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Ultrasound screening for hips at risk in developmental dysplasia. Is it worth it?
R W Paton1, M S Srinivasan, B Shah
1Department of Orthopaedic Surgery, Blackburn Royal Infirmary, Lancashire, UK.
Insights
Routine ultrasound screening for developmental dysplasia of the hip (DDH) using
Area of Science:
- Pediatric Orthopedics
- Diagnostic Imaging
- Public Health Screening
Background:
- Developmental dysplasia of the hip (DDH) is a condition requiring early detection.
- Risk factors are often used to guide screening, but their effectiveness is debated.
- Ultrasound is a common imaging modality for infant hip assessment.
Purpose of the Study:
- To evaluate the effectiveness of ultrasound screening for DDH based on 'at-risk' factors and clinical instability.
- To determine the predictive value of established risk factors for hip dislocation.
- To compare detection rates between different screening referral criteria.
Main Methods:
- Prospective ultrasound screening of 1107 infants with 'at-risk' factors between 1992 and 1997.
- Assessment of hip dislocation and dysplasia using Graf's alpha angle under six months of age.
- Analysis of detection rates based on clinical presentation (Ortolani-positive/unstable) and presence of risk factors.
Main Results:
- The overall rate of hip dislocation was 2.2 per 1000 live births.
- Only 31% of dislocated hips were identified through 'at-risk' screening alone.
- Screening clinically unstable hips yielded a detection rate of 1 in 11, significantly higher than screening 'at-risk' factors alone (1 in 75).
Conclusions:
- Established 'at-risk' factors have poor predictive value for DDH when used as a sole screening tool.
- Routine ultrasound screening targeting only 'at-risk' groups is insufficient to reduce late dislocation rates.
- Screening of clinically unstable hips, with or without risk factors, demonstrates a high detection rate for DDH.
Abstract:
Between May 1992 and April 1997, there were 20,452 births in the Blackburn District. In the same period 1107 infants with hip 'at-risk' factors were screened prospectively by ultrasound. We recorded the presence of dislocation and dysplasia detected under the age of six months using Graf's alpha angle. Early dislocation was present in 36 hips (34 dislocatable and 2 irreducible). Of the 36 unstable hips, 30 (83%) were referred as being Ortolani-positive or unstable; 25 (69%) of these had at least one of the risk factors. Only 11 (31%) were identified from the 'at-risk' screening programme alone (0.54 per 1000 live births). Eight cases of 'late' dislocation presented after the age of six months (0.39 per 1000 live births). The overall rate of dislocation was 2.2 per 1000 live births. Only 31% of the dislocated hips belonged to a major 'at-risk' group. Statistical analysis confirmed that the risk factors had a relatively poor predictive value if used as a screening test for dislocation. In infants referred for doubtful clinical instability, one dislocation was detected for every 11 infants screened (95% confidence interval (CI) 8 to 17) whereas in infants referred because of the presence of any of the major 'at-risk' factors the rate was one in 75 (95% CI 42 to 149). Routine ultrasound screening of the 'at-risk' groups on their own is of little value in significantly reducing the rate of 'late' dislocation in DDH, but screening clinically unstable hips alone or associated with 'at-risk' factors has a high rate of detection.