vet-tech-animal-diseases-2-musculoskeletal-diseases-part-2

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darlene.m.nelson
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137702
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vet-tech-animal-diseases-2-musculoskeletal-diseases-part-2
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2012-02-25 20:19:44
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vet tech animal diseases musculoskeletal part set
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vet tech animal diseases 2 musculoskeletal diseases part 2 set
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  1. Fracture
    • any interruption in the cortices of a bone
    • always shave and look for hole in skin
    • hard to break a bone on an animal - need to make sure it was an accident
  2. Cortex of a bone
    the outer or superficial part of an organ or bodily structure (e.g. bone)
  3. Open Fracture
    • aka compound fracture
    • the bone has pentrated the skin and been exposed to the environment
    • worst kind of fracture
    • not sterile
    • bone may retract back in, but still considered open as skin broken and hole all the way to bone
    • bacteria can get in (or probably has if bone retracted) and infect bone
  4. Osteomyelitis
    • infection of the bone
    • very painful
    • fracture will not heal
    • attend to wound cleaning - surgically open the wound, lavage, etc
  5. Closed fracture
    the skin remains intact, although the bone is fractured
  6. Classification of bone fractures
    • shaft (metaphyseal) fractures
    • Greenstick
    • simple
    • comminuted
  7. Greenstick fracture
    • fracture through one portion of the cortex
    • no displacement of bone
    • e.g. down middle of shaft or partially across, but not all the way across
    • must take x-ray in the correct plane or you won't see it
    • for x-rays:
    • - first do AP & lateral
    • - if not seeing anything, take lateral, cranial, caudal & other directions
  8. Simple fracture
    • bone is broken through entire cortex
    • forms 2 (& only 2) separate pieces
    • may be transverse, oblique or spiral
  9. Transverse simple fracture
    • straight across
    • hardest to repair
    • hard to get good rotational therapy
  10. Oblique simple fracture
    slanted
  11. Spiral simple fracture
    • occurs with rotation
    • eg tibia when skiing without quick release bindings
  12. Comminuted fracture
    • the bone is broken into multiple fragments
    • large fragments are referred to as butterflies
    • problematic
    • - periosteum brings blood to bone
    • - if pieces don't have periosteal attachment, will die w/in 10-15 days & will have painful draining necrotic abcess
  13. Compression fracture
    occur in short bones & flat bones (in juveniles, on long bones as well)
  14. Fracture classification
    • epiphyseal fracture
    • - juvenile animals
    • -- involve the growth plates - physis (weak point in bone)
    • -- salter fractures - classified as 1-5
    • -- not as big a deal in animals as humans (angulation in joints can compensate)
    • adult animals
    • - Y fractures
    • - T fractures
  15. Bone healing
    • requires:
    • - stabilization of fractured bone ends
    • -- multiple methods
    • - sterile environment
    • -- closed vs. open fracture
    • - formation of callus
    • -- problematic for epiphyseal fractures
  16. Callus
    • connective tissue scaffolding to hold bone
    • big problem in joint as it interferes with movement
  17. Causes of bone fracture
    • trauma
    • pathological fractures
  18. Fractures from Trauma
    • requires significant force to fracture a bone
    • rule out abuse - report it to vet -> ASCPA, animal control
  19. Pathological fractures
    • there is a primary disease that weakens the bone
    • 2 major causes:
    • - cancer (neoplasia)
    • - metabolic disease
  20. Pathological fracture - cancer
    • primarily osteosarcoma
    • treatment is amputation
  21. Metabolic disease
    • primary hyperparathyroidism
    • - regulates calcium & posphorus balance
    • chronic renal failure (pseudohyperparathyroidism)
    • improper diet
    • - fresh diet done wrong
    • - can be irreversible
  22. Clinical signs of fracture disease
    • history of trauma
    • - something had to happen to break the bone
    • pain or localized tenderness - frequently swelling
    • deformity
    • - especially in through & through fractures
    • loss of function
    • - three legged lame
    • crepitus
    • - can feel bone ends moving against each other
    • localized swelling or bruising
    • sometimes see animals that defy explanation
    • - lab w/ fractured ramus of mandible accidentally hit by baseball bat
    • - happy as can be
    • - adrenaline can mask much pain for ~45 min - 1 hour
  23. Fracture disease diagnosis
    • history - trauma?
    • physical exam
    • - muzzle, treat gently, lots of pain
    • - palpation - bones wiggle
    • imaging
    • - radiographs
    • -- 2 views
    • -- often may need to sedate as need to move leg around
  24. Fracture disease treatment
    • requires:
    • - reduction of bones ends - correct anatomical position
    • - stabilization of bone ends
    • - sterile environment
    • -- risk of osteomyelitis
    • method determined by:
    • - open or closed
    • - age of patient - juveniles heal fast; elderly very slowly
    • - which bone is fractured
    • - type of fracture
    • - size of the animal
    • - species - e.g. horse w/ broken leg is put down
    • - how does bone normally fit together?
    • - what will normally pull on it (distractive forces)?
  25. Osteomyelitis
    inflammation of bone or bone marrow, usually due to infection
  26. Methods of fracture repair
    • splints
    • casts
    • pins
    • plates
    • screws
    • external fixators
    • or combinations of these
  27. Splints and casts
    • effective for:
    • - closed fractures
    • - distal extremities
    • -- below stifle/elbow
    • - young animal
    • -- heal really quickly
    • -- can change splint as they grow
    • can get plastic casts in various sizes that can be trimmed to fit
  28. Thomas splint
    • for fractures of femur & humerus
    • aluminum loop hooked to greater trochanter
    • tape bottom to foot
    • ~10 - 12 week healing time
    • low cost method to fix
  29. Casts
    • similar to splints
    • older animal
    • - once stopped growing; ~6 - 18 months
    • destructive animal
    • - casts are fiberglass; can't chew off
    • large or heavy animal
    • - can't do cat or chihuahua
    • - need to have a cast saw in-house to get it off
    • toes showing/not - 2 schools of thought:
    • - 1. encase foot
    • -- pro: no bands of pressure
    • -- con: can't see foot swelling if too tight
    • - 2. toes exposed
    • -- pro: can see swelling if too tight
    • - which you use will depend on what vet prefers (can be different for each vet in a practice)
    • if too tight, foot will tingle & animal will chew at foot
    • owner:
    • - need to keep clean/dry (vet wrap shrinks when wet)
    • - observe whether animal chewing at splint/cast, need to come in as too tight
  30. Pins & Wires
    • everything must be ultra-sterile
    • intramedullary pins (steinman pins)
    • - usually titanium
    • - open or closed placement
    • -- open placement lets you see fracture & guide pin more carefully
    • -- need to be really good if closed
    • - Jacobs chuck used to place it (separate surgery pack for chuck, key & extender)
    • - basically a rod down the center of the bone
    • simple fractures
    • - transverse, oblique, spiral - only 2 pieces of bone
    • - flat bones
    • -- bend pin slightly; ends stick out
    • -- figure 8 with wires
    • wires to improve stbilization
    • - cerlage - circle - passed completely around
    • - hemicerlage - through bone & around
    • - stainless steel suture wire
  31. Plates & screws
    • sometimes you can't pin bones
    • comminuted fractures - lots of pieces
    • flat bones
    • large breeds - could bend pins
    • ASIF (Association suisse internal fixation)
    • - developed for alpine skiers w/ spiral fracture of tibia
    • - must go there for advanced training
    • - need specialized equipment
    • -- specialize titanium plates & screws
    • -- ~$10,000 - $15,000 for sterilizable tool case with plates & screws
    • -- also need compressed air & special drills to drill holes for screws & tap to drill threads
    • -- then can put screws in
    • -- if don't use tap, will create microfractures in the bone when put screw in
    • sterility mandatory
    • - stay in the body
    • - never come out
    • - if bone infected, must take care of that first
    • no callus as no movement in the bone unlike with pins & wires/splints/casts
    • muscle can get tie down between femur & quads in connective tissue
    • - can also happen on humerus, but usually not
  32. External fixators
    • sometimes can't use internal fixators - infection, open, owner $, etc
    • Kirschner apparatus
    • - open fractures
    • - comminuted fractures
    • - abnormal bone conformation
    • - cost considerations
    • - inability to find plates for small animal, e.g. cat
    • even if a practice doen't do internal fixation, it may do this
  33. Pathologic fractures
    • concomitant illness weakens bone leading to fractures
    • - cancer (neoplasia)
    • -- most common is osteosarcoma
    • - metabolic disease
    • -- primary hyperparathyroidis - extremely rare
    • -- chronic renal failure (pseudohyperparathyroidism)
    • -- improper diet - eg raw feeding w/o balancing Ca & K
  34. Osteosarcoma
    • osteo - bone
    • sarcoma - tumor arising from connective tissue
    • large breed dogs - usually older
    • long bones
    • - radius & ulna
    • - femur
    • - tibia, scapula, humerus
    • intermittent lameness
    • pathologic fracture
    • most common orthopedic tumor in kids
    • highly malignant tumor - generally by the time dx, it's too late
    • frequent metastasis to lungs
    • doesn't occur frequently in cats
  35. Osteosarcoma diagnosis
    • difficult to diagnose
    • - owner thinks it is arthritis, until eventually, dog lands on leg, breaks it, screams
    • - dx before break, exam - looks a lot like pan-o
    • radiographs
    • - limb
    • -- by the time you find it in the bone, it has usually spread
    • -- may see starburst pattern - disease destroying bone while body trying to repair causes abnormal architecture
    • - lungs
    • -- looking for metastasis
    • -- if see them, they will be dead w/in 3 months
    • definitive dx
    • - biopsy = cellular understanding of disease, e.g ELISA, histopathology, biopsy)
  36. Osteosarcoma treatment
    • can easily spend $10,000
    • usually only if no obvious metastasis in chest
    • amputation
    • - heals ~ 2 weeks
    • - humans would be disabled and/or disfigured
    • - dogs don't care - happy cause they aren't in pain
    • radiation
    • - only after amputation
    • - local only
    • - don't lose fur
    • - usually daily for 6 weeks
    • chemotherapy
    • - only after amputation
    • - cis-platin (drug)
    • -- toxic in cats
    • -- chemotherapeutic
    • -- costly
    • - usually weekly
    • - don't usually get vomiting
    • euthanasia
    • - can't repair pathological fracture
  37. Osteosarcoma prognosis
    • grave
    • die w/in 12 months of dx even with aggressive treatment
    • - even with amputation and chemo
    • - range 3 months to 2 uears
    • - eventually start coughing & can't breath
  38. Hyperparathyroidism & pseudohyperparathyroidism
    Ca:P must remain in balance w/in the body
  39. Parathyroid gland
    • responsible for maintaining appropriate blood calcium levels by removing calcium from storage in bones
    • produces 2 hormones that regulate blood calcium
    • body manages phosphorus
  40. Primay hyperparathyroidism
    • extremely rare
    • usually tumor
  41. Pseudohyperparathyroidism
    • occurs when there is an imbalance of Ca:P in the body due to either:
    • - renal disease - kidney unable to excrete phosphorus
    • - improper diet
    • dairy cow pasture must be seeded with Ca rich plants
  42. Pseudohyperparathyroidism clinical signs
    • pathological fracture
    • "rubber jaw"
    • - mandible decalcifies quickly
    • - literally can flex mandible
  43. Pseudohyperparathyroidism diagnosis
    • chemistry
    • radiographs
    • - bone looks mottled or thin, not thick (white)
  44. Pseudohyperparathyroidism treatment
    • correct underlying disease
    • - parathyroid tumor
    • - renal disease - binders
    • - drugs to help lay down bone again
    • improve the diet
    • - fat & muscle meat (table scraps) are phosphorus laden
  45. Osteomyelitis
    • see more in cats than dogs as there are more penetrating (to bone) wounds in front legs (not necessarily fractured)
    • bones lie deep in body; relatively well protected from infection
    • infection of the bone
    • secondary to contaminated wounds - eg bite wounds
    • open fractures
    • non-sterile fracture repair
    • hematogenous spread
    • - to bone through blood
    • - eg brucellosis
    • very difficult to treat
    • draining tracts that don't heal
    • keeps bone from healing
  46. Osteomyelitis clinical signs
    • lameness
    • swelling
    • drainage (fistula)
    • - probe wound w/ hematocrit - will go into bone
    • fever
    • - deep in body as immune system is working hard
  47. Osteomyelitis diagnosis
    • clinical signs
    • x-rays:
    • - can see degradation of bone
    • - culture & sensitivity to figure out exactly what's growing
    • -- if it's sensitive to clindamycin than can treat as closed wound (also no sequestrum)
  48. Sequestrum
    a piece of dead bone separated from the sound bone in necrosis.
  49. Osteomyelitis treatment
    • debridement - open surgically
    • sequestrum removal
    • bone stabilization - external
    • antibiotic therapy
    • - clindamycin (antirobe - brand) up to 8 weeks
    • -- can cause GI tract upset
    • -- best bone pentration; only one that gets into bone readily
    • - may need to lavage with antibiotics if clindamycin not effective
    • amputation
    • - may recover sooner and be more functional
  50. Osteomyelitis prognosis
    • fair
    • won't die

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