Ottawa Knee Rule
The Ottawa Knee Rules should be applied to all patients aged 2 and older with knee pain/tenderness in the setting of trauma.
The Ottawa Knee Rules were derived to aid in the efficient use of radiography in acute knee injuries.
- Rules have been prospectively validated on multiple occasions in different populations and in both children and adults.
- Numerous studies found sensitivities for the Ottawa Knee Rules of 98-100% for clinically significant knee fractures. One study did find a sensitivity of just 86%.
- Specificities for the Ottawa Knee Rules typically range from 19%-50%, though the rule is not designed/intended for specific diagnosis.
- When used appropriately, the amount of knee x-rays obtained can be reduced by around 20-30%.
- The Ottawa Knee Rules are useful in ruling out fracture (high sensitivity) when negative, but poor for ruling in fractures (many false positives).
Tips from the creators at University of Ottawa:
- Tenderness of patella is significant only if an isolated finding.
- Use only for injuries <7 days.
- “Bearing weight” counts even if the patient limps.
Precautions from the creators at University of Ottawa:
- Clinical judgment should prevail if examination is ureliable:
- Intoxication.
- Uncooperative patient.
- Distracting painful injuries.
- Diminished sensation in legs.
- Always provide written instructions.
- Encourage follow-up in 5-7 days if pain and ability to walk is not better.
- Patients without criteria for imaging by the Ottawa Knee Rules are highly unlikely to have a clinically significant fracture and do not need plain radiographs.
- Application of the Ottawa Knee Rules can cut down on the number of unnecessary radiographs by 20-30%, which has proven to be cost effective for patients without reducing quality of care. (Nichol 1999)
Result:
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From the Creator
- Why did you develop the Ottawa Knee Rule? Was there a clinical experience that inspired you to create this rule for clinicians?
- We found that emergency doctors were ordering many imaging studies for knee injuries that were then found to be normal. I thought if there were a set of rules with criteria developed by emergency physicians, for emergency physicians, they would help this problem of unnecessary imaging and shorten emergency department wait times and costs.
- What pearls, pitfalls and/or tips do you have for users of the Ottawa Knee Rule? Are there cases when it has been applied, interpreted, or used inappropriately?
- As a general rule in the emergency department, x-rays are rarely useful because most injuries are soft tissue, and an x-ray does not show ligament injury.
- What recommendations do you have for health care providers once they have applied the Ottawa Knee Rule besides imaging, or when imaging is negative?
- If negative, the patient will inevitably need further assessment and follow-up to deal with soft tissue injuries and may even need an orthopedic consult.
- What are some situations in which you see clinicians interpreting the rule improperly or incorrectly leading to inappropriate x-ray utilization?
- Sometimes doctors don't properly assess the patient's ability to bear weight. Most patients can and will walk, but it may take a little encouragement from the physician.
See More Info section for the definition of ability to bear weight.
About the Creator
Ian Stiell, MD, MSc, FRCPC, is Professor and Chair, Department of Emergency Medicine, University of Ottawa; Distinguished Professor and University Health Research Chair, University of Ottawa; Senior Scientist, Ottawa Hospital Research Institute; and Emergency Physician, The Ottawa Hospital. He is internationally recognized for his research in emergency medicine with a focus on the development of clinical decision rules and the conduct of clinical trials involving acutely ill and injured patients treated by prehospital services and in emergency departments. He is best known for the development of the Ottawa Ankle Rule, the Canadian C-Spine Rule, and Canadian CT Head Rule and as the Principal Investigator for the landmark OPALS Studies for prehospital care. Dr. Stiell is the Principal Investigator for 1 of 3 Canadian sites in the Resuscitation Outcomes Consortium (ROC) which is funded by CIHR, NIH, HSFC, AHA, and National Defence Canada. Dr. Stiell is a Member of the Institute of Medicine of the U.S. National Academies of Science.
To read more about Dr. Stiell's work, visit his website.
To view Dr. Ian Stiell's publications, visit PubMed
