The aim of this study was to analyze meniscal sutures under cyclic loading conditions for different suture types (vertical and horizontal mattress sutures) 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 tear 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 applied with a crosshead speed of 50 mm/min. Three different maximum loads (10 N, 20 N, and 40 N) were used. The preload was set at 5 N. After cyclic loading, 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. Gapping was more marked with higher loads and with the weaker suture material (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 after cyclic loading were higher with PDS-0 and PDS-1 sutures. With these suture 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 tissue 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 view, PDS 0 and PDS 1 sutures are recommended for meniscal sutures to guarantee a high primary stability, a small amount of gapping, and few partial tissue failures.

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Four-point bending creep behavior of mullite ceramics with monomodal and bimodal distribution of grain sizes was studied in the temperature range of 1320-1400 • C under the stresses between 40 and 160 MPa. Mullite ceramic with bimodal grain size distribution was prepared using aluminum nitrate nonahydrate as alumina precursor. When ␥-Al 2 O 3 or boehmite were used as alumina precursors, mullite grains are equiaxial with mean particle size of 0.6 m for the former and 1.3 m for the latter alumina precursor. The highest creep rate exhibited the sample with monomodal morphology and grains in size of 0.6 m, which is about one order of magnitude greater than that for the monomodal morphology but with grains in size of 1.3 m. The highest activation energy for creep (Q = 742 ± 33 kJ/mol) exhibits mullite with equiaxial grains of 1.3 m, whereas for sample with smaller equiaxial grains the activation energy is much smaller and similar to mullite ceramics with bimodal grain morphology. Intergranular fracture is predominant near the tension surface, while transgranular more planar fracture is predominant near the compression surface zone.