MODIFIED TANTALUM ACETABULAR COMPONENTS FOR REVISION OF LARGE ACETABULAR DEFECTS: EARLY TO MID-TERM RADIOLOGICAL OUTCOMES

Acetabular defects can be managed with hemispherical shells with/without modular porous augments. Modified acetabular components serve the purpose of augments however allow for orthogonal screw placement. We report the clinical and radiographic outcomes of intra-operatively modified tantalum acetabular components for large acetabular defects. Eighty-five revisions (82 patients) with minimum 2-years follow-up were reviewed since 2013: Paprosky 2A (2), Paprosky 2B (9), Paprosky 2C (14), Paprosky 3A (36), and Paprosky 3B (24) defects; chronic pelvic discontinuity (CPD) 36 (42.3%). Proximal component translation >3mm, measured with EBRA, was used to diagnose loosening. Two components (2.4%) migrated >3mm, and both occurred within the first 24 months. The first mechanical failure occurred before the 8-weeks post-operative follow-up between the tantalum cup and tantalum femoral cone used to reconstruct the ischium; there was inadequate cement and no intercomponent screw was utilized. Despite the acetabular component migration from the ischium, the acetabular component appears osseointegrated to the ilium in this case with CPD. Six acetabular components (7%) were revised or partially revised: 1 (1.1%) for the above mechanical failure; 2 (2.2%) for periprosthetic joint infection; 1 for recurrent instability (a partial revision where the superior acetabular component osseointegrated to the ilium was preserved, but the inferior component loosened from the ischium and was revised; 1 for a periprosthetic acetabular fracture; and 1 in a patient with chronic pain and an RSA measurement of proximal cup migration greater than 1mm. In the last case, grade 1 loosening (fluid egress between the cup and ischium) was identified. Revision of large acetabular defects with intra-operatively modified tantalum components show promising results.