Pull-out and shear failure strengths of arthroscopic meniscal repair systems

Abstract

Meniscal repair is common and recommended in young patients. Suture techniques and fixation devices were developed for stronger, more facile repairs. Three devices (T-Fix, Meniscal Staple, Meniscus Arrow) were biomechanically compared to horizontal PDS suture. Peripheral tears were created in porcine menisci and repaired using the manufacturer's technique. An Instron was used to distract the menisci at 50 mm/min in axial-pullout and longitudinal shear loads. Load to failure curves and peak failure loads were noted. Load to failure in axially loaded pull-out mode was: Staple, 4.195+/-3.70 N; Arrow, 39.755+/-11.37 N; T-Fix, 45.892+/-13.99 N; Suture, 107.65+/-22.37 N. Analysis of variance with post hoc testing revealed Staple failure at lower load than all devices and Suture failure at higher loads than all devices; Arrow and T-Fix were similar. The data varied significantly from that obtained in shear. Shear loads to failure were: Staple, 8.39+/-8.62 N; Arrow, 27.67+/-14.33 N; T-Fix, 57.47+/-17.05 N; Suture, 64.15+/-17.05 N. Analysis of variance, power analysis, and pair-wise multiple comparisons revealed significant differences between: Suture and Staple, Suture and Arrow, and T-Fix and Staple. No differences were noted between Suture and T-Fix, T-Fix and Arrow, or Arrow and Staple. In pullout, Suture and T-Fix maintained better apposition at low loads. As load increased, the menisci separated until device failure. Arrows allowed low load separation but held tissue until failure. Staples failed at low load. For shear, the menisci attempted to reorient parallel to the force. The devices failed in a pull-slide pattern. Suture failed by pull-through. Meniscal repair devices are easy to use and may provide resistance to shear and pull out. The resistance to pullout loads was very different than the resistance to longitudinal shear loads.

Meniscus Repair and Transplantation: A Comprehensive Update

“…5,9,17,35,78,80,81 Vertical sutures are superior to both horizontal sutures and meniscus arrows in mean load-to-failure values. 4,16,52,78 The superior strength of vertical sutures is hypothesized to be due to the perpendicular orientation to the circumferential collagen bundles of the meniscus.…”

Shear Force at Failure and Stiffness of All-Inside Meniscal Repair Devices

“…[10] Zantop et al examined the difference between horizontal and vertical suture patterns by applying a cyclic load in shear. They found that horizontal suture had less elongation between cycles and higher load to failure than vertical sutures, but did not examine any of the all-inside devices.…”

“…This testing setup was modified from that previously described. [10] A pre-load of 2 N was applied and load-to-failure testing was performed at a constant displacement rate of 12.5 mm/sec. This displacement rate was consistent with previous studies that evaluated the ultimate pullout strength of sutures and suture anchors and is reflective of a rapid loading force.…”

“…Few biomechanical studies have addressed shear forces relative to meniscal repairs despite the fact that these may more closely mimic knee kinematics in the postoperative rehabilitation or athletic setting. [8][9][10] It is possible that weight bearing in conjunction with tibiofemoral rotation during knee flexion could produce shear forces capable of disrupting healing meniscal tissue, particularly if the fixation strength was inadequate. Traditional teaching supports weight-bearing limitations during the initial 4 to 8 weeks after meniscal repair.…”

Histoacryl glue in meniscal repairs (a biomechanical study)

“…Thus, we standardised the meniscal areas to be tested (333.7±56.0 mm 2 ). After the application of Histoacryl to the 25 mm of the tear site, the remaining meniscal horns were excised in order to maintain this standardisation and to ensure that the repair device, not the meniscal tissue, provided the fixation's stability [13].…”