Bispherical Metal Augment-enabled Controllable Acetabular Distraction for Chronic Pelvic Discontinuity: Mid-term Clinical and Radiographic Outcomes of a Retrospective Single-center Case Series.

Background: The acetabular distraction technique utilizing porous shells and augments is effective for chronic pelvic discontinuity. We report a modified technique employing a novel bispherical augment to achieve controllable distraction and enhanced reconstruction. Methods: We conducted a retrospective case series of 15 consecutive revision total hip arthroplasties performed for the treatment of chronic pelvic discontinuity at a single institution between 2017 and 2021. A modular revision system of bispherical augment with a highly porous hemispherical shell was used for defect reconstruction and acetabular distraction. The mean follow-up was 5.4 years (4.0-8.1 years). Primary outcomes were implant survivorship free from aseptic loosening and radiographic healing of the discontinuity were assessed, and complications were documented. Results: One patient (6.7%) required acetabular revision for aseptic loosening at 3.5 years. One patient required bearing exchange for recurrent dislocation at 3 months postoperatively. Radiographic healing of the discontinuity was achieved in 93.3% (14/15) of hips. One asymptomatic patient had a nonprogressive radiolucent line. Mean Harris scores improved significantly from 28.6 preoperatively to 76.3 at latest follow-up ( Conclusions: The application of a bispherical augment to enable a modified, controllable acetabular distraction technique provides a reliable alternative method for reconstructing chronic pelvic discontinuity; further larger cohorts and longer follow-up are needed.