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Femoral, aseptic loosening of custom UKR prostheses due to various causes
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Researchers found a high rate of aseptic loosening and femoral component loosening at short-term follow-up for custom, medial compartment unicondylar knee replacement prostheses, according to study results published in the Journal of Arthroplasty and presented at a meeting.
“We found a relatively high rate of loosening, particularly with the femoral component in the short- to intermediate-term follow-up,” Carl T. Talmo, MD, vice chair of orthopedic research at New England Baptist Hospital and first author of the study, said at the meeting. “There were multiple potential sources of failure that could not be evaluated.”
In an interview with Orthopedics Today, Talmo said femoral component loosening is not a commonly reported failure mode in other types of unicondylar knee replacement (UKR), which led him to question if this issue is unique to this study or to the implant used. However, more research into critically larger numbers of these prostheses implanted by different surgeons at different institutions is needed to identify whether the implant is the weak link, he said.
“I cannot confirm through this study there is legitimately and definitively a problem with this implant or the process, but I do think it is our responsibility as orthopedic surgeons [who] are implanting this or doing research related to this, that we take a closer look,” Talmo said.
Talmo and colleagues studied patient data, demographics, risk factors, operative reports, clinical follow-up and radiographs in a retrospective review of 115 custom medial-compartment UKRs (ConforMIS) performed by a single surgeon in which the primary outcome measure studied was revision surgery. Secondary outcome measures included radiographic failure and clinically failed implants, Talmo said.
Results showed 29 UKRs failed, after which patients underwent either revision UKR or total knee replacement.
“There were 10 failures for aseptic loosening of the femoral component, eight for loosening of the tibial component, four for loosening of both, two for progression of osteoarthritis, four for infection and one due to a dislodged polyethylene insert,” Talmo said.
The relationship was not statistically significant between component loosening and side of the implant, range of motion, tibial insert thickness and patient age, gender or BMI, he said.
According to Talmo, future research should involve independent researchers with no industry sponsorship so there is no possibility of bias in the results.
“My [feeling] is I can only put forth the results that we have, and I hope that we get other reports that are not industry-sponsored because, whether there is a bias or not, we cannot extract that bias from someone who is looking at a publication,” he said. – by Casey Tingle
- References:
- Talmo CT, et al. J Arthroplasty. 2018;doi:10.1016/j.arth.2018.03.010.
- Talmo CT, et al. Paper 37. Presented at: American Association of Hip and Knee Surgeons Annual Meeting; Nov. 2-5, 2017; Dallas.
- For more information:
- Carl T. Talmo, MD, can be reached at 125 Parker Hill Ave., Roxbury Crossing, MA 02120; email: ctalmo@nebh.org.
Disclosure: Talmo reports no relevant financial disclosures.
Perspective
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C. Lowry Barnes, MD
The single-surgeon data are certainly different than my own experience and that of our multicenter study groupwith the same customized unicondylar implants. We have recently submitted a manuscript, still in review, in which eight surgeons enrolled 120 patients. At an average of just under 4 years follow-up, weve seen only two revisions (1.7%) related to the implant and an additional two related to disease progression. The revision rates and outcome scores weve seen compare favorably to published rates for other off-the-shelf implants.
The study results seen in our multicenter study have shown high patient satisfaction rates, high patient-reported outcome scores and low revision rates. This is obviously in marked contrast to the referenced report, and many variables could play a role. Hopefully, manuscript review by editors will help distinguish the differences, and I certainly hope both papers are critically reviewed.
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