Musculoskeletal Ageing

Musculoskeletal Ageing

1. Muscle

   • Sarcopenia
     • age related loss of muscle mass and strength
     • muscle atrophy with ageing is partly due to decreased physical activity
     • relative muscle mass less than 2 standard deviations below a sex-matched control group (aged 18-40)
     • presarcopenia is simply a loss in muscle mass
       • primary sarcopenia
         • age related
         • treatment
           • resistance and aerobic exercises
           • increased protein uptake
           • vitamin D supplementation
           • no pharmacological therapies
       • secondary sarcopenia
         • activity, disease and nutrition related
     • cachexia is different from sarcopenia as it is associated with underlying illnesses or inflammatory conditions
     • nutritional, hormonal, metabolic and immunologic factors all affect muscle mass
     • MSK ageing syndrome in the muscles
     • obese sarcopenia (obese patients with sarcopenia have poorer outcomes)
   • ageing leads to muscle being composed of more type 1 fibres than type 2
   • with ageing the number of active motor units decreases but each motor unit pool becomes larger
   • CT/MRI research gold standard

2. Cartilage

   • decreased water content
   • fragmentation of aggrecan and chondroitin sulfate
   • a loss or thinning of cartilage causes a reduction in the joint space and in the range of movement of the joint
     • joint instability
   • X-rays or CT scans can show a loss of joint space and MRIs can show thinning or fissuring of the cartilage

3. Bone

   • peak muscle and bone mass are reached in early adult life and afterwards there is usually a progressive decline in muscle and bone mass
     • the rates of decline are different in males and females
       • bone strength is highly correlated with its density
         • DXA scan with T-score results
   • osteoarthritis is a MSK ageing syndrome in the joints
   • osteoporosis is a MSK ageing syndrome in the bones

4. Degenerative disorders

   • characterised by progressive deterioration and loss of function in the organ/tissue
   • not purely an age-related process
   • Generic processes that come with ageing
     • decreasing amount of tissue
     • altered molecular disposition of the matrix
     • accumulation of degraded molecules
     • reduced efficiency of functional tissue
     • altered levels of trophic hormones, growth factors and cytokines or altered ability of cells to respond to these signals
     • alterations in the loading pattern of tissues or the tissues response to loading

5. Tendon

   • tendinosis
     • involves the degeneration of the tendon's collagen
       • loss of strength
       • increase in bulk

6. Ligament

   • ligaments can experience myxoid/cystic degenerative changes and thicken with hypertrophy
   • altered collagen synthesis
     • reduced elasticity

7. Weightlessness

   • consequences of prolonged space flight
     • fluid shifts
     • negative energy balance
     • skeletal and cardiac muscle atrophy
       • muscles decondition
         • hypotension due to reduced blood volume
     • bone mineral degradation
       • increase in bone resorption and decrease in bone formation
       • a lot of calcium salts are taken from bone and excreted in urine when first in space
     • radiation exposure
   • when first in space there is an initial reduction in energy intake due to space motion sickness
     • short flights
       • reduced energy intake
       • management improves
       • 14 days
     • long flights
       • significant weight loss
     • exercises required causes there to be more energy expelled than that taken in
       • also causes a negative nitrogen balance
         • protein deficient
       • but exercise is the best known method to restrict bone and muscle mass loss
         • 7-14 day mission - 15 mins of exercise per day
         • 30 day mission - 30 mins of exercise per day

8. Functions of musculoskeletal system

   • an efficient means of limb movement
   • acts as an endoskeleton for protection and support
   • serves as a reservoir of minerals for calcium homeostasis
   • provides an environment for bone marrow

9. Consequences

   • altered gait
   • altered balance
     • leads to falls and fear of falls
       • social isolation
   • chronic pain