The Stability of the Porous Tantalum Components Used in Revision THA to Treat Severe Acetabular Defects

Abstract

Background: The acetabular components used in revision total hip arthroplasty (THA) to treat severe acetabular bone defects have high rates of re-revision at mid to long-term follow-up. Early translation of acetabular components used in revision THA is a good predictor of later loosening, and radiostereometric analysis (RSA) is the most sensitive method to measure migration. The objectives of the present study were to use RSA to compare the migration of the porous tantalum acetabular components used to treat severe bone defects with the previously established acceptable proximal translation threshold of ≤1 mm within 2 years, and to determine the effect on migration of the addition of inferior screws through the component into the ischium or pubis. Methods: RSA was utilized to measure the migration of 55 porous tantalum components used to treat severe acetabular defects (28 Paprosky IIIA, 27 Paprosky IIIB; 21 hips with pelvic discontinuity) at a mean follow-up of 4 years (range, 2 to 12 years). Results: Forty-eight of the 55 components migrated less than the threshold that predicts later loosening (>1 mm) and 50 had not been re-revised at the time of the latest follow-up. Seven components, none of which had inferior screw fixation, exceeded the translation threshold. Of these, 6 were implanted to treat pelvic discontinuity. Of those 6 components, 5 were re-revised for loosening related to patient symptoms. At 2 years, the absolute median proximal translation of components with inferior screw fixation was |0.3| mm (range, |0.1| to |0.9| mm), compared with |0.4| mm (range, |0.03| to |16.4| mm) for those without inferior screws (p = 0.04). Conclusions: As measured with use of RSA, the majority of porous tantalum acetabular components used in a revision THA to treat severe acetabular defects had acceptable early migration. This predicts good long-term survivorship of these components. The use of inferior screws further improved acetabular component fixation. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Accuracy of EBRA‐cup measurements after reconstruction of severe acetabular defects at revision THR

“…Acetabular components used at revision THR have larger amounts of migration than those used at primary THR 25 and have a higher rate of revision THR within 10 years 4,26 . Measuring early migration of revision acetabular components accurately is important to establish if new surgical techniques and implant designs are likely to have good long‐term outcomes 27 .…”

Extended Ischiopubic Fixation Using Porous Metal Augments In Cementless Acetabular Reconstruction During Revision Total Hip Arthroplasty

“…Won et al [21,22] indicated that there are compressive forces in the superior iliac rim and distractive forces at the inferior ischial rim around a non-press t acetabular shell, which would cause cephalad rotation. Moreover, Solomon et al [1] demonstrated inferior ischial and/or pubic screw xation reduced the proximal translation and sagittal rotation of the components in a radiostereometric analysis with revision THA. Jones et al [23] found that insu cient ischial xation in uenced the survival of custom ange acetabular components and a lack of inferior ischial xation predisposed the components to fail.…”

“…In the presence of a massive acetabular bone defect in the setting of revision total hip arthroplasty (THA), the primary stability of a hemispheric cementless cup is typically achieved via 3-point xation given that the continuity of the acetabular rim no longer exists and rim xation is thus not feasible [1][2][3]. A jumbo cup is often used to span the enlarged cavity and to reach 3 bony points located at the iliac and ischiopubic segments of a hemipelvis, thereby maintaining initial stability of the acetabular component [2].…”

“…While options exist to reconstruct the iliac supportive point, including the use of "doming" or " ying buttress" techniques [4] with metal augments or structural allografting, no good methods currently exist to reconstruct supportive ischiopubic points and facilitate "3-point xation". Jenkins et al [4] and Solomon et al [1] strongly recommended routinely driving multiple zone 3 screws into the inferior hemipelvis to improve the ischial and/or pubic xation of the component in cases where major bone loss was identi ed. Unfortunately, in the presence of bone loss, inferior screws do not always achieve good bony purchase.…”

Titanium cage reconstruction of acetabular defects in revision hip arthroplasty results in favourable outcomes: up to 17 years follow-up

“…Although the initial studies have been reported high success rates in acetabular reconstruction with tantalum cages and attributing their superior biologic fixation properties, subsequent long-term follow-up showed less favourable outcomes. 7 The authors have stated that the old problem of translation and rotation may still occur if the primary fixation of the component is not adequate. The threshold of >1 mm proximal translation within 2 years is likely to a consequent 90% loosening rate.…”