Trochlear morphology in healthy people: implications for osteochondral allograft transplantation

Introduction

The unique anatomy of the trochlea makes osteochondral allograft (OCA) grafting of femoral trochlear lesions challenging but could be improved with better understanding of trochlear morphology.

Objectives

To assess trochlear width, depth, and sulcus angle via magnetic resonance imaging (MRI) in patients without patellofemoral problems and determine whether bench measurements of donor femurs can better match donors and patients.

Methods

An analysis was performed on 209 deidentified MRIs (average age: 25.8 years, ages 12-57). Trochlear width and depth were measured 15 mm and 20 mm distal to the most proximal articular surface. MRIs were classified into groups based on trochlear depth (Group 1: 0-4.0 mm; Group 2: 4.1-6.0 mm; Group 3: >6.0 mm). Difference in depth at the 2 distances was calculated. The same protocol was performed on 23 cadaveric knees.

Results

Mean trochlear depths at 15 mm and 20 mm were significantly different between groups. Group 3 had significantly larger trochlear widths than Groups 1 and 2. All MRIs showed an increase in trochlear depth between 15 and 20 mm (mean increase: 1.31 ± 0.78 mm). There was no significant difference in trochlear depths between MRI and cadaveric groups. For MRI groups at 15 mm, the resultant apex decreased 10° between Groups 1 and 2 and 7.4° between Groups 2 and 3.

Conclusions

Assuming trochleae are perfect isosceles triangles, one can measure trochlear width and cartilage sulcus angle via MRI to assess trochlear depth. Consideration of trochlear depth and its distribution may enable more accurate matching of OCAs.