Leeds-Keio artificial ligament: a new concept for the anterior cruciate ligament reconstruction of the knee.

The features of the Leeds-Keio artificial ligament, which was developed as a collaborative project between the University of Leeds in the UK and Keio University, are introduced. The ligament is made of polyester, and has a mesh structure. The diameter of the polyester fibers is 22 microns. The ligament has a tensile strength sufficient for anterior cruciate ligament (ACL) reconstruction, and fatigue tests have shown satisfactory durability of the ligament. The stiffness of the Leeds-Keio artificial ligament is about 200 N/mm, which is similar to the natural ACL. A combination of a bone plug and stapling is used for the bone fixation, taking into consideration the strength in both the initial mechanical fixation and the long term fixation. From an animal study, it was shown that fibrous tissue was induced around the artificial ligament, and the collagen fibers became aligned in the longitudinal direction of the ligament. For the clinical experience, one-hundred and thirty five cases were reviewed. The Lachaman sign disappeared in 87.4%, and the pivot shift sign disappeared in 88.1%. Side-to-side difference of anterior displacement of the knee, measured with a KT-2000 knee arthrometer at 30 degrees of flexion, was less than 3 mm in 85.9%. More than 90% of the patients experienced full range of motion. Thus, from the clinical results, it can be concluded that reasonable stability was obtained with the operation. If the Leeds-Keio artificial ligament may not be the perfect substitute for the ACL, both experimental and clinical studies indicate that it represents a major forward step in the history of knee ligament surgery.