Microstructural properties of the anterior cruciate ligament

The anterior cruciate ligament (ACL) of the knee is one of the most commonly injured structures in musculoskeletal medicine. Although the ligament is widely researched and studied for its macroscopic biomechanical role in knee stability, surprisingly few studies have analyzed the microscopic material properties of this important ligament. Several recent studies, however, have evaluated the microstructural and fiber alignment properties of the ACL. The anteromedial (AM) region of the ACL has a different cellular composition and exhibits greater fiber alignment and failure strength compared to the posterolateral (PL) regions. Furthermore, these properties vary in a linear fashion across the ligament moving from anterior to posterior, rather than just differing in discrete anatomical bundles. This information provides a greater understanding of the native properties of the human ACL and serves as a guide for surgical techniques.