Elastin content is high in the canine cruciate ligament and is associated with degeneration

Cruciate ligaments (CLs) are primary stabilisers of the knee joint and canine cranial cruciate ligament disease (CCLD) and rupture is a common injury. Elastin fibres, composed of an elastin core and fibrillin containing microfibrils, are traditionally considered minor components of the ligament extracellular matrix (ECM). However, their content and distribution in CLs is unknown. The purposes of this study were to determine the elastin content of canine CLs and to ascertain its relationship to other biochemical components and histological architecture. Macroscopically normal CLs were harvested from Greyhounds (n=11), a breed with a low risk of CCLD. Elastin, collagen and sulfated glycosaminoglycan content were measured and histological scoring systems were developed to quantify ECM changes using a modified Vasseur score (mVS) and oxytalan fibre (bundles of microfibrils) staining. Elastin contents were 9.86±3.97% dry weight in the cranial CL and 10.79±4.37% in the caudal CL, respectively, and did not alter with advancing histological degeneration. All CLs demonstrated mild degenerative changes, with an average mVS score of 11.9±3.3 (maximum 24). Increasing degeneration of the ligament ECM showed a positive correlation (r=0.690, P