Bones and joints Flashcards
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
What is the function of bone?
-Protection
-Haematopoesis
- support
-Lipid and mineral storage
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)
What is an osteoid
Unmineralised extracellular matrix
What is an osteocytes function
Osteoblast that is entomed in lamella in lacunae- mineralises osteoids
What is the function of osteoclasts
Monocyte derivatives, resorb bone via secretion of H+ and lysozyme enzymes
What are the phases of bone formation
Woven:
- embryo/ fracture
- full of osteoids (unmineralised ecm)
- collagen randomly arranged
Lamella:
- Compact/ spongy
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
What is meant by spongy bone
- interior of bone
- Honeycomb texture
- Light and porous
- non structural fill
How are osteoblasts activated
hormone/ damage
What affects bone formation
- PTH
- Vitamin D
- Calcitonin
- (BMP) Bone morphogenic proteins
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
What is the role of calcitonin
Opposes action of PTH
-Lowers blood calcium levels
- deposits calcium in bones
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
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
How does osteogenesis imperfecta affect dentistry
- Caution with XLA
-GA risk: chest defomity/ cardiac issues - Brown/ blue/ pruple/ soft dentine teeth
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
- Attach to hydroxyapatite binding sites
Particularly on surfaces that are actively resorbing - 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
