Injury and the Healing Process. Introduction to Injury When an injury takes place some responses are predictable, but others are unexpected It is not.

Injury and the Healing Process

Introduction to Injury

When an injury takes place some responses are predictable, but others are unexpected

It is not clear if the stages are the same in acute and chronic injuries

An athletes point of view of an injuryPainful problem that prevents or hampers sport performance

Tissue Damage

Microscopic traumaInvolves damage to a structure at a microscopic level

Macroscopic traumaIs obvious, visible damage to a structure

Individual cell holds the key to the regulation of the body’s trauma response

Sports Medicine Goals

When an injury occurs the sports med teamMinimize the adverse effects of traumatic inflammatory response

Promoting tissue repair

Expediting a safe return to performance

Challenged to understand and anticipate the cellular response in predicting the recovery from injury

Injury Mechanisms

Human movement during sport and exercise is typically faster and or produces greater force

As a result, the potential for injury is also heightened

Understanding the different forces that act upon the body- you can understand how to prevent injuries

Force

Defined as a push or a pull acting on the body

When a force is sustained by body tissue, two factors help determine if injury occurs

The size and magnitude of the force

The material properties of the involved tissues

Magnitude of Force

Small forcesThe response of the loaded structure is elastic

When the load is removed the material will return to its original size and shape

Large forcesExceeds the materials elastic limits- the structure is unable to elastically rebound to its original shape

Some amount of deformation results

Magnitude of Force

Larger forcesExceed the material’s ultimate failure limit

Produces mechanical failure of the structure

Translates to a bone fracture or rupturing of a soft tissue

Direction

The direction of force is applied has important implications for injury potential

Many tissues are stronger in resisting force from some directions than from others

Lateral ankle sprains are much more common than medial ankle sprains, because ligament support of the ankle is much stronger on the medial side

Categories of Force

Force acting along the long axis of a structure is an Axial force

4 categories of forceCompression

Tension

Shear

Torque

Compressive Force

Axial load that produces a squeezing or crushing effect is a compressive force

Weight of the human body constantly produces compression on the bones

When a football player is sandwiched between two tacklers, the force upon the player is compressive

Often result in bruises or contusions

Tensile Force

Axial loading in the direction opposite of that of compression in called tension

Pulling force that stretches the object to which it is applied

Muscle contraction produces a tensile force on the attached bone, enabling movement

When the ankle is inverted, the tensile force results in an ankle sprain

Shear Force

Force that acts parallel or tangent to a plane passing through an object

Tends to cause one part of the object to slide, displace, or shear with respect to another part of the object

Torque

A rotary or twisting force is termed torque or torsion

Excessive torque's can produce injuryUsually generated by forces external to the body rather than by the muscles

Torsion results in the creation of shear stress throughout a structure

Causing such injuries as a spiral fracture

Stress

When a given force is distributed over a larger area, the resulting stress is less than if the force where distributed over a smaller area

If a force is concentrated over a small area, the mechanical stress is relatively high

Football and hockey pads- distribute any force sustained across the entire pad, thereby reducing the stress acting on the player

Strain

The amount of deformation an object undergoes in response to an applied force

Application of a compressive force to an object produces shortening and widening of a structure

Tensile force produces lengthening and narrowing of a structure

Shear results in internal changes in the structure acted upon

Acute vs. Chronic

Acute InjuryCaused by a single traumatic forceForce is of large magnitudeDefinitive moment of onsetPredictable process of healingMacrotrauma Ruptured ACLFractured Humerus

Chronic InjuryCased by repeated forcesForce is of small magnitudeOver a period of timeStress injuryMicrotraumaStarts when pain and inflammation become evidentMay persist for months or even years

Body’s Response to Force

Tendon, ligament, muscle and bone respond to gradually increased stress by becoming larger and stronger

Overuse syndromes and stress fractures result from the body’s inability to adapt to an increased training regimen

Soft Tissue Injuries

Behave in characteristic ways when subjected to different forms of loading

Skin

Tendon

Ligament

Muscle

Collagen

Major building block of soft tissue

Protein that is strong in resisting tension

Allows tissues to stretch slightly under tensile loading, providing flexibility

Skin Injuries

Skin is the body’s first layer of defense against injuryMost frequently injured body tissueDifferent Types of Skin Injuries

AbrasionsBlistersSkin BruisesIncisionLacerationPuncture Wound

Abrasions

Minor skin injuries

Caused by a shear force

Skin is scraped with sufficient force, usually in one direction, against a rough surface

The greater the applied force, the more layers of skin that are scraped away

Blisters

Minor skin injuries

Caused by repeated application of shear in one or more directions

Occurs when a shoe rubs back and forth against foot

Result is the formation of a pocket of fluid between the multiple layers of skin

Skin Bruises

Contusion

Injuries resulting from compression sustained during a blow

Damage of the underlying capillaries

Causes the accumulation of blood within the skin

Incision and Laceration

IncisionClean cut

Produced by the application of a tensile force to the skin as it is stretched along a sharp edge

LacerationIrregular tear in the skin

Typically results from a combination of tension and shear

Puncture Wound

Formed when a sharp object penetrates the skin and underlying tissues with tensile loading

Puncture wound can come from:Shoe spike

Nail

Categories of Injury

Muscle bruises or contusionResult from compression sustained from heavier blows

Injuries vary in severity according to the area and depth over which blood vessels are ruptured

Rated according to the extent to which associated joint range of motion is impaired

Categories of Injuries

Strain and SprainsCaused by an abnormally high tensile force that produces rupturing of the tissue and subsequent hemorrhage and swelling

Categorized as first, second, and third degree injuries

First Degree Injuries

Some pain

Only involve micro-tearing of the fibers

No readily observable symptoms

Mild discomfort

Local tenderness

Mild swelling

Ecchymosis

NO loss of function

Second Degree Injury

More severe pain

More extensive rupturing of the tissue

Detectable joint instability

Muscle weakness

Limited joint range of motion

Third Degree Injury

Produce severe pain

Major loss of tissue continuity

Loss of range of motion

Complete instability of the joint

Tendonitis

Chronic condition

Characterized by pain and swelling with tendon movement

Prolonged chronic inflammation of muscle or tendon can result in the accumulation of mineral deposits, known as calcification

Bursitis

Involves irritation of one or more bursa, the fluid filled sacs

Serve to reduce friction in the tissues surrounding joints

Can be acute or chronic

Soft Tissue Healing

Normal healing process takes place in a regular and predictable fashion

Three Phases Acute Response

Repair and Regeneration

Remodeling

Acute Phase

Also known as the reaction phase

Lasts for the first several days following an injury

Inflammation is major reaction in this phase

Characteristics of the inflammatory process:Redness, Local Heat, Swelling

Pain and Loss of Function

Vasoconstriction

Vasoconstriction occurs in the acute phaseCurtails the loss of blood

Enables initiation of clotting

Hypoxia and Necrosis occur due to lack of oxygen and blood in the area

Hypoxia Reduced oxygen in tissue

Necrosis Death of tissue

Vasodilatation

Vasodilatation also occurs in the acute phaseOccurs after vasoconstrictionBrought on by chemicals released by the bodyIncreased blood flow causes swelling in area of injuryBroken blood vessels and damaged cells form a hematomaSpeeds the arrival of specialized cells that will ingest dead cells and any foreign material or infectious agentsThe resulting swelling also stimulates nerve endings to cause pain

Repair and Regeneration Phase

Takes place from about 2 days following the injury through the next 6-8 weeksBegins when hematoma has diminished in size allowing room for growth of new tissueExcept for skin, all other soft tissues replace damaged cells with scar tissueHealing begins with the accumulation of fibroblasts to produce scar tissue

Repair and Regeneration Phase Cont…

Fibroblasts begin to produce immature collagen

The scar tissue that is formed is less strong and less functional than the original tissue

Development of the scar also causes the wound to shrink in size, resulting in decreased flexibility of the affected tissue

Remodeling Phase

Begins about 3 weeks post injury, overlapping the repair and regeneration phase and continues for a year or more

Maturation of the newly formed tissue

Decreased fibroblast activity

Organization of the tissues increases and normal chemical activity resumes

Severe Muscle Injuries

Severe muscle injuries can result in scarring or the formation of adhesions

After severe injury, muscle may regain only about 50% of its pre-injury strength

AdhesionsTissues that bind the healing tissue to adjacent structures

Happens within the muscle

Inhibits muscle fiber regeneration

Tendon and ligament injuries

Have few reparative cells

Healing may take more than a year

If these tissues undergo abnormally high tensile stress before scar formation is complete, the newly formed tissues can be elongated

This may result in permanent joint instability

Bone Injury Healing

Three Phases ProcessAcute Phase

Repair and Regeneration

Remodeling Phase

Acute Phase

Last approximately 4 days

Hematoma is formed

Vasodilatation occurs

Edema

Tissue chemical changes

Repair and Regeneration Phase

Osteoclasts come to the area of injury to reabsorb damaged bone tissueOsteoblasts build new boneA callus is forms between the fractured bone ends

A callus is a fibrous vascularized tissue containing immature boneStrengthens with time through remodeling phase

Fixation devices are only implanted when it appears unlikely that the fracture will not heal properly

Remodeling Phase

Osteoblasts and Osteoclasts activity continues until normal shape and strength has restored

Time is the largest requirement for proper none union to take place

Complete remodeling may take many years

Nerve Injuries

Most commonly injured by tensile or compressive forces

When a nerve is loaded with tension, the nerve fibers tend to rupture prior to the rupturing of the surrounding tissue

The nerve roots on the spinal cord are not protected by connective tissue and are particularly susceptible to tensile injury, especially stretching of the brachial and cervical plexus

Compression Injury to Nerves

More complex

Severity depends on the magnitude and duration of the loading force

Nerve function is highly dependent on oxygen provided by blood vessels

Damage to the blood supply caused by a compressive injury results in damage to the nerve

Nerve Injuries

Symptoms can rangePain

Discomfort

Complete loss of sensation

Chronic irritation/inflammationLead to chronic pain along the nerve’s path

Pinching of a nerveResults in a sharp wave of pain that is transmitted through a body segment

Nerve Healing

Completely severed nerveHealing does not occur

Loss of function is typically permanent

Incomplete nerve injurySometimes possible for regeneration

Regeneration is relatively slow

Pain

Universal Symptom common to most injuries

Individual’s perception of pain is influenced by four factors:

Physical

Chemical

Social

Psychological

Neurological Basis of Pain

Small diameter, slow transmission nerves carry pain impulsesFast transmission nerves carry other sensations: touch, temperature, proprioceptionLocated in superficial skin layersCan be stimulated by mechanical stresses such as trauma, swelling, and muscle spasmOther pain receptors are chemo-sensitivePain threshold can become progressively lower

Gate Control Theory

Spinal cord is organized in such a way that pain or other sensations may be experiencedAn area or “gate” within the spinal cord organizes input stimulus and transmits stimulus to the brainTherefore, stimulation from the larger, faster nerves can selectively “close the gate” to the smaller, slower pain fibersConcept explains why cold can numb the pain as well as why acupuncture, acupressure and skin irritants provide some relief against pain

Factors That Mediate Pain

Body produces natural “pain killers” that are chemicals similar to morphine called endorphins

Endorphins block nerve receptors sites that transmit pain

Pain is a mixture of physiological and psychological factors

Individuals vary in their pain thresholds

Referred Pain

Pain that is perceived at a location remote from the injury site

Pain is thought of as an error in perception on the part of the brain and body

Some referred pain is predictableHeart attack-left shoulder and arm

Spleen- left shoulder/arm

Nutrition and Healing

Proper nutrition is essential to provide the necessary nutrients for wound healing

Proteins Vital role in repair, growth and maintenance of body tissue

CarbohydratesMain energy fuel for the body and important for repair and healing

Nutrition and Healing

VitaminsImportant role in wound healing

Vitamin B, C, A,E, and K are all important

SupplementsAre not necessary for healing as long as athlete diet is nutritionally balanced

The End

Any Questions??