Thursday 26 May • Viewing time: 1 minute

Our research has helped surgeons make informed decisions on how to treat and minimise joint replacement infections — transforming patient outcomes.

Every year, thousands of orthopaedic operations take place in the UK, with joint replacement surgery being the most common.

For the majority of patients, this surgery relieves chronic pain and allows them to resume the activities and hobbies they once enjoyed.

However, no surgery is risk-free. A small percentage of procedures lead to infection, which can have devastating effects on the patient.

This is where we come in. As a Professor of Microbiology in the Biomolecular Sciences Research Centre, I’ve been privileged to lead an expert multidisciplinary team of researchers working with professionals at the forefront of orthopaedic surgery, to research bone cement and specific antibiotics to help change surgical practice and patient outcomes.

Treating infection

Infection in joint replacements can happen during or after the operation, and can even occur years after surgery has taken place.

It happens when bacteria present on the skin spreads to the surgical wound, or (more rarely) when bacteria enter via the bloodstream.

Infection can cause severe pain as the prosthesis begins to fail and become loose around the bone. This can lead to swelling and extreme discomfort, with patients often finding it difficult to move and sleep.

In a health and wellbeing questionnaire used by medical professionals, patients experiencing an infected prosthesis reported “worse than death” scores.

Such patients require additional surgery to remove infected tissue and replace the joint. However because lots of patients have more than one illness, surgery isn’t always a safe option. That’s why prevention is key.

The need for a new antibiotic formulas

Antibiotics are used in joint replacement surgery to treat infection or as a preventative measure. To maximise effectiveness, antibiotics are included in the cement used to secure the prosthesis into the bone, which allows high concentrations to be delivered where they are needed.

This is more favourable than intravenous methods (where antibiotics are administered directly into a vein) as it reduces resistance by limiting exposure of the patients’ natural microflora to prolonged antibiotics.

But with antibiotic resistance growing, there’s still work to do to ensure infections that occur in orthopaedic surgery can be treated effectively.

Overcoming antibiotic resistance

Antibiotic resistance is one of the biggest threats to public health around the world. It happens when bacteria become resistant to the antibiotic that’s intended to kill them. This has led to the emergence of ‘superbugs’, where certain strains of bacteria have developed resistance to a number of different antibiotics. These types of infections can be especially serious and difficult to treat.

There are many different kinds of antibiotics, however there is one standard antibiotic included in bone cement called gentamicin.

In recent years, there has been a growth of gentamicin resistant infections and as a result, there is a need for a wider range of antibiotics to be included in bone cement to effectively treat or minimise infection.

Expanding the range of antibiotics

Preventing infection in joint replacement surgery is key, as replacing an infected prosthesis is a complex procedure that requires specialised implants and tools, as well as the facilities of an operating theatre.

For years, we’ve been collaborating with clinicians from the orthopaedic and microbiology departments at Sheffield Teaching Hospitals NHS Foundation Trust to expand the range of antibiotics used in bone cement.

Before our work started, there was a lack of manufacturer-independent information on the effects of adding additional antibiotics to bone cement. With uncertainty around whether the physical properties of the cement would be impacted, or if they would work properly.

Using our expertise in microbiology, analytical chemistry and materials science, we developed new laboratory techniques to test the effects of different antibiotics in bone cement.

We received funding from ZimmerBiomet, Pfizer AIR Foundation and the Society for Applied Microbiology and the Cavendish Hip Foundation, which allowed us to test how five different antibiotics performed within bone cement compared with the widely used antibiotic gentamicin.

Our results indicated that all five were effective in killing the bacteria present in prostheses infections, and were able to maintain physical strength of the bone cement.

Informing surgical practice

Our research has been influential in clinical decision making. Since we began our work, 12 hip or knee prosthesis revision operations have been undertaken by orthopaedic surgeons in Sheffield Teaching Hospitals NHS Foundation Trust. In these procedures, our work on bone cement and specific antibiotic research directly influenced what additional antibiotic beyond the standard gentamicin would be most effective in treating the infection.

Not only have we increased the range of antibiotics that can be used in bone cement for joint replacement operations, we’ve also informed the way surgeons can prepare and use orthopaedic materials.

We’ve shown that a DIY approach where surgeons make informed decisions on preparing antibiotic-loaded cement can be just as good as pre-prepared antibiotic-loaded cement that is available on the market.

This not only saves a lot of money, but allows more hospitals to adopt this new approach — ensuring patients' outcomes are increasingly improved.

Our research has been disseminated among consultant orthopaedic surgeons at Sheffield Teaching Hospital, and has also generated interest around the UK and beyond, including ENDO Klinik, a specialist clinic in Germany with a worldwide reputation for bone, joint and spinal surgery.

Life-saving work

Our work is incredibly rewarding because it has the power to really make a difference to people’s lives.

I remember hearing how our research was considered to be life-saving after clinicians made an informed decision on how to treat a spinal infection based on our findings — it’s moments like this that makes me love what I do.

The success of the research is down to the sheer amount of collaboration between us scientists at Sheffield Hallam, and Sheffield-based orthopaedic surgeons. Thanks to this, we’ve been able to access clinical expertise and directly inform clinical practice.

Looking forward, there’s a shift in orthopaedic surgery to move away from cemented prosthesis to cementless, where the bone grows around the prosthesis and adheres to it over time.

As a result, we’re currently investigating new ways to locally deliver antibiotics to treat and minimise infection, including using a coating that releases drugs from cementless prostheses.

We hope to continue to make breakthroughs within this field to improve patient outcomes and transform lives.