Quantitative analysis of collagen fibrils of human cruciate and meniscofemoral ligaments

The ultrastructural anatomy of collagen fibril diameters in the cruciate an d meniscofemoral ligaments, from four young human cadaver knees (mean age, 20 years, range, 17-22 years) was studied using transmission electron micro scopy, Samples were harvested from the proximal, middle, and distal regions of the anterior and posterior cruciate ligaments, and the meniscofemoral l igament. Photomicrographs were taken and assessed quantitatively using imag e analysis software to determine the collagen fibril diameters and eccentri cities, and the percentage of total cross sectional area occupied by collag en, The collagen fibril diameter for the anterior cruciate ligament was fou nd to be largest in the distal region but it decreased as it moved proximal ly, The posterior cruciate ligament had an opposite trend because it decrea sed from the proximal to the distal region. For the meniscofemoral ligament , the fibrils of the middle region were larger than those of the proximal a nd distal regions. The percentage of total cross sectional area occupied by collagen, however, did not vary significantly between regions. Fibril ecce ntricity also varied little between ligament or location, The variability o bserved in fibril diameters may account for the different mechanical proper ties of the ligaments.