The OAR are a very good clinical decision instrument when used properly. They are designed to simply help decide which emergency department patients with ankle injuries require an X-ray. They should only be used after a proper assessment has been completed.
Explore This IssueACEP Now: Vol 37 – No 02 – February 2018
Over time, the OAR seem to have transformed from an emergency department X-ray utilization tool to an emergency department ankle examination tool. This is not what the OAR were intended for. While this observation is anecdotal from my experiences teaching in the emergency department, during courses, and following up with ED patients with acute ankle injuries in the minor fracture clinic, you may find this pattern sounds familiar.
For some practitioners, the ED ankle assessment has been condensed to the application of the OAR. If a patient twisted an ankle, one asks about weight-bearing, then palpates the four sites of tenderness for the OAR (the posterior 6 cm of the lateral malleolus, the posterior 6 cm of the medial malleolus, the navicular, and the base of the 5th metatarsal). After checking the distal neurovascular status, the ankle exam is done! When indicated, the X-ray is ordered and interpreted, and if negative, the patient is diagnosed with STI of the ankle. Next patient! Well, not so fast.
While the OAR have some value, they are only a small part of the emergency department ankle assessment. Beyond the OAR, there are other vital aspects of the ankle/foot assessment. A proper emergency department ankle assessment requires understanding:
- The mechanism of injury, the forces involved, and the events after injury
- Previous injuries to the ankle (and to the opposite, comparison ankle)
- Relevant past medical history (neuropathy, long-term steroids, etc.)
- An efficient and complete exam of the lower leg, ankle, and foot (Look, Feel, Move—inspect, palpate, range of motion)
- The specific differential diagnosis based on the patient’s injury and evaluation
With all of this, one can then interpret the X-rays in the context of the patient’s differential diagnosis. Radiologists are often asked to interpret X-rays without clinical information. As emergency physicians, we obviously have access to the clinical side. Interpreting X-rays without that clinical information is unnecessarily stacking the deck against us.
These three cases highlight the importance of the history and examination of the anterior aspect of the ankle. All three were seen by excellent emergency physicians. Despite that, all three were subtle misdiagnoses. All three were operative cases. All three had worrisome histories and were tender over the anterior aspect of the ankle, but these findings were not discovered in the emergency department. Two of the three had abnormal X-rays. In retrospect, some may call them fairly obvious radiologic abnormalities. However, the concerning mechanisms were not identified by history, and focal tenderness was not identified on exam. As a result, these uncommon injuries were not part of the differential and were not sought on X-ray interpretation. Just as a pneumothorax can be hard to see if you don’t look for it, these injuries can easily be overlooked if they are not considered. The clues to consider them are often found in the patient’s history and physical exam.