Chapter 9: Mechanisms and Characteristics of Sports Trauma

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. 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

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

12. 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

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

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

18. 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

19. 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

20. 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

22. 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

23. 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

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

26. 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

27. 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

29. 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

30. 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

31. 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

32. 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

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

34. 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

35. 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

36. 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

38. 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

39. 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

41. 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

43. 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

45. 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

47. 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

48. Synarthrotic Amphiarthrotic Diarthrotic

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