Function of the Ligament Augmentated Device Under Simulated Anterior Cruciate Ligament Reconstruction and Rehabilitation

Summary

In this study, functional properties of artificial ligaments (LAD and Dacron, n = 4 respectively) were examined biomechanically. The artificial ligaments underwent a testing procedure which simulated surgical and postsurgical conditions including initial tensioning, fixation, and range of motion exercise. First, the specimen was set on an Instron type testing machine and it underwent a creep test with a 49 N load for 5 minutes. Then the specimen underwent a cyclic stress relaxtion test (CSRT) where it was cyclically stretched between 0 and 5% deformation 100 times. Load during the cycling was recorded. Finally, the specimen was loaded to failure. One human tibialis posterior tendon was tested in the same way, and the relaxation properties of the artificial ligaments and the human tendon were compared with each other. Based on the experimental data, the sharing of loads during the CSRT between the artificial ligament and the human tendon was calculated when these two materials were used in combination.

The load in either of the artificial ligaments decreased from 49 N to zero after the CSRT while a load of 7 N was still existent in the human tendon. The ratio of load between the ligament augmentated device (LAD) and the human tendon at 5% deformation was calculated to change from 65:35 to 74:26 during the CSRT.

This study demonstrated functional differences between the artificial ligaments and the human tendon. This difference should be considered when composite grafts (artificial ligament and human tendon) are used in ligament reconstruction.