Medial condyle trochlear offset (MCTO) is a measurement to assess the height of the medial trochlear facet with respect to the trochlear groove 1.
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Usage
Medial condyle trochlear offset has been described for the assessment of trochlear dysplasia in skeletally immature patients 1. It measures and/or quantifies a flat or hypoplastic medial facet, described in type B-D of the Dejour classification 2, as a risk factor for patellofemoral instability 1.
Measurement
The distance between the most anterior point of the medial trochlear facet and a tangential line through the trochlear groove parallel to the posterior bony contours of the femoral condyles is measured 1. In severely hypoplastic medial facets the measurement can yield a negative value 1. The measurement is conducted on the most superior/proximal axial image showing complete cartilage coverage of the trochlea 1.
Interpretation
A cut-off value of ≤1 mm was found to be highly specific and fairly sensitive for patellofemoral instability, with a reported sensitivity and specificity of 75% and 93% in that study 1.
History and etymology
Medial condyle trochlear offset was described by M. Stepanovich in 2016 as a measurement for skeletally immature patients 1.