3. TENDONS
Tendons are anatomic structures interposed
between muscles and bones transmitting the force
created in the muscle to bone, and, in this way,
making joint movement possible.
They are one of the strongest connective tissue in
human body withstanding numerous mechanical
forces.
They are viscoelastic structures exhibiting both
elastic and viscous behaviour.
4. Paratenon covered tendons
e.g., patellar, achilles tendons
have rich vascular supply and thus heal better
often injured due to trauma and most often fail at the
musculotendinous junction
tendon-bone junction
Sheathed tendons
e.g., hand flexor tendons
less vascularized and have avascular areas that
receive nutrition by diffusion
often injured due to laceration and at risk for adhesions
5. Tendon composition
Water
Collagen ( type I and type III ) -> 90%
1-5% proteoglycan (decorin & aggrecan)
0.2% inorganic components copper,manganese and
calcium
Tendons are basically group of collagen bundles
Separated by endotenon and covered by epitenon.
8. Tendon cells or Tenocytes
Tenocytes are fibroblast-like differentiated cells that
form the mature tendon. Tenocytes synthesize the
extracellular matrix, inducing assembly of early
collagen fibers, which are the basic units of the
tendon
9. TENOCYTES PROPERTIES
Are spindle shaped cells arranged in direction of
muscle loading in arrays
Secrete collagen type I predominantly (95 %)
but also secretes type III collagen in small amounts
Help in healing of tendons
10. BIOMECHANICAL EFFECTS
Exercise strengthens tendons
Immobilisation has detrimental effects.
Tensile strength decreases with age.
Heat decreases tensility/strength .
Strength varies with hydration,pH,tempreature.
Tendons can bear 5-10% more tension as
compared to bone.
11. STAGES OF TENDON HEALING
Hemostasis Platelets initiate coagulation
cascade
Fibrin clot and fibronectin
interaction leading to
chemotaxis to stabilize torn
tendon edges
5-15 min
Inflammation Fibroblasts produce type III
collagen
macrophages help initiate
healing and remodeling
1-7 days
Organogenesis Tissue modeling via large
amounts of disorganized
collagen and angiogenesis
7-21 days
Remodeling Tissue remodeling replacing
type III collagen to type I
collagen
Upto 18 mths