Neither All-Inside, nor Inside-Out, nor Outside-In Repair Demonstrates Superior Biomechanical Properties for Vertical Meniscal Tears: A Systematic Review of Human Cadaveric Studies

Abstract

To systematically review the literature regarding the biomechanical properties of different repair techniques and fixation methods for vertically oriented meniscal tears. Human cadaveric studies evaluating the biomechanical properties of different repair techniques for vertically oriented meniscal tears were identified using the PubMed, EMBASE, and CINAHL databases. Primary outcomes included load to failure (LTF), displacement, stiffness, peak contact pressure, and contact area of repaired menisci. Repair techniques from included studies were reclassified into a total of 19 distinct all-inside (AI), inside-out (IO), or outside-in (OI) techniques. Sixteen studies were included (420 total menisci). Contact pressure and area were restored to intact-state values across all 5 compressive load studies at low knee flexion angles, but not at higher knee flexion angles (i.e., >60°). There were no significant differences in contact pressure or area between AI, IO, and OI techniques across all studies. Some studies demonstrated statistically significant advantages in tensile properties with IO techniques when compared to AI techniques, while others found AI techniques to be superior. No studies directly compared tensile properties of OI techniques to those of AI or IO techniques. Vertical mattress suture configurations resulted in significantly greater LTF and decreased displacement compared to horizontal mattress configurations in 67% of studies comparing the two techniques. There was no difference in the rate of tissue failure in AI (66.97%), IO (60.38%), or OI (66.67%, χ2 = 0.83, p=.66) techniques. Contact mechanics are reliably restored following repair of vertical meniscal tears at low flexion angles, but inconsistently restored at higher flexion angles, regardless of technique. Vertical mattress configurations outperformed horizontal mattress configurations under tensile load. There is conflicting data regarding the comparison of tensile properties between AI and IO techniques. Ultimately, neither AI, IO, nor OI repair demonstrated superior biomechanical properties in the present literature.