RSA Measurements of Implant Instability in a Paprosky III Pelvic Defect with Discontinuity: A Case Report.

CASE: We report a case of acetabular reconstruction for a large defect with pelvic discontinuity that underwent 4 revisions for dislocations over a 3-year period. This allowed assessment of implant stability both on imaging, using measurements on plain radiographs and radiostereometric analysis (RSA) against both ilium and ischium, and direct assessment during each surgery. Only implant stability measured with RSA correlated with intraoperative revision findings. CONCLUSION: This case underlines the role of RSA in assessing early acetabular implant stability in pelvic discontinuity and the importance of assessing the stability of the implant against both ilium and ischium.