Bones and joints Flashcards by Amberine Wadee

What is the composition of bone

Non-cellular matrix:
ECM: type 1Collagen associated with calcium hydroxyapatite , regulatory proteins & growth factors

Cellular matrix:
- Osteoblasts, osteocytes, osteoclasts

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What is the function of bone?

-Protection
-Haematopoesis
- support
-Lipid and mineral storage

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What is the function of osteoblasts

Secrete uncalcified/ unmineralised extracellular matrix (known as osteoids) which is later mineralised

regulate bone resoprtion: rich in APL
-Synthesis matrix
express receptors for PTH, Glucortocioids, vit D, Oestrogen (influence remodelling)

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What is an osteoid

Unmineralised extracellular matrix

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What is an osteocytes function

Osteoblast that is entomed in lamella in lacunae- mineralises osteoids

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What is the function of osteoclasts

Monocyte derivatives, resorb bone via secretion of H+ and lysozyme enzymes

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What are the phases of bone formation

Woven:
- embryo/ fracture
- full of osteoids (unmineralised ecm)
- collagen randomly arranged

Lamella:
- Compact/ spongy

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What is meant by ‘Compact bone’

Type of lamella bone
- dense rigid
- found in outerbone

Contains:
Haversian canal- nerve & lymphatic vessels

Volkmans canal- Horizontally connected- transmit blood

Cannalculi = osteocytes between laemalla and connect by interconnecting tunnels

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What is meant by spongy bone

interior of bone
Honeycomb texture
Light and porous
non structural fill

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How are osteoblasts activated

hormone/ damage

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What affects bone formation

PTH
Vitamin D
Calcitonin
(BMP) Bone morphogenic proteins

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What is the effect of PTH

Regulated by blood calcuium, vitamin D and phosphate levels

Increases intestinal transport of CA & phosphate
Removal of calcium from bone
Increases absorption of vitamin D in upper small intestine

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What is the role of calcitonin

Opposes action of PTH
-Lowers blood calcium levels
- deposits calcium in bones

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What are the stages of fracture healing

Fracture: inital haematoma: formed with granulation tissue- results in inflammation causing immune response
Proliferation stage: macrophages move in and devour debris & dead cells

proliferation of fibroblasts
-differenation of osteoclasts and osteoblasts

3.Bone callus: primary callus, osteoids replace with mature bone & becomes mature callus (6 weeks- 3months+) new bone is liad down along lines of stress,

Remodelling:
reduces size of bone callus, bone ends rejoin so now a whole bone
- bone marrow cavity is restored, new bone is laid down along lines of stress

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What is osteogenesis imperfecta & signs and symptoms

Autosomal dominant
collagen defect (affect 1-5)

signs & symptoms:
- blue sclera, bruising easily, deafness, loose joints/ tendons
- +/- cardiac complications
- short stature
- multiple fractures

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How does osteogenesis imperfecta affect dentistry

Caution with XLA
-GA risk: chest defomity/ cardiac issues
Brown/ blue/ pruple/ soft dentine teeth

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What is cleidocranial dysplasia & its presentations

Autosomal domiant- defect of skull & clavicle

Presentations:
- clavicles absent/ defective
- brachycephalic: broad short skull
- hypoplastic midface: mandibular protrusion
- +/- clefts

How does cleidocranial dysplasia affect dentistry

Hypodontia
supernumeraries
-Retained decidious dentition
abnormaltieis with dentition: root formation, cysts

What is osteopetrosis & how does it present

Excessive bone density due to defect in osteoclastic activity & remodelling
- risk of fracture for bones but normal healing

clinical presentations:
- incidental radiographically
-bone pain, fractures, osteomyelitis
- +/- anaemia
- susceptible to infections : RISK OF SEPSIS

How does ostepetrosis affect dentistry

fractures of jaw
osteomyelitis (surgical complications)
if infection confirmed it is difficult to eradicate
-consider abx

What is rickets

acquired childhood disease due to lack of vitamin D/ calcium:

fish & eggs

How does rickets affect dentistry?

fractures

What is osteoporosis
- How is it diagnosed

Demineralised bone mass
Low bone density
Results in fragile bones

affects: 1 in 3 women

diagnosed: FRAX tool, DEXA scan

What are the signs and symptoms of osteoporosis

asymptomatic until fracture- back pain, reduced height overtime with stooped posture

How does osteoporosis affect dentistry

Patients are on bisphosphonates- risk of MRONJ - Pt weaker bones fractures

How is osteporosis managed

Exercise Ca, Vit D supplements HRT +/- Bisphosphonates Medications: hormone replacement, bisphosphonates, PTH, fluoride, vitamin D, calcitonin

What is the mechanism of bisphosphonates

1. Attach to hydroxyapatite binding sites Particularly on surfaces that are actively resorbing 2. Impairs osteoclastic ability to bind to the bony surface & inhibit resorption - Reduce osteoclast activity by promoting osteoclast apoptosis & inhibit new osteoclast developing

What is fiborous dysplasia

benign, chronic fibro-osseous lesions in craniofacial region - monostoic/ polystoic - chronic disorder: scar tissue grows in place of normal bone - fiborous tissue weakens bone overtime Linked with Albrights syndrome: bone, skin, endocrine tissues

How does a pt with fibrous dysplasia present & how is it diagnosed

Firm swelling in maxilla Diagnosis: Imaging: appear dense ground glass, poorly defined margins raised APL & urinary hdroxyproline biospy

What is pagets disease

Common in 40 years old, unknown aetiology, change in balance of remodelling of bone

What are the signs and symptoms of pagets disease & how is it diagnosed

Bone pain, no symptoms in early stages, systemic effects - Enlargement of maxilla -bulging zygomatic area - hypercementosis of teeth Diagnosis: radiographs shows lysis and sclerosis - raised ALP - normal Ca, PO

What is the tx for pagets disease

bone bisphosphonates - calcitonin: pain relief

What are the systemic effects associated with pagets disease

Musculoskeletal: - bone pain, bone deforbity, fractures, osteoarthritis, spinal stenosis Neurological: Tinnitus, cranial nerve, basilar impressions, hearing loss, cardiovascular: - congestive heart disease, increase CO, aortic stenosis, generalised atheroscleoriss metabolic: hypercalcaemia, immboilsation neoplasia: - sarcoma, giant cell tumour

How does PTH work

- acts on kidneys : increases renal reabsorption -reabsorption of phosphate - increases absoprtion of calcium in gut - promote osteoclastic bone resoprtion: rise in calcium plasma levels & ALP

What is primary hyperparathyroidism

too much PTH - associated with adenoma

What are the signs and symptoms of primary hyperparathyroidism

- Associated with renal tones - Hypercalcemia - Bone pain - Fractures -Pathological fractures -Giant cell tumours -peptic ulcers - pancreatitis - hypertension

How does hyperparathyroidism affect the hesd and neck

- Local swelling in mandible - corneal calcification - thinning bone trabeculae - Develop bony lesions - jaw/ skull lesions - pepperpot skull - fibrous replacement of reabsorbed bone- osteitis fibrosa cystica

What is the tx for hyperparatyrodisim

Surgical removal of adneoma post-op issue with hypocalcemia

What is secondary hyperparathyroidism caused by

Response to persistently low calcium: - chronic renal failure - malabsoprtion

How does secondary hyperparathyroidism affect dentistry

- Giant cell lesions - Brown tumourd -GC lesions - Other systemic issues