Tag Archive | tantalum

Complex Reconstructions Call for Creative Solutions

Metastatic disease around the acetabulum often leads to patients needing total hip arthroplasty (THA), plus supplementary acetabular reconstruction. Traditional methods such as the Harrington reconstruction technique have shown good short-term outcomes, but there are concerns that a cemented acetabular component in this setting is at risk for failure in the longer term. Newer approaches, such as using cementless tantalum acetabular components with augments, have also shown promise. Houdek et al. compared these 2 approaches and report the findings in the July 15, 2020 issue of The Journal.

The authors followed 115 patients who underwent THA for metastatic disease at 2 tertiary sarcoma centers, with a mean 4-year follow-up among surviving patients. They compared the outcomes of 78 Harrington reconstructions with those of 37 tantalum reconstructions, with surgeons at each center exclusively performing 1 of the 2 techniques. The cohorts were comparable at baseline regarding age, sex, severity of systemic disease and acetabular defects, and pelvic discontinuity. Functional outcomes improved in both groups, but there were no significant between-group differences. The main statistical finding of the study was that a higher percentage of patients in the Harrington reconstruction group (27%) needed a reoperation than those in the tantalum group (8%), with a hazard ratio of 4.59 (p=0.003).

Historically, there has been an understandable lack of long-term follow-up in this fragile patient population; 94 of the 115 patients in this study died of systemic disease progression at an average of 16 months after surgery. Overall patient survival was only 34% at 2 years and 15% at 10 years. Despite these grim mortality numbers, Houdek et al. claim that with advances in treatments for metastatic cancer, patients are living longer and therefore may benefit from more durable acetabular reconstructions.

This study leaves unanswered the question of whether the theoretic advantage of bony ingrowth with tantalum is what accounted for the decreased reoperation rates. As Albert Aboulafia, MD notes in his Commentary on this study, the authors did not review radiographs or postmortem histology to look for evidence of osseointegration. But Houdek et al. do present a potential avenue for further investigation. And what remains clear is that metastatic disease around the hip is a complex problem, and that we as surgeons should continue to investigate promising treatment strategies to improve patient outcomes (even if only palliative) and enhance biological fixation.

Click here for a 4-minute video in which co-author Matthew Houdek explains the rationale for this study.

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

Are Tantalum Hip Implants Safe?

I have been told that daytime TV is punctuated by a continual stream of ads for personal-injury lawyers asking if you have been injured by a particular medication or medical device.  Since 2002, billions of dollars have been paid out in lawsuits over metal-on-metal hip replacements containing cobalt and/or chromium, the “loose” ions of which increase the risk for aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL)—which are sometimes referred to as “pseudotumors.” So orthopaedic surgeons understandably want to know more about the potential long-term implications of newer metal technologies such as tantalum.

“Trabecular Metal” is a trade name for tantalum-based bone-ingrowth material that is now quite common in acetabular cups and revision shells used for total hip arthroplasty (THA). In the March 4, 2020 issue of the The Journal, Brüggemann et al. investigated the safety of these tantalum components. They retrospectively reviewed blood tantalum levels in 30 patients who underwent primary THA with no tantalum components, 30 patients who received a tantalum cup during a primary THA, and 84 patients who received a tantalum shell during a revision. Tantalum levels in 59 blood-donor volunteers served as controls. The authors also measured subsets of lymphocytes (CD8+ and CD4+ T-cells) that are thought to be associated with the immunologic cascade causing ALVAL.

At an average follow-up of 4 years, Brüggemann et al. found that median tantalum concentrations were 0.051 µg/L  in those receiving primary tantalum implants and 0.05 µg/L in those receiving primary implants without tantalum. (The “detection limit” for tantalum used in this study was 0.05 µg/L.) Patients receiving revision tantalum shells had median serum tantalum levels of 0.091 µg/L.  Time since surgery did not affect tantalum levels.

The authors also found a weak negative correlation between increased tantalum concentration and lower concentrations of CD8+ T-cells. Clinically, none of the hips in this series was deemed loose, and the Harris hip scores among all subjects were good to excellent.

It seems that with stable tantalum implants, any increase in serum concentrations of tantalum is small, but we don’t yet know the longer-term implications of these small increases. While it’s also reassuring that the lymphocyte activation associated with ALVAL does not seem to occur with these tantalum implants, I agree with the authors’ conclusion that this study “cannot exclude the possibility that even low tantalum concentrations confer a risk to patients’ health.”  Clearly, longer-term studies are needed.

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media