When to Get an Ankle X-Ray
Following up on my recent post and as promised, I will run through the criteria you should use to determine IF an ankle x-ray is necessary.
The purpose of an ankle x-ray is to detect if there are any fractures (broken bones) following a severe sprain which would influence management of the injury. Evidence strongly supports the Ottawa Ankle Rules as accurate instrument for excluding fractures of the ankle and mid-foot.
WHY USE IT? 1# The Ottawa ankle rule were derived to aid in the efficient use of radiography in acute ankle and midfoot injuries. Its application can reduce the number of unnecessary radiographs by as much as 25-30%.
2# The Ottawa ankle rules has an insanely high sensitivity rating (90-100%). What this means is that individuals who don’t satisfy the Ottawa ankle rule criteria are highly unlikely to have a clinically significant fracture and hence do not need plain radiographs.
HOW TO USE IT?
~ An ANKLE X-RAY SERIES is only required if there is pain in the malleolar zone AND any of variables A or B or E. ~ A FOOT X-RAY SERIES is only required if there is pain in the midfoot zone AND any of variables C or D or E. A. Bony tenderness along distal 6 cm of posterior edge of fibula or tip of lateral malleolus B. Bony tenderness along distal 6 cm of posterior edge of tibia/tip of medial malleolus C. Bony tenderness at the base of 5th metatarsal D. Bony tenderness at the navicular E. Inability to bear weight both immediately after injury and for 4 steps during initial evaluation Tips/Precautions: - Palpate the entire distal 6cm of the fibula and tibia - Be caution in using the criteria for patients under age 18 - Clinical judgment should prevail if examination is unreliable - Encourage follow-up in 5-7 days if pain and ability to walk is not better - In the case of a stress fracture an x-ray might not display any signs until 10-14 days (until healing begins)