Total hip arthroplasty in patients with severe hip dysplasia and congenital pubic diastasis: report of two cases

BACKGROUND: Congenital bladder exstrophy is a rare malformation which is often associated with pubic diastasis and hip dysplasia. We reported the case two patients who underwent total hip arthroplasty (THA) due to advanced osteoarthritis combined with large congenital pubic diastasis (> 10 cm). CASE PRESENTATION: The first patient, a 39 years old woman with a pubic diastase and severe hip dysplasia on both sides was treated with a primary two-staged bilateral THA. Both hips were treated with a cementless osteoconductive cup (TM, Zimmer-Biomet) and a cementless stem (Alloclassic SL, Zimmer-Biomet). A 10° elevated rim liner of the cup was used in order to avoid dislocation. The main problem was represented by the fixation of the cup, given the retroverted acetabulum along with the elevated rotation centre due to the dysplastic hips. In the case two, a 52 years woman presented dysplastic osteoarthritis of the left hip. A conventional hemispherical cup (Alloclassic-Allofit, Zimmer-Biomet) was placed in the retroverted acetabulum combined with a cementless stem (Fitmore A, Zimmer-Biomet) attached at the metaphyseal proximal femur bone. CONCLUSION: Our results suggest that THA may be a good strategy to manage advanced hip osteoarthritis in patients with dysplasia and congenital pubic diastasis. LEVEL OF EVIDENCE: IV, case series.