Four-point Molding: A New Cast Molding Technique for Closed Reduction Treatment of Developmental Dysplasia of the Hip
Duangjai Leeprakobboon MD* Kamolporn Kaewpornsawan MD*, Perajit Eamsobhana MD*
Affiliation : * Department of Orthopedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Background : In order to achieve added stability in a hip spica cast and decrease unnecessary open reduction, the authors
have devised a new hip spica cast molding technique that has been named, “Four-point molding technique”. Our aim was to
evaluate the efficacy of this technique, in terms of its ability to deliver a stable, concentric reduction of the hip.
Material and Method: The authors retrospectively reviewed the patients, aged 6-24 months, that were diagnosed with DDH
and who had undergone closed reduction with a hip spica cast. The authors used the four-point molding technique on all
patients. The authors evaluated radiographs for redislocation during the 12 weeks of cast treatment and followed-up to 1 year
after hip spica cast removal. 15 children (15 hips) who were treated over a14-year period were included in the present study
to determine the success rate of this procedure.
Results : From 1996-2010, there were 15 unilateral DDH patients who were treated with the four-point molding technique.
The average age of the patients at the time of the reduction was 17 months (age range: 8-23 months). The treatment was
86.6% successful in 13 children (95% CI 0.62-0.96). The average duration in the hip spica cast was 12.5 weeks. Mean follow-
up was 23.1 months. Two children were unable to be concentrically reduced with sufficient stability with closed reduction and
therefore required open reduction and osteotomy.
Conclusion : Four-point molding is simple, gives good result, and with low complications. The authors propose this
technique for use in closed reduction treatment for DDH.
Keywords : DDH, Closed reduction, Hip spica cast, Four-point molding technique
