Diseases of the Musculoskeletal System

1. Diseases of the Musculoskeletal System Chapter 37

6. Skeletal • Skeletal trauma/fractures • Incidence • 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)

7. - 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

9. Clinical • Signs/symptoms • 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

10. 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

11. 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

13. Clinical • 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

14. 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

15. Primary tumors less common • 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

16. Malignant bone tumors • Osteogenic sarcoma (=osteosarcoma) most common • 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 • Usually age 30-50 yrs • Slow-growing • May break through bone surface • Interior of pelvis, ribs, prox femur, humerus • Surgical excision

18. 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

20. 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

21. Degeneration • Mostly at larger weight-bearing joints (also fingers) • Related to • 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

22. 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

23. 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

24. 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

26. Sytemic effects variable • Generalized weakness, malaise • Rheumatoid nodules form • 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

27. 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

28. 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

29. 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

30. 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 • Ice relieves swelling • Analgesics • Alternating heat/cold if more severe form • Surgery, immobilization if tearing, bleeding

31. 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

32. Common sites • Tendons of hands, feet • Knee • Upper arm - w/ lifting excess wt • Thigh • Ankle • Heel - w/ forced flexion • Sprain = tear in ligament • Common sites • Wrist • Ankle • Elbow • Knee

33. Avulsion = total sep=n tendon/ligament from bone • Due to abnormal stress • Young athletes (sprinters, hurdlers, runners) • Pathophysiology • 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

34. Clinical • Pain C sharp, localized • Soft-tissue swelling • Joint swelling • Flexion deformities • If in extremities, motion affected • Treatment • Suture tendon/ligament • Tendon/ligament grafting