Augmentation of a ruptured posterior cruciate ligament provides normal knee joint stability during ligament healing.

OBJECTIVE To identify an augmentation technique which would provide mechanical protection for the healing posterior cruciate ligament. DESIGN Six human knee specimens were tested in vitro for posterior knee joint stability after augmenting the cut posterior cruciate ligament by six different techniques using a resorbable double strand Polydioxanone augmentation device. BACKGROUND A fresh isolated rupture of the posterior cruciate ligament is often treated conservatively. Results have shown that it can heal, but ligament elongations occur frequently. Therefore a method is needed to provide posterior knee joint stability during ligament healing. METHODS The effect of different femoral augmentation insertions on posterior knee stability was tested by recording the antero-posterior (AP) position of the tibia and the augmentation force. Testing was performed during flexion--extension cycles and under posterior shear loads. RESULTS The insertion combination that proved to stabilize the joints best consisted of one augmentation strand leading along the antero-lateral posterior cruciate ligament fibres and inserting at the distal end of the Blumensaat line and one strand leading along the posteriormedial fibres and inserting in the middle of the Blumensaat line. AP translations similar to those occurring in healthy knee joints could be achieved. CONCLUSIONS It is possible to restore normal posterior knee joint stability by implanting a double strand augmentation device. This can help a posterior cruciate ligament to heal under non-elongated conditions.