Ligaments feature wavy collagen fibers that act as natural shock absorbers to prevent tears during sudden movements.

Ligaments are composed primarily of Type I collagen fibers organized in a hierarchical structure. At the microscopic level, these fibers exhibit a distinct zig-zag or wavy geometry known as 'crimp.' This pattern is essential for the mechanical behavior of connective tissues during the initial phase of loading.When a joint is subjected to stress, the crimp pattern straightens out in a process called the 'toe region' of the stress-strain curve. This allows the ligament to elongate with very little resistance, absorbing the initial kinetic energy of a sudden movement. Research published in the Journal of Anatomy highlights that this mechanism prevents the collagen fibrils from reaching their breaking point prematurely.Once the crimp is fully straightened, the ligament becomes significantly stiffer to provide necessary joint stability. This transition from high flexibility to high tensile strength is what prevents dislocations and severe sprains. Studies by biomechanical researchers like Viidik in the 1970s established that the angle and period of these waves vary depending on the specific ligament and its functional requirements.The crimp structure is not permanent and can be affected by age and activity levels. Regular physical activity helps maintain the elasticity of these fibers, while immobilization can lead to a loss of crimp and increased stiffness. Understanding this microscopic architecture is vital for orthopedic surgeons when designing grafts for ligament reconstruction surgeries like ACL repairs.