Rotator Cuff Lab Flashcards
what is the structure of tendons?
-dense regularly arranged tissue that attaches muscle to bone
-highest tensile strength of all connective tissue
-high proportion of collagen
-closely packed parallel arrangement in direction of force
what are the 3 components of tendons?
-tendon
-bone insertion
-muscle-tendon junction
how are tendons vascularised?
sparsely
what is the composition of tendons?
-cellular (fibroblasts/tenocytes) 20%
-extracellular 80%
70% H20
30% solids - collagen I, ground substance, elastin, collagen III
how do tendons heal?
via extrinsic and intrinsic processes
what are the 3 phases of tendon healing?
inflammation (day 0-7)
repair (day 3-60)
organisation and remodelling (day28-180)
how is tendon healing controlled?
-PDGF (chemotaxis)
-TGFb (collagen type)
what happens during inflammation?
-inflammatory cells migrate from epitendinous tissue (sheath, periosteum, soft tissue)
-epitendon and endotendon
-defect rapidly filled with granulation tissue, haematoma and tissue debris
-matrix proteins lay down as scaffolding for collagen synthesis
what happens during repair?
-fibroblast/tenocyte migrate to zone od injury and begin to synthesise collagen by day 5
-initially collagen type 3 produced which is laid down in a random orientation
what happens during 4th week of repair?
-intrinsic fibroblasts proliferate and these cells take over the healing process both synthesising and reabsorbing collagen
-switch to production of collagen type I
-vascular ingrowth via collagen/fibronectin scaffolding
what happens during the organisation phase?
-final stability acquired during this phase by the normal physiological use of the tendoon
-accompanied by cross linking between fibrils further increasing tendon tensile strength
-complete regeneration never achieved
why is complete regeneration never achieved?
-defect remains hyper cellular
-thinner collagen fibrils
