Greater deformation and lower stiffness, but similar ultimate failure strength with fixed-loop cortical suspensory device compared to metal interference screw for femoral fixation of bone-patellar tendon-bone grafts in anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to compare a contemporary fixed-loop cortical suspensory devices (CSDs) with metal interference screws (IS) for femoral bone-patellar tendon-bone (BPTB) graft fixation in anterior cruciate ligament reconstruction (ACLR). METHODS: Seven matched pairs of fresh-frozen human cadaveric knees underwent anatomical ACLR with BPTB grafts. Femoral fixation was randomized to a fixed-loop CSD or metal IS. Specimens underwent cyclic loading at 50 and 100 N at 1 Hz until failure or up to 1000 cycles. Comparison between the fixation methods for cyclic displacement, displacement at failure, construct stiffness and ultimate load to failure was performed. Comparisons between fixation methods were performed using paired t tests. RESULTS: Fixed-loop CSD fixation demonstrated significantly greater cyclic displacement than IS fixation (2.8 ± 0.9 vs. 1.7 ± 0.5 mm; p = 0.008). Displacement at failure was significantly higher (12.3 ± 1.7 vs. 7.9 ± 1.1 mm; p = 0.004), and construct stiffness was lower (46 ± 10 vs. 84 ± 18 N/mm; p = 0.002) with CSD fixation compared to IS fixation. There was no significant difference in ultimate load to failure (CSD fixation; 563 ± 109 vs. IS fixation; 668 ± 217 N; p = 0.31). Failure occurred mainly as lateral cortical fractures with CSD and proximal graft avulsions with IS fixation. CONCLUSION: Fixed-loop CSD fixation of BPTB grafts demonstrated greater deformation and lower stiffness than IS fixation, and with similar ultimate failure strength. The clinical relevance of the observed difference remains uncertain. LEVEL OF EVIDENCE: N/A.