Selective ultrasound screening for developmental hip dysplasia: effect on management and late detected cases. A prospective survey during 1991-2006.

BACKGROUND: Early treatment is considered essential for developmental dysplasia of the hip (DDH), but the choice of screening strategy is debated. OBJECTIVE: We evaluated the effect of a selective ultrasound (US) screening programme. MATERIALS AND METHODS: All infants born in a defined region during 1991-2006 with increased risk of developmental dysplasia of the hip, i.e. clinical hip instability, breech presentation, congenital foot deformities or a family history of DDH, underwent US screening at age 1-3 days. Severe sonographic dysplasia and dislocatable/dislocated hips were treated with abduction splints. Mild dysplasia and pathological instability, i.e. not dislocatable/dislocated hips were followed clinically and sonographically until spontaneous resolution, or until treatment became necessary. The minimum observation period was 5.5 years. RESULTS: Of 81,564 newborns, 11,539 (14.1%) were identified as at-risk, of whom 11,190 (58% girls) were included for further analyses. Of the 81,564 infants, 2,433 (3.0%) received early treatment; 1,882 (2.3%) from birth and 551 (0.7%) after 6 weeks or more of clinical and sonographic surveillance. An additional 2,700 (3.3%) normalised spontaneously after watchful waiting from birth. Twenty-six infants (0.32 per 1,000, 92% girls, two from the risk group) presented with late subluxated/dislocated hips (after 1 month of age). An additional 126 (1.5 per 1,000, 83% girls, one from the risk group) were treated after isolated late residual dysplasia. Thirty-one children (0.38 per 1,000) had surgical treatment before age 5 years. Avascular necrosis was diagnosed in seven of all children treated (0.27%), four after early and three after late treatment. CONCLUSION: The first 16 years of a standardised selective US screening programme for developmental dysplasia of the hip resulted in acceptable rates of early treatment and US follow-ups and low rates of late subluxated/dislocated hips compared to similar studies.

Radiographic measurements of hip dysplasia at skeletal maturity--new reference intervals based on 2,038 19-year-old Norwegians.

OBJECTIVE: Normative references for radiographic measurements commonly used in the diagnosis of developmental dysplasia of the hip at skeletal maturity are incomplete. The present study therefore aimed to establish new gender-specific standards for measurements reflecting the acetabular morphology, namely Sharp's angle, the acetabular roof angle of Tönnis (AA) and the acetabular depth-width ratio (ADR), and measurements reflecting the position of the femoral head related to the acetabulum, namely the center-edge (CE) angle of Wiberg, the refined CE angle of Ogata, and the femoral head extrusion index (FHEI). The joint space width (JSW) is also reported. MATERIALS AND METHODS: The population-based 1989 Bergen Birth Cohort (n = 3,935) was invited at age 19 years to a follow-up during 2007-09, of which 2,038 (52 %) attended. A standardized antero-posterior radiograph was assessed. The normative references are presented as mean ± standard deviation (SD) and 2.5-97.5 percentiles with 95 % confidence intervals. RESULTS: A total of 2,011 (841 males, 1,170 females, mean age 18.6 (SD 0.6)) radiographs were analyzed. Sharp's angle was 38.8° ± 3.5° in males and 40.7° ± 3.5° in females, with 97.5 percentiles of 46° and 47°, respectively. The CE angle was 32.1° ± 6.1° in males and 31.0° ± 6.1° in females, with 2.5 percentiles of 21° and 20°, respectively. The FHEI was 86.0 % ± 6.3 % in males and 85.6 % ± 6.6 % in females, with 2.5 percentiles of 74° and 73°, respectively. CONCLUSIONS: Updated gender-specific reference ranges for radiographic measurements commonly used for hip dysplasia at skeletal maturity are reported, similar to or slightly wider than those described in the literature. Statistically significant gender differences have been confirmed for most of the measurements.

Radiological findings for hip dysplasia at skeletal maturity. Validation of digital and manual measurement techniques.

OBJECTIVE: To report on intra-observer, inter-observer, and inter-method reliability and agreement for radiological measurements used in the diagnosis of hip dysplasia at skeletal maturity, as obtained by a manual and a digital measurement technique. MATERIALS AND METHODS: Pelvic radiographs from 95 participants (56 females) in a follow-up hip study of 18- to 19-year-old patients were included. Eleven radiological measurements relevant for hip dysplasia (Sharp's, Wiberg's, and Ogata's angles; acetabular roof angle of Tönnis; articulo-trochanteric distance; acetabular depth-width ratio; femoral head extrusion index; maximum teardrop width; and the joint space width in three different locations) were validated. Three observers measured the radiographs using both a digital measurement program and manually in AgfaWeb1000. Inter-method and inter- and intra-observer agreement were analyzed using the mean differences between the readings/readers, establishing the 95% limits of agreement. We also calculated the minimum detectable change and the intra-class correlation coefficient. RESULTS: Large variations among different radiological measurements were demonstrated. However, the variation was not related to the use of either the manual or digital measurement technique. For measurements with greater absolute values (Sharp's angle, femoral head extrusion index, and acetabular depth-width ratio) the inter- and intra-observer and inter-method agreements were better as compared to measurements with lower absolute values (acetabular roof angle, teardrop and joint space width). CONCLUSION: The inter- and intra-observer variation differs notably across different radiological measurements relevant for hip dysplasia at skeletal maturity, a fact that should be taken into account in clinical practice. The agreement between the manual and digital methods is good.