What does bone "do"?
– Provide structural support for the body
– Protect vital organs
– Act as a home for bone marrow
– Provide a reservoir for minerals (eg calcium)
NEED TO GO OVER BONE BIOLOGY, ROLE OF VIT D and its SUBSTITUTES, HOW DEPOSITION IS CAUSED, ROLE OF PTH ETC
What is an Osteoclast, and what is its role?
An Osteoclast is a type of bone cell theat resorbs bone tissue.
Osteoclasts are regulated by several hormones, including parathyroid hormone (PTH) from the parathyroid gland, calcitonin from the thyroid gland, and growth factor interleukin 6 (IL-6). This last hormone, IL-6, is one of the factors in the disease osteoporosis, which is an imbalance between bone resorption and bone formation.
What is the role of Parathyroid Hormone (PTH) in bone remodelling?
PTH enhances the release of calcium from the large reservoir contained in the bones.Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH.
PTH also enhances active reabsorption of calcium and magnesium from distal tubules and the thick ascending limb or the kidney, and absorbtion of Calcium from the Small Intestine.
What is the role of Calcitonin in bone remodelling?
Calcitonin acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).
Specific effects in bone:
Inhibits osteoclast activity in bones.
Stimulates osteoblastic activity in bones.
In very basic terms - what is the difference between Trabecular and Cortical bone?
Trabecular bone is the "Scaffolding", and Cortical bone is the "Cover".
"Systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk"
Deficiency of which sex hormone is a risk factor for Osteoporosis?
How is Osteoporosis usually diagnosed?
Osteoporosis is usually diagnosed with a DEXA Scan (Dual Energy X-Ray Absorpitometry).
The diagnosis is based on a measurement of Bone Mass Density (BMD) in g/cm2.
With reagrds to the measurement of Bone Mass Density in Osteoporosis, what is meant by the "Z" score?
#standard deviations from age and
With regards to the measurement of Bone Mass Density in Osteoporosis, what is meant by the "T" score?
#standard deviations from gendermatched
young adult mean
With regards to the measurement of Bone Mass Density in Osteoporosis, what is the classification of disease, with relation to the T score?
0 to -1 = normal
-1 to -2.5 = osteopenia
-2.5 below = osteoporosis
-2.5 and below with fracture = severe osteoporosis
Name two drugs that increase bone formation.
– Strontium Ranelate
Name two drugs that decrease bone resorption.
– RANK Ligand inhibitors (Denosumab)
Name some Biphosponates, and state what effect they have.
– Alendronic acid, Risedronate, zolendronic acid, ibandronate
– Inhibit osteoclasts
What type of drug is Denosumab? What does it do?
Denosumab is a RANK Ligand inhibitor
Prevents osteoclast differentiation, activation and survival
– ‘Biological’ drug – humanised antibody
– Subcutaneous injection every 6 months
– Side effects
Rarely ONJ, atypical fracture
– Often given with calcium and vitamin D supplement
What is Teriparatide, and how does it work?
This is a Recombinant human parathyroid hormone
• Normally PTH causes bone loss
• BUT given in pulses
– Increases bone production (anabolic)
– Increases BMD
What is the common term given to the condition Osteomalacia?
What are the actions of Vitamin D?
– Maintain calcium homeostasis
– Maintain bone health
– Increase Ca2+ from the gut
– Increase phosphate absorption from gut
– Osteoclast function / maturation
What is the effect of a Vitamin D Deficiency on bone density?
Low Vitamin D leads to reduced Calcium absorption from the gut. This in turn leads to low Serum Calcium, and a subsequent increase in the release of PTH from the parathyroid glands. PTH causes Calcium resorption from bone, which in turn reduces bone mineralisation (creates "sort bones").
Name some causes of Vitamin D Deficiency.
- Inadequate sunglight
- Inadequate diet
- Abnormal metabolism of vit D (Renal or Hepatic disease)
- 1-alpha hydroxylase deficiency (rare)
- congenital vitamin d resistance (rare)
What is Rickets?
Rickets is a condition that affects bone development in children. It causes the bones to become soft and weak, which can lead to bone deformities.
What is Osteomalacia? What are the clinical signs of this disease?
Osteomalacia is the softening of the bones caused by defective bone mineralization secondary to inadequate amounts of available phosphorus and calcium, or because of overactive resorption of calcium from the bone as a result of hyperparathyroidism (which causes hypercalcemia, in contrast to other aetiologies). Osteomalacia in children is known as rickets.
In a Vitamin D deficient patient, what would you expect from the following tests:
- Serum 25(OH) Vitamin D
- Serum PTH
- Serum calcium
- Serum phosphate
- Alkaline phosphatase
Serum 25(OH) Vitamin D - LOW
Serum PTH - INCREASED
Serum calcium - LOW/NORMAL
Serum phosphate - LOW
Alkaline phosphatase - INCREASED
What is Pagets Disease?
Paget disease of bone is a chronic disorder that can result in enlarged and misshapen bones. Paget's is caused by the excessive breakdown and formation of bone, followed by disorganized bone remodelling. This causes affected bone to weaken, resulting in pain, misshapen bones, fractures and arthritis in the joints near the affected bones.
What is the first manifestation of Pagets disease?
The first manifestation of Paget's disease is usually an elevated alkaline phosphatase in the blood. Overall, the most common symptom is bone pain.
What is the difference between Monostotic or Polyostotic Pagets disease?
Monostotic - affects one bone
Polyostotic - Affects many bones
Which clinical (blood/urine) results would be definitive of Pagets Disease?
• High alkaline phosphatase (NB. liver disease)
• Normal calcium, vitamin D, PTH, phosphate
– Urinary hydroxyproline increased
– Isotope bone scan – increase uptake
Which class of drug is used to treat Pagets disease? Can you give any examples?
Which conditions are indicated by the following sets of results?
This is VERY likely to be an EMQ type question. Learn it.
What effect does a decrease in plasma calcium have on plasma CaHPO4 absorption?
Plasma CaHPO4 absorption increases when there is a decrease in plasma Calcium.
UV light converts 7- dehydrocholesterol to ______.
Cholecalciferol is converted in the liver to _______
Without the effect of PTH, what is 25-cholecalciferol converted to in the Kidneys?
24,25 D variants.
In the presence of PTH, what is 25-Cholecalciferol converted to in the kidneys?
What is the hormonal response to hypophosphataemia?
Increased Calcitriol, leading to decreased PTH, leading to a decrease in bone calcium resorption, an increase in intestinal phosphate absorption, and a decrease in phosphate excretion from the urine.
Which disease is related to a problem with bone density and strength?
Which disease is related to a problem with bone mineralisation?
Which disease is related to a disorder of bone formation?
What is the Berg balance scale?
A Formal assessment of balance, often used in the provision of elderly care.
What is the "TUG" test?
This is the "timed get up and go" test. It's used when assessing an elderly patients ability to mobilise.
Which blood measurement is taken as the level of Vitamin D in the body?
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 80nmol/l. Is this an acceptable level? What does it show?
Anything over 75 nmol/L shows their on bloody good form. This patient is HEALTHY!
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 48 nmol/l. Is this an acceptable level? What does it show?
Anything under 50nmol/L indicates that Vitamin D supplementation is needed.
(They also probably need to stop staring at computer screens in the library revising, and actually go outside where this is thing called the SUN.)
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 23 nmol/l. Is this an acceptable level? What does it show?
This is not good.
< 25nmol/l means that Calciferol is indicated (high risk of rickets and osteomalacia).
Daily recommendations of 400IU(10g) per day only sufficient to prevent rickets.
According to Saunders et al., most hip fractures of the elderly occur where?
In care homes.
Bone density is a ____ indicator of fractures in individuals.
Bone density is a poor indicator of fractures in individuals.
The DIPART trial looked at what?
Vitamin D consumption in individuals.
Is poor vidual acuity a risk factor for falls?
YES. There is a large body of evidence to support this.
What is the Hayflick limit?
The Hayflick limit (or Hayflick phenomenon) is the number of times a normal human cell population will divide until cell division stops. Empirical evidence shows that the telomeres associated with each cell's DNA will get slightly shorter with each new cell division until they shorten to a critical length.
‘A loss of continuity of the substance of a bone due to physical force’
"Complete loss of contact between articulating surfaces of a joint".
What is meant by the term "Sublaxation"?
This is similar to dislocation. There is some contact between articulating surfaces, but they are no longer congruous.
What are the four stages of Fracture repair (regeneration)?
What are the advantages and disadvantages (to healing) of fracture fixation (i.e. a metal plate)?
Modifies MECHANICS of fracture healing (direct bone healing, restructuring of bone).
Dispersal of fracture haematoma alters the biology of fracture healing, almost always adversely.
What does this image show?
This shows a failed fracture implant. The implant has failed before the fracture could heal.
What is Myositis ossificans?
This is calcified soft tissue near a joint, restricting movements.
Following a car accident 2 weeks ago, in which he broke his left femur, a man present so to A and E with confusion, respiratory distress and a petechial rash across his legs and chest. What do you suspect has caused this?
The cause of this is likely to be a Fat Embolism. Fat globules can form in lung parenchyma and peripheral circulation after long bone fracture or other major trauma.
What is compartment syndrome?
Muscle swelling within a closed osseo-fascial compartment, with increased pressure leading to capillary ischaemia and death of both muscle and nerve cells.
What is meant by the term "Malunion"?
This is the term used to describe a fracture that has united, but in a poor position. There may be shortening, angulation, displacement and/or rotation.
What does the phrase "Delayed Union" refer to?
A delayed union refers to a situation in which a bone union (from a fracture) fails to occur within the expected time. X-Ray may show abnormal bone resorption, or a poor quality callus.
What is meant by the term "Hypertrophic non-union"?
This is a poorly healing fracture. The bone ends are viable, and have a good blood supply, but their is inadequate stability. The treatment is to achieve stability, in order to allow union.
What is meant by the term "Atrophic non - union"?
This is a non healed fracture. There is no evidence of cellular activity, bone ends may be narrow and porotic. Treating this is difficult, and may require removal of fibrous bone ends.
What is meant by the term "Avascular Necrosis"?
This is bone death due to blood supply disruption.
Revascularisation takes 6-18 months. The affected bone will be soft, and distorted in shape.
What is Osteitis?
Infection of a bone.
What is meant by the term "Pathological Fracture"?
"A fracture occurring following minimal stress through abnormal bone"
Whqat is a "greenstick fracture"?
A greenstick fracture occurs when a bone bends and cracks, instead of breaking completely into separate pieces. This type of broken bone most commonly occurs in children because their bones are softer and more flexible than are the bones of adults.
What is a "Salter Harris Fracture"?
Salter-Harris fractures are epiphyseal plate fractures and are common and important as they can result in premature closure and therefore limb shortening and abnormal growth.
What is a Smith's Fracture?
This is when you fracture the distal radial head, causing posterior displacement of the hand, typically after reaching to "catch your fall".
What is a "Collies Fracture"?
This is a fracture of the radial head (rare), causing anterior displacement of the hand.
What is the name given to this type of injury?
This is a Salter Harris fracture.
What is the name given to this injury?
This is a Salter Harris fracture.
What is the name given to this type of injury?
This is a Femoral Neck Fracture
What is the name given to this type of fracture?
This is an intraarticular fracture.
What is the name of this injury?
This is fracture of the pubic ramus.
What is the name given to this injury?
This is a sub trochenteric neck of femur fracture.
Which muscles cause flexion at the knee?
- Semi tend
- Semi memb
- Biceps fem
Which peripheral nerve supplies the knee flexors?
The Tibial portion of the Sciatic Nerve
Which peripheral nerve supplies the Quadriceps?
The Femoral Nerve.
What is the root origin of the Sciatic nerve?
The Nerve root origin of the Sciatic nerve: L4-S3.
Which muscles of the thigh are supplied by the Femoral nerve?
- Vastus Lateralis
- Rectus Femoris
- Vastus Medialis
- Vastus Intermedius
Which muscles cause plantar flexion of the ankle?
- Flexor hallucis and digitalis longus
- Tibialis posterior
Which muscles cause dorsiflexion of the ankle?
- Tibia anterior
- Extensor hallucis
- Digitalis longus
- Peroneus Tertius
Which muscles cause inversion of the ankle?
- Tibia posterior
- Flexor dig long
- Tibia anterior
- Extensor hal long
Which muscles cause Eversion of the ankle?
- Peroneus longus
- Peroneus brevis
- Extensor digitalis longus
Learn these bad boys!
Which nerve root supplies Plantar flexion of the ankle?
Which nerve root supplies dorsiflexion of the ankle?
Which nerve root supplies muscles of inversion of the ankle?
Which nerve root supplies muscles of eversion of the ankle?
Which nerve supplies the Short head biceps femoris, and the sup. and deep Peroneal muscles of the leg?
The Peroneal nerve bro. The peroneal nerve.
Which nerve supplies the muscles of extension at the ankle?
The Deep peroneal nerve.
Which myotome supplies knee flexion?
Intra-osseous blood supply to bone is via the _____ _____.
Extra-Osseus blood supply to bone is via which two things?
Extra- Osseous supply is via:
- Muscle attachments
- Circular anastomoses
Blood supply to the Femoral head is via which vessels?
- Via medial & lateral femoral circumflex arteries
- Retinacular (subsynovial) vessels
- Intra-osseous vessels
- Foveal vessels
Where can you readily identify the Lateral Femoral circumflex artery?
At the intertrochanteric line.
A Fracture proximal to the intertrochanteric line is known as an _____ fracture. A Fracture distal to the intertrochanteric line is known as an _____ fracture.
A Fracture proximal to the intertrochanteric line is known as an intracapsular fracture. A Fracture distal to the intertrochanteric line is known as an extracapsular fracture.
What injury does this image show?
Central dislocation of the left hip.
What is meant by the term "Heterotopic ossification"?
The process of bone tissue formation outside of the skeleton.
Which nerve is likely to be damaged by a hip dislocation?
The Sciatic nerve. This could lead to a sciatic nerve palsy.
Describe the anatomical borders of the Femoral Triangle.
•Superorly- Inguinal ligament
•Medially - Adductor longus
•Laterally - Sartorius
•Floor - Ileopsoas and pectineus
•Roof - Fascia lata,subcutaneous fat
Where does the inguinal ligament run from and to? What goes underneath it? What goes through it?
•Runs from ASIS to PUBIC TUBERCLE
•Femoral vessels go underneath it
•Testicular vessels go through it
What is the name given to the vein that runs underneath the inguinal ligament, and the femoral triangle?
The Great Saphenous Vein.
Which is of greater concern - Deep or superficial venous thrombosis of the leg?
Week 218 EMQ FBK Revision
How does Warfarin work?
Warfarin inhibits the enzyme Vitamin K Reductase, which prevents formation of vitamin K from oxidised vitamin K. Vitamin K is required for the reduction of Glutamic Acid to Alpha-Carboxyglutamic acid, which is a component of tissue factors 2,7,9 and 10.
What is Thrombocytopaenia?
A deficiency of platelets.
Secondary osteoporosis is a disease usually found in younger women. What are the usual causes?
- Oestrogen deficiency
- Glucocorticoid use/cushings (the cortisol suppresses osteoblasts and subsequent bone growth)
- Hyperparathyroidism (increased PTh causes < resorbtion).
Alendroate and Zolendroate are drugs used in the management of which condition?
These drugs encourage osteoclast apoptosis, therefore > bone resorbtion.
Raloxifene is a drug used to treat which condition? How does it work?
Osteoporosis. This mimics oestrogen (receptor modulator) - increases osteoblastic activity.
What are the causes of Osteomalacia/Rickets?
- Vit D deficiency
- Abnormal Vit d metabolism (renal or hepatic disease)
- Hypophosphataemia - PO4 req'd to make hydroxyapatite
- Drugs - bisphosphonates (mineralisation inhibitors)
- Congenital: congenital alpha-1 reducatse deficiency, Vit D resistance or Hypophosphataemic.
Which enzyme, typicall associated with the liver, is produced by osteoblasts in bone mineralisation, and is commonly found to be raised in Paget's disease?
Alkaline Phosphatase (ALP)
A loss of continuity of the substance of a bone due to physical force
A complete loss of contact between articulating surfaces of a joint
Joint not congrous - partial dislocation.
Define "Transverse fracture"
A fracture straight across a bonem, in a perpendicular plane. Usually due to bending force.
Define "Spiral fracture"
A fracture usually due to torsion (twisting)
Define "Comminuted fracture"
Bone shattered into multiple fragments, usually due to high enrgy crushing forces.
Define "Impacted fracture"
Wedging/crushing of two fragments of same bone into eachother.
Define "Compression fracture"
Collapse of a section of bone - think of a vertebral wedge.
Define "Periarticular Avulsion"
Fracture at muscle attachment, due to a sudden sharp contraction - often a sports injury.
Define "Greenstick fracture"
In children. "Bent bone" - due to torsion or bending.
Define "Physeal fracture"
These asre fractures through the epiphyseal growth plate in children.
Name the six types of hip fracture - 3 intracapsular, and 3 extracapsular
- Fracture of head of femur (rare , usually in younger pts)
- Fracture of neck of femur - most common in elderly
- Avascular necorsis of head - often occurs in displaced fractures
- Trochanteric - avulsion of trochanter from femur
- Intertrochanteric - elderly, rel. to osteoporosis
- Subtrochanteric (high energy trauma)