Connect iss Lecture 8
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Transcript of Connect iss Lecture 8
Changes In Tissue During Injury, Immobilization,and
Remobilization
Part I: Review
• Identify Normal Connective Tissue
• Components of Normal Connective Tissue
• Collagen and Elastin
• Proteoglycans & Water
• Fibroblasts and Chondrocytes
• Soft Tissue Changes Following Injury
Normal Connective Tissue
• Characterized by intercellular material– Glycoprotein fibers– Protein polysaccharide ground substances– Other cells
• Functions– Provide nourishment for overlying epithelial
tissue– Link muscle & bone as tendons– Allow movement
Categories of Connective Tissue
• Loose Connective– Areolar: most abundant in the body– Adipose: fat (in the body, not the head)– Reticular: framework of branching fibers;
found in lymph, bone & liver
• Dense Connective– Collagenous & elastic fibers– Tendons , ligaments & skin
Components of Normal Connective Tissue
• Extracellular Components– Collagen, Elastin, Reticular fibers – Provide the matrix of connective tissue– Water & Glycosaminoglycans (GAG)– Provide lubrication & spacing between collagen
fibers
Components of Normal Connective Tissue
• Cellular Components– Fibroblasts & Chondrocytes
• Provide material for the matrix
Collagen Flow Chart
Collagen synthesized by Fibroblast
Procllagen 3 chain of
amino acids
Tropocollagen molecule
building blocks
Fibrils Fibers
Tendon ligaments
Skin
Clinical Implications For Understanding Collagen Tissue
• In mature collagen the intermolecular cross-linking is strong.
• In newly formed collagen the cross links are weak and can easily be pried apart.
• Avoid excessive force with mobilization in the early healing stages.– Tendency to damage cross links: can cause
mechanical weakness of the tissue.
Collagen Fiber Arrangement
• Tendons: parallel – Provide stiffness & strength with a
unidirectional load
• Ligaments: Looser, different directions– Multidirectional
• Skin: random arrangement– Stretching
Proteoglycans & Water• Form ground substance
• Gel like: provide spacing & lubrication between collagen microfibrils
• Hydrophilic: draws water into tissue
• Water is necessary for diffusion of molecules through tissue (exportation of metabolites)
• The spacing, along w/ water, prevents adjacent fibers from linking, thereby reducing friction.
Fibroblasts & Chondrocytes
• Cellular components of C/T
• Building blocks
• Fibroblasts – Found in ligaments, tendons, fascia, joint
capsules.
• Chondrocytes– Found in the collagen matrix of articular
cartilage.
Soft Tissues Changes Following Injury
• Two types of cellular events take place in order to repair tissue:– Immunological– Reparative
Immunological
• Immediate
• Prevents bacteria from entering injured area.
• Macrophages & leukocytes
Soft Tissues Changes Following Injury
• Reparative– Initiated about 48 hours after injury.– Collagen initially held by blood clots begins to
form a weak mesh.– During this period adhesions of collagen have
little mechanical strength.– Collagen deposition
• Increases 5th day
• Peaks 14th day
• 120 days: reduction of collagen turn over
Changes With Immobilization
• Research has shown adverse effects with prolonged immobilization.
• Changes take place from cellular matrix to gross tissue levels.
• Areas affected:– Collagen matrix– Ligaments/tendons– Muscle– Periarticular & intraarticular tissues
Effects of Immobilization on Collagen Matrix
• Increase in production of collagen– Deposits in random fashion, not along the lines
of stress.
• Decrease in GAG & H2O– Causes a loss of lubrication and a closer
contact of fibers– Abnormal cross-linking
• Restricted normal interfibril gliding
Immobilization On Ligaments & Tendons
• Ligaments– Loss of strength/ stiffness at the insertion point.– Harwood et al, 1990: atrophy of the ligaments
• Tendon– Atrophy – Gelberman 1986: extensive obliteration of
space between tendon and sheath • Adhesions / impediment of glide between sheath &
tendon
Effects of Immobilization On Muscle
• 2º shortening of the muscle
• Results in a 40% reduction of sarcomeres (Lederman)
Effects of Immobilization On Periarticular &
Intraarticular Structures• Atrophy of the capsule, ligaments &
synovial membrane
• Adhesions & abnormal cross-links
• Synovial tissue: most sensitive to effects of immobilization, undergoing fibrofatty changes– Mature fibrofatty tissue will cover non-
articulating areas and form adhesions.
Adhesions, Contractions, Cross-Links, Scar Tissue & Contractures
• Adhesions: “fibrous band holding parts together that are normally separated”
• Form in tendons and sheath, and in the joint capsule.– Can be stronger than original tissue.– Watch out when performing aggressive stretching: could
avulse normal tissue.
Contraction / Cross-links
• Contraction: tightening of tissue – Myofibroblasts pulling together. Eg., Scars– ROM exercises prevent this.
• Cross-links– Chemical bonds within & between the collagen
molecules.– Reduce tissue extensibility.
Contractures/ Scars
• Contractures- – Indicate loss of movement.– Shortening of CT & muscle for increased cross
linking.– Reduced by stretching or movement.
• Scar– Changes in cell & matrix after damage.
Effects Of Mobilization On Tissue
• Connective tissue matrix– Turn-over of collagen / remodeling lines
of stress.
– Improves GAG synthesis.
– Maintains inter-fibril distance /lubrication.
– Reduces abnormal cross linking.
Effects Of Mobilization On Tissue
• Joints– Pressure fluctuations important for
formation/removal of synovial fluid.
– Vital to articular cartilage health.
• Ligaments• Greater strength
Effects Of Mobilization On Tissue
• Muscle– Muscle regeneration is dependent on longitudinal
mechanical tension provided by passive stretching.
– Research (1966/91) shows the implication of longitudinal mechanical tension in promoting parallel alignment of the myotubules to the lines of stress.
• PROM can improve ROM and increase the cross -sectional area of muscle; also the number & size of sacromeres return to preimmobilization levels.
Effects Of Mobilization On Tissue
• Tendons– Higher tensile strength; less likely to rupture.– Decrease adhesion formation.– Early mobilization produces a higher DNA and
cellular content vs delayed mobilization. – Revascularization of blood vessels.
Summary
• Movement provides:– Direction for the deposition of collagen.
– Vascular regeneration.
– Reduces excessive cross-linking and adhesions.
Considerations
• Early stages– Little mechanical strength.
– Avoid aggressive stretching.
• Remodeling phase– Strong bond.
– Can be more aggressive.
We’d like to thank you foryour attention!
Please put your chairs in the upright position before
exiting the room.Please learn with us
again soon!