[Update on metal-on-metal hip joints]

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Adverse event monitoring

Context:

• Metal-on-metal (MoM) hip implants are associated with potential local and systemic adverse events.
• The clinical significance and prevalence of these metal-associated issues remain under investigation.
• Implant characteristics and patient factors influence adverse event development.

Purpose:

• To review the risk factors associated with adverse events in metal-on-metal hip implants.
• To discuss the clinical relevance and influencing factors of metal-associated problems.
• To provide guidance on the use of MoM hip implants based on head size and type.

Summary:

• While data on risk factors for adverse events with metal-on-metal (MoM) hip implants are increasing, their prevalence and clinical relevance are debated.
• Implant type, position, and patient-specific factors can affect outcomes.
• Small MoM heads (≤32 mm) and certain resurfacing arthroplasties demonstrate good long-term survival.
• Large head MoM implants (>36 mm) are advised against due to unsatisfactory results.

Impact:

• Informs clinical decision-making regarding the selection of MoM hip implants.
• Highlights the importance of considering implant size and type for patient outcomes.
• Contributes to the ongoing debate on the safety and efficacy of MoM hip arthroplasty.