BACKGROUND: Porous tantalum components and augments have demonstrated short to midterm fixation stability in acetabular total hip arthroplasty (THA) revision but do not offer a novel option to decrease the postoperative dislocation rate. Recently, dual mobility (DM) cups have gained interest to decrease the prevalence of recurrent hip instability after revision hip arthroplasty, but this issue was not confirmed combined with use of tantalum reconstruction devices. Therefore, we did a retrospective study aiming to: (1) evaluate at a 5-year minimum follow-up period the dislocation rate (and other intra- and postoperative complications), (2) assess radiographic results specifically looking at osseointegration and restoration of the hip center, (3) and also clinical results in a cohort of patients who underwent complex acetabular reconstruction with trabecular metal revision components associated with a cemented DM socket.
HYPOTHESIS: Using a DM socket cemented in porous tantalum components can reach the low risk of hip dislocation reported with DM components in revision setting without increasing the risk of a mechanical failure.
METHODS: A cross-sectional study identified 174 THA revision including an acetabular revision. Were excluded 118 revisions with acetabular defects Type 1, 2a or 2B according to Paprosky's classification, as well as 18 hips revised without a dual mobility and 3 patients (3 hips) lost to follow-up. Were thus included in this study 35 hips (35 patients) implanted with uncemented total hip arthroplasty revision using both trabecular metal acetabular cup-cage reconstruction and a cemented DM cup. Seven hips were classified Paprosky types 2C, 15 type 3A and 13 types 3B. Patients were followed with clinical and radiological evaluation regarding dislocation rate, infection, reoperation or re-revision, osseointegration and restoration of the hip center, and functional results according to the Harris hip score and psoas impingement presence.
RESULTS: At a mean follow-up of 8.1±1.8 years (5.1-12.6), one dislocation was recorded, and one acute deep infection. No patient required a cup re-revision for septic or aseptic loosening. The survivorship at 8years regarding revision for any cause as an endpoint was 96.5% (CI95%: 92-99). Osseointegration of TM implants was analyzed and found no acetabular migration at the last follow-up in the cohort. The mean hip center position was optimized from 48±7mm (37-58) to 34±5mm (29-39) vertically and from 26±5mm (-18-36) to 24±8mm (7-31) horizontally without reaching significance (p=0.1). On the last follow-up X-rays, the mean acetabular inclination was 47̊±9̊ (32̊-61̊). According to the criteria of Hirakawa, 97.1% (34/35) of the hip centers were restored. One cup (2.9%) was more than 5mm proximally from the hip center, and none more than 10mm. Clinical results assessed a Harris Hip Score improved from 36±17 (23-62) preoperatively to 82±15 (69-93) at last follow-up (p<0.0001). Two patients (2/35, 5.7%) complained of psoas impingement.
CONCLUSION: This study suggests effectiveness of DM cups in association with a tantalum-made acetabular shell for reconstruction of large bone defect in THRs for both solving postoperative instability and aseptic loosening without increasing the re-revision rate for any reason in a midterm follow-up.
LEVEL OF EVIDENCE: IV; observational study.