Osteoporosis

1. Osteoporosis Stephanie Wetmore, PT PED 596: Adv. Cardiac Rehab Wayne State College

2. Osteoporosis • A disease characterized by irregularities in the quantity and architectural arrangement of bone tissue that lead to decreased skeletal strength and increased vulnerability to fractures.

3. Normal Physiology • Functions • Provides support to body • Protects vital organs • Assists in movement via leverage • Hematopoiesis (blood cell production) • Storage area for Ca++

4. Cell Types • Osteoblasts • Synthesize bone • Remodeling and repair • Osteoclasts • Responsible for bone resorption • Remodeling and repair • Osteocytes • Primary cells of mature bone • Osteoblasts surrounded by matrix during bone formation • Maintenance and resorption

5. Bone Formation & Growth • Intermembranous ossification • Bone forms directly in the embryonic connective tissue • Endochondral ossification • A “scale model” of hyaline cartilage is replaced by bone • Process of formation for most bones

6. A Closer Look at Endochondral Ossification and Growth • 1. Formation of cartilage skeleton in embryo (6-12 wks gestation) • 2. Ossification and growth occur in subsequent months • 3. When ossification completed, growth in length occurs at epiphyseal plates

7. 4. Widen by multiplication of cartilage cells and cancellous bone replaces the dying cartilage • 5. Growth in width occurs by depositing of compact bone beneath the periosteum (outer surface) and enlargement of the marrow cavity by bone resorption • 6. Growth ceases when epiphyseal plate is replaced by bone.

8. Endochondral Ossification & Growth

9. Homeostasis • Balance between bone formation & resorption • Remodeling process • Old bone destroyed by osteoclasts • New bone constructed by osteoblasts • Dependent upon Ca++, P, and vitamins (esp. vit. D) • Controlled by hormones

10. Regulation of Bone Formation & Growth • Vitamin D • Increases rate of Ca++ absorption from intestine • Growth Hormone • Needed to stimulate proliferation of cartilage cells at growth plate • Vitamin C • Important in synthesis of collagen • Thyroxin • Increases rate of replacement of bone at growth plate and needed for synthesis of GH

11. Vitamin A • Stimulates resorption of bone • Estrogens & androgens • Promote ossification and maintenance of matrix • Parathyroid hormone & Calcitonin • Regulate release of Ca++ from bone

12. Parathyroid hormone & calcitonin • When blood Ca++ levels are low, PTH is released. • Release of PTH increases rate of bone resorption, which increases the concentration of Ca++ in the blood. • When blood Ca++ levels are high, calcitonin is released, which inhibits resorption.

13. Pathophysiology • Osteoporosis can be either hormonally induced or mechanically induced. • Mechanical • Electrical changes created with weight bearing stimulate activity of osteoblasts, which lead to a build up of Ca++. • This does not occur without weight bearing (when someone is on bed rest)

14. As we age normally • Birth to age 20-30 • GH influences deposition of bone, which exceeds resorption rate • Age ~50 to age 80 • Resorption exceeds deposition due to decreased osteoblast activity and changes in Ca++ metabolism

15. Rates of Bone Loss with Normal Aging • Female >30-35 • Lose .5-1% of bone mass/year • Postmenopausal Females • Lose 2-3% bone mass/year until ~age 70 • Women will lose ~45-50% in lifetime • Men will lose ~20-30% in lifetime

16. Normal Bone vs. Osteoporosis

17. Normal vs. Ostoeporosis

18. Classification System

19. Epidemiology of Primary Involutional Osteoporosis • Most common fracture sites • Wrist, vertebrae and hip

20. Caucasian Women Vertebral 15.6% Hip 17.5% Wrist 16% Overall 39.7% Caucasian Men Vertebral 5% Hip 6% Wrist 2.5% Overall 13.1% Risk of Fracture

21. Fracture Risk (cont.) • Wrist & hip fractures are most commonly the result of a combination of bone loss and moderate trauma such as a fall • Of all NH admissions, 21% are made following a hip fracture. • Vertebral compression fractures can occur simply by coughing, bending forward or hugging.

22. Risk Factors • Advancing age – 1.4 to 1.8 fold increase with each decade • Gender – women > men • Family or personal hx of fx as an adult • Repeated fx’s, severe stooped posture

23. Risk factors (cont.) • Race – Caucasian & Asian > African American or Hispanic • Bone Structure and Body Weight – small-boned and thin women (<127#) are at greater risk • Menopause/Menstrual history • Normal, premature (<45 y/o) or surgical • Late onset menarche (>15 y/o) or prolonged amenorrhea – anorexia nervosa, bulimia, excessively low body fat

24. Risk Factors (cont.) • Lifestyle/Nutrition • Cigarette smoking – inhibits estrogen • Alcoholism • Inadequate intake of Ca++ • Sedentary lifestyle • High caffeine consumption and phosphoric acid intake (cola drinks) • Eating disorders

25. Are you getting enough Calcium?

26. What is adequate Ca++ intake? • Age 1-3 years 500 mg/day • Age 4-8 years 800 mg/day • Age 9-18 years 1300 mg/day • Age 19-50 years 1000 mg/day • Age >50 years 1200 mg/day

27. Glucocorticoids Corticosteroids Excessive thyroid hormones Anticonvulsants Gonadotropin releasing hormones Methotrexate Cyclophosamide Dexamethasone Lithium Cyclosporine A Heparin or Coumadin Cholestyramine No ERT or HRT Low testosterone levels Chemotherapeutics Antacids Isoniazid Immunosuppressants Diuretics Risk Factors…Medications

28. Arthritis Glycocorticoid excess Lung disease (COPD) Organ transplants SCI Hyperthyroidism Hyperparathyroidism Chronic kidney/liver disease RA RSD Malabsorption problems Turner syndrome CVA MS Lupus IDDM Chronic inflammation Chron’s disease CA Burns Asthma Mental illness (depression) Risk Factors…Chronic Diseases

29. Bone Mineral Density Testing • Painless, non-invasive test, which identifies osteoporosis, determines fx risk and monitors response to treatment.

30. WHO Definitions • Normal • +/- 1 SD of the young adult mean • Low Bone Mass (osteopenia) • -1 to –2.5 SD of the young adult mean • Osteoporosis • >-2.5 SD of the young adult mean • Severe (established) osteoporosis • >-2.5 SD of the young adult mean & one or more osteoporotic fractures

31. DEXA Images & Reports

32. Pharmacology • Estrogen Replacement Therapy/Hormone Replacement Therapy • Reduces bone loss, increases bone density, reduces risk of fx in postmenopausal women • Increase risk of uterine and breast CA, increased risk of thromboembolism

33. Biphosphonates • Alendronate Sodium (Fosamax) • Reduces bone loss, increases bone density, reduces risk of spine and hip fractures • Side effects include bone, muscle and/or joint pain and headache • Risedronate Sodium (Actonel) • Slows bone loss, increases bone density and decreases spine and hip fractures • Also approved for men & women to prevent and/or treat steroid-induced osteoporosis

34. SERMs family • Selective estrogen receptor modulators • Raloxifene (Evista) • Prevent bone loss, increase bone mass and decrease risk of vertebrae fracture • Side effects: DVT, leg cramps, syncope, arthralgia, tendon disorder and vertigo – chest pain, myalgia and arthritis possibly (<placebo).

35. Calcitonin (Miacalcin) • Naturally occurring hormone involved in Ca++ regulation and bone metabolism • Slows bone loss, increases bone density and relieves pain associated with vertebral fractures

36. Exercise Testing Modification/Exercise Limitations/Capacity • Weight-bearing exercise and resistance training recommended with precautions

37. Weight-bearing Exercise • Brisk walking is ideal • Alternatives: hiking, stair climbing, dancing and racquet sports • Contraindicated = stair steppers, bicycling (including stationary), rowing machines, running and high-impact aerobics • Stair steppers – combination of unilateral WB and force to depress step • Bicycle – increased flexion • Rowing machines – deep forward bending (flexion)

38. Testing Contraindications • Sub maximal cycle ergometer • Step-tests

39. Resistance Training • Light weights recommended • Major muscle groups emphasized • Slow progression over several months • Fatigue after 10-15 reps • Increases do not exceed 10% per week • Proper technique • Every third day • If joint swelling, limping or pain after, decrease weight by 25-50%.

40. Resistance TrainingContraindications • Weight carrying tests • Repetitive lifting tests

41. Flexibility Exercises • Flexion exercises contraindicated if vertebral bone density decreased or risk of compression fx • Avoid knee to chest • Forward bending • Touching the toes • Partial sit-up • Okay if thoracic spine stabilized and do not lift head and chest above T-6 level.

42. Flexibility ExercisesContraindications • Sit-and-reach test • Curl-up muscular endurance test

43. Other exercise • HR, BP, ECG, ventilation frequency, tidal volume, oxygen saturation and expired oxygen and carbon dioxide should not be affected by osteoporosis medications. • Increasing kyphosis of the thoracic spine will make it more difficult to expand the lungs fully during inspiration

44. Sample Exercise Prescription • Brisk walking 15-20 minutes 3-4x/wk • Begin with 5-minute walks and increase by one minute every other session • Flexibility program – body extender, shoulder pinches, chin tucks, elbow backs, arm reaches and back arches daily • Sinaki & Mikkelsen study • Flexion programs – 86% fx rate • Extension programs – 16% fx rate • Control group – 67% fx rate • Flex/Ext programs – 57% fx rate

45. Sample Exercise (cont.) • Resistance Training • Every third day • Major muscle groups especially those integral to fall prevention • Hip extensors, flexors, adductors, abductors, quadriceps, ankle dorsiflexors & plantar flexors and trunk extensors & stabilizers • One set 10-15 reps • Increase no greater than 10% per week for amount of weight

46. Resources • National Osteoporosis Foundation • http://www.nof.org • American Academy of Orthopedic Surgeons • http://www.aaos.org • Lewis, C.B. (1990), Aging: The Healthcare Challenge (2nd ed.) • Sinaki & Mikkelsen (1988) • Katz & Sherman (1998)