Does the Ingrowth Surface Make a Difference? A Retrieval Study of 423 Cementless Acetabular Components

The effect of factors such as design, alloy and coating type on bony or fibrous tissue ingrowth was evaluated in a study of 423 retrieved cementless acetabular shells representing 16 shell designs. Small-beaded (250 μm) porous coatings, either with or without hydroxyapatite (HA) coatings, proved to be the superior porous surface for bone ingrowth. Small-beaded shells that were Duofix coated had predominantly fibrous tissue ingrowth. In addition to bead size, alloy type and surface type have significant effect on bone ingrowth. In contrast, there is no significant association between bone ingrowth and time in situ, with most bone ingrowth occurring early. Although roughened, press-fit shells have acceptable clinical and Registry data, they showed some of the lowest ingrowth/ongrowth scores of all the shells tested.