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Systemic release of cobalt and chromium after uncemented total hip replacement
D N Kreibich1, C G Moran, H T Delves
1Freeman Hospital, Newcastle upon Tyne and Southampton General Hospital, England.
Insights
Elevated serum cobalt levels indicate aseptic loosening in hip arthroplasty patients. This finding suggests cobalt testing can help identify loose implants after porous-coated hip replacement surgery.
Area of Science:
- Orthopedic Surgery
- Biomaterials Science
- Clinical Chemistry
Background:
- Uncemented porous-coated arthroplasty is a common procedure.
- Aseptic loosening is a significant complication.
- Metal ion release from implants is a concern.
Purpose of the Study:
- To measure serum cobalt and chromium levels in patients with uncemented porous-coated hip arthroplasty.
- To determine if elevated metal ion levels correlate with aseptic loosening.
- To assess the diagnostic value of serum cobalt for detecting loose components.
Main Methods:
- Serum samples were collected from three groups: revision for aseptic loosening, stable arthroplasty, and arthritis awaiting hip replacement.
- Atomic absorption spectrophotometry was used for metal ion analysis.
- Statistical analysis was performed to compare groups and calculate relative risk.
Main Results:
- Serum cobalt levels were significantly elevated in patients with aseptic loosening compared to stable implants and controls (p < 0.05).
- Serum chromium levels did not show a significant difference between groups.
- A serum cobalt level > 9.0 nmol/l was associated with a relative risk of 2.8 for component loosening.
Conclusions:
- Serum cobalt elevation is a potential biomarker for aseptic loosening in uncemented porous-coated hip arthroplasty.
- Serum cobalt testing may aid in the diagnosis of implant instability.
- Further research is warranted to validate these findings and establish clinical guidelines.
Abstract:
We measured the levels of cobalt and chromium in the serum in three groups of patients after uncemented porous-coated arthroplasty. Group 1 consisted of 14 consecutive patients undergoing revision for aseptic loosening. Group 2 comprised 14 matched patients in whom the arthroplasty was stable and group 3 was 14 similarly matched patients with arthritis awaiting hip replacement. Specimens were analysed using atomic absorption spectrophotometry. Aseptic loosening of a component resulted in a significant elevation of serum cobalt (p < 0.05), but not of serum chromium. The relative risk of a component being loose, if the patient had a serum cobalt greater than 9.0 nmol/l, was 2.8.