Salvaged Failed Roof Rings and Antiprotrusion Cages: Surgical Options and Implant Survival

Abstract

Failed acetabular reinforcement rings (ARR) (roof rings and antiprotrusion cages) may require another ARR reconstruction or another type of acetabular device with or without a bone graft. The purpose of this study was to propose surgical options for salvage of failed ARRs and to compare the failure rate of each surgical option. We reviewed 33 first ARRs (12 roof rings and 21 antiprotrusion cages) which were revised and converted to a new acetabular reconstruction. Operative reports, radiographs, and clinical data were evaluated. Minimum follow-up was 24 months (average 57 months; range 24-209 months). 33 failed first ARRs were converted to one of three types of acetabular reconstruction, Trabecular Metal (TM) cup in 14, cup-cage in 7 and a second ARR in 12. The TM cup group (TM cup and cup-cage) had a significantly longer survival than the second ARR group (P = 0.025) on log-rank analysis. Treatment of a failed first ARR by a TM cup and a cup-cage provides better results when compared to treatment by a second ARR. Restoration of bone stock is the main factor in determining whether a TM cup or cup-cage rather than another conventional ARR can be used.