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

Purpose. To compare the early medial open approach (MO) with the anterior approach (AO) performed after the appearance of the ossific nucleus for DDH that has failed closed reduction or presented late. Methods. We present the experience of 2 UK surgeons with prospectively gathered data for MO (26 hips) compared with that of a third surgeon in the same unit for the AO (21 hips) in 41 children under 24 months of age at index surgery. Femoral head osteonecrosis (FHO) risk was predicted using the height-to-width index of Bruce et al, measured at 12–18 months post reduction, and graded with the Kalamchi and MacEwen classification where follow-up exceeded 3 years. Acetabular index (AI) was measured at or close to 2 years post reduction. Results. Age at time of surgery averaged 11.2 months (3.1–24) for the MO group and 17.8 months (12–24) for the AO group. Average follow-up was 4.3 years (13 months to 12 years). FHO was evident or strongly predicted in 2/26 hips (7.7%) in the MO group and 2/21 (9.5%) in the AO group. AI improved by 8.8° (4–12°) and 7.9° (6–10°) respectively at 2 years post reduction (p>0.05). One case of early recurrent dislocation in the MO group required revision surgery via an anterior approach. The height to width index cut-off value of 0.357 at 12–18 months post reduction accurately predicted FHO risk in cases with longer follow-up. Conclusions. The medial open approach was not associated with a higher risk of FHO compared to a protocol of waiting for the appearance of the ossific nucleus before proceeding to reduction via an anterior approach. There was no significant difference in acetabular remodeling in the first two postoperative years between the protocols despite earlier reduction in the MO group