To understand the most frequently used radiological measurements after total knee arthroplasty,
discuss common pitfalls and their significance to clinical practice.
The knee joint is a complex structure allowing movement in three-dimensions.
There are several bony landmarks that are significant for the proper placement of prosthesis components intraoperatively.
The most often used technique for total knee arthroplasty is the mechanical alignment: cutting articular surface perpendicular to the mechanical axis.
Misalignment in any plane can lead to biomechanical changes: ligamentous imbalance,
dysfunction of quadriceps muscle,
Right after the knee prosthesis operation,
the first X-ray is performed to evaluate the initial prosthesis position.
Imaging findings OR Procedure Details
Femoral component varus/valgus alignment
Femoral component varus/valgus alignment is determined by alpha angle (Fig.
This is an angle between long axis of femur and a line tangential to articular surface of femoral condyles.
It should correspond to the angle between mechanical and anatomical femur axis and be between 3°-7° valgus.
Femoral component flexion/extension alignment
Femoral component flexion/extension alignment is determined by gamma angle (Fig.
This is an angle between long axis of femur and the most distal femoral fixation surface.
Posterior condylar offset...
Malposition of knee prosthesis may lead to an early revisional operation.
Radiologists should be familiar with radiological measurements.
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Biomechanical analysis of a changed posterior condylar offset under deep knee bend loading in cruciate-retaining total knee arthroplasty.
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