Phases of Soft and Bony Tissue Healing (Post Lecture Review)

Phases of Soft and Bony Tissue Healing (Post Lecture Review)

Multiple Choice

Soft tissues are:

• Bones

• Skin, muscles, tendons

• Blood and lymph vessels

• Everything that isn't made of bone.

• None of the above

Cartilage Healing

• Limited healing abilities. Why? Mainly avascular.

• If only articular cartilage is injured: it fails to elicit (request/produce) clot formation and fails to elicit (request/produce) a cellular response

• Remember: when injuries occur the injured cells have to release chemical mediators in order to begin the healing process! So if cells don't release these then the injury is unable to heal.

Cartilage Healing

• Typically the injury remains the same due to lack of healing.

• If subchondral bone is involved in the injury then healing will occur. Why? Because unlike cartilage bones are vascularized.

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Cartilage Healing

• The difference in the general healing process we learned and what occurs with cartilage is:

• Instead of granulation tissue being replaced with collagen it is first replaced with chondrocytes (happens about 2 weeks post injury).

• After about 2 month the chondrocytes have completely replaced the granulation tissue. At this time collagen begins replacing the chondrocytes.

Multiple Select

(Hint there are two answers that you should select.)

Cartilage's lack of healing abilities is due to its:

• avascularity

• location

• lack of collagen

• cells don't release chemical mediators when injured

Multiple Choice

Whats the big difference between cartilage healing and other soft tissue healing?

• None of these options are correct.

• Granulation tissue is replaced next by collagen

• Granulation tissue is replaced next by chondrocytes and then by collagen

• Granulation tissue is not replaced

• All of these options are correct.

Multiple Choice

Ligaments connect _____ to _____.

• bone to bone

• muscle to bone

• muscle to muscle

• tendon to bone

Ligament Healing

• Phase 1: During the first 6 weeks post injury -

• Vascular proliferation occurs

• Fibroblasts begin laying fibrin

• Fibrin clot formed (bridge between two torn ends of the ligament)

Ligament Healing

• Phase 2: Collagen fibers begin replacing the clot creating a random woven pattern.

• After the collagen fibers have replaced the clot there is a decrease in fibroblastic activity and a decrease in vascularity.

• Phase 3: Max increase in the collagen

• When ligaments fail its usually one of two reasons: (a) a large enough scar wasn't produced or (b) the healing process was unable to reconnect the ligament to the bone.

Muscle Healing

• Phase 1 immediately following injury: hemorrhaging, edema, and phagocytic activity

• Phase 1 a few days later: there is a proliferation of ground substance (jelly, clear substance that fills in the holes of the tear)

• Phase 2: fibroblasts begin producing a gel-like matrix surrounds the injured tissue. Leads to fibrosis and scarring.

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Muscle Healing

• Phase 3: myoblastic cells form in injury area and regenerate new myofibrils.

• Injuries typically occur in the large, force-producing muscles (i.e. hamstrings/quadriceps).

• Regardless of level of injury rehabilitation process is often lengthy.

• Returning to play too soon often leads to reinjury and the restarting of the healing process.

Multiple Choice

When a muscle is injured what, initially (phase 1), fills the gaps in the muscle?

• Ground substance

• Collagen

• Chondrocytes

• Gel-like Matrix

• Myofibrils

Multiple Choice

When muscles are healing from injury what do fibroblasts produce?

• Collagen

• Chondrocytes

• Fibrin Clot

• Gel-like matrix

Multiple Choice

Muscle healing: Instead of collagen what replaces the gel-like matrix that was formed during phase 2 of the healing process?

• Collagen

• Chondrocytes

• Myofibrils

• None of the options listed are correct.

Tendon Healing

• Harder to heal without surgical intervention. Due to:

• Requires a hardy union of the torn ends.

• Requires both extensibility and flexibility at attachment site

Multiple Choice

Tendons require a strong union/connection between torn ends and both extensibility and flexibility what substance is needed in high quantities in order to achieve those requirements?

• Collagen

• Fibroblasts

• Ground Substance

• Myofibrils

Tendon Healing

• Phase 1: During the 2nd week of healing we begin to see the tendon adhering to the surrounding tissues, creating a large mass.

• Phase 2: During the 3rd week of healing the tendon begins separating from the large mass but is not strong.

• Phase 3: Fibers are being aligned in a way to withstand the stress and strain required. Fibers also being aligned in a way that provides max extensibility and flexibility.

Nerve Healing

• Specialized tissue with limited healing abilities

• If a nerve cell dies due to injury the nerve itself cannot be healed.

• Peripheral nerves have a better chance at healing than nerves located in the central nervous system.

Multiple Choice

Peripheral nerves are:

• the nerves located outside of the brain and spinal cord

• nerves located inside of the brain and spinal cord

Multiple Choice

The myelin sheath surrounding cells in the peripheral nervous system are:

• Schwann Cells

• Oligodendrocytes

Multiple Choice

The myelin sheath surrounding cells in the central nervous system are:

• Schwann Cells

• Oligodendrocytes

Nerve Healing

• Peripheral nerves have the ability to regenerate/heal after injury because it's myelin sheath is made up of schwann cells.

• When damaged, fibroblasts tell schwann cells to clump up and remove themselves from the injured portion of the nerve. Prevents two things:

• Being removed in the phagocytosis process

• Being buried in scar tissue

Nerve Healing

• Why do Schwann cells make healing possible for peripheral nerves?

• When they receive the signal to remove themselves from the axon they have a unique ability to de-differentiate themselves.

• They will sit dormant and one day there is a signal they differentiate back into Schwann cells and begin bridging the gap between severed nerve ends.

• Will usually take about 3-6 months to complete healing, but could take longer depending on extent of injury and interventions required.

Nerve Healing

• First 3-5 days following injury: the axons below the site of injury begin breaking down into pieces.

• After 3-5 days there is an increase in metabolism and protein production.

• Then the myelinated portion of the axon surrounding the severed end is phagocytized.

Multiple Choice

What makes it possible for peripheral nerves to regenerate?

• Schwann Cells

• Oligodendrocytes

• Chondrocytes

• Dendrites

Multiple Choice

Which type of nerves have the ability to regenerate/heal?

• Central nerves

• Peripheral nerves

Bone Healing - Phase 1

• Step 1: Fracture (damages blood vessels in bone and periosteum)

• Step 2: Damage causes hemorrhaging which leads to blood clot formation. The clot serves as the framework for proliferation of blood vessels.

Bone Healing - Phase 2

• Step 3: After about 1 week fibroblasts begin laying down a collagen mesh.

• Step 4: Chondroblasts create a callus between the broken pieces of bone.

• Step 5: Callus turns from soft to firm and rubbery.

• Step 6: Osteoblasts begin to proliferate and enter the callus from cancellous bone.

Multiple Choice

During which phase of the healing process for bones does callus form?

• Phase 1

• Phase 2

• Phase 3

Multiple Choice

During which phase does the callus crystalize into bone?

• Maturation-Remodeling Phase

• Inflammatory Response Phase

• Fibroblastic Repair Phase

Bone Healing - Phase 3

• Step 7: Callus begins to crystalize into bone and remodeling occurs according to Wolff's Law

• The remodeling process is similar to the initial growth process.

• Osteoblasts continue laying down new bone while osteoclasts continue to remove old, degenerative pieces.

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Multiple Choice

Which type of cell is responsible for new bone growth?

• Osteoblasts

• Osteoclasts

Multiple Choice

Which type of cell is responsible for removing old, degenerative, defective bone?

• Osteoblasts

• Osteoclasts