The development of Australian Standards of Care for Hip Surveillance in Children with Cerebral Palsy: how did we reach consensus?

Hip Imaging in Children With Cerebral Palsy: Estimation and Intrapatient Comparison of Patient-Specific Radiation Doses of Low-Dose CT and Radiography

OBJECTIVES

Hip displacement is the second most common orthopedic problem affecting children with cerebral palsy (CP). Routine radiographic hip surveillance typically involves an anteroposterior (AP) pelvis radiograph. Unfortunately, this imaging protocol is limited by its projectional technique and the positioning challenges in children with CP. Alternatively, hip low-dose computed tomography (LDCT) has been advocated as a more accurate strategy for imaging surveillance as it provides biofidelic details of the hip that is independent of patient positioning. However, the tradeoff is the (presumed) higher radiation dose to the patient. The goal of this study is to estimate patient-specific radiation doses of hip LDCTs and AP pelvis radiographs in CP patients, and perform an intrapatient dose comparison.

MATERIALS AND METHODS

A search of our imaging database was performed to identify children with CP who underwent hip LDCT and AP pelvis radiograph within 6 months of each other. The LDCTs were performed using weight-adjusted kVp and tube current modulation, whereas the radiographs were obtained with age-/size-adjusted kVp/mAs. The patient-specific organ and effective doses for LDCT were estimated by matching the patients to a nonreference pediatric phantom library from the National Cancer Institute Dosimetry System for Computed Tomography database with Monte Carlo-based dosimetry. The patient-specific organ and effective doses for radiograph were estimated using the National Cancer Institute Dosimetry System for Radiography and Fluoroscopy with Monte Carlo-based dose calculation. Dose conversion k-factors of dose area product for radiography and dose length product for LDCT were adapted, and the estimation results were compared with patient-specific dosimetry.

RESULTS

Our study cohort consisted of 70 paired imaging studies from 67 children (age, 9.1 ± 3.3 years). The patient-specific and dose length product-based effective doses for LDCT were 0.42 ± 0.21 mSv and 0.59 ± 0.28 mSv, respectively. The patient-specific and dose area product-based effective doses for radiography were 0.14 ± 0.09 mSv and 0.08 ± 0.06 mSv, respectively.

CONCLUSIONS

The radiation dose for a hip LDCT is ~4 times higher than pelvis radiograph, but it is still very low and poses minimal risk to the patient.

Hip Displacement in Cerebral Palsy: The Role of Surveillance

INTRODUCTION

Hip displacement is common in cerebral palsy (CP) and is related to the severity of neurological and functional impairment. It is a silent, but progressive disease, and can result in significant morbidity and decreased quality of life, if left untreated. The pathophysiology of hip displacement in CP is a combination of hip flexor-adductor muscle spasticity, abductor muscle weakness, and delayed weight-bearing, resulting in proximal femoral deformities and progressive acetabular dysplasia. Due to a lack of symptoms in the early stages of hip displacement, the diagnosis is easily missed. Awareness of this condition and regular surveillance by clinical examination and serial radiographs of the hips are the key to early diagnosis and treatment.

HIP SURVEILLANCE PROGRAMMES

Several population-based studies from around the world have demonstrated that universal hip surveillance in children with CP allows early detection of hip displacement and appropriate early intervention, with a resultant decrease in painful dislocations. Global hip surveillance models are based upon the patients' age, functional level determined by the Gross Motor Function Classification system (GMFCS), gait classification, standardized clinical exam, and radiographic indices such as the migration percentage (MP), as critical indicators of progressive hip displacement.

CONCLUSION

Despite 25 years of evidence showing the efficacy of established hip surveillance programmes, there is poor awareness among healthcare professionals in India about the importance of regular hip surveillance in children with CP. There is a need for professional organizations to develop evidence-based guidelines for hip surveillance which are relevant to the Indian context.

Hip Surveillance in Children With Cerebral Palsy

Hip dysplasia is common in children with cerebral palsy (CP), especially in those children with notable functional impairment. Severity of hip dysplasia has been shown to correlate with higher Gross Motor Function Classification System levels. Migration percentage measured on AP pelvis radiographs is the key radiographic measure quantifying hip displacement in CP. Hip surveillance programs for children with CP exist in Europe, Australia, and parts of Canada and have been adopted as standard of care. These programs have demonstrated improved detection of hip subluxation and appropriate early intervention with a resultant decrease in the number of painful dislocations. Hip surveillance programs provide healthcare providers with guidance for a schedule of obtaining hip radiographs based on patients' age, Gross Motor Function Classification System level, and migration percentage. Although systematic surveillance programs have yet to be adopted in the United States, several centers and organizations are currently investigating the potential and efficacy of hip screening in CP.

Hip Surveillance for Children With Cerebral Palsy: A Survey of the POSNA Membership

BACKGROUND

Currently, hip surveillance programs for children with cerebral palsy exist in Europe, Australasia, and parts of Canada, but a neuromuscular hip surveillance program has yet to be adopted in the United States. The purpose of this study was to report the current orthopaedic practice of hip surveillance in children with cerebral palsy, identify areas of practice variation, and suggest steps moving forward to generate guidelines for national neuromuscular hip surveillance.

METHODS

The entire membership of the Pediatric Orthopaedic Society of North America (POSNA) was surveyed in 2016 for information regarding their practice for hip surveillance in children with cerebral palsy. Detailed information regarding timing, frequency, and practice of hip surveillance was obtained in answers to 26 different questions.

RESULTS

A survey response rate of 27% was obtained (350/1300 members) during the study period. The majority of respondents treated pediatric patients exclusively (97%), worked in an academic practice (70%), and was affiliated with a university (76%). In total, 18% (69/350) of respondents followed a regular cerebral palsy hip surveillance program, about half of whom (44%, 30/69) had adopted the Australian guidelines. Respondents agreed that a dislocated hip in a child with cerebral palsy was painful (90% agreement) and should be prevented by hip surveillance (93% agreement). Furthermore, 93% of respondents indicated they would follow a national surveillance program if one was in place. Age (79%), Gross Motor Function Classification System (81%), and migration percentage (MP) (78%) were all identified as critical elements to a hip surveillance program. The majority of respondents felt that a hip "at risk" for hip displacement had a MP between 20% and 30% (57% of respondents), whereas surgery should be utilized once the MP exceeded 40% (50% of respondents).

CONCLUSIONS

Results from this survey demonstrate 90% of respondents agree that a dislocated hip could be painful and 93% would follow a national surveillance program if available. At a societal level, we have the ability to standardize cerebral palsy hip surveillance, thereby decreasing practice variation and improving quality of care delivery.

LEVELS OF EVIDENCE

Level V.

PREDICT-CP: study protocol of implementation of comprehensive surveillance to predict outcomes for school-aged children with cerebral palsy

OBJECTIVES

Cerebral palsy (CP) remains the world's most common childhood physical disability with total annual costs of care and lost well-being of $A3.87b. The PREDICT-CP (NHMRC 1077257 Partnership Project: Comprehensive surveillance to PREDICT outcomes for school age children with CP) study will investigate the influence of brain structure, body composition, dietary intake, oropharyngeal function, habitual physical activity, musculoskeletal development (hip status, bone health) and muscle performance on motor attainment, cognition, executive function, communication, participation, quality of life and related health resource use costs. The PREDICT-CP cohort provides further follow-up at 8-12 years of two overlapping preschool-age cohorts examined from 1.5 to 5 years (NHMRC 465128 motor and brain development; NHMRC 569605 growth, nutrition and physical activity).

METHODS AND ANALYSES

This population-based cohort study undertakes state-wide surveillance of 245 children with CP born in Queensland (birth years 2006-2009). Children will be classified for Gross Motor Function Classification System; Manual Ability Classification System, Communication Function Classification System and Eating and Drinking Ability Classification System. Outcomes include gross motor function, musculoskeletal development (hip displacement, spasticity, muscle contracture), upper limb function, communication difficulties, oropharyngeal dysphagia, dietary intake and body composition, participation, parent-reported and child-reported quality of life and medical and allied health resource use. These detailed phenotypical data will be compared with brain macrostructure and microstructure using 3 Tesla MRI (3T MRI). Relationships between brain lesion severity and outcomes will be analysed using multilevel mixed-effects models.

ETHICS AND DISSEMINATION

The PREDICT-CP protocol is a prospectively registered and ethically accepted study protocol. The study combines data at 1.5-5 then 8-12 years of direct clinical assessment to enable prediction of outcomes and healthcare needs essential for tailoring interventions (eg, rehabilitation, orthopaedic surgery and nutritional supplements) and the projected healthcare utilisation.

TRIAL REGISTRATION NUMBER

ACTRN: 12616001488493.

Hip-joint congruity after Dega osteotomy in patients with cerebral palsy: long-term results

INTRODUCTION

Neurogenic hip dislocation is quite common in children with cerebral palsy (CP). The purpose of this study was to evaluate the long-term outcome of single-event multilevel surgery (SEMLS) in combination with hip reconstruction by using a periacetabular osteotomy as described by Dega concerning post-operative remodeling and plasticity of the femoral head post-operatively.

METHODS

A total of 72 patients with CP as the primary disease and in whom a complex surgical hip reconstruction was performed during SEMLS between 1998 and 2004 were included in the study. There were 45 men and 27 women, with a median age of 7.6 (4.7-16.3) years at the time SEMLS was performed. The mean follow-up time was 7.7 years (4.9-11.8). X-rays were taken before and after surgery, and Rippstein 1 and 2 were used for follow-up. As the most reliable value for decentration, migration percentage (MP) as described by Reimers was used. To measure hip-joint cover at follow-up, the centre-edge angle was used. The hip was divided into four different categories according to sphericity and congruity. Using this approach, we could evaluate joint remodeling.

RESULTS

Pre-operatively, the mean MP measured by X-ray was 68 %. Directly after surgery, this value decreased on average by 12 % and at the long-term follow-up was 16.0 % on average. A high rate of incongruence was observed on X-rays taken directly after surgery: 66 hip joints were classified as incongruent. The number of aspherical and incongruent joints decreased to 54 at the follow-up examination.

CONCLUSION

Data of our study with high plasticity of the hip joint suggest that even if the femoral head is deformed and a persistent incongruency after surgery is expected, hip reconstruction can be recommended.

Australian Cerebral Palsy Child Study: protocol of a prospective population based study of motor and brain development of preschool aged children with cerebral palsy

BACKGROUND

Cerebral palsy (CP) results from a static brain lesion during pregnancy or early life and remains the most common cause of physical disability in children (1 in 500). While the brain lesion is static, the physical manifestations and medical issues may progress resulting in altered motor patterns. To date, there are no prospective longitudinal studies of CP that follow a birth cohort to track early gross and fine motor development and use Magnetic Resonance Imaging (MRI) to determine the anatomical pattern and likely timing of the brain lesion. Existing studies do not consider treatment costs and outcomes. This study aims to determine the pathway(s) to motor outcome from diagnosis at 18 months corrected age (c.a.) to outcome at 5 years in relation to the nature of the brain lesion (using structural MRI).

METHODS

This prospective cohort study aims to recruit a total of 240 children diagnosed with CP born in Victoria (birth years 2004 and 2005) and Queensland (birth years 2006-2009). Children can enter the study at any time between 18 months to 5 years of age and will be assessed at 18, 24, 30, 36, 48 and 60 months c.a. Outcomes include gross motor function (GMFM-66 & GMFM-88), Gross Motor Function Classification System (GMFCS); musculoskeletal development (hip displacement, spasticity, muscle contracture), upper limb function (Manual Ability Classification System), communication difficulties using Communication and Symbolic Behaviour Scales-Developmental Profile (CSBS-DP), participation using the Paediatric Evaluation of Disability Inventory (PEDI), parent reported quality of life and classification of medical and allied health resource use and determination of the aetiology of CP using clinical evaluation combined with MRI. The relationship between the pathways to motor outcome and the nature of the brain lesion will be analysed using multiple methods including non-linear modelling, multilevel mixed-effects models and generalised estimating equations.

DISCUSSION

This protocol describes a large population-based study of early motor development and brain structure in a representative sample of preschool aged children with CP, using direct clinical assessment. The results of this study will be published in peer reviewed journals and presented at relevant international conferences.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Register (ACTRN1261200169820).

The role for hip surveillance in children with cerebral palsy

Spastic hip displacement is the second most common deformity seen in children with cerebral palsy (CP), and the long-term effects can be debilitating. Progressive hip displacement leading to dislocation can result in severe pain as well as impaired function and quality of life. Recent population-based studies have demonstrated that a child's Gross Motor Functional Classification System (GMFCS) level is most predictive for identifying hips "at-risk" for progressive lateral displacement. As a result, in many developed countries, hip surveillance has now been adopted as an integral piece of the comprehensive care puzzle for the management of children with spastic hip displacement. This paper reviews the spectrum of treatments available for progressive hip displacement, examines the current literature on the success of hip surveillance, and illustrates an example of a current hip surveillance program stratified by the GMFCS level.