Chapter 9: Mechanisms and Characteristics of Sports Trauma

Mechanical Injury Trauma is defined as physical injury or wound sustained in sport, produced by internal or external force Mechanical injury results from force or mechanical energy that changes state of rest or uniform motion of matter Injury in sports can be the result of external forces directed on the body or can occur within the body internally

Tissue Properties Relative abilities to resist a particular load Strength pressure or power is used to imply force (defined as a push or pull) Load can be a singular or group of outside or internal forces acting on the body. Stress is resistance to a load Body tissues are viscoelastic and contain both viscous and elastic properties Point at which elasticity is almost exceeded is the yield point When exceeded mechanical failure occurs resulting in damage

Tissue Stresses Tension (force that pulls and stretches tissue) Stretching (pull beyond yield point resulting in damage) Compression (force that results in tissue crush) Shearing (force that moves across the parallel organization of tissue) Bending (force on a horizontal beam that places stress within the structure)

Skin Injuries Break in the continuity of skin as a result of trauma Anatomical Considerations Skin (external covering) or integument represents the largest organ of the body and consists of 2 layers Epidermis Dermis (corium) Soft pliable nature of skin makes it easy to traumatize

Injurious Mechanical Forces Include friction, scraping, compression, tearing, cutting and penetrating Wound Classifications Friction blister continuous rubbing over skin surface that causes a collection of fluid below or within epidermal layer Abrasion Skin is scraped against rough surface resulting in capillary exposure due to skin removal Skin Bruise (contusion) Compression or crush injury of skin surface that produces bleeding under the skin

Laceration Wound in which skin has been irregularly torn Skin Avulsion Skin that is torn by same mechanism as laceration to the extent that tissue is completely ripped from source Incision Wound in which skin has been sharply cut Puncture Penetration of the skin by a sharp object

Skeletal Muscle Injuries High incidence in athletics Anatomical Characteristics Composed of contractile cells that produce movement Possess following characteristics Irritability Contractility Conductivity Elasticity

Three types of muscle Cardiac Smooth Striated (skeletal) Skeletal Muscle

Acute Muscle Injuries Contusions Result of sudden blow to body Can be both deep and superficial Hematoma results from blood and lymph flow into surrounding tissue Localization of extravasated blood into clot, encapsulated by connective tissue Speed of healing dependent on the extent of damage

Can penetrate to skeletal structures causing a bone bruise Usually rated by the extent to which muscle is able to produce range of motion Blow can be so severe that fascia surrounding muscle ruptures allowing muscle to protrude

Signs & Symptoms of Severe Contusions Athlete reports being struck by hard object Impact causes pain and transitory paralysis Due to pressure on and shock to motor and sensory nerves Palpation reveals hardened area Possible ecchymosis or tissue discoloration

Strains Stretch, tear or rip to muscle or adjacent tissue Cause is often obscure Abnormal muscle contraction is the result of 1)failure in reciprocal coordination of agonist and antagonist, 2) electrolyte imbalance due to profuse sweating or 3) or insufficient strength applied to a greater demand May range from minute separation of connective tissue to complete tendinous avulsion or muscle rupture

Muscle Strain Grades Grade I - some fibers have been stretched or actually torn resulting in tenderness and pain on active ROM, movement painful but full range present. MILD Grade II - number of fibers have been torn and active contraction is painful, usually a depression or divot is palpable, some swelling and discoloration result. MODERATE Grade III- Complete rupture of muscle or musculotendinous junction, significant impairment, with initially a great deal of pain that diminishes due to nerve damage. SEVERE

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

Tendon Injuries Wavy parallel collagenous fibers organized in bundles - upon loading Can produce and maintain 8,700- 18,000 lbs/in2 Collagen straightens during loading but will return to shape after loading Breaking point occurs at 6-8% of increased length Tears generally occur in muscle and not tendon

Recovery requires gradual loading and conditioning 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 reabsorption of collagen fibers Results in weakening tendons Collagen reabsorption occurs in early period of sports conditioning and immobilization making tissue susceptibility to injury – Recovery requires gradual loading and conditioning

Muscle Spasms A reflex reaction caused by trauma or 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

Overexertional Muscle Problems Reflective in muscle soreness, decreased joint flexibility, general fatigue (24 hours post activity) 4 indicators of possible overexertion Muscle Soreness Overexertion in strenuous exercise resulting in muscular pain Generally occurs following participation in activity that individual is unaccustomed

Two types of soreness Acute-onset muscle soreness - accompanies fatigue, and is transient muscle pain experienced 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 microtrauma to muscle or connective tissue structures Prevent soreness through gradual build-up of intensity

Muscle Stiffness Does not produce pain Result of extended period of work Fluid accumulation in muscles, with slow reabsorbtion back into bloodstream, resulting in swollen, shorter, thicker muscles --resistant to stretching. Light activity, motion, massage and passive mobilization assists in reducing stiffness

Muscle Cramps Painful involuntary skeletal muscle contraction Occurs in well-developed individuals when muscle is in shortened position Experienced at night or at rest

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

Myofascial Trigger Points Discrete, hypersensitive nodule within a tight band of muscle or fascia Classified as latent or active Latent trigger point Does not cause spontaneous pain May restrict movement or cause muscle weakness Become aware of presence when pressure is applied

Active trigger point Causes pain at rest Applying pressure = pain = jump sign Tender to palpation with referred pain Tender point vs. trigger point Found most commonly in muscles involved in postural support Develop as the result of mechanical stress Either acute trauma or microtrauma May lead to development of stress on muscle fiber = formation of trigger points

Chronic Musculoskeletal Injuries Progress slowly over long period of time Repetitive acute injuries can lead to chronic condition Constant irritation due to poor mechanics and stress will cause injury to become chronic Chronic muscle injuries Representative of low grade inflammatory process with fibroblast proliferation and scarring Acute injury is improperly managed

Myositis/fasciitis Inflammation of muscle tissue or fascia Plantar fascitis Tendinitis Gradual onset, with diffuse tenderness due to repeated microtrauma and degenerative changes Obvious signs of swelling and pain

Tenosynovitis Inflammation of synovial sheath In acute case - rapid onset, crepitus, and diffuse swelling Chronic cases result in thickening of tendon with pain and crepitus

Ectopic Calcification (myositis ossificans) Striated muscle becomes chronically inflamed resulting in myositis Can result in muscle that lies directly above bone Osteoid material accumulates rapidly and will either resolve in 9-12 months or mature with repeated trauma With maturation, surgery is required for removal Common sites, quadriceps and brachial muscle

Atrophy and Contracture Atrophy is wasting away of muscle due to immobilization, inactivity, or loss of nerve functioning Contracture is an 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, resulting in accumulation of scar tissue

Synovial Joints Anatomical Characteristics – between bones Consist of cartilage and fibrous connective tissue Joints are classified as Synarthrotic - immovable Amphiarthrotic - slightly moveable Diarthrotic - freely moveable (synovial articulations) Synovial Joint characteristics Capsule or ligaments Capsule is lined with synovial membrane Hyaline cartilage Joint cavity with synovial fluid Blood and nerve supply with muscles crossing joint

Synarthrotic Amphiarthrotic Diarthrotic

Joint Capsule Bones are held together by a fibrous cuff Extremely strong and can withstand cross- sectional forces

Ligaments Sheets or bundles of collagen that form connection between two bones Both intrinsic (inside the capsule) and extrinsic (outside the capsule) Strong in the middle, weak at the ends

Synovial Membrane Lines articular capsule Secretes and absorbs fluid - serves as lubricant Articular Cartilage Provides firm flexible support - semifirm connective tissue with primarily ground substance No direct blood or nerve supply

Fibrocartilage: makes up vertebral disks, symphysis pubis and menisci Elastic: external ear and eustachian tubes Hyaline: composes nasal septum, larynx, trachea, bronchi, and articular ends of bone Covers ends of bones in diarthrodial joints which serves as cushion and sponge

Additional Synovial Joint Structures Fat Pads located in elbow, knee, to fill spaces between bones that form joints (lie between synovial membrane and the capsule) Articular Disks Additional fibrocartilanginous disks Aid in dispersion of synovial fluid Meniscus

Nerve Supply Capsule, ligaments, outer aspects of synovial membrane and fat pads are well supplied Inner structures (synovial membrane, cartilage and articular cartilage) also supplied

Types of Synovial Joints Ball and socket - allows movement in all plane (hip) Hinge - allows for flexion and extension (elbow) Pivot - rotation about and axis (cervical atlas and axis) Ellipsoidal - elliptical convex and concave articulation (wrist) Saddle - reciprocally convex-concave (carpometacarpal joint of thumb) Gliding - all sliding back and forth (carpal joints)

Functional Synovial Joints Differ in their ability to withstand trauma depending on skeletal, ligamentous, and muscular organization Synovial Joint Stabilization Muscle tension helps to limit synovial joint movement Ligaments can extend due to right angle structural design but are not elastic

Articular Capsule and Ligaments Help maintain anatomical integrity and structural alignment of joints Ligaments tend to be stronger in the middle and weak at the ends

Synovial Joint Trauma Major factor in injury is viscoelastic properties of ligaments and capsule While constant compression is damaging, periodic tension increases overall strength of tissue Synovial Joint Injury Classifications Acute Joint Injuries Sprains Result of traumatic joint twist that causes stretching or tearing of connective tissue Graded based on the severity of injury

Grade I - some pain, minimal loss of function, no abnormal motion, and mild point tenderness Grade II - pain, moderate loss of function, swelling, and instability Grade III - extremely painful, inevitable loss of function, severe instability and swelling, and may also represent subluxation

Can result in joint effusion and swelling, local temperature increase, pain and point tenderness, ecchymosis (change in skin color) and possibly an avulsion fracture Most vulnerable joints include ankles, knees, and shoulders

Acute Synovitis Synovial membrane can be acutely injured via contusion or strain Irritation of membrane results in increased fluid production and swelling occurs

Subluxations, Dislocations and Diastasis High level of incidence in fingers and shoulder Subluxations are partial dislocations causing incomplete separation of two bones Luxation presents with total disunion of bone apposition between articular surfaces

Factors associated with dislocations – 1) loss of limb function 2) gross deformity 3)swelling and point tenderness X-ray is the only absolute diagnostic technique (able to see bone fragments from possible avulsion fractures, disruption of growth plates or connective tissue) Dislocations (particularly first time) should always be considered and treated as a fracture until ruled out “Once a dislocation, always a dislocation”

Chronic Joint Injuries Stem from microtrauma and overuse Include, osteochondrosis, osteoarthritis, and in adolescence epiphyseal injuries

Osteochondrosis Causes not well understood Degenerative changes to epiphyses of bone during rapid child growth With the apophysis, an avulsion fracture may be involved, including pain, swelling and disability

Osteoarthritis Wearing away of hyaline cartilage as a result of normal use May be the result of direct blow, pressure of carrying and lifting heavy loads, or repeated trauma from an activity such as running or cycling Commonly affects weight bearing joints but can also impact shoulders and cervical spine

Bursitis Bursa are 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

Capsulitis and Synovitis Capsulitis is the result of repeated joint trauma Synovitis can occur acutely but will also develop following mistreatment of joint injury

Bone Functions Body support Organ protection Types of Bone Classified according to shape Flat bones - skull, ribs, scapulae Irregular bones - vertebrae and skull Short bones- wrist and ankle Long bones - humerus, ulna, tibia, radius, fibula, femur

Gross Structures Diaphysis - shaft - hollow and cylindrical - covered by compact bone Epiphysis - composed of cancellous bone and has hyaline cartilage covering - provides areas for muscle attachment Periosteum - dense, white fibrous covering - contains blood vessels and osteoblasts

Bone Injuries While bones have viscoelastic properties, bone is fairly rigid and serves as a poor shock absorber Anatomical Weak Points Stresses become concentrated in areas where changes in shape and direction occur

Load Characteristics Bones can be stressed or loaded to failure by tension, compression, bending, twisting and shearing Amount of load also impacts the nature of the fracture More force results in a more complex fracture Some bones will require more force than others

Bone Trauma Classifications Periostitis - inflammation of the periosteum - result primarily of contusions and produces rigid skin overlying muscle (acute and chronic) Acute bone fractures - partial or complete disruption that can be either closed or open (through skin) - serious musculoskeletal condition - Fracture occurs either directly (point of applied force) or indirectly

Types of fractures include: depressed, greenstick, impacted, longitudinal, oblique, serrated, spiral, transverse, comminuted, and avulsion

Stress fractures- no specific cause but with a number of possible causes: Overload due to muscle contraction, altered stress distribution due to muscle fatigue, changes in surface, rhythmic repetitive stress vibrations

Progression involves, focal microfractures, periosteal or endosteal response (stress fx) linear fractures and displaced fractures Typical causes include Coming back to competition too soon after injury Changing training habits (surfaces, shoes….etc) Variety of postural and foot conditions Early detection is difficult, bone scan is useful, x-ray is effective after several weeks

Major signs and symptoms include focal tenderness and pain, (early stages) pain with activity, (later stages) with pain becoming constant and more intense, particularly at night, (exhibit a positive percussion tap test) Common sites involve tibia, fibula, metatarsal shaft, calcaneus, femur, pars interarticularis, ribs, and humerus

Epiphyseal Conditions - three types can be sustained by adolescents (injury to growth plate, articular epiphysis, and apophyseal injuries) Occur most often in children ages 10-16 years old Classified by Salter-Harris into five types (see photo on next slide) Apophyseal Injuries - Young physically active individuals are susceptible Serve as sites of origin and insertion for muscles Common avulsion conditions include Sever’s disease and Osgood-Schlatter’s disease

Nerve Trauma Abnormal nerve responses can be attributed to injury or athletic participation The most frequent injury is neuropraxia produced by direct trauma Lacerations of nerves as well as compression of nerves as a result of fractures and dislocations can impact nerve function

Anatomical Characteristics Provides sensitivity and communication from the CNS to muscles, sense organs and various systems in the periphery Each nerve cell has an axon that conducts nerve impulse Various neurological cells in CNS help to form framework for nervous tissue

Nerve Injuries Two main causes of injury - compression and tension May be acute or chronic Physical trauma causes pain and can result in a host of sensory responses (pinch, burn, tingle, muscle weakness, radiating pain)