Biomechanical Comparison of Meniscal Allograft Root Fixation Techniques: Anterograde Interference Bone Plug Fixation Yields Favorable Results Compared to Transosseous Suture Fixation Alone.

PURPOSE

To compare the biomechanical properties of 2 different fixation techniques (interference bone plug fixation vs transosseous suture fixation) of the posterior horn of the medial meniscus using a porcine model.

METHODS

Twenty-six matched pairs of fresh-frozen juvenile domestic porcine knees were used in this study. Specimens were randomly distributed among 3 groups: (1) native meniscus groups, (2) interference fixation, and (3) transosseous suture fixation. In each group, the posterior segments of the tested medial menisci were gripped with the freeze clamps and fixed to the tensile testing machine. Samples were preconditioned, followed by cyclic tension-relaxation for 1000 cycles between 10 and 30 N at 0.5 Hz and finally pulled to failure at a rate of 0.55 mm/s. The cyclic elongation, stiffness to failure, mode, and ultimate load to failure were recorded.

RESULTS

There was no significant difference in ultimate load to failure between the interference fixation (169.71 ± 71.98 N) and transosseous suture fixation (222.73 ± 72.40 N) groups ( = .118), both were significantly less than that of the native meniscus (405.46 ± 95.62) ( < .001). Interference fixation displayed cyclic elongation (1.04 ± 0.71 mm) and stiffness (69.10 ± 25.8 N/mm) that were not significantly different from the native meniscus tissue (0.78 ± 0.53 mm and 83.1 ±26.28 N/mm) ( = .359 and  = .224), in comparison to transosseous suture fixation, which did show increased cyclic elongation (1.85 ± 1.44 mm) ( = .047) and decreased stiffness (34.72 ± 10.2 N/mm) ( < .001).

CONCLUSION

Interference fixation of the posterior horn of the medial meniscus has superior cyclic elongation and stiffness when compared to transosseous suture fixation. Interference fixation and the native meniscus model have a similar stiffness and cyclic elongation.

CLINICAL RELEVANCE

The significance of our study is that using interference fixation for meniscal allograft transplantation has the potential to reduce short term surgical failures as well as long term complication rates.