A systematic review and meta-analysis of cases of prosthetic hip-associated cobalt toxicity in patients with prosthetic hip ceramic bearing fractures subsequently revised to metal-on-polyethylene implants.

Abstract

Prosthetic hip-associated cobalt toxicity (PHACT) remains a rare but serious complication, potentially leading to missed diagnoses and delayed treatment. This systematic review explores cases of PHACT associated with fractured ceramic bearing followed by revision surgery with metal-on-polyethylene implants. Notably, patients in this subgroup often exhibited earlier symptom onset and elevated cobalt ion levels. Through a systematic review, we aim to explore and summarise the most common symptoms and clinical outcomes associated with PHACT among this specific patient subgroup. Our focus is on identifying patterns of systemic symptoms and associated clinical outcomes. Adhering to PRISMA guidelines, we conducted a structured search across PubMed, Medline, and Scopus databases. Inclusion criteria comprised published case reports or case series detailing PHACT cases after ceramic bearing fractures revised to metal-on-polyethylene bearings. Over 30 cases were identified, and their clinical presentations and outcomes were analysed. The majority of PHACT cases in this cohort presented with cardiovascular manifestations (cardiomyopathy, cardiogenic shock, and heart failure), neurological symptoms (visual impairment, sensorineural hearing loss, and cognitive impairment), and endocrine dysfunction (thyroid dysfunction). Various atypical symptoms were also observed. PHACT within this patient group presents insidiously with diverse, sometimes overlapping, systemic symptoms. The study highlights the potential for missed diagnoses due to the lack of apparent risk factors or related medical history. This review strongly advocates for proactive, registry data-driven identification of at-risk patients, as well as the opportunity for follow-up assessment and cobalt level monitoring. This study also highlights the importance of ceramic-on-polyethylene based revision in cases of ceramic bearing fractures.