Radiographic evaluation of anterior cruciate ligament reconstruction
Radiographic evaluation of anterior cruciate ligament (ACL) reconstruction involves:
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femoral component
- a line is drawn along the posterior cortex of the femur
- a second line is drawn along the roof of the intercondylar notch of the femur (Blumensaat line)
- the point of intersection of these two lines should be at the inferior portion of the femoral component of the graft
- the angle measured between a line drawn along the femur diaphysis and the femoral tunnel angle must be ~39°; angles of approximately ≤17° are associated with rotational instability
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tibial component
- the tibial component should be entirely posterior to and parallel or more steep to and the line drawn along the roof of the intercondylar notch (Blumensaat line)
- when the femoral tunnel is drilled through the tibial tunnel, it is recommended to drill the tibial tunnel at an angle of 65° to 70° in the coronal plane, tibial tunnel angle of ≥72° is associated with greater loss of flexion and anterior laxity
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tibial or femoral canal widening
- loss of parallel walls and increase in diameter >2 mm from reconstruction time
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hardware complications
- migration of Endobutton into the femoral canal
- interposing soft tissue between Endobutton and femoral shaft
- migrated/displaced interference screw from the tibial or femoral canal
- proud/intramuscular screw tip