Healthcare & Clinical
Ottawa Ankle & Foot Rules: Evidence-Based Radiograph (X-Ray) Triage Formula
Determine whether ankle series and/or foot series radiographs are clinically indicated after acute blunt ankle trauma using Stiell's ~98–99% sensitive Ottawa Ankle and Midfoot Rules.
Eliminate 30–40% of unnecessary ankle and foot X-rays with ~99% fracture sensitivity!
Most acute ankle sprains in emergency departments and sports clinics have no clinically significant fracture, yet routine defensive X-rays waste hours and radiation! Ian Stiell's universally validated Ottawa Ankle Rules separate assessment into two anatomical zones: (1) ANKLE X-ray series is required ONLY if there is pain in the malleolar zone AND either bone tenderness along the posterior edge/tip of the distal 6 cm of the lateral or medial malleolus OR inability to bear weight for 4 steps both immediately and in the ED!
(2) FOOT X-ray series is required ONLY if there is pain in the midfoot zone AND either point bone tenderness at the base of the 5th metatarsal or the navicular bone OR inability to bear weight for 4 steps! When neither rule triggers, clinically significant ankle/midfoot fracture is ruled out with ~98%–99% sensitivity.
| Anatomical Zone Pain | Focal Bone Tenderness OR 4-Step Inability | Ottawa Ankle Series | Ottawa Foot Series |
|---|---|---|---|
| Malleolar Pain = 1, Midfoot = 0 | Distal 6 cm Malleolar Tenderness = 1 | Ankle X-Ray Indicated | No Foot X-Ray Needed |
| Malleolar = 1, Midfoot = 1 | Unable to Bear Weight 4 Steps = 1 | Ankle X-Ray Indicated | Foot X-Ray Indicated |
| Malleolar Pain = 1, Midfoot = 0 | Ligament tenderness only (Bone = 0, Walks 4 steps) | No Ankle X-Ray Needed | No Foot X-Ray Needed |
Ottawa Ankle X-Ray Series Decision Formula
Checks binary 0/1 flags for Malleolar_Pain (B2) combined with Malleolar_6cm_Bone_Tenderness (B3) OR Unable_4_Steps (B4).
=IF(OR(B2 < 0, B2 > 1, B3 < 0, B3 > 1, B4 < 0, B4 > 1), "Invalid Binary Flag (0 or 1)", IF(AND(B2 = 1, OR(B3 = 1, B4 = 1)), "Ankle X-Ray Series Indicated", "No Ankle X-Ray Needed"))Ottawa Midfoot X-Ray Series Decision Formula
Checks Midfoot_Pain (B5) combined with Navicular_or_5thMet_Tenderness (B6) OR Unable_4_Steps (B4).
=IF(OR(B4 < 0, B4 > 1, B5 < 0, B5 > 1, B6 < 0, B6 > 1), "Invalid Binary Flag (0 or 1)", IF(AND(B5 = 1, OR(B6 = 1, B4 = 1)), "Foot X-Ray Series Indicated", "No Foot X-Ray Needed"))Try the example
Use the original values or change them to test your understanding.