DPT 5010 CT Physiology Flashcards
Typical Composition of CT
- Cells
- Extracellular Matrix
a. fibers
b. ground substance
Dense CT: Tendons and Ligaments
% composition
- Cells (20%)
- Extracellular Matrix (80%)
a) fibers- collagen type 1 (70%) and type III (3-10%)
b) ground substance - glyoproteins (cell & fiber adhesions)
- proteoglycans
- WATER very high percentage over all
- collagen type 1 (70%) and type III (3-10%)
Collagen
STRONG - similar to steel
- made in RER of fibroblasts
- triple helix (HIGH tensile strength)
- 19 different types
- most lig. & tendons have more collagen then elastin
Vascularity & Innervation of Tendons & Ligaments
limited blood supply = limited healing
depends on location (MCL heals well, ACL does not)
mechanoreceptors and specialized nerve endings
= PAINFUL injuries (proprioception and pain)
Stress/ Strain Curve: toe region
almost no stress, strain 1.5%
tissue elongates, crimp pattern flattens in collagen
Stress/ Strain Curve: plastic range
region of progressive failure/ disruption of collagen fibers and bonds
after force is removed, it will not return to original shape/length
Stress/ Strain Curve: Linear Elastic Region
relationship between stress & strain consistently linear
stretching of collagen fibers
once tensile force removed, tissue returns to original shape, but may take additional time if force was prolonged
strain 4-5%
Tendon or Ligament Failure
curve flattens –> visible narrowing of tendon or ligament–> then failure
ultimate stress & ultimate strain
elongation of >8%
2 things can happen:
- tear directly through lig or tendon
- pull away of only attachment (evulsion fracture)
Effects of Immobilization on Tendons & Ligaments
remember not muscles
- Increased collagen turnover (more immature)
- disorganized fibers
- increased collagen cross-linking
- decreased water content and GAGs
-reduced stiffness, reduced loads @ failure = tissue not as strong! , tissue contractures
Immobilization: Clinical Implications
- maintaining tensile loads provides some protection against loss of strength
- balance: benefits of mobilization vs. need for protective healing
- we may allow them to do isometrics
Tendon and Ligament Aging
&
Clinical Impications
- tensile strength improves w/ maturation
- max tissue strength @ skeletal maturity
- gradual decrease in strength through adulthood
(reduced collagen content, increased cross-linking of fibers, decreased water content, lower ultimate load) - -> higher rate of injury w/ less force
- -> less able to stabilize joint (potential DJD)
Biological Effects: Hormones
Relaxin- during pregnancy, relaxes tendons and lig. (precaution for joint-play)
Estrogen- reduces collagen synthesis and fibroblast proliferation, (i.e. diminished tensile strength of ACL during estrogen peak in menstrual cycle)
Hyperparathyroidism- (i.e. w/ renal failure)
Elevated parathyroid hormone- causes high bone turnover and bone respiration @ tendon insertions –> avulsion fx & tendon ruptures
Elevated blood calcium and phosphate –> soft tissue calcification = tendon weakness
CT and Disease
- Ehlers-Danlos (genetic, defective collagen, hyper mobility, subluxation & dislocations)
- Down’s Syndrome (general ligament laxity)
- Diabetes & Adhesive Capsulitis (increased glucose in blood may bind w/ collagen –> accumulate in joint capsule –> cause stiffness, impaired collagen repair or autoimmune rxn) mechanism still unclear
CT & Steroid/Corticosteroid & Antibiotic Use
Steroid/Corticosteroid:
i. dysplasia of collagen fibrils
ii. weakness of tendons & ligaments
iii. anabolic steroid abuser example: tear pec major because that lig. is weak
Antibiotics:
Some antibiotics associated with increased risk of spontaneous tendon rupture (can see PPT)
Chronic Renal Failure & Tendon Rupture
15% patients w/ chronic kidney disease on hemodialysis suffer spontaneous tendon ruptures
Depends on:
length of disease
time on dialysis (maybe)
co-morbidities: hormones, antibiotics and steroids
