Suture Anchor and Reverse Suture Anchor show Superior Biomechanical Efficacy to Transtibial Pull-out Repair for Posterior Medial Meniscus Root Tears in Porcine Model

To investigate the biomechanical efficacy of the reverse suture anchor (RSA) technique compared with the transtibial pull-out (TP) and suture anchor (SA) techniques using in vitro porcine knee models of PMMRTs. 32 fresh frozen porcine tibiae with medial meniscus intact were randomly assigned to four groups (eight specimens each). A standardized posterior medial meniscus root tear (PMMRT) was established in 24 specimens. SA, TP, and RSA techniques were used to repair PMMRTs in 8 specimens respectively, while the native posterior medial meniscus roots (PMMRs) were left intact as a control in eight specimens. Pressure sensitivity, stress, cyclic load and failure load tests were performed. To evaluate differences in group variables, ANOVA was used to compare differences among ≥ three groups and Tukey's test was used to compare data between two groups. Significance level was set at P < .05. The SA and RSA groups had a wider contact area and higher pressure at the meniscus suture site and attachment area than the TP group (P < .001) while there was no significant difference in pressure sensitivity or stress between SA and RSA (P > .05). The SA, RSA and TP groups had significantly higher displacement during cyclic loading and significantly lower maximum load and stiffness during load-to-failure testing compared with the native PMMR (P < .05). The SA and RSA groups had significantly lower displacement after 100 (0.83 mm and 0.92 mm vs 1.77 mm, P < .01), 500 (1.64 mm and 1.52 mm vs 3.08 mm, P < .01), and 1000 cycles (2.22 mm and 1.91 mm vs 4.53 mm, P < .01) and significantly higher failure load compared with TP (114 N and 119 N vs 77 N, P < .01). No significant difference between SA, RSA and TP was observed for displacement at failure or stiffness (P > .05). The RSA repair technique has similar biomechanical efficacy to the SA technique. It offers better biomechanical efficacy than the TP technique for PMMRT repair, making it a feasible and effective surgical procedure. The three repair techniques did not reach the strength of the native PMMR. The RSA technique retrogradely implants anchors into the tibial bone tunnels to achieve a fixation effect comparable to that of traditional anchors, with shorter sutures in the bone tunnels and a more operable surgical procedure. The RSA technique not only provides satisfactory biomechanical properties for the repair of PMMRTs, but also greatly reduces the technical difficulty of surgery. However, repairing of PMMRTs still does not restore the strength of the repaired meniscal root to the native meniscus.