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Hips with severe bone loss amenable to reconstruction with 3-D printed implants
Reconstruction techniques have improved for severely compromised hips, but consensus is needed on how to best treat severe bone loss, a presenter noted.
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Use of 3-D printed models to create individualized orthopaedic implants provides an alternative for surgeons who perform revision total hip arthroplasty in patients with severe bone loss, according to a presentation at the Current Concepts in Joint Replacement Spring Meeting.
“Individual implants represent yet another tool for the reconstructive surgeon,” Thorsten Gehrke, MD, of Helios ENDO-Klinik in Hamburg, Germany,told Orthopaedics Today Europe. “These devices can be helpful in situations of catastrophic bone loss where everything else does not work,” he said.
Individual implants
In his presentation, Gehrke noted the use of jumbo cups, cup-cage systems and cup rings can usually address the problems associated with Paprosky classification type 3A and type 3B bone loss. However, he said 3B defects with pelvic discontinuity can cause more extensive problems that cannot be corrected by cup-cages and rings because these implants do not provide posterior support. Furthermore, he said, although trabecular metal designs can improve results compared to cup-cages, these may also fail when used in extreme cases of bone loss.
According to Gehrke, the aMace acetabular revision system (Mobelife, Materialise), which is based on the patient’s defect according to Paprosky’s classification, can help detect good bone quality. It allows for preoperative planning based on CT, which helps with reconstruction of the anatomical center of rotation, and provides proposals to the surgeon, regarding screw positioning, and drill templates that provide the best direction and length of drilling.
“[You] have to remove, sometimes, a little bit of bone [to] fit the implant better into the pelvis and, if the trial is fitting well, then you can put in the definite implant,” Gehrke said.
Despite the advantages of the individual implant, he noted its biggest disadvantage is its expense.
“It has many advantages, but also disadvantages, mainly the price because the reimbursement does not cover the implant cost, at least in Germany,” Gehrke said.
Longer-term results needed
According to Gehrke, there are no mid- to long-term results available for individual implants used in reconstructive surgery in situations that involve catastrophic bone loss, despite evidence for performance of these implants in consecutive case series.
He noted it is a technically challenging situation when patients must undergo re-revision after an acetabular component used in revision total hip arthroplasty fails.
“Difficult cases with pelvic discontinuity require reconstruction of the acetabulum with traditional, but often suboptimal devices, especially if the pelvic discontinuity is combined with the Paprosky type 3B,” Gehrke told Orthopaedics Today Europe.
“There is still no consensus regarding the best option for reconstructing hips with severe bone loss,” Gehrke said. “Although the introduction of ultraporous metals has significantly increased the surgeon’s ability to reconstruct severely compromised hips, there remain some that cannot be managed readily using cups, augments or cages. In such situations, custom acetabular components may be required.” – by Casey Tingle
- Reference:
- Gehrke T. Paper #101. Presented at: Current Concepts in Joint Replacement Spring Meeting; May 22-25, 2016; Las Vegas.
- For more information:
- Thorsten Gehrke, MD, can be reached at Helios ENDO-Klinik Hamburg, Holstenstrasse 2, 22767 Hamburg, Germany; email: thorsten.gehrke@helios-kliniken.de.
Disclosure: Gehrke reports he receives fees for consulting and speaking from Waldemar Link GmbH & Co.