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Overall value:
90 pts
The Ottawa Rules app helps healthcare providers make better decisions on using diagnostic imaging to evaluate patients with knee, ankle, foot and spine injuries, with a goal to reduce unnecessary imaging that also reduces wait times and healthcare costs.


100 pts
App Interface Usability
The app is set of easy-to-follow decision trees
85 pts
Multimedia Usage
The app includes illustrations and high quality videos
92 pts
Real World Usability
The app is set of evidence-based rules to determine if imaging is needed for bone injuries
82 pts

Busy schedule in primary care more than often requires providers to think fast and make quick decisions, including those about necessity of performing certain procedures and imaging tests, such as X-ray and CT scans.

Reducing unnecessary testing also reduces long wait times and health costs, but making decisions if imaging tests are necessary or not for some patients could be challenging without the clear set of rules.

For this purpose, Dr. Ian Stiell and his research group of emergency department physicians at The Ottawa Hospital and the University of Ottawa, developed the Ottawa Rules, which is a set of rules used to help health professionals decide whether an X-ray and CT scans are needed for patients with bone injuries.

These rules have been validated by more than 20 studies that have repeatedly proved that the Ottawa Rules reduce unnecessary imaging, thus leading to the reduced emergency room wait times and significant savings for hospitals. 

However, despite the fact that Ottawa Rules have been used by clinicians and hospitals worldwide, the creators of the Rules were still facing the challenge of dissemination, i.e. they were aware that the rules were still not as widely used as possible.

This was one of the reasons why they also brought the Ottawa Rules to the smartphones and developed the app we review today. The Ottawa Rules app is free app available for both iPhone and Android, and it is designed to help doctors and healthcare providers make smarter and more efficient decisions when it comes to using radiographic imaging tests to evaluate patients who may be suffering from bone injuries.

Additionally, the Ottawa Rules app is part of a research study at Ottawa Hospital, but this is completely optional, which means that users can download and use the app without being part of the research study.

The app opens to the main screen with three existing rules that have been bundled together to provide better decision making support to medical providers, including Canadian C-Spine Rule, Ottawa Knee Rule and the Ottawa Ankle Rules.

Each of these rules features easy-to-follow evidence-based decision trees that help providers determine whether an x-ray or CT scan is needed for spine, knee or ankle injuries.

The Rules try to clear out the high-risk factors first to determine the seriousness of the injury and urgency of imaging procedure. For example, C-Spine rule will ask you about the age of your patient (age 65 or older), if the paresthesias are present in the patient's extremities, or about the dangerous mechanisms that may have caused the injury. If any of these high-risk factors is confirmed, imaging test would be advised. 

Otherwise, the medical providers would be asked about low-risk factors which allow safe assessment of range of motion and determine if imaging is necessary. The decision tree for C-Spine Rule also includes cases when the rule is not applicable, for example if vital signs are unstable, if the patients is less than 16 years old, if there's known vertebral disease, and so on.

For example, you have a clinical scenario of 60 year old male with suspected spine injury, who fell from the chair (about 1 feet elevation), and who was able to sit in ER. The absence of midline c-spine tenderness is noted, but the patient couldn't rotate his necks 45 degrees left and right, so the imaging would be advised.

Other two rules considering ankle and knee injuries provide advice in a bit different manner. They do not have questionnaire, but provide straightforward advice in which cases is x-ray of knee, ankle or foot required, along with examination tips and cases when clinical judgment should prevail over the rules.

All rules are referenced with links to all publications, including derivation, validation and implementation studies, as well as systematic review for each rule. All publications open on PubMed. 

Rules also contain high quality multimedia that includes illustrations and videos showing how each rule is applied at the bedside on simulated patients. These videos open outside the app (on YouTube), but nevertheless they're great addition. 

One thing that the Ottawa Rules app is missing is information on the likelihood ratios for each rule. You can find it in the linked articles, but it would be much better if it's within the app (Rules) as well.

Another thing to note is that many other medical calculator apps already contain the Ottawa Rules, so providers might not find it necessary to download another app just for these rules, but uses other apps that include multiple medical calculators.

This however, doesn't spoil our overall impression with this app. The Ottawa Rules app is a great tool that brings validated rules at the fingertips, helping decrease the overuse of diagnostic imaging for bone and muscle injuries.

Benefit: The app might be particularly useful to emergency medicine, primary care and orthopedics providers who treat patients with spine, ankle and knee injuries


  • Easy to use interface with straightforward decision trees
  • All information is evidence-based and well-referenced
  • The app contains illustrations and videos
  • Lack of likelihood ratios
  • Other medical calculator apps already contain the Ottawa Rules among other calculations and scores, so some providers might not want to download this app alone

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