Total Knee Arthroplasty (TKA) is the most common elective procedure in Canada. The numbers of TKA is rising, with the greatest increase in rates in those aged 20–59 years in whom pain and mobility symptoms are typically less severe. While TKA is a very effective treatment for individuals with knee osteoarthritis, 15–30 per cent of TKA recipients report little to no symptom improvement or dissatisfaction with results. There is also a small risk of side-effects after surgery, like blood clots, infections, and heart attacks.

Previous studies have shown that this information is not well known by patients, who overestimate the potential benefits and underestimate the potential harm. Moreover, the probabilities of benefit and harm differ from patient to patient — those with more severe symptoms have more chance of improvement while younger age is a risk factor for infection and earlier need for further surgery. This individualized information is not available for patients and their surgeons to discuss when making the decision to have surgery.

Study Aim

The aim of this study is to evaluate the effectiveness of an individualized, patient-reported outcome measure (PROM)-based decision aid to improve decision quality for patients considering knee replacement in routine clinical practice. The study is based in Alberta, where routine PROMs have been collected pre- and post-surgery for many years. This historical data enables individualized estimates of benefit and harm to be approximated.

Study Methods

A prospective two-arm randomized control trial (RCT) was embedded into routine care at a high-volume orthopaedic clinic in Edmonton, Canada. Participants included adults over the age of 30 years who were considering TKA and scheduled for a consultation at the clinic. Participants were randomized to either the treatment arm (patient decision aid) or control arm (routine practice) at their routine online pre-surgical PROM assessment. Both groups also reported treatment preferences and answered a set of knowledge questions, along with other questions about whether they suffered from decisional conflict. The decision aid for the patients in the treatment arm provided information about patients’ options including their expected outcomes, both from average outcomes from existing research and individualized outcomes based on age, sex, and BMI based on previous patients in Alberta. The preference report was placed in the surgeon chart, and aimed to inform decision making about the appropriateness of surgery for each individual. After their consultation with the surgeon, patients reported their experience of shared decision-making using the CollaboRATE scale. The primary outcome for this study is decision quality, which requires a patient to be knowledgeable and chooses a treatment option that matches their treatment preferences.

Accessing the Decision Aid

While the study is still awaiting publication, we are making a version of the patient decision aid available for researchers to view. This is an updated version of the decision aid which has integrated feedback from the trial, and uses publicly available UK PROM data for demonstration purposes. We encourage others to integrate local PROMs data into the decision aid and to share their contributions with the research community.

The decision aid is built in the open-source decideapp software, and is currently hosted on the Centre for Health Evaluation and Outcome Sciences (CHÉOS) servers at St Paul’s hospital. While the decision aid is copyrighted, it is available to researchers, clinicians and administrators to use free of charge. The decision aid can be linked to a local REDCap survey using the REDCap API in such a way that no identifiable information is sent to the decision aid (see REDCAP link diagram below). Or, the software can be freely installed on your own server. The content can be changed with permission — see terms below.

  • See a demo linked to REDCap here
  • See a demo with an example patient here

For further information, please contact Nick Bansback (

Principal Investigator

Dr. Nick Bansback
Program Head, Decision Sciences


Deborah Marshall (University of Calgary), Logan Trenaman (CHEOS/UBC), Karen MacDonald (University of Calgary), Dawn Stacey (University of Ottawa), Gillian Hawker (University of Toronto) and Jeffrey Johnson (University of Alberta)

Status: Ongoing

Additional Information

Decision Aid Schematic

Click image to enlarge.

REDCap Link Diagram

Click image to enlarge.

Terms of Use

The patient decision aid is built on the decideapp platform, an open source framework for developing decision support tools. It uses the EQ-5D-5L and Oxford Knee Score (both instruments require a license for use, found here and here; we have permission to use only as a demonstration). The rest of the decision aid uses instruments that also have copyright restrictions (decision quality instrument and SURE scale), but that are available for researchers, clinicians and administrators to use free of charge. The remaining content of the decision aid has copyright restrictions but is also free for use by researchers, clinicians and administrators. The content can be changed for local contexts, but we ask updaters to request permission to apply changes, and make the updated instrument available for free and open to the public for demonstration purposes. Please email nick [dot] bansback [at] ubc [dot] ca for more information.