Med Child Neurol 1992;34:547–551.

References

13. Rosenbaum P, Paneth N, Leviton A, et al. A report: the definition and classification of cerebral palsy April 2006. Dev Med Child Neurol Suppl 2007;109:8–14.

1. Hägglund G, Andersson S, Düppe H, et al. Prevention of dislocation of the hip in children with cerebral palsy. The first ten years of a population-based prevention programme. J Bone Joint Surg [Br] 2005;87-B:95–101. 2. Hägglund G, Lauge-Pedersen H, Wagner P. Characteristics of children with hip displacement in cerebral palsy. BMC Musculoskelet Disord 2007;8:101. 3. Reimers J. The stability of the hip in children. A radiological study of the results of muscle surgery in cerebral palsy. Acta Orthop Scand Suppl 1980;184:1–100. 4. Soo B, Howard JJ, Boyd RN, et al. Hip displacement in cerebral palsy. J Bone Joint Surg [Am] 2006;88-A:121–129. 5. Pountney TE, Mandy A, Green E, Gard PR. Hip subluxation and dislocation in cerebral palsy - a prospective study on the effectiveness of postural management programmes. Physiother Res Int 2009;14:116–127. 6. Martinsson C, Himmelmann K. Effect of weight-bearing in abduction and extension on hip stability in children with cerebral palsy. Pediatr Phys Ther 2011;23:150–157. 7. Graham HK, Boyd R, Carlin JB, et al. Does botulinum toxin a combined with bracing prevent hip displacement in children with cerebral palsy and "hips at risk"? A randomized, controlled trial. J Bone Joint Surg [Am] 2008;90-A:23–33. 8. Silva S, Nowicki P, Caird MS, et al. A comparison of hip dislocation rates and hip containment procedures after selective dorsal rhizotomy versus intrathecal baclofen pump insertion in nonambulatory cerebral palsy patients. J Pediatr Orthop 2012;32:853–856. 9. Hägglund G, Lauge-Pedersen H, Persson M. Radiographic threshold values for hip screening in cerebral palsy. J Child Orthop 2007;1:43–47. 10. Dhawale AA, Karatas AF, Holmes L, et al. Long-term outcome of reconstruction of the hip in young children with cerebral palsy. Bone Joint J 2013; 95B:259–265.

14. Hagberg B, Hagberg G, Olow I. The changing panorama of cerebral palsy in Sweden 1954-1970. I. Analysis of the general changes. Acta Paediatr Scand 1975;64:187– 192. 15. Surveillance of Cerebral Palsy in Europe. Surveillance of cerebral palsy in Europe: a collaboration of cerebral palsy surveys and registers. Surveillance of Cerebral Palsy in Europe (SCPE). Dev Med Child Neurol 2000;42:816–824. 16. Palisano R, Rosenbaum P, Walter S, et al. Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39:214–223. 17. Palisano RJ, Rosenbaum P, Bartlett D, Livingston MH. Content validity of the expanded and revised Gross Motor Function Classification System. Dev Med Child Neurol 2008;50:744–750. 18. Elkamil AI, Andersen GL, Hägglund G, et al. Prevalence of hip dislocation among children with cerebral palsy in regions with and without a surveillance programme: a cross sectional study in Sweden and Norway. BMC Musculoskelet Disord 2011;12:284. 19. Palisano RJ, Cameron D, Rosenbaum PL, Walter SD, Russell D. Stability of the gross motor function classification system. Dev Med Child Neurol 2006;48:424–428. 20. Dobson F, Boyd RN, Parrott J, Nattrass GR, Graham HK. Hip surveillance in children with cerebral palsy. Impact on the surgical management of spastic hip disease. J Bone Joint Surg [Br] 2002;84-B:720–726. 21. Robb JE, Hägglund G. Hip surveillance and management of the displaced hip in cerebral palsy. J Child Orthop. 2013;7:407–413. 22. Terjesen T. The natural history of hip development in cerebral palsy. Dev Med Child Neurol 2012;54:951–957.

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Prevention of dislocation of the hip in children with cerebral palsy: 20-year results of a population-based prevention programme.

In 1994 a cerebral palsy (CP) register and healthcare programme was established in southern Sweden with the primary aim of preventing dislocation of t...
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