Strength retention properties of self-reinforced poly L-lactide (SR-PLLA) sutures compared with polyglyconate (Maxon) and polydioxanone (PDS) sutures. An in vitro study.

Recent developments in manufacturing techniques have led to the development of strong bioabsorbable materials such as self-reinforced poly L-lactide (SR-PLLA) sutures. The aim of the study was to investigate the mechanical properties of SR-PLLA sutures in comparison with polyglyconate (Maxon) and polydioxanone (PDS) sutures in vitro. Sutures made of SR-PLLA (0.3, 0.5 and 0.7 mm diameter), Maxon (0.3 and 0.5 mm diameter) and PDS (0.3 and 0.5 mm diameter) were studied by immersion in phosphate-buffered distilled water (pH 7.4) at 37 degrees C for 40 weeks. The breaking force of straight sutures and suture knots was measured. Tensile strength and percentage elongation were calculated. Means, standard deviations, differences between means, and confidence intervals for differences between means were evaluated. SR-PLLA, PDS and Maxon sutures of 0.3 and 0.5 mm diameter were of comparable initial tensile strength. Initial knot tensile strength values were lower than those of their counterpart straight sutures. Maxon sutures had lost their tensile strength by 12 weeks; PDS sutures by 20 weeks. SR-PLLA sutures of 0.3 mm diameter had a strength of 161.6 MPa and those of 0.5 mm diameter had a strength of 134 MPa at 40 weeks. The highest percentage elongation of straight sutures (62.8% and 62%) was exhibited by PDS; the lowest by SR-PLLA (35.6% and 35%). In loop tests, PDS showed the highest percentage elongation (43.7% and 58.1%) and SR-PLLA had the lowest values (19.7% and 33%). SR-PLLA sutures had the most prolonged strength retention in vitro, but the lowest elongation (elasticity). Compared with straight sutures, knots had lower tensile strength and elongation values. SR-PLLA sutures can be applied to the closure of wounds that need prolonged support, such as bone.