Increased content of type III collagen at the rupture site of human Achilles tendon

Abstract

We compared the type 1 and I11 collagen amounts and cross-linked telopeptides at the rupture site and two other sites of the same tendon. Tendon saniples of ten individuals with total Achilles tendon rupture and six healthy cadavers were collected. The newly synthesized type I and 111 procollagens were assessed by extracting the soluble propeptides PINP, PICP and PIIINP. The insoluble matrix was solubilized by heat denaturation and trypsin digestion. Hydroxyproline, the cross-linked telopeptide structures of type I (ICTP and SP 4) and I11 collagens (IIINTP) and the degradation product of type I11 collagen (tryptic PIIINP) were measured from the digests.The type 111 collagen content was significantly increased at the rupture site when compared to control sites (5-and 12-fold increased) or cadavers (5-fold increased). No changes in the amounts of newly synthesized type I and I11 procollagens were observed. The ICTP content decreased and the SP 4/ICTP ratio increased along with ageing, suggesting a structural change in the type of cross-link in the carboxyterminal telopeptide of type I collagen.Type 111 collagen has accumulated at the rupture site probably due to microtrauinas and the subsequent healing process. The increased content of type I11 collagen can cause thinner collagen fibers, decrease the tensile strength and may finally result in total rupture of the tendon. The age-related change in the nature of the cross-link in the carboxyterminal telopeptide may contribute to this weakening.

Gene expression and matrix turnover in overused and damaged tendons

“…These data are consistent with the hypothesis that increased matrix turnover is associated with the sub-clinical matrix degeneration that precedes the clinical condition. Similar biochemical evidence now exists for the Achilles, suggesting that remodelling of the tendon is a general feature of tendinopathy (Eriksen et al, 2002). Whether this remodelling weakens the tendon is a moot point, since many cases of painful tendinopathy persist for months if not years, and do not go on to rupture.…”

The Effect of Corticosteroid on Collagen Expression in Injured Rotator Cuff Tendon

“…Collagen protein typing of injured tendons has shown that type-III collagen can increase up to 15% of total collagen content following injury 43 . Collagen fibers have been found to be not only smaller in diameter but also structurally weaker to tensional forces when type-III content is higher 43,50,51 . Consequently, the type-III to type-I collagen expression ratio is an ideal dynamic indicator of tendon injury response and also provides an important insight into the functional strength and resiliency of the tendon.…”

“…Additionally, the information gained from this acute injury model may provide insight into chronic injury responses. Investigators have demonstrated that elevated levels of type-III collagen are present in chronic tendinopathies and degenerative tendon tears as well 30,43,50 .…”

Effects of physical characteristics, exercise and smoking on morphometry of human Achilles tendon: an ultrasound study

“…For example, thickening of Achilles tendon is a precursor tendon ruptures. [7][8][9][10] To determine the pathological changes for the size of Achilles tendon, it is necessary to to know the normal size. In this study, we aimed to reveal the normal morphometric values of Effects of physical characteristics, exercise and smoking on morphometry of human Achilles tendon: an ultrasound study*…”