The Fate of Grafting Acetabular Defects During Revision Total Hip Arthroplasty

Abstract

Background Acetabular defects are frequently grafted during revision THA. Previous studies using plain radiographs report high rates of graft incorporation. However, given plain radiographs underestimate osteolysis, it is unclear whether plain radiographs adequately reflect graft fill or incorporation. Questions/purposes We determined if (1) graft fill; or (2) incorporation (measured as graft-bone contact) differed with complete revision and grafting compared to liner exchange and grafting; (3) defect fill and incorporation could be assessed on plain radiographs; and (4) the cost of bone grafting differed with these two procedures. Methods We identified 40 patients who underwent revision THA for aseptic loosening or polyethylene wear and osteolysis, either with retention of a well-fixed cup or complete acetabular revision in which bone graft was used. Lesion size, percent fill, and graft healing was quantified from CT scans. A limited cost analysis was performed using the current hospital costs for implants, bone grafts, and bone graft substitutes. The minimum followup was 1 year (mean, 4.8 years; range, 1-11 years). Results The average defect fill was 30% (range, 0%-81%). The average percent of healing to host bone was 24% (range, 0-66%). Complete revisions had a higher percent defect fill compared to head/liner changes (47% versus 17%) as well as a higher degree of graft healing to host bone compared to head/liner changes (36% versus 14%). High resolution CT demonstrated lower percentages of defect fill and graft healing than previous reports based on plain radiographs. Bone grafting costs exceeded implant costs in the head/liner exchange group; however, the overall cost was higher in the complete revision group. Conclusions Higher degrees of defect fill and healing were seen with complete revisions compared to head/liner exchanges. Compared to CT scans, plain radiograph assessment tended to overestimate defect fill and healing. Level of Evidence Level III, therapeutic study. See the guidelines online for a complete description of level of evidence.

Large Acetabular Defects Can be Managed with Cementless Revision Components

“…Fourth, our radiographic measurements were made using plain radiographs which may underestimate the preoperative size of defects and overestimate the degree of graft incorporation. Mall et al noted only 47% of graft fill and 36% graft healing in acetabular osteolytic defects following complete component revision using postoperative CT scan analysis [25]. This is much lower than previously reported rates of 90-100% using plain radiographs for analysis [26,40].…”

“…Mehendale et al suggested that complete radiographic incorporation was only present with 40% of patients treated with irradiated bone [30]. Mall et al have recently reported a 30% average defect fill and 24% average bone healing rate using CT scans for evaluation, with lower graft incorporation rates among patients treated with impaction grafting behind retained acetabular components than during cases where component revision had been accomplished [25].…”

Revision Total Hip Arthroplasty with Retained Acetabular Component

“…In patients with osteolysis detected prior to acetabular component loosening, retention of the acetabular component has multiple advantages, including decreased morbidity and preservation of pelvic bone stock [2][3][4] . Structurally stable lytic defects can be addressed with bonegrafting through screw holes or around the periphery of a wellfixed acetabular component 5 . Aggressive debridement and curettage of these lesions in combination with exchange of the Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work.…”

“…polyethylene liner to a highly cross-linked polyethylene liner may be sufficient to halt the lytic process [5][6][7] . Proponents of this approach reserve full acetabular revision for patients with a loose or malpositioned acetabular component.…”

“…On the cross-table lateral radiograph, acetabular component anteversion was measured as the angle between the long axis of the acetabular opening and a line perpendicular to the long axis of the body 12 . The anteversion safe zone for this study was defined as 5°to 25°1 5 .…”