Ottawa knee rule validation

Prospective validation of a decision rule for the use of radiography in acute knee injuries.

Stiell IG, Greenberg GH, Wells GA, et al. JAMA 1996 · PMID 8594242 · doi:10.1001/jama.1996.03530320035031

Question

Does the Ottawa knee rule safely identify adults with acute knee injury who need radiographs to exclude fracture?

Design

Prospective validation study in the emergency departments of two Canadian university hospitals.

Patients

Adults presenting to emergency departments with acute knee injury.

Intervention

Application of the Ottawa knee rule (age 55 or over, isolated patellar tenderness, fibular head tenderness, inability to flex to 90 degrees, inability to weight bear four steps)

Comparison

Radiography or follow-up as reference standard for clinically important fracture

Primary outcome

Sensitivity of the rule for clinically important knee fracture

Key result

The rule identified all clinically important fractures in the validation cohort (sensitivity of 100%) and would have reduced the need for knee radiographs substantially.

Limitations

Specificity is modest, and it was derived and validated in adults, so applicability to young children is limited.

Impact on practice

Standard decision tool in UK emergency departments to decide which acute knee injuries need an X-ray.