Current tissue engineering strategies in anterior cruciate ligament reconstruction

Rupture of the anterior cruciate ligament (ACL) is one of the most common ligamentous injuries of the knee. Limitations of allografts and autografts in ACL reconstruction as well as recent advancements in biology and materials science have spurred interest in developing tissue-engineered ACL replacements that have the potential to mimic the native ACL in terms of both biological and mechanical properties. This article reviews the current literature regarding contemporary tissue engineering strategies. The four basic components of tissue engineering, biomaterial scaffolds, cell sources, growth factors, and mechanical stimuli, as applied to the development of tissue-engineered ACL replacement grafts, will be systematically addressed. In addition, animal models that have been used to test these tissue-engineered ACL replacements will also be reviewed. To date, there is no tissue-engineered ACL construct that has been successfully implanted in humans. We expect that continued progress in designing a viable tissue-engineered ACL replacement will accompany rapidly advancing techniques in materials science and biology.