ottawa_knee_rule: Ottawa Knee Rule

In cliot: Clinical Indices and Outcomes Tools

Ottawa Knee Rule

Description

Calculates the Ottawa Knee Rule to determine the need for knee radiography (X-ray) in patients with acute knee injury. The rule is highly sensitive for detecting fractures, allowing clinicians to safely rule out fractures without imaging if none of the criteria are met.

Usage

ottawa_knee_rule(age, isolated_patella_tenderness, fibula_head_tenderness,
                 inability_to_flex_90, inability_to_bear_weight)

Arguments

age	Numeric. Patient age in years. (Age >= 55 is a positive criterion).
isolated_patella_tenderness	Numeric (0 or 1). Is there isolated tenderness of the patella (no bone tenderness of the knee other than the patella)? (1 = Yes).
fibula_head_tenderness	Numeric (0 or 1). Is there tenderness at the head of the fibula? (1 = Yes).
inability_to_flex_90	Numeric (0 or 1). Is the patient unable to flex the knee to 90 degrees? (1 = Yes).
inability_to_bear_weight	Numeric (0 or 1). Is the patient unable to bear weight both immediately after the injury and in the emergency department (defined as taking 4 steps, even if limping)? (1 = Yes).

Value

A list containing:

Result	Recommendation regarding the need for X-ray ("Indicated" or "Not Indicated").
Reasoning	List of specific criteria met that triggered the indication.
Test_Characteristics	Note on the sensitivity of the rule.

References

Stiell IG, Greenberg GH, Wells GA, et al. Derivation of a decision rule for the use of radiography in acute knee injuries. Ann Emerg Med. 1995;26(4):405-413. doi:10.1016/s0196-0644(95)70106-0

Examples

# Example 1: X-ray Indicated (Age)
# 60yo, no other symptoms
# Result: Indicated
ottawa_knee_rule(60, 0, 0, 0, 0)

# Example 2: X-ray Indicated (Inability to flex)
# 30yo, Unable to flex to 90 degrees
# Result: Indicated
ottawa_knee_rule(30, 0, 0, 1, 0)

# Example 3: No X-ray
# 25yo, Minor pain, able to walk, full flexion, no bony tenderness
# Result: Not Indicated
ottawa_knee_rule(25, 0, 0, 0, 0)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.