CH 9 Mechanisms and characteristic of musculoskeletal and nerve trauma

Trauma

physical injury or would, produced by internal or external force

Mechanical injury

Results from force or mechanical energy that changes state of rest or uniform motion of matter

Tissue Properties

• load

• stiffness

• stress

• strain

• yield point

Load

An external force acting on the body causing internal Load.

• An external force acting on the body causing internal

reactions within the tissues.

Stiffness

• ability of a tissue to resist a load

• Greater stiffness= Greater magnitude load can resist

Stress

internal resistance to a load (ability for a tissue to absorb a load placed on it)

Strain

Internal change is tissue (that is length) resulting in deformation (ability for tissue to deform when a load is applied)

Tissue properties chart

Elastic properties=stiffness retain flexibility

plastic changes= pass yield point, increase flexibility. too far—> tissue failure (injury)

Body tissues

Viscoelastic and contain both viscous and elastic properties

Yield point

• Point at which elasticity is almost exceeded

• if deformation persists, following release of load, permanent or plastic changes result

• When yield point is far exceeded, mechanical failure occurs resulting in damage.

Tissue loading types

• Tension

• Shearing

• Bending

• Torsion

Tension

force that pulls and stretches tissue

Shearing

Force that moves across the parallel organization of tissue

Bending

• Two force pairs act at opposite ends of a structure (4 points)

• Three forces cause bending (3 points)

• already bowed structures encounter axial loading

Torsion

• Loads caused by twisting in opposite directions from opposite ends

• Shear stress encountered will be perpendicular and parallel to the loads

Traumatic vs Overuse injuries

• Nature of physical activity dictates that over time injury will occur

• Can be defined based on mechanism

  • Traumatic (direct blow) versus overuse (repetitive dynamic us over time)

Acute vs chronic injuries

• When injury is acute: something has initiated the injury process

• Injury becomes chronic when it doesnt properly heal

Muscle properties

• Anatomical characteristics

  • composed of contractile cells that produce movement

• irritability/excitability

• contractility

• elasticity

• plasticity

irratibility/excitability

innervation (electrical component)

contractility

a muscles ability to respond to stimulus

elasticity

a muscle returns to its original length after stretch

plasticity

the ability of a muscle to return to a new length after stretch

eccentric vs concentric

• Isotonic activity- concentric and eccentric contraction—> same muscle/ muscle group

• Concentric: The muscle shortens while generating tension to overcome an external resistance.

• Eccentric: The muscle lengthens while generating tension to resist or decelerate an external load.

Muscle strains

• Stretch, tear, or rip to muscle or adjacent tissue

• cause is often obscure

• may range from minute separation of connective tissue to complete tendinous avulsion or muscle rupture

Muscle strain grades

• Pathologically, strain is very similar to contusion or sprain with capillary or blood vessel hemorrhage

• time required for healing may be lengthy

• often involves large and force producing muscles

• treatment and recovery may take 6-8 weeks depending on severity

• return to play too soon could result in reinjury

1. slight

2. some still attached

3. completely disconnected

Grade one

Some fibers have been stretched or actually torn resulting in tenderness and pain on active ROM, movement painful but full range present

grade two

Number of fibers have been torn and active contraction is painful, usually a depression or divot is palpable, some swelling and discoloration result

Grade three

Complete rupture of muscle or musculotendinous junction, significant impairment initially with a great deal of pain that diminishes due to nerve damage

Muscle Cramps

• painful involuntary skeletal muscle contraction

• occurs in well developed individuals when muscle is in shortened position

Muscle guarding

• following injury, muscles within an effected area contract to splint the area in an effort to minimize pain through limitation of motion

Involuntary muscle contraction

• in response to pain following injury

• not spasm, which would indicate increased tone due to upper motor neuron lesion in the brain

Muscle spasms

• A reflex reaction caused by trauma (can be muscle fatigue)

• two types

  • Clonic: alternating involuntary muscular contractions and relaxations in quick succession

  • Tonic: rigid contraction that lasts a period of time

• may lead to muscle or tendon injuries

Muscle soreness

• overexertion in strenuous exercise resulting in muscular pain

• generally occurs following participation in an activity that individual is unaccustomed to

Types of Muscle soreness

• Acute-onset muscle soreness: accompanies fatigue and is transient muscle pain experiences immediately after exercise

• Delayed-onset muscle soreness (DOMS): pain that occurs 24-48 hours following activity that gradually subsides (pain free 3-4 days later)

  • Potentially caused by slight micro trauma to muscle or connective tissue structures

• Prevent soreness through gradual build up of intensity

  • progressive gradual increase in resistance

  • be cautious of exercises that emphasize eccentric movement

Fibroblast

Type of cell that produces collagen and elastin

Biological middle age

35-40 (collagen decrease)

Tendons

• Wavy, parallel, and collagenous fibers organized in bundles upon loading

  • can produce and maintain 8700 -18000 pounds per square inch

  • collagen straightens during loading but will return to shape after

• Breaking point occurs at about 10% of increased length

• Tears generally occur in muscle and not tendon

Tendon Injuries

• Repetitive stress on tendon will result in microtrauma and elongation causing fibroblasts’ influx and increased collagen production

• Repeated microtrauma may evolve into chronic muscle strain due to reabsorbtion of collagen fibers

• Results in weakening tendons

• Collagen reabsorption occurs in early period of sports conditioning and immobilization making tissue susceptible to injury- requires gradual loading and conditioning

Tendinitis

• Gradual onset, with diffuse tenderness due to repeated microtrauma and degenerative changes

• inflammation of the tendon

• obvious signs or swelling and pain

Tendinosis

• Without proper healing, tendinitis may begin to degenerate and result in tendinosis

• Less inflammation and more visibly swollen with stiffness and restricted motion (affects joint function)

• Sometimes a tender lump will appear

• More common in middle or older age

• Treatment involved stretching and strengthening

Tenosynovitis

• Inflammation of synovial sheath

• In acute cases: Rapid onset, crepitus, and diffuse swelling

• Chronic cases result in thickening of tendon with pain and crepitus

• Often occurs in long flexor tendon of the digits and the biceps tendon

• Due to nature of injury, anti inflammatory agents may be helpful

Active trigger point

• Causes pain at rest!!!

• Applying pressure=pain=jump sign

• Tender to palpation with referred pain

• Tender point (no pain at rest) vs trigger point

• Found most commonly in muscles involved in postural support

Contusions

• Result of sudden blow to body

• Can be both deep and superficial

• Hematoma results from blood and lymphs flow into surrounding tissue

  • Localization of extravasated blood into clot, encapsulated by connective tissue

  • Speed of healing dependent on the extent of damage

  • (Gravity can pull the fluids away from the site of impact)

Atrophy

Wasting away of muscle due to immobilization, inactivity, or loss of nerve functioning

Contracture

• Abnormal shortening of muscle where there is a great deal of resistance to passive stretch

• Generally the result of a muscle injury, which impacts the joint, results in accumulation of scar tissue

Cartilage types

1. Hyaline/Articular - located in joints - function= allow smooth joint motion

2. Fibrocartilage - Functions = act as a shock absorber & increase joint stability

Synovial Joint injuries

• Hyaline/ Articular cartilage

• Fibrous connective tissue capsule

• Ligaments

• Capsule with synovial membrane

• Joint cavity with synovial fluid

• Blood and nerve supply

• Muscles

• Menisci/ Labrum (fibrocartilage)

Ligament Sprains

• Result of traumatic joint twist that causes stretching or tearing of connective tissue

• Graded based on severity of the injury

Ligament sprain grades

• Grade one: Some pain, minimal loss of function, no abnormal motion, and mild point tenderness

• Grade two: Pain, moderate loss of function, swelling, and instability with tearing and separation of ligament fibers

• Grade three: Extremely painful, inevitable loss of function, sever instability and swelling, and may also represent sublaxion

Ligament sprain effects

• Can result in join effusion and swelling, local temperature increase, pain and point tenderness, ecchymosis (change in skin color)

• Greatest difficulty with grade one and two sprains is restoring stability due to stretched tissue and inelastic scar tissue formation

• To regain joint stability, strengthening of muscles around the joint is critical

Dislocations and Subluxations

• Result in separation of bony articulating surfaces

• Subluxation

  • Partial dislocations causing incomplete separation of two bones

  • bones come back together in alignment

Dislocation key items

• Only qualified individuals should attempt to reduce a dislocated joint

• 1st thing to check after a joint is reduced= neurovascular structures

  • sensation in fingers, grip, pulse, capillary refill time

  • check bilaterally and compare

Dislocations

• High level of incidence in fingers and shoulder

• occurs when at least one bone in a joint is forced out of alignment and must be manually or surgically reduced

• Gross deformity is typically apparent with bilateral comparison revealing asymmetry

Dislocations and fractures

• Dislocations (particularly the first time) should always be considered and treated as a fracture until ruled out

  • Dislocation does not always equal fracture

• Once a dislocation, always a dislocation

  • second time requires less force/stress

Osteoarthritis

• Wearing of hyaline cartilage

• Changes in joint mechanics lead to joint degeneration

• Commonly affects weight-bearing joints but can also impact shoulders and cervical spine

Osteoarthritis symptoms

• Pain (as a result of friction)

• Stiffness

• Prominent morning pain, localized tenderness

• Creaking and grating

• Either it is generalized joint pain or localized to one side of the joint

Bursitis

• Bursa: fluid filled sacs that develop in areas of friction

• Sudden irritation can cause acute bursitis, while overuse and constant external compression can cause chronic bursitis

• Signs and symptoms include swelling, pain, and some loss of function

• Repeated trauma can lead to calcification and degeneration of internal bursa linings

• Purpose: decrease friction

Bones (gross structures)

• Diaphysis

• Ephiysis

• Periosteum

Diaphysis

• Shaft: Hollow and cylindrical

• Covered by compact bone

• Medullary cavity contains yellow marrow and lined by endosteum

Ephiysis

• Ends of the bone covered by articulate cartilage

• Composed of cancellous bone and has hyaline cartilage covering

• Provides areas for muscle attachment

Periosteum

• Dense covering over diaphysis

• Dense, white fibrous covering that penetrates bone via Sharpeys fibers

• Contains blood vessels and osteoblasts