Does a combined screw and dowel construct improve tibial fixation during anterior cruciate ligament reconstruction?

Purpose The aims of the present study were to compare the biomechanical properties of tibial fixation in hamstring-graft ACL reconstruction using interference screw and a novel combination interference screw and dowel construct. Material and Methods We compared the fixation of 30 (2- and 4-stranded gracilis and semitendinosis tendons) in 15 fresh-frozen porcine tibiae with a biocomposite resorbable interference screw (Group 1) and a screw and dowel construct (Group 2). Each graft was subjected to load-to-failure testing (50 mm/min) to determine maximum load, displacement at failure and pullout strength. Results There were no significant differences between the biomechanical properties of the constructs. Multivariate analysis demonstrated that combination constructs (beta = 140.20, p = 0.043), screw diameter (beta = 185, p = 0.006) and 4-strand grafts (beta = 51, p = 0.050) were associated with a significant increase in load at failure. Larger screw diameter was associated with increased construct stiffness (beta = 20.15, p = 0.020). Conclusion The screw and dowel construct led to significantly increased fixation properties compared to interference screws alone in a porcine model. Increased screw diameter and utilization of 4-strand ACL grafts also led to improvement in load-to-failure of the construct. However, this is an in vitro study and additional investigations are needed to determine whether the results are reproducible in vivo.

Automated summary

The study aimed to compare the biomechanical properties of tibial fixation in hamstring-graft ACL reconstruction using different fixation methods. Results showed that the screw and dowel construct provided significantly improved fixation properties compared to interference screws alone in a porcine model. Larger screw diameter and 4-strand ACL grafts also led to better load-to-failure performance of the construct. More research is needed to confirm if these results are reproducible in vivo.