Research Projects
An Investigation of the Carcinogenicity of Metals Commonly Used in Surgical Implants, Cobalt, Chromium and Titanium

Every year, tens of thousands of patients in Hong Kong receive an orthopaedic or dental implant containing metals such as cobalt, chromium and titanium. Since the European Chemicals Agency (2020) classified pure cobalt metal as a Category 1B carcinogen, manufacturers of products containing ≥ 0.1% of this metal must perform a risk assessment and justify that there are no viable alternatives. 

The up-classification of cobalt metal to a carcinogen without evidence that its use in implants is carcinogenic may cause unnecessary concern to the many patients who have, or may require such implants. 

The Objectives will be as follows: 

1) To determine if metals commonly used in implants, cobalt, chromium and titanium ions may affect cellular metabolism in an in vitro osteoblast cell model.

2) To determine if metals commonly used in implants, cobalt, chromium and titanium ions may be carcinogenic, in an in vivo mouse animal model. 

Significance: Studies investigating carcinogenicity and using physiologically relevant molecules of heavy metals have never been performed before. Results from this study will inform, if and how metals commonly used in implants can be carcinogenic. Results from this study would be made available to the European Chemicals Agency and if it can be shown that these metals are safe at physiologically relevant states, then the Agency can reconsider its designation of cobalt use in the context of surgical implants. 

Professor JPY Cheung, Department of Orthopaedics and Traumatology

Graduated from the University of Hong Kong with a Bachelor of Medicine and Bachelor of Surgery (MBBS), Professor Jason Cheung trained as an Orthopaedic Surgeon at the Queen Mary Hospital. He is a Clinical Professor with the Department of Orthopaedics and Traumatology at the University of Hong Kong. His main research interests are paediatric growth and spinal deformity, developmental lumbar spinal stenosis, management of cervical myelopathy and orthopaedic infections.

For more information or to express interest for this project, please email the supervisor or the specified contact point in the project description.  Interested candidates are advised to enclose with your email:

1. your CV,
2. a brief description of your research interest and experience, and
3. two reference letters (not required for HKUMed UG students seeking MRes[Med]/URIS projects).

Information on the research programme, funding support and admission documentations could be referenced online at the Research Postgraduate Admissions website. General admission enquiries should be directed to rpgmed@hku.hk.

HKUMed MBBS students interested in the Master of Research in Medicine (MRes[Med]) programme may visit the programme website for more information.  

HKUMed UG students interested in the Undergraduate Research Internship Scheme (URIS) may visit the scheme’s website for more information.