Structural Allograft Supporting a Trabecular Metal Cup Provides Durable Results in Complex Revision Arthroplasty

Abstract

BackgroundRevision total hip arthroplasty (THA) is challenging specially in the presence of severe acetabular bone deficiency. We report the use of a highly porous revision shell augmented by structural allograft to provide structural support and coverage to the acetabular component. MethodsWe identified 56 patients (58 hips) undergoing revision THA, where a trabecular metal revision cup was supported by structural allograft. Mean follow-up was 5.4 years (range 2-12 years). Preoperatively acetabular bone defects were classified as Paprosky 2A in 6 hips (10%), 2B in 12 hips (21%), 2C in 12 hips (21%), 3A in 11 hips (19%), and 3B in 17 hips (29%). Structural allograft configuration was classified as type 1 (flying buttress) in 13 hips, type 2 (dome support) in 23 hips, and type 3 (footings) in 17 hips, with 5 hips having combined configurations. ResultsAll hips showed evidence of union between the allograft and host bone at latest follow-up, 14 hips had partial resorption of the allograft that did not affect cup stability. Three acetabular components demonstrated failure of ingrowth. Survivorship-free from radiographic acetabular loosening as end point was 94% at 5 years. The 5-year survivorship with revision for any reason as end point was 90%. ConclusionTrabecular metal shells combined with structural bone allograft in revision THA demonstrate excellent midterm survival, with 94% of acetabular components obtaining stable union onto host bone at 5 years. Allograft restored bone stock with minimal resorption, and when it occurred did not alter the survivorship of the acetabular component.