Musculoskeletal Pathology Flashcards
non neoplastic msk conditions
connective tissue diseases
metabolic diseases
fractures
degenerative diseases
connective tissue disorders
autoimmune conditions
inflammatory diseases characterised by the presence of autoantibodies
often present with MSK symptoms/signs
how can autoimmune disorders be diagnosed
by their autoantibodies
some conditions have a strong association with autoantibodies whereas some do not
what is Rheumatoid arthritis
inflammation of joints autoimmune basis -rheumatoic factor -auto antibodies agains Fc IgE can ne systemic - absence of joint disease - many manifestations
histology of rheumatoid arthritis
lots of plasma cells
lots of inflammatory cells
what is pannus
inflammatory granulation tissue formed in the acute phase of rheumatoid arthritis
associated with destructive changes in the joint
what happens in acute phase of rheumatoid arthritic
pannus formation
hyper plastic/reactive synovial
chronic rheumatoid arthritis
cartilage is destroyed causing loss of joint space
fibrosis, deformity
SLE (systemic lupus)
systemic autoimmune condition
autoantibodies are directed at structural parts of DNA
two main autoantibodies found in SLE
ANA
anti double stranded DNA
acute features of inflammatory arthrides
odema, fibrin, reactive features in synovial cells
3 metabolic bone diseases
pagets (cellular remodelling and deformity of bones) osteomalacia (vit D metabolism abnormalities causing bone softening) crystal arthropathies (accumulation of crystals in joints)
An example of crystal arthropathy
gout
what is gout
ureate crystals in joint space
what is pseudo gout
calcium pyrophosphate crystals in joint space
how are ureate crystals formed
uric acid is the end product of purine synthesis
adenine and guanine are purine based
therefore ureate is formed in DNA replication
What is hyperuricaemia
increased production or reduced excretion of ureate
what causes hyperuricaemia
usually idiopathic sometimes enzyme defect -HGPRT Increased cell turn over -psoriasis -cancer (tumour lysis following chemo)
what is the most common cause of gout
under excretion of ureate
often a drug side affects (thiazide diuretics)
how do the ureate crystals end up in the joints
precipitation of crystals due to reduce solubility of ureate
unclear how they end up in joints
clinical manifestations of gout
cause secondary degenerative changes in joint
deposition in soft tissue
renal disease
what are the pathological findings in gout/ investigation
cytology - joint fluid examined under cross polarised light to detect needle shaped crystals
Histology of gout
amorphous eosinophilic debris and inflammation (giant cells)
crystals lost during tissue processing
looks similar to pryophosphate form
what is pseudo gout
calcium pyrophosphate
usually seen in older individuals in the large joints
pseudo gout symptoms
usually asymptomatic
incidental finding on x-ray
range of joint pain, acute, chronic ect.
crystals aren’t distinct histologically
what is Paget’s disease
abnormality of bone turn over
increase osteoclastic activity
more bone but the bone isn’t normally structured so patients develop fracture with minor trauma
whats a cause/sign of pagets disease
alk phos levels high in isolation
viral infections that can cause pagets disease
paramyxovirus, measles, RSV
what are then 3 stages of pagets disease
osteolytic
mixed
burned out
leads to thick excess bone with abnormal reversal lines- mosaic pattern
signs of pagets disease
pain - micro fracture or nerve compression
enlargement and abnormal shape of bones
increased metabolism (heat, warm skin, AV shunt, high output heart failure)
secondary malignancy -osteosarcoma
what are the initial phases of a fracture
haematoma - fibrin mesh
influx of inflam cells
cytokine release
after week 1- callus, organised haematoma, early recruitment and remodelling at ends of bone
1-3 weeks after fracture
maximum girth of callus
causes for delayed fracture healing
poor blood supply
poor nutrition
too much movement
too great a distance ect.
causes of pathological fracture
osteoporosis
tumours
benign or malignant
what is avascular necrosis
bone infarction
accounts for 10% of hip replacements
often asymptomatic until bone collapses
causes for avascular necrosis
trauma alcohol dysbarism steroid injection sickle cell disease infection
what does avascular necrosis look like
usually wedge shaped infarct, often subcortical
histology - creeping substitution - new bone growing over old bone, seen in healing phase
example of degenerative joint disease e
osteoarthritis
what causes degenerative joint disease
mechanical injury can be secondary if load if abnormally distributed, previous fracture or anatomical abnormality
degenerative joint disease histologically
not smooth cartilage, vertical cracks, roughing and fibrillation of the joint surface
sometimes subchondral cyst formation
osteophytes
