The cranial cruciate ligament (CCL) and the lateral collateral ligament (LCL) are critical stabilizers of the canine stifle joint. A study published in May 2006 in Okajimas Folia Anatomica Japonica compared the two ligaments, revealing why the CCL is more vulnerable to rupture, a common cause of joint instability and lameness in dogs.
Microscopic analysis showed that most collagen fibrils in the CCL measured only 70–80 nanometers in diameter, while the LCL contained larger fibrils averaging 105 nanometers. This structural difference contributed to reduced tensile strength in the CCL. Fibroblasts with enlarged nuclei were also observed at the periphery of the CCL’s collagen bundles, suggesting altered cellular activity compared to the LCL.
Biochemical analysis revealed that the CCL contained approximately 17 times more chondroitin sulfate (CS) than the LCL, while levels of hyaluronic acid and dermatan sulfate did not differ significantly. The high CS concentration was associated with reduced resistance to tension and greater susceptibility to stretching and tearing under stress.
Mechanical testing confirmed that the CCL expanded less and withstood lower forces before failure compared to the LCL. The authors concluded that the combination of smaller fibril diameters and biochemical composition weakens the CCL, making it particularly prone to rupture, especially during overextension of the stifle joint.
These findings highlight how structural and biochemical properties explain the high incidence of CCL injuries in dogs, offering insights for improving prevention, surgical repair, and rehabilitation strategies.
Source: Ueda, H., Matsukawa, T., Watanabe, T., Hosaka, Y., & Takehana, K. Okajimas Folia Anatomica Japonica, May 2006.
