Does a navigation system for ACL replacement realistically predict the length change of tendon grafts?

摘要

Introduction: The aim of computer-assisted navigation in the replacement of the anterior cruciate ligament (ACL) is the standardized implantation of a tendon graft. Insertion points of the graft as close as possible to ideal isometry are desirable to avoid excessive graft strain during the healing period. However, conventional drill guides providing femoral drill tunnels at a constant distance to the dorsal cartilage rim take the individual anatomy of a patient only little into account. Navigation allows planning of the drill tunnels according to the patient's anatomy more individually [1,2]. Aim of this study was to investigate if a computer-navigated system realistically predicts the graft length change during knee joint flexion. Methods: The ACLs of 32 cadaveric knee joints (age 47-90) were replaced by a tendon transplant. In 16 joints the surgical procedure was performed using conventional drill guides (Arthrex). The other 16 joints were operated with a computer navigation system (ACL Logics Universal, PRAXIM-medivision). An experienced surgeon, who is used to do both procedures clinically, operated both groups. The navigation system allowed planning of the insertion points before drilling the tunnels for graft placement. At first the areas of the ACL insertions and the shape of the intercondylar notch were digitized. Then, the system provided an isometry map predicting the areas of least anisometry.