Osteoporosis and Musculoskeletal Health

Ageing and Musculoskeletal Health

• An 80-year-old woman tripped and broke her right hip.
• She had been living alone and watching TV.
• She had a prior history of a hip fracture 20 years prior.
• She had fallen at home 6 months prior to the current injury.

Osteoporosis

• Osteoporosis is a significant cause of morbidity and mortality.
• Bone is constantly remodeling, with bone being reabsorbed by osteoclasts and new bone being deposited by osteoblasts.
• An imbalance between bone resorption and bone formation leads to osteoporosis.
• Inadequate peak bone mass (20-30 years) is a risk factor.
• Estrogen suppresses osteoclast bone resorption. Lack of estrogen increases bone resorption and decreases bone formation.
• DXA scan (dual energy x-ray absorptiometry) measures bone mineral density, lean body mass, and fat mass.
  • The diagnosis of osteoporosis is made when bone mineral density is 2.5 SD below the comparison group (20-year-old sex-matched healthy adult).

Vitamin D and Bone Health

• Factors that may affect Vitamin D in this age group include:
  • Decreased intake
  • Reduced time outside or institutionalization
  • Reduced intestinal absorption
• Vitamin D precursor 25-hydroxyvitamin D is measured to assess dietary vitamin D sufficiency.

Who is at risk? - Non-Modifiable Factors

• Advanced age
• Female
• European and Asian ancestry
• Family history of fracture
• Previous fracture (≥2x)
• Rheumatoid arthritis
• Gastrointestinal disorders (Crohn's, Celiac, gastrectomy, severe liver disease)

Who is at Risk? - Modifiable Factors

• Tobacco smoking inhibits osteoblast activity.
• Low Body Mass Index (BMI)
• Alcoholism inhibits calcium absorption, and liver disease interferes with vitamin D activation.
• Soft drinks contain phosphoric acid, displacing calcium from the diet.
• Insufficient activity impacts bone health. Weight-bearing exercises increase bone mass. Physical fitness reduces the risk of falls. Excessive exercise can cause structural bone exhaustion.
• Serum 25-OH Vitamin D < 20 ng/mL
• Calcium intake

Osteoporosis - Treatment

• Bisphosphonates are commonly prescribed for osteoporosis.
• They preferentially bind calcium, forming strong bonds with bone mineral.
• They prevent bone resorption and increase bone formation for about a year.
• Side effects can include GI reflux (Gastroesophageal Reflux Disease)

Sarcopenia

• Age-related loss of skeletal muscle mass and strength.
• Appendicular muscle mass is 2 standard deviations below the mean for young healthy adults (measured via DXA scan).
• Sarcopenia is highly predictive of incident disability and all-cause mortality.
• Causes are poorly understood. Potential causes include denervation of motor units, net conversion of fast-type II muscle fibers into slow-type I fibers (loss in muscle power), and lack of physical activity.

Sarcopenia - Prevention

• Resistance training is an effective measure against this.
• Positive influence on the neuromuscular system, hormone concentrations, and protein synthesis rates.
• Studies show an increase in protein synthesis rates after just 2 weeks of resistance training in adults (76-92 years old).

Obesity in Older Adults (Sarcopenic Obesity)

• Prevalence of older adults experiencing sarcopenia and obesity.
• Variables that may be involved include: decreasing resting metabolic rate (RMR) and decreasing physical activity as well as potentially an increase in inflammatory cytokines and an accelerated loss of muscle mass.
• High muscle mass, but poor quality muscle. This can impact the risk of frailty and loss of independence.

Sarcopenic Obesity - Treatments

• Weight loss may exacerbate age-related declines in fat-free mass (FFM).
• Diet-induced weight loss may result in 75% fat mass and 25% FFM.
• Exercise may improve physical functioning but may not result in substantial weight loss.
• The optimal treatment for sarcopenic obesity is controversial.

This quiz covers key concepts of osteoporosis and its impact on musculoskeletal health, particularly in the elderly. It includes information on bone remodeling, risk factors, and diagnosis of osteoporosis through DXA scans. Test your knowledge on how age affects bone health and fracture risks.