Medial condyle trochlear offset

Medial condyle trochlear offset is a measurement to assess the height of the medial trochlear facet with respect to the trochlear groove .

Usage

Medial condyle trochlear offset has been described for the assessment of trochlear dysplasia in skeletally immature patients  . It measures and/or quantifies a flat or hypoplastic medial facet, described in type B-D of the Dejour classification , as a risk factor for patellofemoral instability .

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. In severely hypoplastic medial facets the measurement can yield a negative value . The measurement is conducted on the most superior/proximal axial image showing complete cartilage coverage of the trochlea .

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 .

History and etymology

Medial condyle trochlear offset was described by M. Stepanovich as a measurement for skeletally immature patients .