The goal of this clinical trial is to learn if the Pain Coach App will result in less opioids being prescribed to and used by patients undergoing Shoulder/Hip/Knee Arthroplasty surgery while maintaining the same or better pain control versus standard of care. The main questions it aims to answer are:

1. Will elective shoulder, hip and knee arthroplasty patients using PainCoach App be prescribed and/or use less opioids, measured by total morphine milliequivalents (MME) after surgery when compared to those treated as standard of care while maintaining similar pain control?
2. Will arthroplasty surgeons using PainCoach App write more patient-specific prescriptions resulting in a reduction in opioids prescribed after surgery with no increase in further opioids prescribed in the months following surgery?
3. Will the use of Pain Coach App lead to equal or reduced healthcare system utilization after surgery?
4. Will patients and surgeons using PainCoach App find it helpful enough to use it again and recommend to colleagues, family and friends?

Researchers will compare participants assigned to use Pain Coach App vs participants assigned to standard of care arm to see if there are differences in opioid prescriptions and self reported use.

Participants will either use the Pain Coach App or follow standard of care instructions and be followed forward for the opioid prescriptions dispensed in community and self-reported opioids use at study end.

This will be a randomized, parallel group prospective interventional study. Patient participants will be consented and then randomized using a tool built into RedCap to either the "treatment group" and a "control group". The treatment group will be sent an email with instructions to set up a Pain Coach Account and download the app onto their mobile device. (Phone or tablet)The control group will not be offered Pain Coach technology and will just follow the usual care pathway for arthroplasty patients. When a participant in the treatment arm completes the initial questionnaire within the app (known as the Pain Coach Profile) this information will be used by a pharmacist in the study to create a suggested prescription for that patient. This suggested prescription will be provided to the patients surgeon for them to review and either accept, edit or discard based on their own clinical judgement.- For the rest of the study the patients in the treatment arm will have access to the Pain Coach app functionalities and use them as they require/prefer. A survey will be sent to both treatment and control groups after their surgery on Post Op Day 2 and 30 to assess pain control. There will be an interim analysis once 281 participants have been recruited into each treatment arm. At this point a retrospective chart review will be used to identify ED related visits for surgical pain within 90 days will be compared between groups at 6 months, also the amount of opioids prescribed (and number of refills) up to 3 months after surgery will be recorded and compared between groups. If at this point there is a statistically significant difference between groups the study will end early. Otherwise it will control until 561 participants are assigned to each group. This will provide 80% power to detect a minimally clinically important difference of 10% reduction in opioid prescribing between groups.

Inclusion Criteria:

• Elective total shoulder (day surgery only), hip or knee arthroplasty completed within NSH, starting at the HI or DGH
• OR date for surgery is known and booked
• Able to access the internet via mobile device (has access to smart phone)
• If expresses concern about low tech IQ, has a support person available
• Able to read and write in English

Exclusion Criteria:

• Non-elective arthroplasty surgery procedures (trauma, fractures)
• Bilateral knee or hip arthroplasty
• Unable to read or write in English
• Lacks capacity to provide consent due to cognitive impairment
• No access to internet or mobile device to use self-help pain management tools
• Inpatient Shoulder arthroplasty as residents write these discharge prescriptions