Cortical Tibial Press-Fit Fixation Demonstrates Comparable Biomechanical Performance With Interference Screw Fixation...

The optimal graft choice and fixation technique remain a topic of ongoing debate in both primary and revision anterior cruciate ligament (ACL) reconstruction (ACLR). Cortical tibial press-fit fixation offers known advantages such as eliminating the need for hardware, thereby reducing cost and avoiding complications related to implants, while also potentially minimizing bone tunnel enlargement.

To investigate the time-zero biomechanical properties (cyclic displacement, stiffness, and load to failure) of cortical tibial press-fit technique using bone-patellar tendon (BPT) graft for ACLR and compare with metal interference screw fixation to determine the potential clinical benefit of this technique.

Controlled laboratory study.

A total of 24 skeletally mature porcine knees were used. After determining the bone mineral density (BMD) of each specimen, the specimens were randomly assigned to their respective groups. One group underwent interference screw (9 mm-diameter × 25 mm-length) fixation using a BPT autograft, while the other group underwent implant-free cortical tibial press-fit fixation. Biomechanical testing included 3 loading phases: (1) preconditioning (10-50 N for 10 cycles); (2) submaximal cyclic loading (50-200 N for 1500 cycles); and (3) load to failure testing at a 20 mm/min loading rate. Groups were compared for stiffness, cyclic displacement and ultimate load to failure using Mann-Whitney U tests and for failure mode using a Fisher exact test.

Both groups of specimens showed similar BMD characteristics (P = .59). There was no significant difference in cyclic displacement (interference screw group, 5.73 ± 1.71 mm; press-fit group, 5.03 ± 1.70 mm; P = .38), or total displacement (interference screw group, 11.02 ± 3.37 mm; press-fit group, 10.33 ± 3.70 mm; P = .76). The mean cyclic displacement of the bone plugs was not significantly different between groups (interference screw group, 0.06 ± 0.05 mm; press-fit group, 0.03 ± 0.05 mm; P = .19). Stiffness at the last submaximal loading cycle was comparable between the groups (interference screw group, 65.32 ± 11.16 N/mm; press-fit group, 70.27 ± 13.39 N/mm; P = .76). Mean ultimate load at failure was 586.4 ± 75.9 N (range, 467.9-745.9 N) for the interference screw fixation group and 639.0 ± 149.2 N (range, 485.1-1050.5 N) for the press-fit group and (P = .51). All specimens failed due to tendon avulsion at the tendon-bone junction or tendon rupture at the midsubstance.

In this porcine patellar tendon ACLR tibial fixation model, cortical tibial press-fit fixation provided adequate primary stability, demonstrating similar cyclic displacement, construct stiffness, and ultimate load characteristics compared with interference screw fixation.

Cortical tibial press-fit technique may represent an effective method for ACLR.