LIVRE JDG 2012

Magnetic Resonance Imaging in Patellofemoral Instability

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Table 1 (suite)

Medial Condylar Height Line 1 is drawn across the posterior margins of the medial and lateral condyles.

MCH is the distance from the most anterior margin of the medial condyle to

Line 1 that is perpendicular to line 1.

% of Epicondylar

Width MCH

MCH expressed as a percentage of the transepicondylar width.

Lateral Trochlear

Inclination

Line 1 is drawn across the posterior margins of the medial and lateral condyles.

Line 2 is drawn along the lateral slope of the trochlear groove. LTI is the angle

between the two lines. A positive angle opens laterally.

Limb Geometry

TTTG

TT-TG offset is defined as the lateral distance of the tibial tuberosity with respect

to the center of the trochlear groove, measured parallel to a line connecting the

posterior condyles. One way to measure the offset is as follows:

Connect posterior condyles of femur

Draw perpendicular reaching apex of femoral groove

Scroll to apex of tibial tuberosity and leave cursor there

Scroll back to trochlear slice

Draw a line to the 1

perpendicular and measure. This line is parallel to the

posterior femoral condylar line

Coronal Measurements

Varus-Valgus

Line 1 is drawn through the axis of the femur, and line 2 is drawn through the

axis of the tibia. CA is the angle between these two lines.

Lateral Condylar Height LCH is the distance from the physeal scar to the lateral margin of the lateral

femoral condyle articular surface.

Medial Condylar Height MCH is the distance from the physeal scar to the medial margin of the medial

femoral condyle articular surface.

Patellar Station

Using the sagittal image through the mid patella facet as determined on

axial image, the following measurements are made.

Patella Station A:

Measured from the most proximal articular margin of the

patella to the most distal (nonarticular) aspect of the patella.

Patella Station B:

Measured from most proximal to most distal articular

margin of the patella.

Patella Station C:

Measured from the most distal aspect of the patella to the distal

insertion of the patellar tendon at the tibial tuberosity (patella tendon length).

Patella Station D:

Measured from the most distal articular surface of the

patella to the anterior margin of the articulating surface of the tibia plateau.

Patella Station E:

Measured from the most distal aspect of the articular

surface of the patella to the distal insertion of the patellar tendon at the tibial

tuberosity.

Patella Station F:

Measured from the most distal aspect of the patella to the

anterior margin of the articulating surface of the tibia plateau

Patellar Trochlear

Overlap

Measures the length of the overlap between patellar and trochlear articulating

cartilage.

Trochlear Bossing (AP)

Anterior posterior dimensions are estimated on sagittal image.

Insall-Salvati Ratio

Station C divided by Station A

Modified Insall-Salvati

Ratio

Station E divided by station B

Caton-Deschamps

Ratio

Stations D divided by station B

Morphology Ratio

Station A divided by station B

Femoral Contacting

Surface Ratio

Station B divided by the trochlear overlap.