Division of flexor tendons causes progressive degradation of tendon matrix in rabbits

Deep flexor tendons of 30 rabbits were divided at the ankle level. The effects of unloading on the synthesis and content of matrix components, the synthesis of DNA, and dry weight were investigated. The ability of the tendons to synthesize collagen during short-term culture and the contents of matrix components decreased inversely to the time of unloading. 12 weeks following division, the fibrocartilagnious segments had lost 2/5 of their dry weight, 2/3 of proteoglycan and 1/3 of collagen and non-collagen protein content. Less pronounced losses were observed in the non-fibrocartilaginous segments. A transient increase in cell proliferation in both types of segments was found. These findings indicate that divided flexor tendons undergo a progressive degradation, degradation, which may have implications for delayed suture of deep flexor tendon injuries.