Influence of different suture strengths on meniscal sutures subjected to cyclic loading conditions

The aim of this study was to analyze meniscal sutures under cyclic loading conditions for different suture types (vertical and horizontal mattress sut ures) and suture materials (absorbable monofilament sutures: PDS 2-0; PDS-0 , and PDS-1 USP). Testing was performed on medial porcine menisci, using a well-established biomechanical testing model with a complete longitudinal t ear 3 mm from the periphery of the meniscus. Sixty specimens were used. One suture was tested at a time. During cyclic testing 100 load cycles were ap plied with a crosshead speed of 50 mm/min. Three different maximum loads (1 0 N, 20 N,and 40 N)were used. The preload was set at 5 N. After cyclic load ing, the specimens were loaded until failure. During cyclic loading,a gap appeared between the two parts of the meniscus, and partial tissue failures were observed at the surface of the meniscus. C apping was more marked with higher loads and with the weaker suture materia l (p < 0.001). Using PDS 0 and PDS 1 sutures, less partial tissue failures were observed compared to PDS 2-0 (p < 0.001). The ultimate failure loads a fter cyclic loading were higher with PDS-0 and PDS-1 sutures. With these su ture materials vertical sutures were stronger than horizontal sutures (p < 0.05). Using PDS 2-0 this difference could not be found. These results show that the primary strength of meniscal sutures depends on the suture material. The frequency and the amount of gapping and partial t issue failures,which can be observed under cyclic loading,are less distinct with PDS-0 and PDS-1 compared to PDS 2-0. From a biomechanical point of vi ew, PDS 0 and PDS 1 sutures a re recommended for meniscal sutures to guaran tee a high primary stability, a small amount of gapping, and few partial ti ssue failures.