Abstract
Several methods of treatment are available in the revision of loose acetabular components associated with significant bone loss. Jumbo cups are the preferred treatment for large acetabular defects with segmental and cavitary defects. By definition, a jumbo cup has a minimum diameter of 62 mm in women, 66 mm in men, or is greater than 10 mm larger than the normal contralateral acetabulum. They are easier to use and less expensive than cages, bulk supporting allografts, or custom cups. Proper technique is for bone to be moved, not removed. The acetabulum is reamed larger to gain more host-bone surface area. The acetabulum should then accommodate the large shell and maximise the shell host-bone contact for long-term biological fixation. The preferred shell is one with high porosity to maximise the potential area for bone ingrowth when less bone contact is present. At least 50% host-bone to shell contact is ideal but not mandatory. The larger surface area of a jumbo cup provides more opportunity for bone ingrowth. Therefore having an initially stable cup is more important than the amount of host-bone contact. Jumbo cups are only contraindicated in acetabulae that lack the superior lateral acetabulum and the posterior column. In that situation, fortunately uncommon, a cup/ cage reconstruction is used.
We reported a retrospective review of 690 acetabular revisions performed from 1986–2005. Jumbo cups were used in 196 (28%) of all the acetabular revisions and greater than 95% of the cases with large defects. This is the largest series or revisions with jumbo cups reported. Significant bony deficiencies were present; 68% were Paprosky type II and 25% were Paprosky type III. The average follow-up for the jumbo cups was ten years. Five revisions and two resection arthroplasties were performed for failure. The probability of survival of the jumbo cups was 98% at four years and 96% at 16 years.
Porous jumbo cup acetabular revision with supplemental screw fixation provides good to excellent intermediate- and long-term outcomes.
