Two Cases fo Subcutaneous Rupture of the Patellar Tendon

The author encountered two rare cases of patellar ligament body rupture complicated with complex ligament damage and conducted investigations on the damaging mechanism from the viewpoint of ligament biomechanics. The load exerted on the patellar ligament reaches a maximum and ACL tension increases, when the knee joint is in a slight flexion (specifically at an angle of about 50 degrees). It can be inferred that changes in the mechanical strength of a bone-ligament-bone complex occur depending on stress orientation and action timing, which in turn cause differences in rupture site location.