I had a female patient come into the office the other day complaining of left ankle pain following tripping on the ice the day before after leaving her home having an inversion ankle injury. She was currently being treated in our clinic for balance and hip pain, but hasn’t sought care from a medical physician for current complaint.
Upon examination, she was able to walk into the office but marked antalgic gait pattern using a standard cane (which she always uses). She acknowledged that she was able to walk immediately following the accident and feels symptoms are getting better. She had apparent swelling in the lateral/inferior aspect of the rearfoot with ecchymosis noted in this region as well (black/blue, not yellow).
Notable objective findings:
Positive Ottawa Ankle Rules with Bone Tenderness at B, but negative for other realms of the guidelines.
She also had negative provocation to moderate depth palpation to the anterior talofibular ligament and posterior calcaneofibular ligament.
Additionally, she had negative pain provocation with 128hz tuning fork at location B and ~4” above this location along fibula shaft.
My course of action was education that I did not think she had a fracture, but I could not rule it out 100%. She had a positive finding on the Guidelines and it would be best to seek out a plain film radiograph.
She sought care from PCP, had x-rays and they were negative.
Therefore, it got me thinking more about how to fine tune the specificity of the Ottawa Ankle Rules, as they only have ~32% specificity, which is very low. I would suggest the probability of an ankle fracture arriving in a physical therapy office is much lower than at an emergency room (where initial rules arose), therefore, the specificity of this test would be even lower. So, the average 13% of inversion injuries that are fractures could be more around 5-7%, even lower! Therefore, the rate of false positives would be even higher. After speaking with her, examining her walking in the clinic (more than 4 steps), the time frame from injury over 24 hours ago and her opinion that it was only a sprain—all gave me a hunch that she did not, but went with the clinical guidelines. Therefore, I did some research.
I came across this article by Dissman and Han in 2006. They examined the result of tuning fork test on the tip of the lateral malleolus and distal fibula shaft and compared it to lateral & A/P x-rays following an inversion injury.
Based on Table 3 above, the sensitivity was still at 100% but specificity increased to 61% to the tip of the lateral malleolus and 95% to the distal fibula shaft, therefore, the specificity increased 3 fold if positive tuning fork test to distal fibula shaft and two-fold to tip of lateral malleolus.
This was only a pilot study and had large confidence levels, so take what you want from it. I have seen several cases in the past where I did not think there was a fracture, the patient did not think there was a fracture, but the guidelines are unable to rule out.
So, my question to you….do you utilize all 3 aspects of evidence-based practice or rely just on the research guidelines? I know it is best practice for this case to refer out for imaging, but what about other diagnostics that are less sensitive…such as clinical instability tests and/or vertebrobasilar insufficiency?
Dissman PD, Han KH. The tuning fork test—a useful tool for improving specificity in “Ottawa positive” patients after ankle inversion injury. Emerg Med J. 2006 Oct; 23(10): 788–790.