HSE320 Exercise, Osteoporosis and Ageing Week 9 Lectures PDF

6/17/2019 HSE320 Exercise, Health and Disease Exercise, Osteoporosis and Ageing Part A: Understanding Osteoporosis, How it is Diagnosed and the Key Risk Factors...

6/17/2019 HSE320 Exercise, Health and Disease Exercise, Osteoporosis and Ageing Part A: Understanding Osteoporosis, How it is Diagnosed and the Key Risk Factors Learning Objectives On completion of this presentation, you should be able to:  Define osteoporosis and describe its consequences.  Understand how osteoporosis is diagnosed.  Identify risk factors for osteoporosis and fractures, and why fracture risk differs between men and women.  Become familiar with the different methods available to define fracture risk.  Briefly summarize treatment options for osteoporosis and fractures. What is Osteoporosis? Osteoporosis is a disease characterised by low bone mass and micro-architectural deterioration of bone tissue leading to compromised bone strength predisposing a person to an increased risk of fracture. Normal Bone Osteopenia is the term used to describe low bone density. It is not a disease. It merely indicates a state of relatively low bone density, that is, your bone density is low when compared to the standard. Osteoporotic Bone 1  6/17/2019 Osteoporosis: Facts and Figures Current Prevalence  4.74 million Australians over 50 years of age 4.74 million (66%) have osteoporosis or osteopenia; 22% of Poor bone health these have osteoporosis and 78% osteopenia. Future Projections  By 2022, it is estimated there will be 6.2 million Australians over the age of 50 with osteoporosis or osteopenia.  That is a 31% increase from 2012. A ‘Silent’ Disease  As many as 4 out of 5 people with osteoporosis don't know that they have it even though they are at risk of fracturing a bone. Source: Osteoporosis Costing All Australians, 2012 - 2022 A new burden of disease analysis. The Real Enemy is a Fracture! Only 56% of all women with a fracture had osteoporosis Percentage of women with and without osteoporosis (BMD T-score ≤ 2.5 at the spine and/or femoral neck) in the fracture group Sanders K et al. Bone 2006 May; 38(5):694‒700. Osteoporotic Fractures  In 2012, 140,822 fractures occurred in Australia as a result of osteoporosis and osteopenia. In 2013 3.4 min One fracture every 3.4 minutes (395 per day) By 2022 2.9 One fracture every 2.9 minutes (501 per day) min  Globally, 1 in 3 women and 1 in 5 men aged over age 50 will experience osteoporotic fractures.  By 2022, it is expected that there will be a 30% increase in the annual number of fractures if no further action is taken to improve diagnosis and management of osteoporosis. Source: Osteoporosis Costing All Australians, 2012 ‐ 2022 A new burden of disease analysis. 2  6/17/2019 David Parkin Vertebral Crush Former AFL player and four-time premiership Fracture coach now living with osteoporosis “ I was running down the stairs when I fractured my vertebrae” Age-specific Fracture Incidence Of all osteoporotic fractures in Australia, 46% are vertebral, 16% are hip and 16% are wrist Adapted from Sambrook et al. Lancet 2006; 367:2010‒8. The Fracture Cascade  The risk of future fractures rises with 15 RR = 7.3 Incidence of new vertebral fx (%) each new fracture RR = 5.1 10 – This is known as the 'cascade effect’ RR = 2.6 5  Following a low trauma fracture, there is a 2‒4 fold increase in the risk 0 of a subsequent fracture 0 1 1 2 No. of vertebral fractures at baseline  Women who suffer a spinal fracture are >4 times more likely to have another fracture within the next year, compared to women who have never had an osteoporotic fracture Cooper et al. J Bone Miner Res 1999; 7:221‒7; Centre et al. JAMA 2007; 297(4):387‒94; Klotzbuecher et al. J Bone Miner Res 2000;15:721 Figure adapted from Lindsay R et al. JAMA 2001; 285:320‒3. 3  6/17/2019 Hip Fractures are Associated with Morbidity One‐year Hip Fracture Mortality and Morbidity Unable to carry out at least one independent ADL Difficult with at least one 80% essential ADL Patients (%) Unable to walk 60% independently Permanent disability 40% Death 30% 24% Data fro Lu‐yao et al Am J Pub Health. 1994; 84:1287–1291 and Cooper C, Am J Med, 1997;103(2A):12S‐17S. Pathogenesis of Osteoporotic Fractures Most Fractures Result from a Fall 95% of hip fractures in people aged over 65 years are the result of a fall Low peak Postmenopausal Age-related bone mass bone loss bone loss Sarcopenia Low bone Other risk factors (loss in muscle mass, strength and/or function strength Non-skeletal Poor bone quality (propensity to fall) Fracture = (architecture) Fall + Low BMD Sideways fall: 3‐5 fold  risk hip fx A 1‐SD reduction in BMD  the Fall on trochanter: 30‐fold  risk hip fx risk of fracture 2‐3 fold Gain and Loss of Bone 1250 Men Ageing 1% / yr 1. Maximise Peak Bone Mass Achieved around the age of 20‒30 1000 years. A 10% increase in PBM may delay the development of Bone mass (g) Women osteoporosis by 13 years 750 2. Prevent or Slow Bone Loss 500 A 1 SD reduction in BMD increases Menopausal the risk of hip fracture 2‒3 fold bone loss 250 3‒4%/yr 3. Prevent Falls Less than 5% of falls result in a 0 fracture, but >90% of hip fractures Birth 18‐30 years Old age result from a fall A 10% loss in bone mass in the spine can double the risk of vertebral fracture A 10% loss in the hip can result in a 2.5 greater risk of hip fracture Klotzbuecher CM et al. Bone Miner Res 2000; 15:721. 4  6/17/2019 Bone is a Dynamic Tissue Normal Bone Remodeling Cycle Bone remodeling is the replacement of old tissue by new bone tissue Activation – Resorption – Formation (ARF) Sequence Resting bone surface Resorption Bone formation Mineralisation 3 weeks 3‒9 months By Cancer Research UK (Original email from CRUK) [CC-BY-SA-4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons The entire human adult skeleton is completely replaced about every 7‒10 years Cortical Bone Loss Around 80% of all fractures are non-vertebral and occur at regions assembled using large amounts of cortical bone. Absolute amount of bone resorbed (lost) on the inner bone surface, and formed on the outer bone surface is more in men than in women. Adapted from Seeman. Osteoporosis Int 2003; 14 (Suppl 3):S2‒8. Aged-related Loss – Trabecular Bone Men Males vs Females Osteoporotic Bone Thinning Women www.ectsoc.org/c040907/arnett.pdf Perforation 5  6/17/2019 Why Do More Women Fracture? 1. Women have a lower peak bone mass and smaller bones compared to men. 2. Women experience greater cortical bone thinning which is related to less periosteal apposition. 3. Women experience an additional accelerated bone loss due to the reduction in oestrogen associated with menopause. 4. Women tend to live longer. Dual Energy X-ray Absorptiometry Current ‘Gold’ Standard for Assessing Osteoporosis Interpreting a DXA BMD Report BMD Z-score: A useful indicator of possible secondary osteoporosis. A Z-score of -2.0 or below should trigger investigations for underlying disease to exclude other causes of bone loss. 6  6/17/2019 Diagnosis of Osteoporosis A DXA bone density test will give you a T-score Compares an individual’s BMD with the mean value for young normal individuals and expresses the difference as a standard deviation (SD) score.  Normal BMD (T‐score ‒1.0 or above) BMD not more than 1.0 SD below young adult mean  Osteopenia (T‐score ‒1.0 to ‒2.5) BMD between 1.0 & 2.5 SDs below young adult mean  Osteoporosis (T‐score ‒2.5 below) BMD 2.5 or more SDs below young adult mean A DXA bone density test will also give you a Z-score Compares an individual’s BMD to the expected BMD for their age and sex. Age and Clinical Risk Factors Fracture Probability Fracture Probability Age and BMD specific Increases with Risk Factors 80 Age of Women 10‐year Hip Fracture Probability (%) 20 + Family history 10‐year Fracture Probability (%) 80 years (hip, spine, humerus, forearm) Osteoporosis 70 years 60 Threshold 60 years 15 50 years + Glucocorticoids 40 10 Prior Fracture 20 No Clinical Factors 5 Age 65 years; BMI 24 kg/m2 0 0 ‐3.0 ‐2.5 ‐2.0 ‐1.0 0.0 1.0 0.0 ‐1.0 ‐2.0 ‐3.0 BMD T‐score BMD T‐score BMD is a strong predictor of fracture. The probability of a fracture by BMD varies by age and the number of clinical risk factors Kanis JA et al. Osteoporos Int 2001; 12:989‒95. Non-modifiable Risk Factors  Genetics – Family history of osteoporosis or minimal trauma fracture  Increasing age  Previous spinal or minimal trauma fracture (back pain)  Height loss (3 cm or more) or kyphosis  Hormonal and metabolic factors – Early menopause – Low testosterone (men) – Hypogonadism – Anorexia nervosa – Low BMI – Hyperthyroidism 7  6/17/2019 Modifiable Risk Factors  Lifestyle factors – Inadequate dietary calcium intake – Vitamin D deficiency – Physical inactivity / sedentary lifestyle – Smoking – Excessive alcohol and caffeine?  Increased risk of falls – Poor lower limb muscle strength and balance – Poor eyesight – Use of sedatives / psychotropics – Cognitive impairment | depression – Polypharmacy Modifiable Risk Factors Medications associated with increased fracture risk  Corticosteroids  Aromatase inhibitors  GnRH agonists  Proton pump inhibitors  Loop diuretics  Anticonvulsants  Antiepileptics  Heparin and warfarin  Antidepressants (SSRIs)  Thyroxine Eastell R et al. Nat Rev Dis Primers 2016 Sep 29; 2:16069. Risk Factors for Osteoporosis Secondary Causes Endocrine Other  Hypogonadism  Rheumatoid arthritis  Hyperthyroidism  Hypercalciuria  Anorexia nervosa  COPD  Type 2 diabetes  Organ transplantation  Cushing syndrome  Immobilisation  Vitamin D deficiency  Stroke Nutritional  Parkinson’s disease  Malabsorption syndrome  Multiple myeloma  Vitamin D deficiency  Leukaemia  Calcium deficiency  Chronic renal insufficiency  Alcoholism  HIV  Inflammatory bowel diseases  Congestive cardiac failure 8  6/17/2019 Risk Assessment for Osteoporosis Medical and Health History Musculoskeletal Lifestyle Factors Document any previous fracture(s); Assess diet, in particular daily record the site and when and how total energy, protein, calcium it occurred. and vitamin D intake. Ask about family history of Assess alcohol intake. osteoporosis and fractures. Ask about current levels of Determine if the person is losing physical activity and immobility height (esp. if height loss ≥3cm). Assess smoking status Ask the patient whether they have Assess menstrual history in back pain, especially sudden, women, including history of severe back pain. ovarectomy Ask about whether they have had a recent fall and document risk factors for falls. Self Assessment Quiz  Question Describe the difference between osteopenia and osteoporosis (and T‐scores and Z‐scores).  True or False? DXA BMD is currently the main method used to diagnose osteoporosis.  Question Describe why the prevalence of osteoporosis differs between men and women?  True or False? Most current pharmacological agents for treating osteoporosis are designed to be anabolic (eg., build additional bone)?  Question List five questions you might ask an individual that has come to you concerned about osteoporosis or osteoporotic fractures?  True or False? Prolonged use of corticosteroids is not a risk factor for osteoporosis. 9  6/17/2019 HSE320 Exercise, Health and Disease Exercise, Osteoporosis and Ageing Part B: Exercise for the prevention and management of osteoporosis Learning Objectives On completion of this presentation, you should be able to:  Understand the theory of how bones adapt to loading (exercise).  Identify the key loading characteristics important for optimising bone health.  Summarise the type and dose of exercise that is needed to enhance bone health at different stages of the lifespan.  Identify which exercises / activities might be contraindicated for people at risk of osteoporosis and fractures. Wolff’s Law Bone will adapt its structure to meet the functional demands placed upon it, and will therefore alter its mass and morphology so that it can withstand the extremes of functional loading. Robling et al. Ann Rev Biomed Eng 8(1):455‐98, 2006 10  6/17/2019 Bones Adapt To Stress Throwing arms of baseball players had about 50% greater mass, size (cross‐sectional area), and thickness. Warden et al. PNAS 111:5337‐5342, 2014 Osteocytes are fabulous gossipers… if you arouse them! Osteocytes: Strain Sensitive Cells Osteoblast (OB)  (bone forming cells) Osteoclasts (OCL) (bone resorbing cells) Osteocytes (Strain sensitive cells) 11  6/17/2019 Frost’s Mechanostat Theory Functional Model of Bone Adaptation Adapted from Schoenau and Fricke. Eur J Endocrinol 159: S27‐31, 2008 Key Loading Characteristics Magnitude (intensity) of loading  Dynamic impact loads (e.g., jumping, skipping etc.) are more osteogenic than low impact or static activities. Rate (speed) of loading  Rapid movements are more stimulating (bone building) than slow movements. Distribution (direction) of loading  Novel or diverse loading patterns are more stimulating than repetitive loads (eg. running). Frequency & number loads  Relatively few loading cycles (repetitions) are needed to elicit bone formation. Amount of rest  Short exercise bouts with rest periods are more effective than continuous loading. Preventing Osteoporosis and Fractures Fracture risk reduction can be largely divided into three domains 1. Maximise Peak Bone Mass It is estimated that a 10% increase in peak bone mass may delay the development of osteoporosis by 13 yrs. 2. Prevent or Slow Bone Loss A 1 SD reduction in BMD increases the risk of hip fracture 2‐3 fold. Up to 50 to 75% of all fractures occur in individuals without osteoporosis. 3. Prevent Falls Less than 5% of falls result in a fracture, but >90% of hip fractures result from a fall. Adapted from Bone Appetit (IOF), 2006 12  6/17/2019 Habitual Physical Activity and Bone Accrual Six‐Year Longitudinal Study in Children/Adolescents Total Body ** Lumbar Spine Femoral Neck * ** ** ** * Peak BMC Accrual (g/yr) Girls Boys Girls Boys Girls Boys Inactive Average Active *P