Week 218 - Fractured Hip Flashcards
Loss of which line on an x-ray might indicated a fractured neck of femur?
Shenton’s line
What contours does Shenton’s line trace?
The inferior border of the superior pelvic ramus and the medial border of the proximal femur
What is the term used for the surgical procedure used to replace an individual’s femoral head without replacing the acetabulum?
A hemiarthroplasty
What two surgical procedures are preferred in extracapsular NOF fractures
Dynamic Hip Screw
Cannulated Screw - provides more rotational stability
What two surgical procedures are generally preferred in intracapsular NOF fractures and why?
Hemiarthroplasty
Total Hip Replacement
As intracapsular NOF fractures carry greater risk of disruption to the blood supply to the femoral head and neck carrying a risk of AVN - may risk in young
How do you classify a NOF fracture as intra or extracapsular?
By the intertrochanteric line which runs between the greater and lesser trochanter - including or distal to this line is considered extracaspular
From which arteries does main blood supply to the hip joint come?
The lateral and medial femoral circumflex arteries
List 3 lifestyle factors that help improve bone health
Exercise (weight-bearing); healthy diet particularly with high calcium and Vit D; exposure to sun - Vit D
List 2 major lifestyle factors which reduce bone health and remodelling capabilities
Smoking
Alcohol
What two hormones have a protective effect on bone
Oestrogen (largely) and testosterone
Explain briefly the role of PTH on calcium in the body
PTH (parathyroid hormone) encourages calcium resorption and so increased blood plasma calcium levels and can, in large quantities, reduce bone strength
Describe the key steps in the Vitamin D production pathway.
UV light contacts skin converting cholesterol into Vit D3 > Liver hydroxylates Vit D3 to 25-hydroxyvitamin D(Calcidiol) > Kidneys further hydroxylate Calcidiol to 1, 25 dihydroxyvitamin D (Calcitriol - most potent form of Vit D!)
What affect does PTH have on serum calcium levels in the body and how?
PTH (parathyroid hormone) increases serum calcium in the body by 2 direct actions and 2 indirect actions. Direct - 1) increases osteoclastic activity in the bones 2) increases renal resorption of calcium
Indirect - 1) GI resorption of calcium 2) increases 1, 25 dihydroxy Vit D
What are the 4 main predisposing factors to osteoporosis?
Age; Female gender; Genetics (FHx); Oestrogen deficiency
name 5 further risk factors for osteoporosis (there are MANY)
Alcohol; smoking; poor diet (eating disorders); inactivity and low BMI
What effect does Vit have on calcium in the body?
Vit D helps calcium to be absorbed from the small intestine
Which hormone acts in opposition to PTH and what does it do?
Calcitonin - it increases bone calcium levels “tones the bone” by increasing osteoblastic activity and reducing osteoclastic activity
What is Trousseu’s sign?
Flexion of wrist and thumb with extension of fingers. it is an indication of hypocalaemia along with tremor/spasm due to increased nerve and muscle cell excitability but with reduced neurotransmitter release at synapses
Name some drugs/treatments which are risk factors for osteoporosis
Glucocorticoids (corticosteroids); Lithium; Chemotherapy; SSRIs; anticonvulsants; GnRH agonists; Methotrexate; Prolonged heparin use; Aromatase inhibitors
What does an Aromatase inhibitor do and what is it used in the treatment of predominantly?
Breast and ovarian cancer - reduces the production of oestrogen
What is a DEXA scan used for and what does it stand for?
Measures bone mineral density (g/cm2)
On a DEXA scan a ‘T’ score of between -1 SD (standard deviation) and -2.5 from the healthy ‘normal’ suggests a diagnosis of what in an individual?
Osteopenia
For a patient to be considered osteoporotic by their DEXA result what should the result show?
A ‘T’ score of -2.5 SD (or below) below the normal
What tool can be used to estimate an individual’s likelihood of suffering with a fragility fracture / osteoporosis?
A FRAX tool - you type in answers regarding known risk factors and it generates a 10-year probability score for that individual suffering a ‘low energy trauma’ fracture to their hip, wrist, vertebrae or shoulder
How do bisphosphonates work in the treatement of osteoporosis?
They decrease / inhibit osteoclastic activity thereby slowing the rate of bone breakdown
How does Strontium Ranelate act to help maintain bone strength?
It affects both osteoclastic and osteoblastic activity to reduce bone resporption (osteoclasts) and increase bone formation (osteoblasts) - only indicated if bisphosphonates are unsuitable
In osteoporotic treatment what does SERMs stand for and how does the drug work?
Selective Oestrogen Receptor Modulators - acts similarly to oestrogen which has a protective effect on bone through increasing bone density
What monoclonal antibody is used in the treatment of osteoporosis?
Denosumab
How does Denosumab act to treat osteoporosis?
By acting on the RANK ligand preventing osteocytes turning into osteoclasts thereby promoting osteoblasts
If hyperparathyroidism can cause osteoporosis how does human recombinant parathyroid hormone treatment help prevent / manage osteoporosis?
Fluctuant levels of parathyroid hormone (as is issued with parathyroid hormone treatment) has an anabolic effect on bone where continuous high levels of parathyroid hormone has a catabolic effect
When osteoporosis exists in men with hypogonadism what treatment might be appropriate?
Testosterone therapy
What is the difference between osteomalacia and rickets?
osteomalacia is simply the term used for ‘Rickets’ in adults - both are the result of a lack of Vitamin D and therefore weaker bones
What is the definition of osteoporosis?
Reduced bone mass (normal mineralisation! - despite the fact a DEXA scan measures bone mineral density!)
Name two drugs with increase bone formation
Teriparatide (recombinant parathyroid hormone)
Strontium ranelate
Name two drugs with decrease bone resorption
Denosumab (RANK ligand inhibitor)
Bisphosphonates
How should Bisphosphonates be taken and why?
At least half an hour before any food and with a full glass of tap water - bisphosphonates will bind to any calcium it comes into contact with
name 3 bisphosphonates
any 3 of the following:
- Alendronic Acid (alendronate)
- Risedronate
- Zolendronic Acid
- Ibandronate
Why should patients on bisphosphonates pay special attention to their gums?
A rare side effect is bone necrosis of the jaw
How is Denosumab administered?
Subcut injection 6 monthly
What 5 things does Vit D do in the body?
1) maintains calcium homeostasis
2) maintains bone health
3) increases Ca++ absorption in the gut
4) increases phosphate absorption in the gut
5) osteoclast maturation / function
What is Paget’s disease?
Disordered bone metabolism - overactive osteoclasts followed by overactive osteoblasts resulting in a woven mosaic effect in the bone - weaker than normal
What are the direct and indirect symptoms of Paget’s disease?
Direct - constant boring bone pain particularly on weight-bearing - pathological fracture - sacromatous change (rare)
Indirect - high cardiac output - compression effects
List the more common sites affected by Paget’s
Spine; Pelvis; Skill; Femur
What compression injuries should you look out for?
Cranial nerve (palsies); Deafness; basilar invagination (potentially leading to brainstem compression and death); Cauda Equina (paraplegia); sciatica
How can you diagnose Paget’s disease?
X-ray; Blood Tests; Isotope Bone Scan (increased uptake); Urinary Hydroxyproline (increased)
What would the following results be (high, low, normal) in a blood test for a Pt with Paget’s - Alkaline Phosphatase;
Calcium; PTH; Vit D; phosphate ?
Alkaline Phosphatase - High
Calcium, PTH, Vit D, phosphate ALL normal
How should you treat someone with Paget’s Disease?
ONLY if SYMPTOMATIC treat with bisphosphonates (Risedronate or Zolendronate)
In a blood test if serum calcium is normal, phosphate is low and Alkaline Phosphatase is high what is the likely diagnosis with regard to bone disease?
Osteomalacia
In a blood test if serum calcium is normal, phosphate is normal and Alkaline Phosphatase is very high what is the likely diagnosis with regard to bone disease?
Paget’s Diease
In a blood test if serum calcium is high, phosphate is low and Alkaline Phosphatase is normal what is the likely diagnosis with regard to bone disease?
Primary hyperparathyroidism
In a blood test if serum calcium is high, phosphate is high and Alkaline Phosphatase is high what is the likely diagnosis with regard to bone disease?
Bone metastases
What affect do corticosteroids have on bone cells?
inhibit osteoblast activity and enhance osteoclastic activity therefore increasing bone resorption
What does calcitonin do?
Inhibits osteoclastic activity
