Mechanical Considerations and Clinical Implications of Joint Arthroplasty Metallosis

The treatment for osteoarthritis (OA) often requires total joint arthroplasty (TJA) when less invasive approaches fail. The annual incidence of TJA is rising. Metal-on-metal (MoM) hip and knee implants were widely used for TJA in the past, but complications have led to their decline. Many patients received MoM implants, and the complications affect many to this day. Metallosis, the accumulation of metal debris in the body, is one of the most dangerous problems associated with TJA and can cause many severe local and systemic effects, including inflammation, pain, and organ dysfunction. The metal release causing metallosis is multifactorial, including wear on the articulating surfaces and trunnionosis. Key risk factors include implant design, taper topography, head size, material properties, and patient factors. Metallosis can present clinically with local pain and inflammation, and with severe systemic effects such as cardiomyopathy and neuropsychiatric symptoms. Adverse local tissue reactions and systemic cobaltism are significant concerns that necessitate early detection and intervention. Biomarkers revolving around cobalt and chromium ion levels are useful for screening and monitoring patients with signs of metallosis. This review aims to provide primary care physicians and orthopedic surgeons with a succinct, updated understanding of the mechanisms, risk factors, and clinical implications of metallosis to better manage TJA patients. Advancements in implant materials provide opportunities to enhance future patient outcomes and reduce the incidence of metallosis, thus promoting safer and more effective TJA.