Ottawa Knee Rules

Purpose[edit | edit source]

A clinic decision rule to help determine need for x-rays or rule out fractures of the knee after acute injury.  "Plain radiographs of the knee are among the most commonly ordered radiographs in U.S. emergency departments; 60% to 80% of patients with knee pain have a knee film at an estimated annual cost of $1 billion."<1>

Criteria[edit | edit source]

If one of the following is present, radiographs are indicated: 

1.  Age>55 years

2.  Islolated patellar tenderness without other bone tenderness

3.  Tenderness of the fibular head

4.  Inability to flex to 90°

5.  Inability to bear weight immediately after injury and in the emergency department (4 steps) regardless of limping.

Research[edit | edit source]

Diagnostic Accuracy[edit | edit source]

Adult Population:  Sensitivity: 1.0 Specificity: .49-.56 

+LR:  1.9-2.3 -LR: 0

A systematic review by Buchmann et al found a negative result on the Ottawa knee rule test is associated with a fracture
probability of less than 1.5% in an adult population.

Pediatric Population:  Sensitivity:  1.0  Specificity:  .43

+LR:  1.8  -LR:  0