High rate of failure of impaction grafting in large acetabular defects

Abstract

We reviewed the results of 71 revisions of the acetabular component in total hip replacement, using impaction of bone allograft. The mean follow-up was 7.2 years (1.6 to 9.7). All patients were assessed according to the American Academy of Orthopedic Surgeons (AAOS) classification of bone loss, the amount of bone graft required, thickness of the graft layer, signs of graft incorporation and use of augmentation. A total of 20 acetabular components required re-revision for aseptic loosening, giving an overall survival of 72% (95% CI, 54.4 to 80.5). Of these failures, 14 (70%) had an AAOS type III or IV bone defect. In the failed group, poor radiological and histological graft incorporation was seen. These results suggest that impaction allografting in acetabular revision with severe bone defects may have poorer results than have previously been reported.

THA Revisions Using Impaction Allografting With Mesh Is Durable for Medial but Not Lateral Acetabular Defects

“…Rigby et al [27] and Van Haaren et al [40] also report poor results in patients with these large segmental defects. Rigby et al explain that the mechanism of failure of these cups consisted of movement and rotation of the cup/cement composite within the graft.…”

“…Low rates of aseptic loosening at different followups have been reported using this technique (Table 6). However, other series also report cup migration and bone graft resorption after IBG in revision surgery when used for large segmental defects [27,40]. We therefore evaluated patients undergoing IBG and a cemented cup to determine (1) the frequency with which the hip center could be restored in hips with Paprosky 3A and 3B defects and in hips with or without the use of metallic mesh during surgery; (2) survivorship of IBG acetabular revision reconstructions in patients with severe Paprosky 3A and 3B defects; and (3) risk factors for failure of the reconstruction, including the use of mesh and defect severity (3A versus 3B).…”

“…Another possible explanation for this failure rate in this series could be that in large segmental defects, the absence of superior bony support leads to a large amount of bone graft being placed at the most loaded area above the acetabular component. Owing to insufficient support for the bone graft, it is likely that micromovement of the prosthesis results in implant failure [40]. RSA studies have shown that almost all impacted sockets migrate in the postoperative period, although the rate of migration decreases with time.…”

“…However, cup migration and bone graft resorption are some of the limitations after IBG in revision surgery when used for large segmental defects despite the use of medial and lateral stainless steel meshes specifically designed to reconstruct segmental bone loss [12,15,27,40]. Because of these concerns, the precise role of IBG as well as the use of mesh (and the kinds of defects for which mesh does not work well) in this setting remains unknown.…”

Custom Acetabular Cages Offer Stable Fixation and Improved Hip Scores for Revision THA With Severe Bone Defects

“…Oversized hemispheric cups have shown good results [9]; however, the extent or geometry of the acetabular bone loss may preclude this option in the presence of more-severe bone defects [12]. Impaction grafting techniques may be inadequate for stabilizing pelvic discontinuity and do not typically provide adequate acetabular component stability in cases in which major portions of the anterior and posterior columns are absent [30,34,35]. Even conventional off-the-shelf cages with structural allografts have had reported relatively high rates of short-and medium-term mechanical failures (from 12.5% to 37.5%) [11,13,23,28,29,31,37].…”