Aging and MSK Flashcards
What causes an accelerated loss of bone density with age?
low reproductive hormones
poor calcium and or vitamin D status,
inactivity, endocrine or GI pathologies
What often accompanies loss of bone mineral?
Changes in trabecular architechure –> makes bone less strong
What is sarcopenia?
Loss of muscle mass due to loss of muscle fibres and reduced muscle cross-sectional area
Describe the changes in muscle with age.
sarcopenia
loss of muscle contractility
loss of neuronal innervation
Describe the changes in terms of percentages for body weight composition from adult to over 75.
adult: 30% of body weight is muscle and 20% adipose
age 75: 15% muscle, 40% adipose
Name 3 clinical consequences of ageing.
osteoporosis
fractures
osteoarthritis
What is osteoporosis?
A disease in which there is a reduction in bone mass in the presence of normal mineralisation
- low bone mass per unit volume
- deterioration of micro-architechture
- increased bone fragility
- increased susceptilbity to low trauma fractures
How would you define osteoporosis clinically?
osteoporosis is a bone mineral density of more than 2.5SD below the mean (in young adults of the same sex)
How would you define osteopenia clinically?
1-2.5 SD below mean bone mineral density (mean is in young adults)
How would you diagnose osteoporosis?
Dual Energy Xray Absorptiometry (DEXA scan)
- assesses bone mineral density (BMD)
- X rays at 2 different energies
- aimed at femur and L-spine
What does the T score from a BMD report indicate?
T score - number of SD below mean for sex and race matched healthy young adult pop (25-35y)
What does the Z score of a BMD report indicate?
The number of SD below the mean for age, sex and race compared with their peirs
Give some risk factors for osteoporosis
Age, low bone mass, Caucasian/asian, previous fragility fracture, positive family history, low BMI, early menopause
Discuss the pathophysiology of osteoporosis.
osteoporosis caused by a loss of coupling in the bone remodelling process
- due to increased bone resorption, decreased bone formation or both
- loss of coupling –> net loss of bone volume
Which type of bone is most affected in osteoporosis?
trabecular bone due to its greater metabolic activity
What is type 1 osteoporosis?
post menopausal
loss of oestrogen - accelerated loss (2-3%) over 6-10 years
What is type 2 osteoporosis?
senile
age related, hyperparathyroidism, Ca2+ deficiency
What drugs are used to treat osteoporosis and what is their effect on bone?
Bisphosphonates - anti-resorptive agents which effect osteoclasts (bone resorption) effect on bone: - decrease bone turnover - increase bone mineralisation - minimal effect on bone volume
How do bisphosphonates work?
Inhibit osteoclastic bone resorption by reducing osteoclastic activity and promoting osteoclast apoptosis
bisphosphanates inhibit mevalonate pathway
osteoclasts lose their ruffled border –> inactivated
Give an example of a bisphosphanate.
Risedronate
How many hip fractures in the UK per year?
75,000
Describe the blood supply to the hip joint
medial and lateral circumflex arteries and the artery to the head of the femur
circumflex arteries are branches of the profunda femoris artery –> anastamose at the base of the femoralneck to form a ring
Medial circumflex artery is responsible for majority of arterial supply
What can happen in an intracapsular fracture of the hip joint?
damage to the medial circumflex femoral artery found around neck of femur –> avascular necrosis of the femoral head
What are the main types of femoral neck fractures?
Intracapsular and extracapsular
What type of femoral neck fractures are grouped under intracapsular fractures?
supcapital
basicervical
transcervical
What type of femoral neck fractures are grouped under extracapsular fractures?
intertrochanteric
subtrochanteric
What is the treatment for intracapsular neck of femur fracture?
operative - hemiarthroplasty (unipolar, bipolar, cemented, uncemented)
total hip arthroplasty
internal fixation
non-operative - those who are too ill to undergo anaesthesia and people who were unable to walk before
What is a hemiarthroplasty?
only the articular surface of the femoral head is replaced
unipolar hemiarthroplasty - replacement of femoral head and neck
bipolar - replacement of femoral neck, head and addition of an acetabular cup
What is the treatment for an extracapsular neck of femur fracture?
dynamic hip screw
intramedullary hip screw
What are possible consequences of hip fractures?
high mortality rate (up to 30% at 1 year)
high morbitity rate - PE, DVT, MI, pressure sores, chest infections, UTIs, reduced mobility, confusion
What is osteoarthritis?
a disorder of the synovial joints that is characterised by:
- focal areas of damage to the articular cartilage
- remodelling of underlying bone and formation of osteophytes - new bone at joint margins
- mild synovitis
Who gets osteoarthritis?
eventually everyone
80% of over 80 year olds
What is the common type of pain associated with OA?
hip OA pain
knee OA pain
joints of cervical spine (cervical spondylosis)
What are the clinical features of osteoarthritis?
pain, stiffness, deformity, joint swelling
Discuss the pathogenesis of OA.
earliest changes - fragmentation and fibrillation of normally smooth surface of articular cartilage (these changes v. common with ageing and may not progress to symptomatic OA)
with disease progression - increasing loss of articular cartilage accompanied by abortive attempts at regen.
later changes: reactive proliferation at the subchondral bone plate
articular surfaces become deformed
What are some radiological features of OA?
decreased joint space (bone articulating against bone = eburnation)
sclerosis - hardening of tissue
osteophytes - bone spurs; most specific sign of OA but is only seen in advanced disease
bone cysts
What is the non-operative treatment for osteoarthritis?
weight loss, exercise, physiotherapy, analgesia/NSAIDs, joint injection
What are the possible operative treatments for osteoarthritis?
- arthroscopy - key hole surgery
- osteotomies - bone is cut to shorten, lengthen or change its alignments
- arthrodesis - artificial induction of joint ossification between 2 bones - done to relieve intractable pain.e.g. using a bone graft
- arthroplasty - articular surface of joint is replaced
What is the point in replacing a hip?
in the past: relief of pain, improve function, return to life, better ROM
in the future: relief of pain, back to work, improve function, better ROM
What are the components of a total hip replacement?
acetabular component
femoral head
femoral stem
what is the most common type of total hip replacement implant?
metal on polyethylene
What are local complications of hip and knee replacements?
leg length inequality dislocation infection loosening neurovascular damage - sciatic/femoral
What are some systemic complications of hip and knee replacement?
UTIs/chest infection
DVT
PE
death
From what age does bone mineral start to decline?
from age 30 rate of loss is 0.5-1% per year
