“Ligament Augmentation Device for Anterior Cruciate Ligament repair: Design and comparative analysis of different biomaterials

Abstract

Anterior cruciate ligament is the most frequently injured ligament in the united states (US). ACL injuries in the US range between 100,000 to 200,000 a year. ACL injuries are more frequent in the people who play sports. Contact and non contact injuries can various degrees of tears or disruption of ACL. Surgical treatment is recommended for people with an active lifestyle. Conservative treatment, the other alternative, can lead to long term complications. The natural ACL is provided with nerves and there are various mechanoreceptors in the ligament. The receptors perform important functions like detecting a change in direction and position of the knee. The ligament is involved not only in providing mechanical strength but also functional stability to the knee. The golden standard for ACL reconstruction is bone patellar bone tendon graft but allograft and autograft come with their own set of complications. Synthetic grafts are no longer being used due to the complications reported in the long run. One of the causes of graft failure was the design of the graft. The synthetic grafts have woven, braided, twisted or a knitted design. This study investigates a new design, a seamless tubular hollow tube with gates on its inside blocking off both the ends and slits along the effective length of the device. Theoretically the device will be implanted along the footprint of the native ACL which will be repaired through primary repair. The device will withstand most of the forces acting on the ligament and allow the ligament to heal through primary repair. A new design was tested on various materials. two types of tests were performed to determine the strength of the design. The extent of elongation seen in the materials was also an important factor. Tensile and Bending test were performed to test the mechanical strength of the device. Comparatively the best results were seen in the case of the device fabricated using semi-rigid polyurethane which was able to under the bending test and showed better results than the composite samples. The study showed that the design is able to withstand the force that lies in the range of the data provided in literature. While the strength of the semi rigid polyurethane samples was 50% of the full tensile strength of old patients. The tensile testing results show that the design will be able to withstand the forces acting on the ligament in the knee joint if the right bio compatible material (biocompatible polymer) with the required mechanical properties is material is used the fabrication of the device.