Chapter 8

The Injury Process

Bellwork

• Open you books to pg 100 and begin reading the inflammatory Process

The Physics of Sports Injury

Connective Tissue• Connective tissues are the most

common type of tissue in the body.• Connective tissues include ligaments,

retinaculum, joint capsules, bone, cartilage, fascia, and tendons.

• In some sports, nearly 50% of acute injuries involve either tendon or muscle.

The Physics of Sports Injury (cont.)

Muscle/fascia are thought to be injured by excessive tension during contractions.

• Tendons are extremely strong structures; strains occur most often at the distal musculotendinous junction (MTJ).

• These strains are the most common soft tissue injuries related to sports.

Mechanical Forces of Injury

Types of Force

• Compressive

• Tensile

• Shear

Mechanical Forces of Injury (cont.)

• Tendons resist tensile forces.

• Bones resist compressive forces.• Ligaments resist tensile forces.

Each type of tissue has a limit for how much force it can withstand (critical force).

The Physiology of Sports Injury

The inflammatory process:

• Is a predictable sequence of physiologic actions that occur when the body reacts in a manner to repair damaged tissues.

• Begins during the first few minutes following an injury.

The body’s initial response to trauma is commonly called swelling.

The Inflammatory Process (cont.)

Normal signs and symptoms of inflammation include:

• Swelling.

• Pain.

• Reddening of skin (erythema).

• Increased temperature in the affected area.

Acute Inflammatory Phase

• Initial trauma destroys millions of cells.

• Vasoconstriction is followed by vasodilation.

• Damage to blood vessels results in blood flow into interstitial spaces causing a hematoma.

• A hematoma is the “localized collection of extravasted blood.”

• Secondary hypoxic injury results in additional cellular destruction.

• Hypoxic?

Acute Inflammatory Phase

Acute Inflammatory Phase (cont.)

In response to injury, chemicals are released that affect nearby cells. The effects of these chemicals are: • Degradative (cellular breakdown).

• Vasoactive (vasodilators).

• Chemotactic (attract scavenger cells).

Acute Inflammatory Phase (cont.)

Hageman Factor is responsible for the manufacture of bradykinin.

• Bradykinin increases vascular permeability and triggers the release of prostaglandins resulting in:

• Vasodilation.• Increased vascular permeability.• Pain.• Blood clotting.

Acute Inflammatory Phase (cont.)

• Plasma proteins, platelets, and leukocytes move out of capillaries and into damaged tissue.

• Leukocytes engage in phagocytosis (damaged cell absorption).

• Macrophages migrate into the damaged area. Arachidonic acid is formed by a combination of leukocyte enzymes and phospholipids derived from cell membranes.

• Arachidonic acid catalyzes the production of leukotrienes.

Acute Inflammatory Phase (cont.)

Acute Inflammatory Phase (cont.)

The acute inflammatory process results in a walling off of the damaged area from the rest of the body.

The process acts to clean up the debris and provide components for healing.

The acute phase lasts up to 3 or 4 days, unless aggravated by additional trauma.

Resolution (Healing) Phase

During this phase, special leukocytes (polymorphs and monocytes) and a type of macrophage (histocytes) migrate into the area of injury.

• These cells break down cellular debris and set the stage for regeneration and repair.

Bellwork

• Describe the major steps that occur during the acute inflammatory phase of an injury. In your answer you must include vasoconstriction, vasodilation, and subsequent hematoma formation.

• You do not need to write anything down, just find the answer and be ready to discuss

Regeneration and Repair

Except for bone, connective tissues heal by forming scar tissue that begins to develop 3–4 days after the injury.• Fibroblasts (proteoglycan- and collagen-

producing cells) migrate into the damaged area.

• Fibroblasts are immature connective tissue fibers that can mature into several different types of cells.

Regeneration and Repair (cont.)

• Angiogenesis is the formation of new capillaries.

• Scar formation may take up to four months.• Scar tissue can be 95% as strong as

the original tissue. Stress on the tissue is helpful for rehabilitation; exercises are critical to this process.

• Bone tissue heals by way of specialized cells (osteoclasts and osteoblasts).

Pain and Acute Injury

• Everyone copes with pain differently.• Pain is as much psychological as

physiological.• Pain results from sensory input received

through the nervous system and indicates location of tissue damage.

• Messages concerning sensory information that travel quickly through the nervous system are given higher priority than pain messages that travel more slowly.

• Pain is not a useful indicator of injury severity.

Pain and Acute Injury

Intervention Procedures

• Sports medicine community has no clear set of criteria for first aid treatment of acute soft- tissue injury.

Cryotherapy includes bags of crushed ice, aerosol coolants, ice cups, ice water immersion, and commercial cold packs.

After the acute phase, thermotherapy is appropriate (i.e., hydrocollator packs, moist warm towels, and ultrasound diathermy).

Intervention Procedures (cont.)

• Modalities such as ultrasound should ONLY be used under the supervision of trained allied health personnel.

• Pharmacologic agents can be used, such as anti-inflammatories and analgesics.• If they must be prescribed by a physician,

these agents represent treatments that are beyond the scope of the coach.

• OTC drugs should also be used with caution. (Consult parents when athlete is under 18 years of age.)

Intervention Procedures (cont.)

Cryotherapy

• Direct application of cold may reduce vasodilation in the first few minutes after injury.

• Application of cold can decrease recovery time by reducing secondary hypoxic injury.

Courtesy of Ron Pfeiffer

Cryotherapy (cont.)

• In extremities, elevation and compression are also helpful in treatment.

• Crushed ice in a plastic bag is an inexpensive modality.

• Elastic wrap secures the ice bag to the body.

Cryotherapy

• Cold application has analgesic effect and reduces muscle spasm.

• Recommended protocol: Apply for 30 minutes, remove for 2 hours, and reapply for another 30 minutes, if needed.

• Risk of frostbite is minimal with crushed ice.

Thermotherapy

Thermotherapeutic agents:

• Should NEVER be applied to an acute injury.

• Increase vasodilation.

• Are useful in the final phases of injury repair.

Pharmacologic Agents

Steroidal and NSAIDs• Both affect aspects of the inflammatory process.• Steroidal drugs resemble gluococorticoids, but the

exact mechanism of their action is unknown.Steroids may:

• Decrease amount of chemicals released by lysosomes.

• Decrease permeability of capillaries.• Reduce WBC phagocytosis.• Reduce local fever.

Pharmacologic Agents (cont.)

Steroids must be used with care.• They can interfere with collagen

formation, decreasing connective tissue strength in injured area.

Steroids may be injected or taken orally and include drugs such as:• Cortisone, hydrocortisone, prednisone,

prednisolone, triamcinolone, and dexamethasone.

NSAIDs

NSAIDs do not have the negative effects of steroids.

• NSAIDs are very popular drugs.

• Common NSAIDs include aspirin, ibuprofen, naproxen, indomethacin,

and naproxen sodium.

NSAIDs (cont.)

• NSAIDs block the conversion of arachidonic acid to prostaglandin.

• Aspirin (Acetylsalicylic acid) has anti-inflammatory, analgesic, and antipyretic effects.

• Research is inconclusive regarding NSAIDs’ effect on tissue healing and strength.

RICE

Best approach to the care of soft tissue injury is RICE along with prescribed pharmacologic agents and supervised rehabilitative exercise.

R = Rest

I = Ice

C = Compression

E = Elevation

The Role of Exercise Rehabilitation

• Properly supervised physical activity is very effective for many injuries.

• Such exercise can have a positive effect on collagen formation.

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Exercise Rehabilitation

• Collagen formation and tissue regeneration require 2 to 3 weeks.

• Rehabilitation must be supervised by professionals with appropriate training, such as a BOC-certified Athletic Trainer or a Physical Therapist with sports medicine training.

Exercise Rehabilitation (cont.)

Rehabilitative exercise is a four-phase process.

• Passive exercise

• Active assisted

• Active exercise

• Resistive

Injury Rehabilitation

• Injury rehab should be considered an ongoing process.

• Injury-specific exercise should be a permanent component in training and conditioning.

• Without this approach, the likelihood of reinjury is high.