Acetabular Distraction and the Cup-in-Cup Technique for the Management of Pelvic Discontinuity: A Case Report.

Periprosthetic pelvic discontinuity is a rare but challenging complication in revision total hip arthroplasty (THA), particularly in the setting of severe acetabular bone loss. Restoration of the hip center and limb length, along with achieving implant stability, are critical for successful outcomes. We present a 68-year-old male with recurrent dislocations and a chronic flexible periprosthetic pelvic discontinuity of the left hip, likely originating from an intraoperative fracture during a prior THA revision, classified as Paprosky IIIB and American Academy of Orthopaedic Surgeons (AAOS) type IV. Imaging revealed a transverse fracture involving the iliopubic and ilioischial rami with significant bone loss. The patient underwent revision arthroplasty using acetabular distraction combined with a modular double-cup construct. A trabecular metal shell was used as a super-augment, and a smaller dual-mobility cup was cemented within the shell to restore the hip center, offset, and limb length. Postoperatively, the patient achieved stable fixation with restoration of limb length and hip biomechanics. Early functional outcomes were favorable, and radiographs demonstrated maintenance of the hip center without evidence of loosening. Acetabular distraction with a modular double-cup construct is an effective strategy for managing chronic flexible periprosthetic pelvic discontinuity with severe acetabular bone loss, providing immediate mechanical stability, restoring the hip center and offset, and offering a reproducible alternative to traditional reconstruction methods.