What is femoral trochlear dysplasia?
Instead of a groove, some patients have a flat or a dome-shaped trochlea. This condition is called trochlear dysplasia. When an individual has a flat or dome-shaped trochlea, the patella loses stability and can track to the outside of the knee as the knee bends.
How is trochlear dysplasia measured?
- the ratio between medial versus lateral trochlear facet length calculated as (medial facet) / (lateral facet) is one way to calculate it 8
- a ratio of <40%, in this case, indicates trochlear dysplasia.
What is trochlear dysplasia?
Trochlear dysplasia can involve a shallow, flattened or convex trochlear groove +/- a hypoplastic (small) or convex lateral femoral condyle 15. This dysplastic deformity of the most superior aspect of the femoral trochlea, in particular, is a risk factor for patellar dislocation during the transition from full knee extension to early knee flexion.
How is trochlear dysplasia treated in patellofemoral instability?
Trochlear dysplasia is a predisposing factor of patellofemoral instability and should be only treated in that context. The treatment of high-grade trochlear dysplasia is trochleoplasty, which aims at correcting the trochlear depth abnormality by recreating a centralized groove, which facilitates the entry of the patella during early knee flexion.
How is trochlear cartilage dysplasia diagnosed?
evaluation on the most cranial/ proximal axial slice containing trochlear cartilage an angle <11° indicates trochlear dysplasia (reported sensitivity and specificity: 93%/87%) 7 generally considered to be the most reliable measurement 15
What does 3 mm trochlear depth indicate?
a trochlear depth <3 mm indicates trochlear dysplasia; Ventral trochlear prominence. distance between the anterior cortex of the distal femur and the most anterior cartilaginous point of the trochlear groove on a sagittal plane through the trochlear groove 8; a distance >8 mm indicates trochlear dysplasia (sensitivity and specificity: 75%/83%)