1. Chapter 9: Mechanisms and Characteristics of Sports Trauma

3. 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

4. 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

5. 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)

6. Soft Tissue Trauma Soft tissue or non -bony tissue is categorized as inert (noncontractile) and contractile tissue Inert tissues include, ligaments, skin, cartilage, capsules, fascia, dura mater and nerve roots Contractile tissue involves muscles and its parts including tendons and bony insertions

7. 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 bogy and consists of 2 layers Epidermis Dermis (corium) –Soft pliable nature of skin makes it easy to traumatize

8. 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

9. –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

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

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

12. 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

13. –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

14. 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) strength imbalance –May range from minute separation of connective tissue to complete tendinous avulsion or muscle rupture

15. –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 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 Grade III- Complete rupture of muscle or musculotendinous junction, significant impairment, with initially a great deal of pain that diminishes due to nerve damage –Pathologically, strain is very similar to contusion or sprain with capillary or blood vessel hemorrhage

17. Tendon Injuries –Wavy parallel collagenous fibers organized in bundles - upon loading Can produce and maintain 8,700- 18,000 lbs/in 2 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

18. –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 – requires gradual loading and conditioning

20. Muscle Spasms –A reflex reaction caused by trauma –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

21. Overexertional Muscle Problems Reflective in muscle soreness, decreased joint flexibility, general fatigue (24 hours post activity) 4 indicators of possible overexertion 1)Muscle Soreness –Overexertion in strenuous exercise resulting in muscular pain –Generally occurs following participation in activity that individual is unaccustomed

22. –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 –Treat with static or PNF stretching and ice application within 48-72 hours of insult

23. 2)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 3)Muscle Cramps –Painful involuntary skeletal muscle contraction –Occurs in well-developed individuals when muscle is in shortened position –Experienced at night or at rest

24. 4)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

25. Myofascial Trigger Points Discrete, hypersensitive nodule within 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

26. 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

27. 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

28. Myositis/fascitis –Inflammation of muscle tissue –Fibrositis or inflammation of connective tissue –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

29. 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

30. 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

31. Synovial Joints Anatomical Characteristics –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

33. Joint Capsule –Bones are held together by a fibrous cuff –Consists of bundles of collagen and function to maintain relative joint position –Extremely strong and can withstand cross- sectional forces –Will be slack or taut depending on joint movement

34. Ligaments –Sheets or bundles of collagen that form connection between two bones –Both intrinsic (inside the capsule) and extrinsic (outside the capsule) –Similar composition to tendons –Strong in the middle, weak at the ends –When placed under undo stress may result in avulsion injury –Viscoelastic properties are primary factor in ligamentous injuries

35. –Constant compression or tension causes ligament deterioration while intermittent stress strengthens –Repeated microtrauma overtime makes capsule and ligaments more susceptible to major acute injuries –Act as protective backup for joint Primary protection is dynamic action of muscle –Under fast loading conditions, ligament will fail, however, they provide maximal protection during rapid movements –Will adapt based on Roux’s law of functional adaptation (organ will adapt structurally to an alteration, qualitative or quantitative of function)

36. Synovial Membrane –Lines articular capsule –Single layer of flattened cells and villi –Secretes and absorbs fluid - serves as lubricant –Fluid contains hyaluronic acid (changes viscosity) Fast movement - thins fluid Slow movement - fluid thickens Articular Cartilage –Provides firm flexible support - semifirm connective tissue with primarily ground substance –No direct blood or nerve supply

37. –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 Can undergo compression and return to normal shape Degeneration producing microtrauma can occur following abnormal compressive forces Receives nourishment from synovium Provides motion control, stability and load transmission

38. 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 Vary in shape and size and connected to capsule Exist in joints that operate in 2 planes of motions Aid in dispersion of synovial fluid Meniscus

39. 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 –Myelinated mechanoreceptors provide joint position sense in fibrous capsule –Non-myelinated fibers supply blood vessels and pain receptors

40. Types of Synovial Joints –6 types 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)

41. 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 With stretching of the capsule, muscle reflex contractions prevent overstretching Nerve supply is governed by Hilton’s Law (capsule, skin and muscle have same nerve supply) Ligaments can extend due to right angle structural design but are not elastic

42. Joint structure vs. ligament contribution to joint stability Muscles absorb forces involved in load transmission and may provide dynamic stabilizing through integration into joint capsule and by crossing joints –Articular Capsule and Ligaments Help maintain anatomical integrity and structural alignment of joints Ligaments have spiral arrangement of collagenous tissue Ligaments tend to be stronger in the middle and weak at the ends Respond quicker than muscle to over-stretching

43. 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 –Subject to same mechanical forces that cause injury 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

44. 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

45. 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 Sometimes difficult to distinguish between sprain and tendon strain Repeated joint twisting could result in arthritis or chronic inflammation

46. –Acute Synovitis Synovial membrane can be acutely injured via contusion or strain Irritation of membrane results in increased fluid production and swelling occurs Results in joint pain along with skin sensitivity With proper treatment, effusion and pain will diminish –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 Diastisis is the disjointing of 2 parallel bones or rupture of a solid joint (symphysis pubis)

47. 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”

48. Chronic Joint Injuries –Stem from microtrauma and overuse –Include, osteochondrosis, osteoarthritis, and in adolescence epiphyseal injuries –Major cause involves failure of muscle to control or limit deceleration –To prevent, a combination of chronic fatigue and training should be avoided, and protective gear should be used to enhance active absorption of impact forces

49. –Osteochondrosis Also known as osteochrondritis dissecans and apophysitis (if located at a tubercle/tuberosity) Causes not well understood Degenerative changes to epiphyses of bone during rapid child growth Possible cause includes 1)aseptic necrosis (disrupted circulation to epiphysis, 2) fractures in cartilage causing fissures to subchondral bone, 3) trauma to a joint that results in cartilage fragmentation resulting in swelling, pain and locking With the apophysis, an avulsion fracture may be involved, including pain, swelling and disability

50. –Osteoarthritis Wearing away of hyaline cartilage as a result of normal use Changes in joint mechanics lead to joint degeneration (the result of repeated trauma to tissue involved) 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 Symptoms include pain (as the result of friction), stiffness, prominent morning pain, localized tenderness, creaking, grating Either generalized joint pain or localized to one side of the joint

51. –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 Repeated trauma can lead to calcification and degeneration of internal bursa linings

52. –Capsulitis and Synovitis Capsulitis is the result of repeated joint trauma Synovitis can occur acutely but will also develop following mistreatment of joint injury Chronic synovitis can result in edema, thickening of the synovial lining, exudation can occur and a fibrous underlying develops Motion may become restricted and joint noises may develop

53. Skeletal Trauma Anatomical Characteristics –Dense connective tissue matrix –Outer compact tissue –Inner porous cancellous bone including Haversian canals

54. –Bone Functions Body support Organ protection Movement (through joints and levers) Calcium storage Formation of blood cells (hematopoiesis) –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

55. –Gross Structures Diaphysis - shaft - hollow and cylindrical - covered by compact bone - medullary cavity contains yellow marrow and lined by endosteum Epiphysis - composed of cancellous bone and has hyaline cartilage covering - provides areas for muscle attachment Periosteum - dense, white fibrous covering which penetrates bone via Sharpey’ fibers - contains blood vessels and osteoblasts

56. –Microscopic Structures Calcium salts impregnate intracellular bone substance (makes bone hard) Osteocytes located in hollow spaces are called lacunae Haversian systems are the structural units of bone Compact bone has interspersed lamellae to fill spaces between canals Cancellous bone has numerous open spaces between thin processes of trabeculae Trabeculae serve as scaffolding and align along points of stress within the bone to add structural strength Blood circulation connects perisosteum with haversian canals through Volkmann’s canal Medullary cavity and bone marrow are supplied directly by one or more arteries

57. –Bone Growth Ossification occurs from synthesis of bones organic matrix (work of osteoblasts and osteoclasts) Involves growth of diaphysis and the epiphyseal growth plates (towards one another) As cartilage matures, immature osteoblasts replace to ultimately form solid bone Deforming forces, premature injury and growth plate dislocation can alter growth patterns and/or result in deformity of bone Bone diameter increases via the activity of osteoblasts adding to the exterior while osteoclasts break down bone in medullary cavity At full size, bone maintains state of balance between osteoblastic and -clastic activity

58. Changes in activity and hormonal levels can alter balance Bone loss begins to exceed external bone growth overtime As thickness decreases, bones are less resistant to forces --osteoporosis Bone’s functional adaptation to stresses follows Wolff’s Law --every change in form and function or in its function alone is followed by changes in architectural design

59. Bone Injuries –While bones have viscoelastic properties, bone is fairly rigid and serves as a poor shock absorber –Brittle nature increases under tension rather than compression –Cylindrical nature of bones make them very strong - resistant to bending and twisting –Anatomical Weak Points Stresses become concentrated in areas where changes in shape and direction occur Gradual changes in shape are much more advantageous

60. –Load Characteristics Bones can be stressed or loaded to failure by tension, compression, bending, twisting and shearing Either occur singularly or in combination Amount of load also impacts the nature of the fracture More force results in a more complex fracture While force goes into fracturing the bone, some energy and force is also absorbed by adjacent soft tissues Some bones will require more force than others Bone’s magnitude of stress and strain is most prevalent at it outer surface and decreases to zero at its center

61. –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

62. Type of fractures include, depressed, greenstick, impacted, longitudinal, oblique, serrated, spiral, transverse, comminuted, blowout, 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

64. Bone becomes susceptible early in training due to increased muscular forces and initial remodeling and resorption of bone 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 events without proper conditioning –Starting initial training too quickly –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

65. 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 Management varies between individuals, injury site and extent of injury More easily managed and healed if on compression side of bone vs. tension (may result in complete fx)

66. 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 –Apophyses are traction epiphyses in contrast to pressure epiphyses. –Serve as sites of origin and insertion for muscles –Common avulsion conditions include Sever’s disease and Osgood-Schlatter’s disease

68. 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

69. Anatomical Characteristics –Provides sensitivity and communication from the CNS to muscles, sense organs and various systems in the periphery –Neuron cell body has a large nucleus with branched dendrites which respond to neurotransmitter substances –Each nerve cell has an axon that conducts nerve impulse –Axons are encased in neurilemmal sheaths (Schwann and satellite cells) –Various neurological cells in CNS help to form framework for nervous tissue

70. 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) –Long term problems (neuritis) can go from minor nerve problems to paralysis –Pain can be referred as well

71. Body Mechanics and Injury Susceptibility Body moves very effectively in upright position - able to overcome great forces even with inefficient lever system Body must overcome inertia, muscle viscosity and unfavorable angles of pull Mechanical reasons for injury - hereditary, congenital, or acquired defects may predispose athlete to injury Body build, structural make-up, habitual incorrect application of skill may also predispose individual to injury

72. Microtrauma and Overuse Syndrome –Injuries as a result of abnormal and repetitive stress and microtraumas fall into a class with certain identifiable syndromes –Frequently result in limitation or curtailment of sports involvement –Often seen in running, jumping, and throwing activities –Some of these injuries while small can be debilitating –Repetitive overuse and stress injuries include Achilles tendinitis, shin splints, stress fx, Osgood- Schlater’s disease, runner’s and jumper’s knee, patellar chondromalacia and apophyseal avulsion

73. Postural Deviations –Often an underlying cause of injury –May be the result of unilateral muscle or bony and soft tissue asymmetries –Sports activities may cause asymmetries to develop –Results in poor pathomechanics –Imbalance is manifested by postural deviations as body tries to regain balance relative to CoG May be primary cause of injury

74. –Injury generally becomes chronic and athletic participation must stop –Athletic trainer should attempt to correct postural conditions –Postural conditions can make athletes exceedingly more prone to injury