Reading Ankle X-rays
Mortise, clear spaces, and stability clues.
Aug 15, 2026 · 3 refs
At a glance
Ankle films answer a stability question: will the talus stay reduced under the plafond? Read the AP, mortise, and lateral in the same order every time so you catch the medial clear-space problem hiding behind an “isolated” fibula fracture.
Technique pointers
Mortise
- Medial clear space
- Tibiofibular clear space / overlap
- Talar tilt
AP / lateral
- Fibula fracture level (Weber thinking)
- Posterior malleolus
- Soft-tissue swelling; plafond involvement (pilon vs malleolar)
If the mortise looks asymmetric, say so — that is the finding that changes the night.
Decision-making
A widened medial clear space with an apparent unimalleolar injury is a bimalleolar equivalent until proven otherwise. Stress views help when standing films are equivocal and soft tissue allows.
Inadequate films get repeated. Guessing syndesmotic integrity from a rotated mortise is how unstable ankles get casted.
High-yield / exam
- Mortise symmetry is the key stability clue
- Medial clear space matters
- Look for posterior malleolus and plafond
- Stress examination when uncertain
Questions
On call and Boards items for this topic are coming.
Open the bank →Your pearl
One line you’d tell a junior at 2am.
References
- 01
Radiographic evaluation of the ankle and foot
2013 · Journal of the American Academy of Orthopaedic Surgeons · review
Systematic radiographic approach to ankle injury and mortise assessment.
- 02
Ankle fractures resulting from rotational injuries
Michelson JD · 1995 · Journal of the American Academy of Orthopaedic Surgeons · review
Links radiographic instability findings to rotational injury patterns.
- 03
OTA teaching on ankle radiographic stability assessment
2018 · Orthopaedic Trauma Association · guideline
Emphasizes mortise interpretation and when stress views add value.
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