Arthroplasty Today - 2026-04-01 - Case Reports; Journal Article
Systemic Cobalt Toxicity Secondary to Tibial Component Malpositioning in Bilateral Primary Total Knee Arthroplasties.
Vallabhaneni N, Gates K, Rainey JP, Gililland JM, Archibeck MJ, Anderson LA
Topics
Key Takeaway
Excessive posterior tibial slope causing flexion gap instability produced the highest reported serum cobalt and chromium levels in primary TKA literature, with systemic toxicity manifesting as cognitive impairment, neuropathy, and cardiac symptoms nearly a decade postoperatively.
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Summary
This case report describes systemic cobalt toxicity in a patient with bilateral primary TKAs where excessive posterior tibial slope generated flexion gap instability and accelerated polyethylene and baseplate wear. Serum cobalt and chromium levels exceeded any previously reported values for primary TKA. Revision surgery confirmed polyethylene and baseplate wear with metallic debris and bone loss consistent with the implant malalignment mechanism.
Key Limitation
Single case report with no quantified tibial slope measurement, no pre-revision serum metal level trend data, and no post-revision toxicity resolution data, making it impossible to establish dose-response relationships or define actionable surveillance thresholds.
Original Abstract
Metallosis and systemic metal toxicity are uncommon complications in modern total joint arthroplasty, typically linked to metal-on-metal hip articulations. We present a case of systemic cobalt toxicity following bilateral total knee arthroplasties (TKAs), where excessive posterior tibial slope caused flexion gap instability and polyethylene wear with subsequent metallic debris release. This patient developed cognitive impairment, neuropathy, and cardiac symptoms nearly a decade after surgery, with the highest serum cobalt and chromium levels reported in literature for primary TKAs. At revision, polyethylene and baseplate wear with metallic debris and bone loss were present. Surgeons should remain vigilant for metallosis and systemic toxicity in painful or unstable TKAs with polyethylene wear from component malalignment or instability. Further studies are needed to define surveillance strategies and management guidelines.