Summary

A biomechanic comparison of repair techniques for radial tears of the lateral meniscus using all-inside devices that shows little advantage and increased cost with all-inside repairs compared to inside-out repairs. Additionally, a novel repair technique, the "hashtag" repair, shows promise to reduce displacement following cyclic loading when compared to traditional repair methods.

Abstract

Background

The lateral meniscus is critical for load transmission across the knee and its absence leads to early degenerative changes. Complete radial tears are equivalent to total meniscectomy and repair should be performed if possible. Double horizontal, cross suture, hashtag and crosstag repairs for radial tears have been described with promising results using an inside-out suture technique.
Hypothesis/Purpose: To biomechanically compare the cross suture, hashtag and crosstag meniscal repairs using all-inside implants (Figure 1).
Study Design: Controlled Laboratory Study.

Methods

Radial tears were created at the mid-body of 36 fresh-frozen lateral human menisci and then repaired, in randomized order, with Fast-Fix™ 360s(Smith & Nephew, Andover, MA) using cross suture, hashtag and crosstag techniques. The repaired menisci were cyclically loaded from 5 to 30N at 1Hz for 500 cycles, then loaded to failure using an ElectroPuls E10000(Instron, Norwood, MA). Displacement following cyclic loading, load at 3mm of displacement, load to failure, and stiffness were recorded. Any differences between repairs were assessed using Kruskal-Wallis and Mann Whitney tests (p<0.05).

Results

Cross suture repairs displaced more following cyclic loading and resisted less load to failure than both the hashtag and crosstag repairs. However, these differences were not statistically significant. The average displacement following cyclic loading of cross suture, hashtag, and crosstag repairs was 4.34 mm(±2.02 mm), 3.46 mm(±2.12 mm), and 3.24 mm(±1.52 mm) respectively(p=0.33). Maximal load to failure was 64.83 N(±17.41 N), 74.52 N(±9.03 N), and 74.98N(±10.50N), respectively(p=0.419).

Conclusion

All-inside cross suture, hashtag and crosstag repairs all displaced >3mm with cyclic loading, which is the threshold for meniscal insufficiency. This contrasts previous studies using inside-out sutures, where hashtag repairs resisted cyclic loading(< 3mm). This could be due to meniscal damage from larger diameter needles(17 versus 21 gauge), increased working distance from the tear(5 mm versus 3mm), and technical difficulty in repairing menisci free of any soft tissue attachments with all-inside implants.