Developmental dysplasia of the hip in neonates: Evolution of acetabular dysplasia after hip stabilization by brief Pavlik harness treatment

Abstract

BackgroundThe recommended treatment duration in neonates with developmental dysplasia of the hip (DDH) varies depending on whether prolonged Pavlik harness therapy is believed to favourably affect the course of the acetabular dysplasia. According to one theory, several months of additional Pavlik harness therapy after achieving hip reduction contributes to correct the acetabular dysplasia. Another theory holds that hip dislocation induces the acetabular dysplasia, which corrects spontaneously once the femoral head is properly seated in the acetabulum. Here, we evaluated this second theory by studying outcomes after early brief Pavlik harness therapy. HypothesisAcetabular dysplasia associated with neonatal hip instability undergoes self-correction provided stable hip reduction is achieved very early after birth. Therefore, the duration of Pavlik harness therapy can be substantially shortened. Materials and methodsWe defined hip instability as either reducible hip dislocation or a very easily dislocatable hip with a soft clunk precluding determination of spontaneous hip position as dislocated or reduced. Static and dynamic ultrasound scans were obtained. Patients with ultrasonographic instability (pubo-femoral distance>5mm with less than 50% of coverage) underwent a second physical examination and received treatment. We re-evaluated 42 abnormal hips in 30 patients after a mean follow-up of 6.7years (range, 5–14years). Mean age at treatment initiation was 5days (range, 1–15days) and mean treatment duration was 34days (range, 15–75days). ResultsMean acetabular angle was 20° (range, 12°–30°) and mean Wiberg's lateral centre-edge angle was 30° (range, 22°–35°). Blunting of the lateral angle of the bony roof was noted in 8 hips at last follow-up. In 1 patient whose hip was stable clinically but unstable by ultrasonography at 21days of age, recurrent dislocation occurred at 5months of age. The Severin class was 1a in all patients. DiscussionDespite continuing controversy about whether hip dislocation induces dysplasia or vice versa, the need for early treatment is universally recognised. The optimal treatment duration, however, remains debated. Proponents of the familial determinism of DDH consider that acetabular shaping is genetically programmed when the femoral head is centred in the acetabular socket. Others advocate routine prolongation of Pavlik harness therapy for 2months or longer, based on the opinion that this strategy decreases the dislocation recurrence rate and that mechanical hip unloading may promote correction of the dysplasia. Mean treatment duration in our population was 34days and our sole objective was to treat the instability. The hip was reduced and held in its proper position long enough to allow sufficient capsule and ligament tightening to stabilise the hip. Under these conditions, the acetabular dysplasia underwent self-correction that was not related to treatment duration. ConclusionVery early Pavlik harness therapy to ensure rapid hip reduction and stabilisation optimises the potential of the acetabulum for spontaneous remodelling. Level of evidenceLevel IV, retrospective study.