Ottawa Knee Rules

As with the Ottawa Ankle Rules, we use these factors to help us to decide when a radiograph is needed in the case of acute knee injuries. These rules were developed as a means of reducing the number of unnecessary knee scans being performed, particularly in emergency rooms. This is very important in that it decreases health care costs and unnecessary exposure to radiography. These rules were developed with a high sensitivity to detecting fractures of the knee, and in some studies up to 100% detection rate was reported, and anything less were in cases of misapplication of the screening tool.

So in the case of an acute knee injury the signs that a patient will need an x-ray to rule out a fracture include:

Having pain in the knee and:

Being 55 years in age and over

unable to bend the knee >90 degrees

tender fibular head on palpation

isolated tenderness of the patellar

unable to weight bear four steps and immediately after the injury

As you can see from these criteria, there are exceptions, for example, these rules aren’t useful in a younger population <18yrs or have altered levels of consciousness. In addition, we never recommend treatment or scans based on one clinical finding, as a thorough clinical history and examination is always important to have in your initial assessment. Which is why it is important that this screening tool is only performed by a registered AHPRA health practitioner who has the necessary background and clinical decision making skills to utilise this tool effectively.