In a study by Glas et.al, the well-known Ottawa ankle rules were compared to the Leiden
ankle rule. Patients eligible for the study included those who came to the emergency department
at a community hospital in the Netherlands with an acute ankle injury. An acute ankle injury was
described as a painful ankle occurring as the result of some form of trauma. Ankle was described
as the malleolar and midfoot areas which are frequently injured due to twisting. Patients were not
eligible if the injury had occurred more than five days prior. The McNemar test was used to
estimate sample size. In order to gain a power of at least 90%, a sample size of at least 609
would be needed. There were 690 patients with an acute ankle injury and of those, 647 were in
the study. The mean age was 35 and 324 subjects were female.
A university hospital developed the Leiden ankle rule in 1991 in the city of Leiden
(Netherlands). There are seven rows which each contain one or multiple variables. If there is at
least one positive variable per row, the stated score is given for that row. This is not applicable to
the last row since it is reliant on on the patient’s age. The score is not doubled if two variables in
one row are positive. The sum of the row scores yields the final score. If the score is higher than
7, a radiograph is recommended.
Leiden Ankle Rule
Clinical Feature
Deformity, Instability, Crepitation
Inability to bear weight
Pulseless or weakened posterior tibial artery
Pain on palpation of malleoli or fifth metatarsal
Swelling of the malleoli or fifth metatarsal
Swelling or pain of the Achilles tendon
Age divided by 10
Score
5
3
2
2
2
1
Variable
For each patient, the physicians filled out a data form created for the trial. By using this
form, variables could be extracted and scores were calculated for each of the rules.
The radiographic data was used as a reference to calculate sensitivity, specificity, missed
fractures, and patients who should have had an x-ray completed. The Ottawa ankle rules caught
66 out of 74 fractures and the Leiden ankle rule caught 59 of the 74 fractures. Physicians were
able to determine 61 of the 74 fractures. Of the 8 fractures missed by the Ottawa ankle rules, 1
was significant. Of the 15 fractures missed by the Leiden ankle rule, 5 were significant. Of the 13
fractures missed by physicians, 1 was significant. X-ray was recommended in 76% of the Ottawa
cases, 46% of the cases in Leiden, and 38% of cases among physicians. Both the Ottawa and
Leiden were created to have 100% sensitivity.
As with anything, there are some disadvantages to using ankle rules. First, the sensitivity
may be affected depending on the training and experience of the physician. Second, neither of
the ankle rules apply to people with specific comorbidities. Overall, the Leiden ankle rule was
less sensitive but more specific than the Ottawa ankle rules. The AUC was also higher for the
Leiden ankle rules whereas the percentage of patients who should have had an x-ray was lower.
Despite the Leiden ankle rules having a higher specificity, more clinically significant fractures
were missed than with the Ottawa ankle rules. It seemed that in many cases, physician judgment
was better or as good as any ankle rule.