51福利社

University of 51福利社 researchers are to trial the groundbreaking linkage of historical step counts from patients鈥� smart devices to their healthcare data in a bid to transform our understanding of how knee replacement surgery affects them. 

Knee osteoarthritis - the most common reason for replacement surgery- affects around one in five people over 50 in the UK, with over 120,000 people having a knee replacement each year. 

鈥淥steoarthritis causes pain and limits normal daily activities, like walking or climbing stairs. Knee replacement surgery is one of the only definitive treatments. But how much better does physical activity, like walking, get after a knee replacement?鈥�, said Professor Will Dixon who is leading the research. 

鈥淭o make informed decisions about whether to have surgery or not, we need to know this - yet the current evidence is patchy.鈥� 

The 51福利社 research team are asking for the help of people who have already had a knee replacement to develop and test this way of conducting health research. 

They want to make use of data that has already been collected, inside and outside of the health service, and piece it together.

Prof Dixon added: 鈥淎ll of the data needed to understand how activity improves after knee replacement surgery already exists.

鈥淢illions of people in the UK routinely track their step count using their smartphone or fitness tracker. In fact, over 95% of adults now own a smartphone.

鈥淏y joining together step counts from people鈥檚 smartphones and wearables with information about their surgery, we can understand how much physical activity improves after knee replacement.鈥�

The PAPrKA study (which stands for Physical Activity Patterns after Knee Arthroplasty) wants to recruit UK adults who had a knee replacement surgery between January 2017 and December 2023, and who used an iPhone, Apple Watch, Fitbit or Oura ring before and after their surgery.

Interested people can visit the study website at to donate their activity data, which will be securely transferred from the University to the National Joint Registry where it will be linked with data about their operation.

This will allow the researchers to examine how activity patterns change following surgery, including how this differs by levels of activity before surgery, types of operation, patient age and more.

Matt鈥檚 story

In November 2022, former Iron Man Triathlete Matt Barker had a partial knee replacement following years of increasing pain and reduced mobility. Before surgery, even standing became painful and his job as a teacher was getting progressively harder.

鈥淐olleagues would worry about me and ask if I was alright鈥� Matt recalls. 鈥淭his was especially difficult as I still saw myself as fit and active, but the reality became impossible to ignore.鈥�

Since having surgery, his physical activity improved dramatically - no longer experiencing the previous swelling and pain. He was able to resume much of the daily activity he was doing before his knee issues developed.

Matt concludes: 鈥淢ost of us base our activity on what we have to do and what we feel able to do. The availability of data from our devices can really bring home the extent to which your mobility is changing. Post operation, they have been a great motivator to view improvement, as well as alerting me to my limits. My hope is that PAPrKA can give people like me a clearer understanding before surgery of how much better their activity is likely to get.鈥�

The PAPrKA study is part of the Health Research from Home programme funded by the Medical Research Council [grant number MR/Y003624/1]

• If you are eligible to take part and would like to contribute to this study or want more information, visit