Diseases of the Musculoskeletal System Chapter 37 Skeletal

Diseases of the Musculoskeletal System Chapter 37

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)

- 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 – – – 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 • • 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 • • 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 – – – 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

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 – – 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 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 – – 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, • 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 • • 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 • • • 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

– 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

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