Optimising outcomes after patellofemoral (kneecap) joint replacement

Ms Martinique Vella-Baldacchino, a specialist registrar in Trauma & Orthopaedic surgery, is a recipient of the Early Careers Research Fellowship for her research into kneecap replacement for patellofemoral joint osteoarthritis. Of the 400,000 patients seen in elective knee clinic around the UK, 18% have kneecap arthritis, complaining of pain affecting daily activities.

Patellofemoral joint osteoarthritis (or kneecap osteoarthritis) can be treated with a total knee replacement or a kneecap replacement. However, treatments offered vary according to the patient’s location. The Early Careers Research Fellow said, ‘Depending on what services are offered in your area, you could either be offered a variety of treatment options such as steroid injections, total knee replacements or a kneecap replacement. Not everyone is offered the same treatment options.’

According to Ms Vella-Baldacchino, ‘A kneecap replacement is a small operation compared to a total knee replacement, your cruciate ligaments, which are really important for stability of your knee, remain in place compared to a total knee replacement.’ The specialist registrar made the analogy, ‘If you had a car that had only one flat tire, would you replace that one flat tire or would you replace all the tires despite the fact that three are in good condition?’

‘It’s been well reported that kneecap replacements require shorter lengths of hospitalisation and are more likely to result in better knee function compared to total knee replacements,’ the fellow said. Unfortunately, the condition predominantly affects females, around the age of 50 to 70. She added, ‘It is well documented that females are more likely to delay surgery because of the impact the recovery can have on their family and they’re more likely to have caregiving roles.’

Vella-Baldacchino’s research involves a systematic review on Outcomes Following Patellofemoral Joint Replacements. She detailed, ‘Having preliminary reviewed the data from the National Joint Registry, there is a huge variability in terms of kneecap replacements, where they are offered around the country, where some surgeons may do none and others are performing 10 per year. So, it really depends on where you are located in the country.’ She continued, ‘Perhaps this may be related to training.  You may be in a place where you’re working for people who do kneecap replacements, and therefore you’re taught how to do it. And if you’re taught how to do it, then you may offer it once you become an independent consultant.’

Success rates of kneecap replacements have improved since their initial development in 1979. The PhD researcher said, ‘The new generation of implants have much higher success rates.’

The main goals of the research are to answer the following questions:

1. Are kneecap replacements safe compared to total knee replacements?
2. Do patients have better function following kneecap replacement surgery?
3. Which patients benefit most from kneecap replacements?
4. How many kneecap replacement do surgeons need to perform to have better outcomes?
5. Does the shape of the kneecap joint influence the success of surgery?
6. What are patient thoughts after having kneecap replacement surgery ? How has it affected their life?

Ms Vella-Baldacchino elaborated, ‘Perhaps if kneecap replacement surgery is shown to be safer and have better outcomes, this may encourage surgeons to offer more kneecap replacements to patients who may benefit from this surgery. ’

The research involves collaboration with Professor Anders Odgaard of University of Copenhagen and Professor Jean-Noël Argenson and Professor Matthieu Ollivier from Aix-Marseille Université’s Institut des Sciences du Mouvement. The collaboration with researchers in Denmark aims to look at outcomes of 50 patients from 2015 who had patellofemoral arthroplasty, compared to total knee arthroplasty for patellofemoral joint arthroplasty and measure their function by using wearable sensors. She described the collaboration with Danish researchers: ‘They’ve shown that patients have far better knee function using patient questionnaires. We are going to bring these patients back at their 5 year follow up mark and measure their knee function.’

Vella-Baldacchino’s research has benefited from working with other researchers and receiving funding. ‘I think being able to collaborate with all these different institutions makes us better researchers,’ she said. ‘I’m really thankful that Orthopaedic Research UK has decided to fund my project, not only for myself but also for patients, a disease that has been under-researched for so many years. Hopefully other funders will also recognise the importance and follow suit, funding other related topics in this field.’