Options for Managing Acetabular Bone Loss in Failed THA
In patients who have a failed THA, acetabular bone loss may be a significant problem. Selecting the optimal management strategy is essential for a successful outcome.
During the Philadelphia Revision Course, four speakers discussed various management options for acetabular bone loss and their clinical indications:
- Wayne G. Paprosky, MD, of Midwest Orthopaedics at Rush University spoke about bulk allografts
- Charles L. Nelson, MD, of the University of Pennsylvania about porous metal augments
- Gwo-Chin Lee, MD, of the University of Pennsylvania about acetabular reconstruction cages
- Adolph V. Lombardi Jr., MD, FACS, of Ohio State University about custom porous-coated cups
According to Dr. Paprosky, the success of bulk allografts depends on the type of acetabular bone deficiency and on patient age.
- The gold-standard allograft treatment, a hemispherical porous-coated cup with or without a cancellous allograft, works well for most type I and type II defects.
- Type III defects, which have more than 3 cm of superior or lateral migration, are more complicated. Type IIIa does not involve ischial lysis, whereas type IIIb does.
- In Dr. Paprosky’s opinion, bulk allografts are mainly useful for type IIIa patients who are relatively young, or for those who have a massive defect that cannot be reconstructed using augments.
- For older type IIIa patients and for type IIIb patients, he recommended porous metal augments instead of bulk allografts.
Porous Metal Augments
Dr. Nelson discussed the use of porous metal augments in acetabular reconstruction. He agreed with Dr. Paprosky that bulk allografts may be used in certain patients and can facilitate restoration of bone stock.
He supported the use of porous metal augments in patients with severe bone loss because they:
- Provide consistent strength, have good short- and intermediate-term outcomes
- Reduce surgical time
- Allow for intraoperative customization because of the range of sizes available
Their main disadvantage is that they only substitute for bone loss and they do not restore bone stock.
Acetabular Reconstruction Cages
Acetabular reconstruction cages are another option for severe bone loss such as pelvic discontinuity, for which conventional hemispherical cups are often ineffective.
Dr. Lee discussed anti-protrusio cages, mentioning their ability to confer stability and rigid fixation and to facilitate restoration of bone stock, independent of fracture healing.
However, they do not allow for biological fixation and may produce unpredictable results when used alone. More promising outcomes have been obtained using cages in combination with cups, bulk allografts, or morselized grafts.
Although standard cups, cages, and augments are appropriate for most patients with acetabular bone loss, certain catastrophic conditions may necessitate the use of custom cups.
Dr. Lombardi discussed several types of custom porous-coated cups that he had used in his practice:
- Custom hydroxyapatite triflange cup
- Metal-on-metal monoblock cobalt-chromium cup with titanium PPS coating
A custom triflange cup can be effective, with 65% of treated patients being revision-free at 2 years, at a cost comparable to that of a trabecular metal cup.
Click the links below to watch the presentations.
Dr. Paprosky’s presentation
Dr. Nelson’s presentation
Dr. Lombardi’s presentation
Dr. Lee’s presentation