Bone and Joints 1 Flashcards
What are the three main types of bone tissue?
cortical
cancellous
woven
what is cortical bone?
Dense and compact bone tissue, forming the outer shell of bones.
- its formed of concentric rings of bone which is adapted to withstand the strain of pressure
what is cancellous bone?
Also known as trabecular or spongy bone, it is less dense and more porous than cortical bone.
- has interconnecting network of rods and plates of bones
- allows for the resistance and compression loads
- main site of turnover for mineral homeostasis
- found inside flat bones and at the end of long bones
what is woven bone?
Immature bone tissue that is temporary and later replaced by more mature lamellar bone.
- more disorganised
- appears in early stages of bone or at fracture sites
- present in pagets or diseases with high bone turnover
what are the 3 major components of bone tissue?
type 1 collagen
non collagen protiens
bone mineral
what is type 1 collagen?
- main protein that forms parallel lamella = offers different densities
what is non collagen protein ?
eg. osteocalcin, fibronectin, ostepontin
Various proteins other than collagen that contribute to the structure and function of bone.
what are bone minerals?
- consist of Ca and phosphate which is in the form of HAP
what are osteoblasts ?
Bone-forming cells that synthesize and secrete the organic components of the bone matrix. they also regulate mineralisation
derived from local mesenchymal stem cells
what are the 2 pathways after the formation of osteoblasts ?
- apoptosis
- or they will line the bone at osteocytes
what are osteoclasts ?
regulate bone resorption
- rich in ARP
- express receptors for PTH, oestrogen and glucocorticoids, vit d, inflammorry cytokines and TGF beta = all these influence bone remodelling
what are osteocytes ?
- derived from osteoblasts
- they activate bone formation by responding to mechanical strain so have a key role in bone resorption
what 3 things affect bone formation, metabolism and blood calcification ?
PTH
vit D
calcitonin
what do bone morphogenic protein (BMP) affect?
bone formation
what are BMP available as and used for?
-available as recombine proteins
- used for grafting/regenerative procedure, in oral surgery
what is the PTH regulated by?
blood calcium, vit D and phosphate levels
what happens when PTH is secreted ?
intestinal transport of phosphate promoted
and removal of ca from bones is
accelerated.
how is dietary vit D absorbed ?
its fat solvable
-absorbed from upper small intestines which promotes intestinal absorption of Ca and P
how is vit D synthesised ?
in the skin due to sunlight and converted via liver and then in kidney to the most active metabolite . Process enhanced by PTH and low Phosphate levels.
what does the most active metabolite of vit d do?
controls bone and enhances Ca absorption
what is the role of calcitonin?
opposes action of PTH and lowers blood Ca levels by promoting deposition of Ca in bones
- other hormones effect formation and metabolism:growth hormone + oestrogen.
bone growth
stages of fracture healing
what are the different types of bone disease ?
Genetic =osteogenesis imperfecta, cleiodocranial dysplasia, osteopetrosis
Acquired = osteomalacia, osteoporosis, fibrous dysplasia, pagets, primary and secondary hyperparathyroidism
Joint Disorders
Arthritides
Muscular dystrophies
what is osteogenesis imperfect ? signs and symptoms
- Rare
- Autosomal dominant
- it is a Collagen defect- Types I-IV = the vary in severity
- AKA brittle bone disease
- Blue sclera
- Deafness
- Brusing easily
- Loose joints/tendons
- +/- cardiac complications
- Short stature
- Multiple fractures easily
what are some dental considerations of osteogenesis imperfecta?
Care with extractions - fracture risk
GA risk - chest deformity / cardiac issues
Teeth - disorder in dentition brown/purple/wear/soft dentine
what is cleiodocranial dysplasia ? signs and symptoms?
Rare defect - mainly involving skull and clavicle- shoulders pointing forwards
Autosomal dominant
Clinically
Clavicles absent or defective - charateristic look Brachycephalic (broad short skull)
Hypoplastic midface = set back
mandibular protrusion= class 3
+/- clefts
Other skeletal defects
what are some dental considerations of cleidocranial dysplasia?
Hyperdontia
Supernumeraies
Retained deciduous dentition
Abnormalities with dentition e.g root formation, cysts etc.
what is osteopetrosis?
Rare disorder
Variabel severity
Excessive bone densitry
Defect in osteoclastic activity and bone remodelling
Although bones are more ‘dense’ - risk of fracture but normal healing
may be anaemic
what are some dental considerations of osteopetrosis?
Often no symptoms
Incidental finding radiographically
Bone pain, fractures, osteomyelitis
+/- anaemia
susceptibility to infections (defective marophages neutrophils) - risk of sepsis
beware of post op = osteomyelitis, jaw fractures
When infection confirmed difficult to irradicate
‘atraumatic’ surgery
consider antibiotics for surgery
what is osteomalacia/ rickets?
childhood disease,
inadequate skeletal mineralisation due to lack of vitamin D / calcium
- vitamin D from sunlight, foods (oily fish and eggs)
recent increase in UK - still low numbers
worse in dark skin and premature children
Tx - vitamin supplements and dietary advice
what are some dental considerations of osteomalacia ?
Rare to see dental effects
If malabosprtion diagnosis - nb radiolucencies and hyperparathyroidism/vit K deficiency
what is osteoporosis?
Diminised bone mass
Low bone density
Causes fragile bones
Elderly
menopausal
asymptomatic until they have a fracture
what are some risk factors with osteoporosis ?
Calcium intake
Reproductive hormones
Parathyroid gland
Physical activity
From 30 years - 1% bone loss per year Post menopausal - 5% loss per year
1 in 3 caucasian women, 50yo - 17.5% risk hip fracture, 16% risk foremar fracture
what are some symptoms of osteoporosis?
often none in the early stages then maybe back pain, reduced height (over time), stooped posture, fracture unexpected
Rx Hormone replacement, bisphosphonates, PTH, fluoride, Vitamin D, Calcitonin
how do we investigate and manage osteoporosis?
Investigations / Diagnosis
FRAX tool DEXA scan
Management
Avoidance Exercise - weight bearing
Ca and Vit D supps +/- HRT Bisphosphonates
mechanism of bisphosphonates?
what is fibrous dysplasia?
- Benign chronic fibro-osseous lesiosn
- Frequent in the craniofacial region
- Monostotic or Polystotic Single bone or multiple
- common in afrocarribean
Chronic disorder Scar-like tissue grows in place of normal bone Fibrous tissue weakens the bone over time
Ix Radiology - ground glass appearance, poorly defined margins Raised serum ALP and Urinary hydroxyproline (Serum Ca and Po normal)
If significant can be surgically reduced - can bleed a lot during GA
Associated Syndromes:
- McCune Albright Syndrome: Some cases may be associated with McCune Albright Syndrome, which involves abnormalities in bone, skin, and endocrine tissues.
what is pagets disease?
Common
3% over 40 years
Causes changes in balance of remodelling of bone Aetiology generally unknown ?
viral / genetic
what is the clinical presentation of pagets ?
Patients often experience bone pain. Systemic symptoms may include various manifestations (see table).
how do we investigate and diagnose pagets ?
Radiographs: including osteolysis, mixed areas of lysis, and sclerosis.
- Biochemical Markers:
+ Serum alkaline phosphatase (ALP) is typically elevated, while calcium (Ca) and phosphate (PO) levels remain normal.
+ Raised urinary hydroxyproline and pyridinoline excretion may be observed.
what happens if pagets becomes widespread?
-causes arterial venous fistula casing high output cardiac failure
- lead to osteosarcomas
whats the tx for pagets?
- Bisphosphonates
- Calcitonin: Calcitonin may be used for pain relief.
How does Paget’s Disease manifest in terms of dental aspects?
may lead to enlargement of the maxilla, and less commonly, the mandible.
- Zygomatic Bulging: Bulging in the zygomatic area can occur.
- Hypercementosis: Hypercementosis of teeth may sometimes be observed
what are the associated risks during surgery?
Surgery may pose risks related to vascularity, leading to either high vascularity causing bleeding or poor vascularization, increasing the risk of osteomyelitis.
Where are the parathyroid glands located, and what is the primary target organ for the hormones they produce?
The parathyroid glands are four small glands situated on the posterior surface of the thyroid gland.
The hormones produced by the parathyroid glands primarily act on the kidneys.
What is hyperparathyroidism?
excessive production of parathyroid hormone (PTH).
what are the characteristics of primary hyperparathyroidism?
- female preponderance and is typically associated with a single parathyroid adenoma.
- Symptoms: About 50% of cases are asymptomatic, but symptoms may include hypercalcemia, bone pain, pathological fractures, giant cell tumors, peptic ulcers, pancreatitis, and hypertension.
- Association: frequently associated with renal stones.
What are the symptoms and characteristics of primary hyperparathyroidism, particularly in the context of bone lesions and dental aspects?
-local swelling, sometimes in the mandible.
- corneal calcification.
- Subperiosteal resorption may occur at the fingertips.
- X-ray findings may show thinning of bone trabeculae.
- Osteitis Fibrosa Cystica: This condition involves fibrous replacement of resorbed bone.
- :Bone lesions occur in 10-20% of cases and may affect the jaw and skull. A “pepperpot skull” appearance may be observed on imaging.
tx for primary hyperparathyroidism
Surgical removal of the adenoma is a common treatment approach.
- Postoperative issues may include hypocalcemia.
- maybe on Ca supplements
What characterizes secondary hyperparathyroidism?
Cause: Parathyroid hyperplasia occurs in response to persistently low calcium levels, often due to chronic renal failure or malabsorption.
- Bone lesions are more common in secondary hyperparathyroidism compared to primary hyperparathyroidism.
what are some of the dental aspects of secondary hyperparathyroidism?
- Giant cell lesions are uncommon and tend to present late in secondary hyperparathyroidism.
- Brown Tumours: These are a characteristic feature associated with bone involvement.
- In middle-aged patients with renal issues, suspicion of parathyroid issues may arise if giant cell lesions are present.
- Patients with secondary hyperparathyroidism may have other systemic issues like renal disease, requiring careful consideration in dental management.
