Abstract
Purpose
The purpose of this study is to investigate whether traditional morphometric parameters of the femur trochlear surface are dependable to classify the severity of the trochlear dysplasia.
Methods
An automatic method to process the distal femur surface is proposed to determine anatomical landmarks and compute morphometric parameters, namely the trochlear depth(TD), the trochlear sulcus angle(SA), the lateral trochlear facet inclination(LFTI), the trochlear facet asymmetry ratio(TFAR) and the ratio between the two (lateral and medial) maximum antero-posterior sizes(CAR) routinately used to quantify trochlear dysplasia. Tests on 11 cadavers and 43 patients, affected by aspecific anterior knee pain, elucidate the role of the parameter cut-off values traditionally used in clinical practice.
Results
Clinical cut-off values lead to incoherent classifications in between the parameters along with some inconsistency with expert-based classifications. The classification based on TD cut-off is in agreement with the clinical evaluation whereas the SA classification provided a falsepositive rate of about 55%. Patients dataset analysis shows that the classifications based on TD and SA cut-off were prone to high rate of false positive (55%) and false negative (39%), respectively. LFTI, TFAR and CAR did not comply with TD and SA parameters. A positive correlation between TD decrease and dysplastic condition severity was however found whereas SA was found little correlated.
Conclusion
The classification of trochlear dysplastic condition drawn by morphometric parameters exhibited notable uncertainty. More sophisticated morphologic analysis of the trochlear region for instance on three-dimensional surface modeling techniques might increase the reliability of the classification.
