tendons basics structure and bimechanics

1. TENDONS
DR.ABHINAV.S.KESARKAR
FIRST YEAR JUNIOR RESIDENT
PDMMC
AMRAVATI

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.

6. STRUCTURE

7. collagen(protocollagen)
Microfibrils
subfibrils
Fibrils
Fascicles
Tendon unit

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

12. STRESS – STRAIN CURVE

13. THANK YOU