By John T Williams1 and Elizabeth K Tissingh2

1T&O ST5, King’s College Hospital, London
2Orthopaedic Trauma Fellow, King’s Centre for Global and Health Partnerships, School of Population Health and Environmental Sciences, King’s College London

Corresponding author e-mail: [email protected]

Published 23rd August 2021

The global supply chain of cobalt has come under increasing scrutiny over the last five years in relation to exploitative and dangerous mining practices in parts of the Democratic Republic of Congo (DRC). There has been widely publicised criticism of electronics and vehicle manufacturers, the major international consumers, with resultant improvements in supply chain due diligence1.  As orthopaedic surgeons we are also large consumers of cobalt alloys, particularly in our arthroplasty components.  Together with our Congolese surgical colleagues, we explored how this affects us in the orthopaedic sector in our recent article published in The Lancet Planetary Health and how we can start to help2.

Two-thirds of the world’s cobalt is mined in the DRC3.  International demand is increasing, largely due to its use in the batteries and circuitry of mobile phones, computers and electric vehicles.  In the orthopaedic sector, cobalt has been a popular implant material since Dr Austin T Moore introduced his hip hemiarthroplasty stem in the 1940s.  Approximately 2,000 metric tonnes of cobalt is now used annually in prostheses across the world4 most notably in knee replacement components.

Cobalt-chromium alloys have excellent fatigue resistance and strength characteristics.  The formation of a corrosion-resistant chromium oxide layer and the additional strength imparted by forging means they are particularly suited to bearing surface applications.  According to our National Joint Registry, cobalt chromium knee replacements systems are consistently amongst the most commonly implanted in the UK. In hip arthroplasty, a wider variety of metals are used for the stem and acetabular components, but cobalt-chromium heads remain commonplace5.

Most of the cobalt mining in the DRC is regulated and on an industrial scale, but approximately 20% of production is from small ‘artisanal mines’, the majority of which are unregulated and unauthorised.  An Amnesty International report estimates a workforce of 150,000 artisanal miners, sometimes in dangerous and precarious circumstances.  Child labour is widely reported, as is mine tunnel collapse, exposure to toxic chemicals and dust, exploitation and environmental destruction1,6.

Despite the recognised human rights risks with the cobalt supply chain, there is a comparative lack of mandatory regulatory compliance requirements.  There is no specific US and European cobalt supply chain legislation, in contrast to the traditional ‘conflict minerals’: gold, tungsten, tantalum and tin7,8.  The supply chains of these minerals must be strictly mapped, reported and comply with international and domestic law.  International guidance from the United Nations and OECD has been expanded in recent years to include cobalt with these minerals, although this has not yet been translated into most countries’ domestic legislation9,10.

This has resulted in a number of initiatives from NGOs to help companies voluntarily improve their due diligence practices.  Notably, the Responsible Minerals Initiative released a Cobalt Reporting Template in 2018.  Currently, at least two orthopaedic implant manufacturers, Stryker® and Johnson & Johnson® are listed as members of the RMI, which is an encouraging sign for our sector11.  The DRC itself is too making efforts alongside NGOs to improve the conditions of its artisanal miners, with the Entreprise Générale du Cobalt (EGC) established in 2019 to attempt to formalise the artisanal small mine (ASM) cobalt sector and establish safe and controlled mining zones12.

© Mining in Congo – Photo Courtesy: Julien Harneis

The widespread issues with ASM mining in the DRC have been widely and often vividly portrayed in the media, NGO reports and have even featured in lawsuits.  The vast majority of the scrutiny has been on the large technology firms that manufacture mobile phones, laptops and more recently electric vehicles – items and brands that are household names1,13.  Consumer and media pressure has led to many of these companies voluntarily improving their due diligence practices specifically in relation to cobalt, made simpler for companies by the aforementioned NGO initiatives.

But, for ourselves in the orthopaedic sector, who is the consumer to apply pressure to the companies?  Consumer choice is much more limited in the NHS: patients don’t get a choice of which knee replacement in the same way they would a mobile phone.  Individual surgeons may have limited or no say in which implants the hospital happens to stock.  Seniors manager and surgeons that make that decision will base it, quite rightly, on safety data and cost implications rather than more nuanced ethical considerations about a company.

Mirroring the changes in society as a whole, we believe that environmental and ethical choices will continue to form an increasing part of surgical practice around the world.  As ‘downstream’ participants in the cobalt supply chain, we have a responsibility to ensure the products we use are safely and equitably sourced.

Our Congolese colleagues made the stark point that few, if any, knee replacements will ever be implanted into patients in their country.  However, there is a real opportunity for cobalt mining to benefit the lives of Congolese people.  It will require a collaborative effort between policy makers, governments and industry, alongside the consumers: hospitals, surgeons and patients.  We hope that by increasing awareness of this issue amongst our professional body and representative organisations, we can encourage the orthopaedic implant sector as a whole to align with the best available industry benchmarks.


  1. Amnesty International. Time to recharge: corporate action and inaction to tackle abuses in the cobalt supply chain. 2017.
  2. Williams JT, Mambu Vangu A, Balu Mabiala H, Bambi Mangungulu H, Tissingh EK. Toxicity in the supply chain: cobalt, orthopaedics, and the Democratic Republic of the Congo. The Lancet Planetary Health. 2021;5(6):e327-e328. 
  3. U.S. Geological Survey, 2020. Mineral commodity summaries 2020: U.S. Geological Survey. Available at:
  4. Weight D. Personal communication with Past President of Cobalt Institute. 2021.
  5. National Joint Registry (2020). National Joint Registry: 17th Annual Report 2020. Available at:
  7. European Union (2017). Regulation (EU) 2017/821 of the European Parliament and of the Council of 17 May 2017: laying down supply chain due diligence obligations for Union importers of tin, tantalum and tungsten, their ores, and gold originating from conflict-affected and high-risk areas. Available at:
  8. US Securities and Exchange Commission (2012). Section 1502 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. Available at:
  9. The Organisation for Economic Co-operation and Development. OECD due diligence guidance for responsible supply chains of minerals from conflictaffected and high-risk areas: third edition. Paris: OECD Publishing, 2016.
  10. United Nations (2011). UN Human Rights Office of the High Commissioner. Guiding principles on business and human rights: implementing the United Nations “project, respect and remedy” framework. New York, NY, and Geneva: UN Human Rights office of the High Commissioner. Available at:
  11. Responsible Minerals Initiative (2021). Members and collaborations. Available at:
  12. Entreprise Generale du Cobalt (2021). EGC Responsible Sourcing Standard. Available at:
  13. Deberdt R, Jurewicz P, Frechette S. Mining the Disclosures 2019: An Investor Guide to Conflict Minerals and Cobalt Reporting in Year Six. 2019. Available at: