Evaluation of Tibial Fixation Devices for Quadrupled Hamstring ACL Reconstruction

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Sports medicine

Background:

• Tibial fixation is a critical component of anterior cruciate ligament (ACL) reconstruction, with known failure modes.
• Adjustable-loop devices (ALDs) are increasingly utilized for graft fixation.
• Limited comparative data exists between ALDs and traditional hybrid fixation (interference screw and cortical button).

Purpose of the Study:

• To biomechanically compare adjustable-loop devices (ALDs) in full-tunnel and closed-socket configurations against hybrid fixation.
• To evaluate the hypothesis that tibial ALD primary stability is non-inferior to hybrid fixation.

Main Methods:

• A porcine tibia-bovine tendon model was used to test five tibial fixation techniques.
• Constructs included hybrid fixation, single cortical fixation (open-suture button or ALD), and closed-socket ALDs.
• Biomechanical testing involved cyclic loading (1000 cycles, 50-250 N) and pull-to-failure analysis.

Main Results:

• No significant difference in ultimate load to failure was observed between ALD constructs and hybrid fixation.
• Cyclic displacement was higher only in the single cortical fixation group with an open-suture button.
• Knotless ALDs (full-tunnel and closed-socket) demonstrated significantly higher remaining graft tension post-fixation compared to hybrid fixation.

Conclusions:

• Knotless adjustable-loop devices (ALDs) provide biomechanically equivalent tibial fixation strength to hybrid methods.
• Both full-tunnel and closed-socket ALD techniques are effective.
• The retention of graft tension during fixation is a key biomechanical factor, potentially more critical than the tunnel configuration.