Structural properties of sutures used in anchoring multistranded hamstrings in anterior cruciate ligament reconstruction: a biomechanical study.

Sutures are frequently used in anchoring hamstring or quadriceps tendon grafts in cruciate ligament reconstruction. Trumpet like widening of the femoral bone canal was found in patients having had anterior cruciate ligament reconstruction with hamstring autograft. We investigated 5-mm Polylene tape (Genzyme, Boston, MA) and Mersilene tape (Ethicon, Somerville, NJ) as well as No. 6 Ethibond sutures (Ethicon) for ultimate load, stiffness, and elongation under tension of 50 N, 150 N, 250 N, and ultimate load. The Mersilene and Polylene tapes were tested in single loops and Ethibond in double loops having a length of 30 mm. The length is similar to that used intraoperatively for the graft fixation. The suture materials were loaded using a material testing machine at a strain rate of 60 mm/min. The ultimate loads of the loops with knots were 474 N +/-24.7 N for Polylene, 437 N +/-38.2 N for Mersilene, and 338 N +/-16.8 N for Ethibond, and was statistically significant (analysis of variance [ANOVA], P<.05). The elongation under a tension load of 50 N was similar for Ethibond (1.2+/-0.216 mm) and Polylene (1.3+/-0.32 mm). Mersilene (1.7+/-0.34 mm) showed an increased elongation (ANOVA, P=.03). The stiffness for Ethibond was 37.1+/-2.7 N/mm, for Mersilene 38.4+/-3.8 N/mm, and for Polylene was 47+/-3.1 N/mm. The Polylene tape appears to be the most suitable material in terms of strength and stiffness. Nevertheless, the stiffness of all the tested materials is greatly inferior to the stiffness of the commonly used grafts. We believe that a stiffer graft construct might reduce motion during the early period of ingrowing.