Cemented dual mobility component in newly implanted porous tantalum shells for severe acetabular defects: medium-term outcomes from a high-volume single-surgeon series

Abstract

The management of severe acetabular bone defects remains challengin due to extensive bone loss and poor soft tissue quality during revision total hip arthroplasty (rTHA). The aim of this study was to assess clinical and radiological outcomes of the use of dual mobility components (DMC) cemented into a newly implanted porous tantalum (PT) acetabular shell during acetabular rTHA. Patients who underwent cementation of a DMC into a newly implanted PT cup between 2014 and 2020 were included. Bone defects were classified according to the Paprosky classification. The primary outcome was to determine the reintervention-free survival rate. The secondary outcome was clinical and radiographic assessment at last follow-up. Thirty-six patients (36 hips), with an average age of 67.9 years (range, 46–90) were included. Paprosky type III defects (61.1%) were more common than type II defects (38.9%), with type IIIa (36.1%) and IIIb (25.0%) predominating. Median follow-up was 67.3 months (range; 17–109). The dislocation rate was 8.3% (n = 3). Four (11.1%) of 36 hips underwent acetabular component revision: 2 (5.5%) for infections, 1 (2.7%) for aseptic loosening, and 1 (2.7%) for dislocation. Cup survival rate was 89.08% (CI 69.54% to 96.38%) at 60 months. The Harris hip score (HHS) improved from 31.8 ± 12.0 to 87.0 ± 14.2 points (p < 0.001). The vertical and horizontal position of the hip center of rotation (COR) improved from 19.4 ± 14.9 mm to 3.8 ± 3.4 mm and from 12.4 ± 9.9 mm to 3.8 ± 3.5 mm, respectively (both p < 0.001). Limb length discrepancy improved from − 7.8 ± 20.6 mm to -1.7 ± 5.6 mm (p = 0.056). DMCs cemented into PT shells could be considered an effective management of severe acetabular bone defects without pelvic discontinuity providing excellent clinical and radiographic results in the mid-term.