Understanding Sports Trauma: Mechanisms & Injuries

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 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

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) strength imbalance • 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 • 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

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 – requires gradual loading and conditioning

29. 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

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

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 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/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

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 • 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