Download Diseases of the Musculoskeletal System

Diseases of the Musculoskeletal
System
Chapter 37
Skeletal
• Skeletal trauma/fractures
– Incidence
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Young males and older adults
Tibia, clavicle, lower humerus (young persons)
Hands, feet -- workplace accidents
Upper femur, upper humerus, vertebrae, pelvis (elderly)
– Osteoporosis
– Diff types (complete/incomplete, open/closed)
• Incomplete -- bones of children
– Flexible
– Growing
• Stress w/ repeated stress (ex athletics)
– Fatigue
– Insufficiency (weight bearing bones)
- Pathophysiology
• Healing similar to soft-tissue injuries stages
– No scar tissue
• Periosteum, blood vessels disrupted
• Bleeding  clot form=n (hematoma)
• Stages
– Hematoma
– Procallus form=n
» Intense inflammatory response
» Fibroblasts, collagen, growth factors, osteoblasts impt
– Callus
» Hardened membr (woven bone)
– Remodeling
» Osteoclasts;  original shape
» Resorption unneeded callus
– Clinical
• Signs/symptoms
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Impaired function
Unnatural alignment; possible rotation, angulation
Swelling
Tenderness
Severe pain (trauma, muscle spasm)
• Stress fractures -- pain with accelerated remodeling
– Relieved by rest
– Treatment
• Realign to normal position (manipulation, traction)
• Surgery
– Prosthesis, screw, plate, etc., possible
• Splints, casts
• Metabolic bone disease (Osteoporosis)
– remodeling imbalance favors bone resorption
– Incidence
• Common disorder of bone metabolism
• Heredity evidence in women
– Fracture due to bone weakness
• Common -- vertebrae, distal radius, proximal femur
• Fractures after trauma
• Compression fractures (esp vertebral)
– Non-symptomatic until indicated by fracture
– Pathophysiology
• Age 
– Bone resorption exceeding bone growth
–  Net bone mass loss
– More rapid in women
» Exaggerated at menopause
» Type I (Postmenopausal)
– Type II C both sexes over age 70
» Neck, hip, humerus, tibia
• May involve postaglandins, interleukins, various growth
factors that affect osteoclasts
• Estrogen decr w/ menopause  incr=d risk
– Estrogen inhibits bone resorption
– Also in young, female athletes
» Training  decr=d estrogen
» Found decr=d bone mass, incr’d fractures
– Clinical
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Pain
Bone deformity
Fractures
Vertebral collapse  hunchback, decr=d height
– Treatment C slow rate of Ca, bone loss
• Incr dietary Ca
• Vit D  incr intestinal abs=n Ca
• Regular, moderate exercise
• Hormone treatment (estrogen, progesterone)
• Reduce risk of falls
• Bone tumors
– Common secondary tumor site
• Primary often prostate, breast, thyroid, lung,
kidney
• Access through blood
• Often axial skeleton (not skull), proximal femur,
humerus
• May induce bone breakdown or bone growth
– Primary tumors less common
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Actively growing bone
Pain early indication
May  bone weakening
Pressure  adjacent bone deformed by abnormal
remodeling
• Metastasis often to lung
• Most more in males than females
– About 1/3 primary tumors benign
• Ex: osteoma of skull and osteoid osteoma of long bone
• Ex: chondroblastoma
– Arises in cartilage of epiphyses of arm, leg bones
– Rare
– Malignant bone tumors
• Osteogenic sarcoma (=osteosarcoma) most common
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Usually age 10-20 years
Knee often
Common metastasis  lung
Previous metastasis by time of diagnosis  poor prognosis
Now better chemotherapy (80% 5 yr recovery rate)
Surgery often
• Chondrosarcoma
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Usually age 30-50 yrs
Slow-growing
May break through bone surface
Interior of pelvis, ribs, prox femur, humerus
Surgical excision
Diseases of the Joints
• Osteoarthritis = Degenerative Joint Disease
– Incidence
• Most common joint disease in US
• Incr=s w/ age
– Age 60 -- most affected
– > 75 yrs -- 85% affected
– Pathophysiology
• Articular cartilage becomes thin, irregular, frayed
– Probably enz breakdown of cartilage
•  Cracks, fissures in articular cartilage
– Fill w/ synovial fluid
– Pathophys (cont’d)
• Penetrates to underlying bone w/ progression
– May  fluid-filled cysts
– Bone forms around cysts
– May  microfractures
• Fibrocartilage plugs form for repair
– Activyt  plugs stripped away, then reformed, then restripped
–  Smooth bone surface
• Fibrocartilage fragments may react at synovial membr
surface
–  inflamm response C> repair
–  decr=d movement
• Cells in synovial membr may dev into osteoblasts
–  form=n bone spurs at joint
–  pain, decr=d movement
– Degeneration
• Mostly at larger weight-bearing joints (also fingers)
• Related to
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Wear-and-tear OR
Biochem defect in joint cartilage OR
Excessive loading (malformed joint, postural defect, obesity) OR
Genetic
– Clinical
• Joint aches, stiffness
– Incr w/ activity; diminish w/ rest
• Progression w/ age
• Loss of mobility if hip, knee affected
– Therapy limited
• Analgesics for pain
• Reduce obvious stresses
• Surgical removal of bone spurs or artificial joint replacement
• Rheumatoid arthritis C systemic disease
involving joints
– Incidence
• About 1% adult pop=n affected
• 3 female: 1 male
• Age of onset usually 20-30 (but also infancy  90's)
• May be due to
– Infection
– Autoimmune disorder
– Genetic predisposition
– Get immune-mediated destruction of joints
• Environmental stimulus  immune response to Ag
• If predisposed, Ab=s transform to Arheumatoid factors@
(Rfs)
• Rfs complex in blood, synovial fluid  inflamm
response at joint
• Inflamm mediators breakdown joint tissue  joint
tissue destroyed
– Get pattern of chronic inflamm=n
• Incr=d number of cells in synovium
•  Thickening of synovium (maybe after cartilage
destroyed by inflamm=n process)
• Thickened synovium covers adjacent joint surfaces
– Over time may enlarge, fill joint space
– In late stage = ankylosis = fused joint
• Causes swelling; stiffness; pain
• Swelling also due to incr=d exudate in synovial membr
– Joint deformities
•  Loss of joint motion
•  Muscular atrophy
– Sytemic effects variable
• Generalized weakness, malaise
• Rheumatoid nodules form
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Focal subcu swelling
Elbow, heel, dorsal surface of head; also internal
Made of macrophages, lymphocytes, collagen, cell debris
Typically painless
• Rheumatoid vasculitis common
– Systemic inflamm=n of blood vessels
– May involve pericardium, pleural effusion
– Therapy C no cure; can’t reverse destruction of
structures
• Relieve pain, reduce swelling (antiinflammatories)
• Reduce stress
• Strengthen assoc=d muscles
• Replace severely effected joints
Diseases of Skeletal Muscle
• Disuse atrophy
– Pathologic reduction in size of muscle fibers
• Follows prolonged bed rest, trauma, nerve damage
– Muscle strength decr=s from baseline
• About 3% per day
– To prevent
• Frequent isometric muscle contractions
• Passive lengthening exercise
– If no reuse in 1 year, regen=n muscle fibers
impaired
• Fibromyalgia
– Chronic musculoskel syndrome
– Get diffuse chronic pain, tenderness w/ no
inflamm=n, fatigue
• Tenderness @ 9 common points in body (neck,
shoulders, hips, knees)
• Profound fatigue
• May  depression
• Also migraine, irritable bowel disease common
– Incidence
• Mostly women
• Peak age = 30-50 yrs
• Increases w/ age
– Probably several causes
• virus,
• Phys/emotional trauma, emotional trauma,
• medication
– Found metab alterations in muscle
• May  pain, fatigue
– Also found diff blood flow to thalamus
• May C> chronic stress response
– Treatment
• Antiinflammatories (not very effective)
• CNS active agents somewhat helpful
• Muscle Strains
– Gen’l term for muscle damage
– Seen after traumatic, sports injuries
• Sudden, forced motion
• Muscle becomes stretched beyond normal length
• May include wounds
– Often involves tendon also
– May include hemorrhage, inflamm=n
– Muscle cells usually regenerate in up to 6 weeks
– Treatment
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Ice relieves swelling
Analgesics
Alternating heat/cold if more severe form
Surgery, immobilization if tearing, bleeding
Musculoskeletal Disorders
• May accompany fractures, dislocations
• Ligament = fibrous connective tissue band
joining bones @ joint
– Needed to support bones, joints
• Strain = tear in tendon
– May be due to major trauma
– Also spontaneous w/ corticosteroid admin,
rheumatoid arthritis, lupus
– Common sites
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Tendons of hands, feet
Knee
Upper arm - w/ lifting excess wt
Thigh
Ankle
Heel - w/ forced flexion
• Sprain = tear in ligament
– Common sites
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Wrist
Ankle
Elbow
Knee
– Avulsion = total sep=n tendon/ligament from bone
• Due to abnormal stress
• Young athletes (sprinters, hurdlers, runners)
– Pathophysiology
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Tearing  inflamm response
Exudate forms @ torn ends
Macrophages, fibroblasts
Repair
– Collagen form=n random, then organized
– Vascular fibrous tissue fuses new, old tissues
– Healing tendon separates from surrounding soft tissue
– Can=t support strong pull for 4-5 weeks
• Clinical
– Pain C sharp, localized
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Soft-tissue swelling
Joint swelling
Flexion deformities
If in extremities, motion affected
• Treatment
– Suture tendon/ligament
– Tendon/ligament grafting