Review Question - QID 5508

Paprosky Type 3B acetabular bone defects describes significant acetabular bone loss, with pelvic discontinuity. Type 3 defects often require reconstruction cages (as seen in Figure A) or acetabular distraction techniques to treat severe bone loss with an associated pelvic discontinuity.

Deficient acetabular bone stock poses a technical challenge in hip arthroplasty surgery. Paprosky classification for acetabular bone loss to helps guide treatment for revision total hip arthroplasty. The classification is as follows:

Type 1: Minimal deformity, intact rim
Type 2A: Superior bone lysis with intact superior rim
Type 2B: Absent superior rim, superolateral migration
Type 2C: Localized destruction of medial wall
Type 3A: Significant bone loss, superolateral cup migration
Type 3B: Significant bone loss, pelvic discontinuity

Sheth et al. reviewed acetabular bone loss in revision total hip arthroplasty. They state that Paprosky Type 1 and 2 defects can usually be managed with porous-coated hemisphere cup secured with screws. Type 3 defects require reconstruction cages to protect with cups and structural augments or custom triflange implants.

Taunton et al. investigated clinical outcomes and cost-effectiveness of using a custom triflange acetabular component to treat pelvic discontinuity in revision THA. They found satisfactory clinical outcomes (81% had a stable triflange component with healed pelvic discontinuity) and cost equivalence with Trabecular Metal cup-cage constructs.

Figure A shows a lateral image of the pelvis with a reconstruction cage and cup construct. Illustration A shows an illustration of the Paprosky classification. Illustration B shows a table of the Saleh/Gross classification. Illustration C shows a table of the AAOS classification.

Incorrect Answers:
Answer 1: Minimal deformity, intact rim = Paprosky Type 1 defects. These can be treated with porous-coated hemisphere cup secured with screws.
Answer 2: Superior bone lysis with intact superior rim = Paprosky Type 2A defect. This can be treated with porous-coated hemisphere cup secured with screws.
Answer 3: Localized acetabular destruction of medial wall = Paprosky Type 2C defect. This can be treated with porous-coated hemisphere cup secured with screws +/- bone grafting.
Answer 4: Absent superior acetabular rim, superolateral migration = Paprosky Type 2B defect. This can be treated with porous-coated hemisphere cup secured with screws, jumbo cups +/- metal augments +/- bone grafting.