Seaberg and Jackson developed a clinical decision rule for performing knee radiographs in patients with acute knee injuries. The rule has been referred to as the Pittsburgh decision rule since the study was done at Mercy Hospital in Pittsburgh, Pennsylvania.


Patient selection:

• Only patients with injury within 7 days of presentation.

• Patients excluded if they had isolated skin injuries, were pregnant, had a history of previous surgery on the knee, or were returning for reassessment of the same knee injury.


Decision rule: A knee radiograph is performed if:

(1) the mechanism of injury is either blunt trauma or fall, AND

(2) one of the following:

(2a) age < 12 years

(2b) age > 50 years

(2c) inability to walk 4 weight-bearing steps in the Emergency Department


Performance when both elements of rule are used:

• In the initial evaluation the sensitivity was 100% and specificity 79%.

• The initial evaluation indicated that it could reduce X-ray studies by 79%.

• In a comparison with the Ottawa knee rule (Seaberg 1998) the sensitivity was 99% and the specificity was 60%.


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