Dacron augmentation of a free patellar tendon graft: a biomechanical study

The mechanical characteristics of a knitted 8-mm Dacron tube used as augmentation for patellar tendon strips was analyzed and compared with ligament augmentation device (LAD) tendon strips. The failure load was found to be the same (approximately 320 N) for both types of ligament augmentations. The typical failure mode in the Dacron augmentations was rupture of the Dacron tube proximal to the proximal bone fragment. The LAD augmentations failed at the suture line. The Dacron composite was stiffer than the LAD composite at low loads, but both composites became stiffer after two load cycles to 40 N with stress relaxation. At the end of the second stress relaxation cycle, the remaining load was significantly higher for the Dacron composite. During the second 2-min stress relaxation period, the Dacron composite lost 23% and the LAD composite lost 28% of the applied load. The stiffness and the elongation to failure was the same for both composites. The study showed that the Dacron tube may have possibilities similar to the LAD for use as an augmentation device.