Biomechanical comparison between suture anchor and transtibial pull-out repair for posterior medial meniscus root tears.

BACKGROUND: Posterior medial meniscus root (PMMR) tears have a serious effect on knee joint biomechanics. Currently used techniques for refixation of the PMMR include the transtibial pull-out repair (TP) and suture anchor repair (SA). These techniques have not been compared biomechanically.

HYPOTHESIS: The SA technique provides superior biomechanical properties compared with the TP technique.

STUDY DESIGN: Controlled laboratory study.

METHODS: A total of 24 fresh-frozen porcine tibiae with attached intact medial menisci were used. The specimens were randomly assigned to 3 groups (8 specimens each). A standardized PMMR tear was created in 16 specimens. Refixation of the PMMR was performed by either the TP or SA technique. The native PMMR was left intact in 8 specimens. All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement after 100, 500, and 1000 cycles; maximum load to failure; stiffness; and displacement at failure were recorded.

RESULTS: Both repair techniques showed a significantly higher displacement during cyclic loading and a significantly lower maximum load and stiffness during load-to-failure testing compared with the native PMMR (P < .05). The SA technique showed a significantly lower displacement after 100, 500, and 1000 cycles (P < .001) and a significantly higher stiffness (P = .016) compared with the TP technique. Maximum load did not differ significantly between the SA and TP techniques (P = .027, Bonferroni adjustment). No significant difference between the 3 groups was observed for displacement at failure (P > .05).

CONCLUSION: The SA technique provided superior biomechanical properties compared with the TP technique. Both repair techniques did not reach the strength of the native PMMR.

CLINICAL RELEVANCE: The favorable biomechanical properties of the SA technique might be beneficial for healing of the repaired PMMR and restoration of meniscus function. Because of inferior time zero stability compared with the native PMMR, slow rehabilitation is recommended after meniscus root repair.