Reading Knee X-rays
Effusion, alignment, and subtle fracture clues.
Aug 31, 2026 · 3 refs
At a glance
A knee series is AP, lateral, and often sunrise / oblique. The lateral tells you effusion (lipohemarthrosis = intra-articular fracture). Plateau depression and lipohemarthrosis are easy to under-call on a busy night.
Technique pointers
AP
- Joint space, alignment, plateau rim, distal femur condyles
- Fibular head and proximal tib-fib joint
Lateral
- Effusion / fat-fluid level
- Plateau posterior sag
- Patella height and a sleeve-type pattern in kids
Obliques help for subtle plateau and tibial spine injuries.
Decision-making
A “sprain” with a fat-fluid level is a fracture until CT or MRI says otherwise. Plateau width and depression change spanning vs early ORIF. Do not call the plateau done from a rotated AP.
High-yield / exam
- Lipohemarthrosis means intra-articular injury
- Look at the plateau rim and spine
- Include the proximal fibula
- Inadequate rotation → repeat, don’t guess Schatzker
Questions
Ortho Skills (Real Life) and Boards items for this topic are coming.
Your pearl
One line you’d tell a junior at 2am.
References
- 01
Radiographic evaluation of acute knee trauma
2012 · Journal of the American Academy of Orthopaedic Surgeons · review
Effusion on the lateral is the intra-articular tell.
- 02
The tibial plateau fracture: the Toronto experience
1979 · Clinical Orthopaedics and Related Research · review
Plateau description still starts with adequate films.
- 03
OTA teaching on knee and plateau radiographic evaluation
2019 · Orthopaedic Trauma Association · guideline
Obliques and a true lateral before you under-call depression.
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