A 62-year-old woman twisted her knee two days earlier while moving
a sofa at her home. Her pain persisted and she needed a cane to
On examination, the lateral aspect of her knee was tender and
there was a small effusion. Flexion was limited to 60°.
There was no tenderness over the patella. Her quadriceps strength
was good and there was no ligamentous instability.
A 24-year-old woman was struck on the lateral aspect of her right
knee by the fender of a slow moving car and fell to the ground.
Swelling of the knee occurred immediately. The patient had no other
injuries aside from several minor bruises.
Examination revealed tenderness of the anterior and lateral aspects
of her knee. There was a moderate joint effusion and flexion was
limited to 45°. There was no ligamentous instability
to valgus and varus stress, and the anterior drawer and Lachman
tests were normal.
- Are there any abnormalities on these patients’ knee
radiographs (Figures 1 and 2)?
- What is the most frequently missed radiographically
apparent fracture in the ED?
Compared to the wrist and ankle, the radiographic anatomy of
the knee is relatively simple and the range of potential fractures
is small (Table 1). However, some fractures can have subtle radiographic
findings and substantial morbidity if missed.
Table 1 Relative Frequencies of Various Fractures
About the Knee in Adult ED Patients
A targeted approach to radiograph interpretation looking
for common and easily missed injuries works well for knee injuries.
It is more effective and efficient than a systematic approach in
which all of the bone contours are traced looking for cortical
breaks or deformities.
Most fractures are apparent on the standard AP and lateral radiographs.
In some cases, supplementary views are needed to detect an injury.
These include: oblique views, an axial patellar (“sunrise”)
view, or intercondylar notch (“tunnel”) view (AP
view with knee flexed).
Tibial plateau fractures are
common, second in frequency only to patellar fractures (...