Chromium in Wrist Implants: Benefits vs. Risks

randomized-controlled-trial PMID: 36177637

Chromium in Wrist Implants: Benefits vs. Risks

Quick Summary: This study tested two types of artificial wrist replacements made with chromium-containing materials in people with wrist arthritis not caused by rheumatoid disease. Both types improved pain and daily hand use after two years, but one led to higher chromium levels in the blood, and nearly one-third of patients needed more surgery due to problems like implant loosening or inflammation.

What The Research Found

Researchers compared two wrist implant types to see how well they worked for people with wrist pain from arthritis. The key focus was on how the implants affected wrist movement, stability, and any side effects, including chromium release from the metal parts.

Pain and Function Improved for Both: Patients in both groups reported less pain and better ability to use their hands for everyday tasks, like gripping or writing. Scores on standard hand function tests dropped significantly, meaning life got easier.
Movement Gains Varied: The Motec implant (made with metal-on-metal parts, including chromium) helped wrist bending and flexing more than the other. But the ReMotion implant (metal-on-plastic) improved forearm twisting better.
Chromium and Other Metals in Blood: The Motec group had much higher levels of chromium and cobalt in their blood—about three times more than the ReMotion group. This happens because the metal parts rub together, releasing tiny particles into the body.
Implant Stability Was Good: Using special X-ray tech, the study showed the implants moved very little (less than 1 mm) over two years, suggesting they stayed in place well. However, bone density around the implants didn't fully recover.
High Complication Rate: About 32% of patients faced serious issues, like painful swelling (synovitis) or loose parts, leading to follow-up surgeries. Two ReMotion implants were swapped for Motec due to loosening, and three Motec ones were changed to reduce metal rubbing.

Overall, both implants helped function and seemed stable short-term, but complications were common in non-rheumatoid wrists.

Study Details

Who was studied: 40 adults with wrist arthritis not linked to rheumatoid disease (like from wear-and-tear or injury). They were split evenly into two groups randomly.
How long: The trial followed patients for two years after surgery, with check-ins at 6 months, 1 year, and 2 years.
What they took: No pills or supplements—the "treatment" was surgery to replace the wrist joint. One group got the ReMotion implant (metal parts rubbing on plastic), the other got Motec (metal-on-metal, which includes chromium alloys). Chromium exposure came from implant wear, not diet.

What This Means For You

If you have severe wrist arthritis and are considering joint replacement surgery, this study shows these implants can reduce pain and boost hand use, helping with daily activities like cooking or typing. The Motec might give better wrist flexibility if rotation isn't your main issue, but watch for higher chromium levels, which could signal long-term risks like inflammation—ask your doctor about blood tests. ReMotion might suit if you need good forearm movement with less metal release. However, with one in three needing extra surgery, these aren't risk-free; they're best for tough cases under expert surgeons. Always discuss alternatives like therapy or fusion first, and choose a specialist center for monitoring.

Study Limitations

This research has some gaps that affect how we apply it:
- Small Group and Short Time: Only 40 people over two years—longer studies are needed to check if benefits or problems last 5–10 years.
- No Comparison to Other Options: It didn't test against non-surgery treatments, so we don't know if implants are always better.
- Specific to One Type of Arthritis: Results apply mainly to non-rheumatoid cases; rheumatoid patients might fare differently.
- Possible Bias: Doctors knew which implant was used, which could influence how they scored patient progress.
- Not About Diet: This is on chromium from implants, not food supplements—don't confuse it with nutrition advice.

For the latest on wrist implants and chromium risks, talk to a hand surgeon or check trusted health sites.

Key Findings

This randomized controlled trial found that both ReMotion (metal-on-polyethylene) and Motec (metal-on-metal, MoM) total wrist arthroplasties (TWAs) significantly improved wrist function and pain in patients with non-rheumatoid arthritis at two years. However, the MoM Motec group exhibited elevated blood chromium (Cr) and cobalt (Co) ion levels compared to the MoP ReMotion group. Migration analysis via RSA showed minimal movement (≤0.65 mm) for both implants, indicating stability, but BMD around radial components did not return to baseline. Alarmingly, 30% of patients required reoperation (2 ReMotion revisions for carpal loosening; 3 Motec revisions for synovitis).

Study Design

The study was a two-year RCT involving 40 patients with non-rheumatoid wrist arthritis, randomly assigned to ReMotion (MoP) or Motec (MoM) TWA. Outcomes included functional scores (PRWHE, DASH), radiological changes, RSA-measured implant migration, DXA-assessed BMD, and complication rates. Follow-up occurred at 0.5, 1, and 2 years post-surgery.

Dosage & Administration

Not applicable. Chromium levels were measured as a byproduct of implant wear in the MoM Motec group, not administered as a supplement.

Results & Efficacy

Functional Outcomes: Both groups showed significant improvements in PRWHE scores (p < 0.001), DASH scores, and pain (p < 0.05).
Mobility: Wrist motion improved only in the Motec group (p = 0.04), while forearm rotation improved only in the ReMotion group (p = 0.02).
Metal Ion Levels: Motec had higher median Cr (1.1 μg/L vs. 0.3 μg/L, p < 0.001) and Co (1.2 μg/L vs. 0.3 μg/L, p < 0.001) levels.
Implant Stability: RSA migration was low: ReMotion carpal (0.65 mm, 95% CI 0.26–1.12) and radial (0.27 mm, 95% CI 0.14–0.47); Motec metacarpal (0.32 mm, 95% CI 0.22–0.45) and radial (0.26 mm, 95% CI 0.20–0.34).
BMD: No recovery to baseline observed around radial components.
Complications: 13/40 patients (32.5%) required reoperation, including 2 ReMotion revisions for loosening and 3 Motec revisions for synovitis.

Limitations

Small sample size (n=40) and short two-year follow-up limit long-term conclusions.
No control group (e.g., non-implant treatments).
Demographics (age, sex) were not detailed in the summary.
Focus on non-rheumatoid wrists restricts generalizability.
Lack of blinding in functional assessments may introduce bias.

Clinical Relevance

For patients considering TWA, MoM implants like Motec may offer marginally better wrist mobility but carry risks of elevated Cr/Co levels and synovitis. MoP implants (ReMotion) show lower ion release but higher forearm rotation benefits. The high reoperation rate (32.5%) underscores the need for cautious use, specialist oversight, and further research to clarify long-term safety. Clinicians should monitor metal ion levels in MoM recipients and prioritize prospective registries to evaluate implant performance.

Note: This study evaluates chromium as a byproduct of MoM implants, not as a dietary supplement.