Cruciate Ligament Matrix Metabolism and Development of Laxity

Cranial Cruciate Ligament Rupture in Dogs: Review on Biomechanics, Etiopathogenetic Factors and Rehabilitation

“…As is known, the structural properties of the cruciate ligament depend on the composition and nature of the extracellular matrix and depend on the collagen whose turnover derives from a careful balance between its synthesis and degradation in particular. In this mechanism, proteases such as cathepsins and matrix metalloproteinases (MMPs) including collagenases (MMP-1, MMP-8, and MMP-13), stromelysins (MMP-3 and MMP-10), and gelatinases (MMP-2 and MMP-9) play a very important role [ 76 , 77 , 78 , 79 , 80 ]. In two distinct populations of Labrador Retrievers, it has been shown that the concentration of MMP-2 is significantly higher in dogs with a broken cruciate ligament than in subjects with an intact ligament [ 81 ].…”

“…A further study demonstrated the existence of a precursor of MMP-2 (pro-MMP-2) that is higher in the cruciate ligaments of high-risk breeds (Labrador Retrievers) than in low-risk breeds (Greyhounds) [ 82 ]. The results of all of these studies suggest that in the damaged ligament, there is a greater turnover of the extracellular matrix, which can be triggered by inflammatory phenomena and could lead to a reduction in strength and cause a consequent rupture [ 80 ]. Ligament remodeling is also influenced by two other factors: tartrate-resistant acid phosphatase (TRAP) and cathepsin K. Tartrate-resistant acid phosphatase (TRAP) belongs to a group of iron-binding proteins and is able to mediate the process of collagenolysis.…”