Abstract
The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone.
The acetabular bed is prepared. If there is less than 2 mm medial bone stock, then morsellised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilization, then a trabecular metal (TM) cup is indicated.
Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring.
We have used trabecular metal augments in 46 acetabular revisions in conjunction with a TM cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions.
We still feel there is a role for structurally acceptable allografts in young patients who are likely going to require another revision. Our long term results have demonstrated that bone stock is restored facilitating the re-revision.
