Today’s topic: implants for revision THA in the setting of acetabular bone loss.
It might help to review the Paprosky classification. However, there is not a 1:1 relationship where a certain class (ex: type IIB) = specific implant. Implant choice depends on the pattern of bone loss as well as surgeon preference and patient characteristics.
What I learned today
I’m aiming for a rapid review here, not an in-depth discussion of each implant. Ain’t nobody got time for that.
Jumbo cup
These basically look like a regular cup, but bigger. Preferred for Paprosky type I or II defects. You need decent bony support and probably some screws.
Augment
Used for type II, IIIA, or IIIB defects. The final augment is first screwed to the bone with a trial cup in place. Then the augment and final shell are cemented together, but the interface with the bone is a non-cemented, porous coating. Season to taste with more screws.
Cup-cage
Suitable for Type IIIA and IIIB bone loss with pelvic discontinuity. The “cage” spans the ilioischial connection, providing initial stability, while the cup may allow for non-cemented biologic fixation over time.
Triflange
In contrast to the cup-cage, a triflange spans the ilium, ischium, and pubis (hence, tri). It’s also used for type IIIA or IIIB defects where a “defect bridging” technique is required instead of “defect matching.”
These implants are custom-made using 3D CT scans of the patient’s pelvis. The benefit of such customization has to be weighed against cost factors and size, however.
Double-cup
This is a newer technique; the JOA paper from 2017 calls it “novel” in the title. Basically, instead of using a custom triflange or cup-cage, you can use a trabecular metal revision shell as a buttress augment.
In the 20 patient case series, 25% suffered a dislocation, with no revisions for acetabular loosening and no cases of aseptic loosening at 2 year follow-up — make of that what you will.
Ice cream cone prosthesis
This is a rare technique but I wanted to include it for the sake of being gnarly. It was described to me as being more of a salvage, tumor scenario prosthesis. You should google some photos for fun because I’m too lazy to include them. Byeeee.
Sources
Sheth NP, Nelson CL, Springer BD, Fehring TK, Paprosky WG. Acetabular bone loss in revision total hip arthroplasty: evaluation and management. J Am Acad Orthop Surg. 2013 Mar;21(3):128-39. doi: 10.5435/JAAOS-21-03-128. PMID: 23457063.
Webb JE, McGill RJ, Palumbo BT, Moschetti WE, Estok DM. The Double-Cup Construct: A Novel Treatment Strategy for the Management of Paprosky IIIA and IIIB Acetabular Defects. J Arthroplasty. 2017 Sep;32(9S):S225-S231. doi: 10.1016/j.arth.2017.04.017. Epub 2017 Apr 23. PMID: 28529110.