Bone, bone disorders and arthritis Flashcards
What is bone formed of?
Organic 1/3 - type 1 collagen + other proteins
Inorganic 2/3 - hydroxyapatite
Cellular structure of bone?
Osteoblasts
Osteocytes
Osteoclasts
Osteoprogentior cells
What do osteoblasts do?
- Produce bone by secreting collagen matrix + calcium salts
Where do osteocytes come from?
- Once osteoblasts lay down lamellar bone then get trapped in their lacunae and become osteocytes
What do osteocytes do?
Maintain bone production and secrete enzymes into matrix to maintain mature bone
What are osteoprogenitor cells? Where found?
- In bone marrow
- Responsible for producing new osteoblasts and osteocytes
- Osteoblasts and osteocytes unable to undergo mitosis
What do osteoclasts do?
- Resorb bone
How do osteoclasts resorb bone?
Release proteolytic enzymes and hydrochloric acid which breakdown the bone
List some chemical messengers associated with bone resorption
Vit D
Para + thyroid hormones
Growth hormones
Ca 2+
List some chemical messengers associated with bone formation
Oestrogen
Calcitonin
Androgens
What happens when metabolic homeostasis not maintained?
Bone formation > bone resorption
OR
Bone resorption > bone formation
What is 1st type of bone laid down?
Woven bone / immature bone
What is immature / woven bone remodelled into?
Secondary bone
What 2 types of bone is secondary bone divided into?
Cortical / lamellar bone - 80%
Cancellous / trabecular / spongy bone - 20%
Describe structure of cancellous bone
- Low density
- Spongy appearance
Describe structure of cortical bone
- Dense
- Compact
- Contains bone marrow
What is role of vit D in bone metabolism?
Increases calcium and phosphate circulating in body
How is vit D obtained?
Sun exposure
Diet - oily fish, red meat, egg yolks
What does a deficiency in vit D lead to in adults / children?
Children - rickets = bowing of long bones
Adults - osteomalacia = softening of bones, bone aches / pains / fractures
Where does parathyroid hormone come from?
Thyroid, bow tie shape gland, 4 parathyroid glands which secrete PTH
What is the role of PTH in bone resorption?
- Promotes kidneys to make vit D
What 2 types of disease are due to malfunctioning PTH gland?
- Primary hyperparathyroidism
- Secondary hyperparathyroidism
What causes primary hyperparathyroidism, what are the effects?
- Due to adenoma (benign glandular tumour) of a PTH gland
- Increases PTH level
- Increases Ca2+ (hypercalcaemia)
- Promotes bone resorption
What causes secondary hyperparathyroidism, what does it lead to?
- Chronic renal disease gives urinary calcium
- To compensate PTH gland secretes more PTH
- Promotes bone resorption
- Leads to kidney failure - renal osteodystrophy
How might hyperparathyroidism present facially?
- In jaws
- Central giant cell granuloma
How might hyperparathyroidism present facially?
- In jaws
- Central giant cell granuloma
How does calcium homeostasis occur? (Briefly)
- PTH secreted
- Ca 2+ and PO4 3- resorbed and Ca2+ reabsorbed from kidneys
- Ca 2+ rises
- Calcitonin secreted
- Ca2+ excreted in urine and deposited in skeleton
- Ca 2+ falls
- Causing PTH to be secreted
What are the 3 stages of healing bone fractures?
- Early inflammatory
- Repair
- Remodelling
What happens during early inflammatory stage?
- 1st 2 weeks
- Bleeding at fracture = form haematoma
- Inflammatory cells and fibroblasts at clot
- BVs enter haematoma forming granulation tissue
What happens during repair stage?
- Takes 4-5 weeks
- Granulation tissue become callus
- Primary callus becomes secondary callus
- Osteoid secreted into area forming new bone
- Proteases degrade ECM
- Collagen fibres enter area
- New woven bone created at fracture
What happens during remodelling stage?
- Takes weeks - months to be complete
- Osteoblasts and osteoclasts coordinate remodelling process
- Compact and woven bone are redistributed and reproportioned
What factors can impact fracture healing? (9)
- Blood supply to site
- Infection
- Bone pathology
- Whether fracture is closed / compound
- Degree of tissue loss
- Co-morbidities
- Use of NSAIDs can impair healing
- Nutritional status
- Smoking and alcohol
Name some specific bone diseases need to be aware of (4), including types of arthritis (3)
- Osteogenesis imperfecta
- Osteoporosis
- Osteopenia
- Paget’s disease
- Osteoarthritis
- Rheumatoid arthritis
- Ankylosing spondylitis
What type of mutation causes osteogenesis imperfecta?
Type 1 collagen mutation
What is a type 1 collagen mutation?
Partial / complete absence of collagen
What are the clinical effects of osteogenesis imperfecta?
- Brittle bones
- Prone to fractures
- Grey discolouration of sclera
- Shortened / bowed long bone shapes
Oral features of osteogenesis imperfecta?
Skeletal class 3
Anterior open bites
Impacted 6s and 7s
Thin grey brown enamel
Dentinogenesis imperfecta
Delayed / premature eruption
What causes osteoporosis?
Osteoclasts fail to resorb bone
Effects of osteoporosis?
More bone formation than bone resorption so bone is denser, less elastic recoil
Oral features of osteoporosis and why?
Thicker bone with increased inorganic components leads to bone marrow being walled off so blood cellular composition deficiency
- Delayed tooth eruption
- Growth impairment
- Nerve entrapment
What is osteopenia?
Bones thinned mildly
What would osteopenia suggest in a young person?
Vit D deficiency
Warning sign
Osteopenia expected in older pts
What is difference between osteopenia and osteoporosis?
Osteoporosis bones are more porous
Which lifestyle factors accelerate bone loss?
High caffeine
High salt
Low BMI
Smoking
Immobility
Alcohol
Which lifestyle factors prevent bone loss?
Calcium rich diet
Vitamins, minerals, green leafy vegetables
Fish and nuts
Which genetic factors accelerate bone loss?
Female
FH osteoporosis
Which genetic factors prevent against bone loss?
Obesity
Which diseases can accelerate bone loss?
Cushing’s syndrome
Hyperthyroidism
Hyperparathyroidism
Which drugs accelerate bone loss?
Corticosteroids
Heparin
Diuretics
Cytotoxic drugs
How can osteoporosis be managed? (7)
Lifestyle changes
Pain relief methods - paracetamol, opioids, acupuncture
Physiotherapy
Physical aids - walking stick, frame
Medx - Vit D, calcium supplements, Bisphosphonates, hormone replacement therapy
Fall prevention
Surgery for fractures / hip replacements etc.
What causes Paget’s disease? (cells)
Overactive osteoclasts increase resorption leading to bone destruction
How do osteoblasts respond to overactive osteoclasts?
Become active and secrete bone which is larger and weaker than normal - leading to bone deformities and fractures
Most commonly affected sites in Paget’s disease?
Pelvis
Spine
Oral relevance of Paget’s disease?
- Dull bone pain, avoid lengthy procedures
- Enlarged mandible and maxillae -can make restorative / pros work challenging
- Hypercementosis - PDL ossified makes XLA hard
Which pts is Paget’s disease commonly seen in?
Over 50 years
(Breast cancer, Paget’s of the nipple, unrelated!!)
Tx options for Paget’s?
Bisphosphonates
Analgesia
Physio
Walking aides
3 main types of Arthritis need to know?
Osteoarthritis
Ankylosing spondylitis
Rheumatoid arthritis
What is osteoarthritis?
Wear and tear degeneration of joints
Low level of chronic inflammation
Where is affected by osteoarthritis?
Large weight bearing joints e.g. hips, knees
Wrists can be affected
Clinical effects of primary osteoarthritis?
Synovial softening
Tearing of cartilage
Bone cysts
Bony spurs / osteophytes in the joint
When does secondary osteoarthritis develop?
Post trauma
Alongside Paget’s / osteoporosis / ankylosing spondylitis
What is the classical history of osteoarthritis?
Pain and stiffness after movement / using a joint
Non inflammatory swelling of joints
Management of osteoarthritis
- Pt education
- Weight loss
- Physio and walking aides
- Analgesia - topical NSAIDs
- Corticosteroid injections (intra articular for single joints, intra muscular for widespread)
- Glucosamine supplement
- Surgery
Types of surgery available for osteoarthritis (4)
- Arthrocentesis (visualise joint space and washing out / remove osteophytes)
- Osteotomy (remove bony deformity)
- Arthrodesis (surgical fusion of unstable joint)
- Total joint replacement
Define Rheumatoid Arthritis
Multi-system inflammatory condition
What and who does RA affect?
Multiple small joints in extremities e.g. hands and feet
Younger pts under 40
What are the classical signs of inflammation?
Heat
Pain
Redness
Swelling
Loss of function
Key differences between OA and RA? (3)
- RA early morning stiffness / OA stiffness after long periods activity
- RA under 40s / OA increasing age
- RA inflammatory / OA non inflammatory
Systemic effects of RA?
- Ophthalmological
- Neurological
- Pulmonary
- Haematological
- Renal
- Dermatological
- Gastrointestinal
- Musculoskeletal
Define ankylosing spondylitis
Chronic inflammatory arthritis
Who and what does ankylosing spondylitis effect?
Young males
Neck and spine
What is AS initially characterised by?
Sacroiliitis - inflammation at sacra-iliac joints where pelvis joins spine
What are the later impacts of AS?
Vertebrae of spine become fused
Fixed deformity at the neck
How should you support a pt with AS in practice?
- Neck support with pillows
- Shorter appt. for comfort
What is the main difference between OA and RA versus AS?
In AS distal / peripheral joints of body are uncommonly affected
What commonly happens with pts who have an auto immune disease?
Accumulate further AI disease
Adverse effects of systemic corticosteroid use?
- Mood disturbances
- Insomnia
- Anxiety
- Depression
- Psychosis
- Cataracts
- Glaucoma
- Hypertension
- Accelerated atherosclerosis
- Lymphocytosis
- Neutrophilia
- Osteoporosis
- Increased fracture risk
- Muscle wasting
- Atrophy of the skin
- Bruising of skin
- Impaired wound healing
- Acne
- GI bleeding
- Gastritis
- Pancreatitis
- Obesity
- Diabetes
- Infertility
- Infection susceptibility
- Delayed growth children
- Increased appetite
- Nightmares
- Fluid retention
