A Biomechanical Comparison of Repair Techniques for Anterior Cruciate Ligament Avulsionfracture under Cyclic Loading

INTRODUCTION Failed treatment for avulsion fracture of the tibial attachment of the anterior cruciate ligament (ACL) leads to anterior knee instability when the avulsion fragment is displaced. Anatomical reduction and fixation of the fragment are widely recommended for type III and IV displaced fracture. Although several surgical techniques for arthroscopic reduction and internal fixation (ARIF) of the avulsion fragment have been developed, the outcome in adult patients varies and prolonged postoperative immobilization has been raised as a risk factor of loss of knee motion (1). Since the period of postoperative immobilization greatly depends on the initial fixation strength at the fixation site, the rigid fixation of the avulsion fragment of the ACL attachment is the key to minimize the motion complications. However, it remains unclear which fixation technique is most effective to obtain the superior initial fixation strength. Therefore, the objective of this study was to compare the initial fixation strength in response to a cyclic load between three different fixation techniques for ACL avulsion fractures: 1) antegrade screw fixation, 2) retrograde screw fixation, and 3) pull out suture fixation.