Anatomical and biomechanical characteristics of human meniscofemoral ligaments.

The meniscofemoral ligaments (MFL) of 26 human cadaver knees were studied to determine their structural importance. The incidence of at least one MFL in each of the specimens studied was 100%, and 46% of the specimens had both MFL ligaments (Humphry and Wrisberg). Another 23% had a single Humphry ligament, and the remaining 31% had a single Wrisberg ligament. A laser micrometer system was used to measure cross-sectional shape and area. The average cross-sectional areas of the Humphry and Wrisberg ligaments were 7.8 +/- 4.7 mm2 and 6.7 +/- 4.1 mm2, respectively. In specimens with both a Humphry and Wrisberg ligament, the larger ligament area was on average 100% greater than the smaller ligament area. The average ratios of the cross sectional areas of Wrisberg and Humphry to that for the PCL within the same knee were 12.0% +/- 7.7% and 11.9% +/- 5.7%, respectively. The structural properties of the MFL bone-ligament-meniscus complex and the mechanical properties of the MFL midsubstance were determined by uniaxial tensile testing. The average stiffness, ultimate load, and energy absorbed at failure were, respectively, 49.0 +/- 18.4 N/mm, 297.4 +/- 141.4 N and 1125.4 +/- 735.8 N/mm. The tangent modulus between 4% and 7% strain was 355.1 +/- 234.0 MPa. Our findings suggest that the MFL is a significant biomechanical structure in the knee because of its size, stiffness, and strength.