Related Experiment Videos
Hip displacement in spastic cerebral palsy: repeatability of radiologic measurement
Jennifer Parrott1, Roslyn N Boyd, Fiona Dobson
1Hugh Williamson Gait Laboratory and Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia.
Insights
Radiologic measures migration percentage (MP) and acetabular index (AI) are reliable for assessing hip displacement in children with cerebral palsy. Measurement errors are acceptable for clinical decisions with standardized methods and consistent raters.
Area of Science:
- Pediatric Orthopedics
- Radiology
- Cerebral Palsy Research
Background:
- Hip displacement is a common complication in children with cerebral palsy.
- Radiographic measurements like migration percentage (MP) and acetabular index (AI) are crucial for management.
- Assessing the reliability of these measurements is vital for accurate diagnosis and treatment planning.
Purpose of the Study:
- To determine the interrater and intrarater reliability of migration percentage (MP) and acetabular index (AI) measurements.
- To evaluate the measurement error for MP and AI in pelvic radiographs of children with cerebral palsy.
- To assess the clinical acceptability of measurement errors for MP and AI.
Main Methods:
- Pelvic radiographs from children aged 11 months to 8 years 5 months were analyzed.
- Measurements of migration percentage (MP) and acetabular index (AI) were performed by experienced raters.
- Interrater and intrarater reliability were calculated, along with measurement errors for single readings and changes over time.
Main Results:
- An experienced rater's measurement error for MP on a single radiograph was within +/-5.8%.
- The error for detecting a change in MP between radiographs was within +/-8.3%.
- For AI, the measurement error was within +/-2.6 degrees for a single reading and +/-3.7 degrees for changes over time.
Conclusions:
- The study demonstrates acceptable reliability for MP and AI measurements in clinical practice.
- Treatment decisions should be based on serial radiographs taken at 6-month intervals.
- Standardized methods, consistent training, and the use of consistent raters are recommended for optimal accuracy.
Abstract:
Radiologic measures of migration percentage (MP) and acetabular index (AI) taken from plain radiographs of the pelvis are the most commonly used tools for determining hip displacement and management options in children with cerebral palsy and spastic hip disease. This study determined interrater and intrarater reliability of MP and AI on pelvic radiographs chosen to represent a wide range of age (11 months to 8 years 5 months), MP (0%-56%), and AI (9 degrees -33 degrees ). The study demonstrated that an experienced rater would be expected to measure MP on a single radiograph to within +/-5.8% of the true value and a change in MP between two radiographs taken at different times to within +/-8.3% of the true value. Similarly for AI, the measurement error for a typical rater would be within +/-2.6 degrees on a single reading and +/-3.7 degrees if recording change between two occasions. The authors believe that the results indicating true change are acceptable in clinical practice, provided treatment decisions are based on a series of radiographs taken at 6-month intervals, methods and training are standardized, and consistent raters are used.