Removal of a cementless acetabular component

REMOVAL OF A CEMENTLESS ACETABULAR COMPONENT

Removal of a well-fixed, porous, cementless acetabular component is difficult and may result in removal of additional bone stock with the need for a larger implant for reconstruction. When the prior implant has been placed against the medial wall of the acetabulum, it is possible that a complete medial segmental bony deficit would result from the extraction. If the reason for revision of the component is malposition with recurrent dislocation, exchanging the polyethylene liner for one with a larger lip or degree of offset may suffice. If not, revision of the ingrown metal backing is done. Our preferred technique for removal of well-fixed porous acetabular components involves an acetabular centering device attached to a rotating handle and blades of varying diameters to disrupt the bone-implant interface. Mitchell et al. reported 31 revisions with this technique, resulting in minimal bone loss and 5 minutes of operative time for cup removal.

TECHNIQUE

■ If no screws are present, leave the liner in place; otherwise,remove the liner to allow screw removal and replaceit to accommodate the centering device. If the liner isexcessively worn or damaged, a trial liner can be used. Atrial bipolar head that matches the inner diameter of thecup can be used to center the blade in a resurfacingacetabular component for which appropriately sized trialliners are not available.

■ Employing a centering device of a diameter matching theinternal diameter of the liner, use a short blade initially todisrupt the interface between the implant and bone (Fig.3-151A). The outer diameter of the implant must beknown to choose the appropriate blade.

■ After a channel has been made by the short blade circumferentially,use a longer blade to disrupt any remainingbone ingrowth at the dome of the implant.

■ Lift the implant out between the blade and centeringdevice (Fig. 3-151B).

Note: this article comes from CAMPBELL’S OPERATIVE ORTHOPAEDICS by S. Terry Canale James H. Beaty.

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