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Normal ranges of hip motion in infants six weeks, three months and six months of age
Insights
Infant hip range of motion studies show persistent flexion contracture, suggesting forceful hip extension may be harmful. Normal development involves greater external than internal rotation in infants.
Area of Science:
- Pediatric Orthopedics
- Developmental Pediatrics
- Biomechanical Analysis
Background:
- Infantile hip development involves specific ranges of motion.
- Understanding normal hip development is crucial for identifying abnormalities and guiding treatment.
- Previous studies have indicated variations in hip range of motion in infants.
Purpose of the Study:
- To establish population means and normal ranges of motion for infant hips.
- To evaluate hip problems and their treatment efficacy.
- To investigate developmental trends in hip flexion contracture, internal rotation, and external rotation in infants.
Main Methods:
- Cross-sectional study design involving two independent samples of 40 infants each.
- Measurements of hip flexion contracture, internal rotation, and external rotation at 6 weeks, 3 months, and 6 months of age.
- Statistical analysis to determine population means, normal ranges, and correlations.
Main Results:
- A mean hip flexion contracture of 19 degrees at 6 weeks decreased to 7 degrees by 3 months, persisting at 6 months.
- Hip flexion contracture consistently decreased from 6 weeks to 3 months in all infants.
- External rotation was consistently greater than internal rotation; internal rotation exceeding external rotation before 6 months is atypical.
Conclusions:
- Persistent hip flexion contracture suggests forceful hip extension may be contraindicated in infants.
- Deviations from normal rotation patterns (internal > external) before 6 months may indicate developmental concerns.
- Further longitudinal studies beyond 6 months are recommended to fully define developmental trends.
Abstract:
Flexion contracture, internal rotation and external rotation of the hip were reported in 40 infants at 6 weeks and 3 months and in an independent sample of 40 infants at 6 months of age. Population means and normal ranges of motion were determined for use in the evaluation of hip problems and their treatment. A mean hip flexion contracture of 19 degrees was present at 6 weeks of age, decreasing to 7 degrees by three months, but still persisting at 6 months suggesting that forceful extension of the hip in infants may be contraindicated. Hip flexion contracture decreased in every child from 6 weeks to three months. In all cases, external rotation was greater than internal rotation. Internal rotation greater than external rotation before the age of 6 months appears contrary to normal development. There was a significant correlation between the changes in hip flexion contracture and internal rotation from 6 weeks to 3 months. An interesting extension of this study would be a longitudinal follow-up of infants beyond 6 months of age to further define these developmental trends.