Comparison between different femoral fixation devices for patellar tendon graft in anterior cruciate ligament reconstruction. An ex-vivo mechanical study on animal model [Confronto tra diversi sistemi di fissazione femorale per il trapianto di tendine rotuleo nella ricostruzione del legamento crociato anteriore. Studio meccanico ex-vivo su modello animale]

Purpose of the study: To evaluate the mechanical properties of Femur-Graft Complex in the anterior cruciate ligament (ACL) reconstruction with patellar tendon (PT) graft, comparing different femoral graft fixation devices. Type of the study: Ex-vivo mechanical study on animal model. Materials and Methods: An ACL reconstruction with PT was carried out on 40 porcine knees. Femoral graft fixation was achieved using four different systems: absorbable interference screw (Group A); transcondylar metal screw (Group B); absorbable pins (Group C); and a new devices that consists of a transcondylar metal screw and a metal pin (Group D). Ten more knees were used as control group. On each sample a cyclic loading test, then a load-to-failure test was performed. Results: Groups B and D showed mean elongation at cyclic loading significantly lower than other groups. Furthermore, Group D showed signiticantly greater mean values than other groups for maximum load, yield load, and stiffness, without signficant differences in comparison with the control groups. Conclusions: Transcondylar fixation devices showed best structural properties of Femur-Graft Complex. Moreover, augmenting compression mechanism with a suspension device, as in Group D, we obtained structural properties similar to those of normal ACL and PT graft.