Indications for imaging
? fractured patella, congenital abnormalities
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Anatomy Demonstrated
Similar to normal AP knee except the patella is better
demonstrated as it nearer the film.
Knee PA for Patella Rt Anatomy
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
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Basic Patient Position
The patient lies prone on the table with the leg aligned to
the long axis of the table, and supported so that the femoral
condyles are equidistant from the film and the patella centered
midway between the condyles.
Note this position may note be possible on an injured patient.
Knee PA for Patella Lt Patient Position
Meschan, I. 1955 An Atlas of Normal Radiographic Anatomy
Saunders, London
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Radiation protection
Direct lead rubber gonad protection using a "half
apron".
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Central Ray
The vertical central ray is directed to emerge through the center
of the patella at 90 degree to the film, midway between the skin
surfaces at the crease on the skin surface.
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 65 |
5 |
100 |
No |
Fine |
No |
18 x 24 cm |
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Evaluation of the Image
Evidence of collimation on four sides equally around the
centering point.
Limits of the examination, superiorly the distal femur,
inferiorly the proximal tibia and fibula laterally and medially
the skin surfaces.
The joint space should be visualised with the proximal articular
surface of the tibia at 90 degrees to the film, the apex of the
patella should be in line with the tibial spines.
Optimal exposure should penetrate all the bone structures and
contrast should be low enough to visualise fully the bone and
soft tissue structures.
Knee PA for Patella Rt, Radiograph
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Related Projections
Knee AP, Lateral and axial "skyline" oblique patella
views.
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Additional modalities
CT
MRI
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