Landmarks of the normal adult human trochlea based on axial MRI measurements: a cross-sectional study.

[trochlear dysplasia]

For deepening trochleoplasty , a procedure used worldwide to correct trochlear dysplasia , only few surgical steps are described precisely . Important surgical landmarks , such as optimal cartilaginous trochlear depth and percentages of the new lateral and medial facet , remain unanswered .A cross-sectional study (January 2011 -August 2012 ) was carried out in adult patients (16 -35 years ) without trochlear dysplasia , who underwent magnetic resonance imaging (MRI ). The main outcome was trochlear depth . The secondary outcome was the lateral /medial facet ratio . Measurements were made on the first axial cut from proximal with complete cartilage coverage of the trochlea . Differences between men and women were assessed .Fifty -three patients (70 % men ) were included . Mean age was 24 .6 years (SD ±5 .5 ). Overall mean trochlear depth was found to be as 4 .0 mm (95 % CI 3 .6 -4 .3 ). Values differed significantly by gender (p =0 .0271 ) with a mean of 3 .4 mm (95 % CI 3 .0 -3 .8 ) for women and a mean of 4 .2 mm (95 % CI 3 .8 -4 .7 ) for men . The mean ratio between the lateral and medial facet was 1 .71 (95 % CI 1 .62 -1 .80 ), the lateral facet contributing 62 .6 % (95 % CI 61 .3 -63 .8 ) and the medial facet contributing 37 .4 % (95 % CI 36 .2 -38 .7 ) to the total cartilage length . For the facet ratio , there was no statistically significant gender difference (n .s .).This study provides data on important landmarks for deepening trochleoplasty based on average MRI measurements in the general population . The difference between the MRI measurement and actual cartilage surface measurement is likely to be minimal , but is yet to be evaluated . Further evaluation of these landmarks by prospectively performing deepening trochleoplasty will determine the value of the clinical implication .II .