Bone and rheumatology Flashcards
describe the two types of resorptions we get in the tooth
internal and external resorption
how can we tell the difference between internal and external resorption
internal = radiolucency is in continum with the canal
externa - radiolucnecy superimposed on the canal
explain the structure of a bone
outer layer = periosteum = vascular CT
outer bone = dense, cortical bone
inner bone = trabecular, less dense
inner space = medulla = bone marrow and site of haemapoeisis
what are the functions of bone (3)
Mineral homeostasis = calcium and phosphate
Houses haemopoietic system
i.e. the bone marrow
Mechanical
Not a static scaffold - constantly remodelled
when might we get haematopoeisis in other sites
if there is dysfunction of bone haematopoiesis, pathology
occurs in spleen = not good
what cells would we see histologically of a remodelling site
osteocytes within matrix = calcified osteoblasts
small osteoblasts on margins
large osteoclasts
a pt has blue tinted sclera, what is this a sign of
osteogenesis imperfecta
what causes osteogenesis imperfecta and what does it affect
collagen 1 mutation
affects most tissues, ears, eyes (blue sclera), bone, teeth
what is achondroplasia
Autosomal dominant
Failure of cartilage maturation at the growth plate
Caused by a mutation of fibroblast growth receptor receptor 3 which causes it to be continually activated (it is a negative regulator of bone growth)
where is the mutaiton in pts with achondroplasia
FGR3 fibroblast growth receptor 3
what is rickets
disorder of bone mineralization
Caused by deficiency in vitamin D or calcium
Can be dietary or metabolic
Failure to mineralise -
>cartilage overgrowth,
failure of longitudinal growth
In the growing skeleton causes rickets due to failure of mineralization of growth plate cartilage
In the mature skeleton, causes bone fragility
what can cause rickets
vitamin D or calcium deficiency = dietary
metabolic = increased blood calcium and bone resorption
what is osteoporosis
Increased porosity of bone due to a reduction in bone mass
what can cause osteoporosis
Age
Hormonal influences
Lifestyle (smoking, alcohol)
Activity = +ve
Genetics
Nutrition (including malabsorption)
why does age affect osteoporosis
Sex steroids maintain mass of bone in adulthood, when women go through menopause, there is a sharp decline of oestrogen causing osteoclast activity to increase
what two main types of bone fracture are there
fragility = due to weakened bone under normal stress
pathological = due to tumour press
what bone is lost first in osteoporosis and why is this relevent
trabecular bone
bones with thin cortical bone and high trabecular bone degrade quickly and become very weak e.g. femoral neck
where are we likely to get fragility fractures with osteoporosis and why
vertebrae, femoral neck, distal radius
low cortical bone : trabecular bone
trabecular bon resorbs first so with little cortical bone = fracture
give three ways we coud possibly treat osteoporosis
bisphosphonates that kill osteoclasts = MRONJ risk
monoclonal antibodies against cytokines e.g. RANK-L
Increase bone formation (experimental treatments, e.g. parathyroid hormone)
what are the three complications of osteoporosis
Fragility fractures (vertebrae, femoral neck, distal radius)
Kyphosis (dowager’s hump)
Loss of height
what is Kyphosis
dowagers hump
hunchbacked appearance of the neck caused by osteoporosis which leads to reduced height
if a pt seems to be getting deformation and resorption of particular bones, what is the likely cause
Pagets Syndrome
what is and what causes Pagets Disease
Cause unknown but there appears to be a genetic component
Characterised by increased bone resorption and poorly- controlled bone formation
what is osteomyelitis
infection of the bone
that can cause necrosis and become blood borne causing sepsis