The Pittsburgh Knee Rules are a clinical decision rule used after an acute knee injury to help clinicians decide when knee radiographs (X-rays) are indicated to look for fracture—and when imaging is often unnecessary. The rule is designed to be simple and highly sensitive for clinically important fractures, helping reduce avoidable X-rays and ED wait times. Medscape Reference+3AAFP+3PubMed+3
Core criteria (how the rule works)
The Pittsburgh rule is applied when the mechanism is blunt trauma or a fall. If that mechanism is present, order a knee X-ray if either:
- Age < 12 years or > 50 years, OR
- Inability to walk 4 weight-bearing steps in the ED/clinic. Medscape Reference+3Wikipedia+3AAFP+3
If the mechanism is blunt trauma/fall and neither criterion is present, a fracture is less likely and an X-ray is often unnecessary (clinical judgment still applies—especially with deformity, high-energy trauma, anticoagulation, concerning exam, etc.). AAFP+2Radiopaedia+2
Accuracy and comparison (quick context)
In a multicenter comparison study, the Pittsburgh rule showed very high sensitivity with better specificity than the Ottawa Knee Rule in that dataset—meaning it can reduce imaging while still being very good at not missing fractures. PubMed+2PMC+2
Orthopedics
Pittsburgh Knee Rule
Helps determine whether knee radiography is indicated after an acute knee injury caused by a blunt trauma or fall.
Patient inputs
Complete every field, then calculate the rule result.
Result
Decision support based on the selected criteria.
Complete the required fields and select “Calculate result.”
This calculator supports clinical decision-making and does not replace clinical assessment, local imaging policy, or evaluation of concerning findings such as deformity, neurovascular compromise, or high-energy trauma.
