Biomechanical Comparison of Knotless Suture Anchor Fixation Versus Transosseous Suture Button Fixation for Posterior Medial Meniscal Root Tears

Background: Posterior medial meniscal root (PMMR) tears have been shown to create a biomechanically unfavorable environment for knee cartilage. While various PMMR repair methods have been shown to restore normal knee biomechanics, there is little consensus on the ideal repair technique. Purpose: To compare PMMR repair using a knotless all-suture anchor versus traditional transosseous fixation using a suture button. Study Design: Controlled laboratory study. Methods: Ten matched pairs of fresh-frozen cadaveric knees were biomechanically tested in intact, torn, and surgically repaired conditions. One limb from each donor was repaired using a traditional suture and bone tunnel technique (control group), while the contralateral limb was repaired with a knotless all-suture anchor (anchor group). The limbs were distributed equally between the 2 surgical procedure groups, so that each group contained a nearly equal number of right and left knees. Results: There were no significant differences in normalized contact area or normalized contact pressure between control and anchor groups at 0°, 30°, or 60° of knee flexion. Contact pressure returned to near-intact values at 0°, 30°, and 60° for both groups. This was also the case at 90° for the anchor group. However, the control group did not return to intact values at 90°, resulting in a significantly ( P = .007) higher normalized contact pressure in the control group compared with the anchor group. This finding was also true at 90° for normalized contact area, which was significantly lower ( P = .0001) in the control group than in the anchor group. Conclusion: At time zero, knotless all-suture repair of PMMR tears performed biomechanically similarly or better than transosseous suture button fixation at 0°, 30°, and 60° of flexion, with significantly improved contact area and contact pressure at 90° of flexion. Thus, knotless all-suture anchor repair may represent a viable alternative technique for PMMR repair. Clinical Relevance: The knowledge that knotless all-suture anchor repair performed as well as or better than a more traditional technique allows for a technically simpler surgery, which precludes the need for drilling through the tibia.