The Miller׳s knot as an alternative to the surgical knotting? Characterization of the mechanical behavior.

Several types of materials and surgical suture patterns are used in conventional surgery. Their combination with an appropriate knot is the basis for correct tissue apposition and healing. Knot security is essential to prevent loosening or slipping before the suture line is completely closed. Nevertheless, the knot itself is the weakest link in any surgical handling. The aim of this study is to determine and compare the mechanical behavior of four surgical knot types (square knot, surgeon׳s knot, square slipknot and Miller׳s knot) performed with three different suture materials (absorbable monofilament glyconate, non-absorbable monofilament polyamide and absorbable braided polyglycolic acid) in a non-biological experimental in vitro model (a tube of synthetic material with non-linear mechanical behavior). The mechanical properties of each suture material are also compared. Ten samples were mechanically tested for each suture and knot using a uniaxial tensile test until complete sample rupture. The failure Cauchy stress and stretch were calculated. The Cauchy stress at 5%, 10% and 15% strain and standard deviation were compared for each suture and knot type. The results demonstrated that all the suture materials had statistically significant differences in their non-linear mechanical behavior. Absorbable monofilament glyconate was the most compliant suture with the greatest tensile strength, while absorbable braided polyglycolic acid was the stiffest. Regardless of the suture type used, the Miller׳s knot had the greatest failure Cauchy stress and stretch, while the square, surgeon׳s and square slipknot had the lowest. In all cases, the Miller׳s knot was more compliant and had greater tensile strength than the other knots. The square knot, surgeon׳s knot, and square slipknot had statistically significant similarities in their mechanical behavior. Therefore, the Miller׳s knot could be classified as the gold standard and an alternative to the surgical knotting.