Ligament Tendon Injury and Repair -Rega Flashcards
What are the components of ligaments and tendons? How much of the tissue volume is water?
- Fibroblasts between collagen fascicles
- Extracellular matrix: type I collagen=86% dry weight. glycine, proline and hydroxyproline
- imbedded in proteoglycan, GAG, water ground substance
56% of the tissue volume is water, n tight association with collagen and GAGs
What is the blood supply for tendons? Ligaments? Which has a greater blood supply?
tendons:
- vessels in the perimysium (covering the tendon)
- periosteal insertion
- surrounding tissues
ligaments:
- microvascularity from insertion sites
- nutrition for cell population, necessary for matrix synthesis and repair
tendons» ligament nutrient
What is a fibril?
collagen chains cross-linked across the diameter of the ligament/tendon
What is a fiber?
multiple fibrils imbedded in matrix with fibroblasts
What is a fascicle?
fibers packed in loose connective tissue
What does the histological appearance of a ligament unloaded look like? what does this allow for?
crimped or wavy
gives it considerable elastic energy storage and recoil–> a lot of deformation (plastic) before it breaks
What does the construction of a ligament allow for? How?
very high tensile strength
- 3 subunit chains in helix
- extensive cross-linkages to other chains
- superhelixed in opposite direction
Where are tendons most likely injured?
myotendon junction (> avulsion at tendon/ligament insertion > failure within tendon/ligament)
What results from immobilized tensions/ligaments? What is this due to?
-degeneration in mechanical properties (decreased strength and stiffness)
due to cross-link degradation NOT doe to a decrease in collagen
What happens to ligament structure when they are repaired?
they lose their wavy orientation –> ligaments do not have remodeling agents –> not as strong
If there is a tear in a tendon, what will present on MRI?
a gap in the tendon due to the elasticity causing retraction of the tendon
What does plasmin do? How does this affect healing within joints?
plasmin degrades fibrin –> inhibiting clot formation
plasmin concentration is higher in the joints than in bone, which causes the inhibition of clots in the synovial fluid
A 35 year old male presents with arm inability to supinate his right forearm after failing to lift a truck out of a snow-filled ditch. MRI taken three days post-injury reveals a complete tear of the distal biceps brachii tendon, with 6 cm gap between the torn ends. What is the primary reason for the extensive gap?
A. Inflammation of the biceps brachii muscle caused gradual retraction of the tendon.
B. The ground substance of the biceps tendon has been dissolved by macrophages in the interval between injury and MRI.
C. The triceps brachii contracted spasmodically, extending the arm and subluxing the torn biceps tendon ends.
D. Elastic energy stored in the stretched tendon caused it to recoil at the time of injury.
E. Avulsion of bone at the distal tendon insertion initiated osteoclastic resorption of the tendon ground substance.
D. Elastic energy stored in the stretched tendon caused it to recoil at the time of injury.
What is hydroxyapatite deposition disease?
common disorder caused by calcium hydroxyapatite deposition in a tendon
can cause chronic or acute pain or be subclinical
