CT-based morphological analysis of the posterior femoral condyle in patients with trochlear dysplasia

The anterior part of the distal femur in trochlear dysplasia has been well investigated; however, to date, posterior morphological characteristics have not been well studied. This study aimed to evaluate whether the posterior femoral condyle in patients with trochlear dysplasia differs from those without trochlear dysplasia.

Computed tomography scans of 75 knees with trochlear dysplasia and 55 knees with normal anatomy of the patellofemoral joint were analyzed retrospectively. Three observers assessed the width, length, and height of the posterior condyle between the two groups. The intra-class correlation coefficient was used to evaluate inter-observer reliability. The independent Student's t-test was used to assess the statistical significance of the qualitative variables.

There was excellent inter-observer reliability (intra-class correlation coefficient 0.91-0.99) for all of the quantitative measurements. There were significant differences between trochlear dysplastic and normal knees. The trochlear dysplasia group had a larger medial posterior condyle and smaller lateral posterior condyle than the control group. Furthermore, proportion of the posterior condyle in the distal femur markedly differed between the two groups: in the trochlear dysplasia group, the medial posterior condyle accounted for a bigger proportion, while the lateral posterior condyle accounted for a smaller proportion.

Patients with trochlear dysplasia have different posterior femoral condyles compared with those without trochlear dysplasia. Patients with this condition have bigger medial posterior condyles and smaller lateral posterior condyles. A greater amount of attention needs to be paid to this abnormality.